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Departement Industriële wetenschappen en technologie Opleiding luchtvaart Afstudeerrichting luchtvaarttechnologie Assessment of the feasibility of instrumental operations in Seville Airport (Spain) Eindwerk aangeboden tot het behalen van het diploma van bachelor in de luchtvaart door Wim Van Hemelrijk o.l.v. Ivan Becuwe, KHBO Luis Pérez Sanz, E.U.I.T. Aeronáutica Academiejaar 2006 - 2007 talent@work KHBO Campus Oostende ● Zeedijk 101 ● B-8400 Oostende ● Tel. +32 59 56 90 00 ● Fax +32 59 56 90 01 ● www.khbo.be Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ Announcements This final project was an exam; the during the representation detected mistakes are not corrected. Use as reference in publications is permitted after affirmative advise of the KHBO- promoter, mentioned on the title page. ___________________________________________________________________________ Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ Preface This final project was realized during a Socrates-Erasmus exchange program at the Escuela Universitaria de Ingeniería Técnica Aeronautica (EUITA), Madrid, Spain. I would like to take this opportunity to thank all the people who supported or helped me during this exchange program. First of all I want to thank my coordinator señor Luis Perez Sanz for explaining us everything with great patience. He was not only a great support during the realization of this final project, he also helped us very well with all the other problems we had. Furthermore I would like to thank señor Holgado as our Erasmus coordinator. He gave us a warm welcome at the school and took care of all paperwork without complaints. Also the people from the documentation centre at the AENA headquarters helped us very well. First of all by letting us in and secondly by giving us the information we needed. I also would like to thank all the people from the KHBO who made this Erasmus exchange program possible. Especially I would like to thank Mr. Roland Defever as head of faculty aeronautics and Mr. Becuwe as my second coordinator. Of course I can not forget to thank my family, who allowed me to study abroad and were of great support during these four and a half months in Spain. Special thanks also go to my friends for keeping in touch during the period I was away. Wim Van Hemelrijk ___________________________________________________________________________ Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ Abstract The subject of my final project is to assess the feasibility of instrumental operations at Seville Airport (Spain). I will define the operational requirements to be met by Seville airport and specify the assessment of the aerodrome obstacle and radio-electrical surfaces. Furthermore, I will verify the feasibility of designing instrument approach and departure procedures for both runways. All this will be explained by means of charts drawn in AutoCAD. De opdracht bestaat erin de haalbaarheid van instrumental operations op Seville Airport (Spanje) te beoordelen. Ik zal de operational requirements die door Seville Airport behaald moeten worden bepalen en de luchthaven obstakel en radio-elektrische oppervlaktes beoordelen. Verder zal ik de haalbaarheid van het ontwerpen van instrumental approach en departure procedures bepalen. Dit alles zal uitgelegd worden aan de hand van kaarten die getekend zijn in AutoCAD. ___________________________________________________________________________ 4 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ Index Announcements Preface Abstract.......................................................................................................................................4 Index ...........................................................................................................................................5 List of Figure ............................................................................................................................11 List of Tables ............................................................................................................................15 List of abbreviations ................................................................................................................16 Introduction ..............................................................................................................................19 1 Preliminary concepts .............................................................................................................20 1.1 Seville Airport ................................................................................................................20 1.1.1 Introduction .............................................................................................................20 1.1.2 Environment ............................................................................................................21 1.1.3 History of Seville Airport ........................................................................................22 1.1.4 Technical Information of Seville Airport ................................................................24 1.1.4.1 General .............................................................................................................24 1.2 Aerodrome Operation and Airspace ...............................................................................26 1.2.1 ICAO Airspace Classification .................................................................................26 1.2.2 Operation Classification: VFR and IFR-flights.......................................................28 1.2.2.1 General: VFR and IFR......................................................................................28 1.2.2.2 Visual flight rules .............................................................................................32 1.2.2.3 Instrument flight rules ......................................................................................33 1.2.3 Aerodrome Airspace................................................................................................36 1.2.3.1 Introduction: airspace around the aerodrome ...................................................36 1.2.3.2 Structure of the airspace ...................................................................................37 1.3 Navigation Aids..............................................................................................................39 1.3.1 Non-Directional Beacons ........................................................................................39 1.3.1.1 Evolution of the NDB.......................................................................................39 1.3.1.2 Role of the NDB ...............................................................................................39 1.3.1.3 Operating principle ...........................................................................................40 1.3.2 Distance measuring equipment................................................................................40 1.3.2.1 Role of the DME ..............................................................................................40 1.3.2.2 Operating principle ...........................................................................................41 1.3.3. VHF Omni directional Beacon ...............................................................................42 1.3.3.1 VOR evolution..................................................................................................42 1.3.3.2 VOR operating principle ..................................................................................44 1.3.4 Instrument Landing System.....................................................................................45 1.3.4.1 ILS Evolution ...................................................................................................45 1.3.4.2 Role of the ILS .................................................................................................45 1.3.4.3 Operating Principle of ILS ...............................................................................46 1.3 4.4 Operating principle of MLS .............................................................................47 1.3.5 Inertial Navigation System ......................................................................................48 1.3.5.1 Role of INS.......................................................................................................48 1.3.5.2 Operating Principles of INS .............................................................................48 1.4 Aeronautical Charts ........................................................................................................49 1.4.1 Coordinate system ...................................................................................................49 ___________________________________________________________________________ 5 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ 1.4.1.1 WSG84 .............................................................................................................49 1.4.1.2 UMT coordinates..............................................................................................50 1.4.2 Aerodrome Obstacle Chart – Type A ......................................................................51 1.4.3 Standard Instrument Departure Chart......................................................................52 1.4.4 Standard Instrument Arrival Chart ..........................................................................55 2 Operational requirements ......................................................................................................57 2.1 General description.........................................................................................................57 2.1.1 Design of procedures ...............................................................................................57 2.1.2 Navaids ....................................................................................................................58 2.1.3 Meteo.......................................................................................................................58 2.1.3.1 Winds................................................................................................................58 2.1.3.2 Visibility ...........................................................................................................60 2.1.3.3 Inflight visibility ...............................................................................................61 2.1.3.4 Runway visual range ........................................................................................62 2.1.3.5 Cloud classification ..........................................................................................64 2.1.3.6 Wind shear........................................................................................................64 2.2 Application to Seville Airport ........................................................................................67 2.2.1 Navaids ....................................................................................................................67 2.2.2 Noise abatement procedure .....................................................................................67 2.2.3 Speed limits .............................................................................................................67 2.2.4 Low Visibility Procedures .......................................................................................68 2.2.4.1 General .............................................................................................................68 2.2.4.2 Ground movement ............................................................................................68 2.2.4.3 Communications failure ...................................................................................69 2.2.5 Meteo.......................................................................................................................69 2.2.5.1 General data......................................................................................................69 2.2.5.2 Wind .................................................................................................................70 2.2.5.3 Visibility ...........................................................................................................71 2.2.5.4 Clouds...............................................................................................................72 2.2.5.5 Wind shear........................................................................................................73 2.2.6 Flow .........................................................................................................................73 2.2.6.1 Commercial flights ...........................................................................................74 2.2.6.2 General aviation................................................................................................74 3 Aerodrome Obstacle Limitation ............................................................................................75 3.1 Aerodrome Obstacle Surfaces ........................................................................................75 3.1.1 Runway classification according to operation.........................................................75 3.1.2 Types of surfaces .....................................................................................................76 3.1.3 Surface description ..................................................................................................76 3.1.3.1 Runway strip.....................................................................................................76 3.1.3.2 Approach surface..............................................................................................76 3.1.3.3 Transitional surface ..........................................................................................77 3.1.3.4 Inner horizontal surface ....................................................................................77 3.1.3.5 Conical..............................................................................................................77 3.1.3.6 Outer horizontal surface ...................................................................................78 3.1.3.7 Take-off climb surface......................................................................................78 3.1.3.8 Obstacle free zone ............................................................................................79 3.2 Aerodrome Obstacle Restriction and Removal ..............................................................81 ___________________________________________________________________________ 6 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ 3.2.1 Obstacle Limitation .................................................................................................81 3.2.1.1 Conical Surface ................................................................................................81 3.2.1.2 Inner Horizontal Surface ..................................................................................81 3.2.1.3 Approach Surface .............................................................................................82 3.2.1.4 Inner approach surface......................................................................................82 3.2.1.5 Transitional surface ..........................................................................................83 3.2.1.6 Inner transitional surface ..................................................................................85 3.2.1.7 Balked landing surface .....................................................................................85 3.2.1.8 Take-off climb surface......................................................................................86 3.2.2 Obstacle limitation requirements.............................................................................87 3.2.2.1 Non-instrument runways ..................................................................................87 3.2.2.2 Non-precision approach runways .....................................................................88 3.2.2.3 Precision approach runways .............................................................................89 3.2.2.4 Runways meant for take-off .............................................................................91 3.2.3 Objects outside the obstacle limitation surfaces......................................................92 3.2.4 Other objects............................................................................................................92 3.3 Application to Seville Airport ........................................................................................94 3.3.1 General ....................................................................................................................94 3.3.2 Calculations of coordinates from WSG84 to UTM.................................................95 3.3.3 Calculation of the surfaces ......................................................................................95 3.3.3.1 Conical Surface ................................................................................................96 3.3.3.2 Inner Horizontal................................................................................................96 3.3.3.3 Approach Surface .............................................................................................96 3.3.3.4 Inner Approach surface ....................................................................................97 3.3.3.5 Transitional surface ..........................................................................................97 3.3.3.6 Inner Transitional .............................................................................................97 3.3.3.7 Balked Landing surface ....................................................................................98 3.3.3.8 Take-off climb surface......................................................................................98 3.3.3.9 Strip .................................................................................................................. 99 3.4 Obstacle assessment .....................................................................................................100 4 Building restricted areas ......................................................................................................101 4.1 Introduction ..................................................................................................................101 4.2 Scope ............................................................................................................................101 4.3 Definitions ....................................................................................................................102 4.3.1 Building .................................................................................................................102 4.3.2 Building Restricted Area (BRA) ...........................................................................102 4.4 General procedure.........................................................................................................103 4.4.1 Definitions and explanation applicable to Figure 4-1 ...........................................103 4.4.1.1 Step 1 ..............................................................................................................103 4.4.1.2 Step 2 ..............................................................................................................104 4.5 Details of the two-step process.....................................................................................105 4.5.1 Step 1 .....................................................................................................................105 4.5.2 Step 2 .....................................................................................................................105 4.6 Transition to the future ATM system planning ............................................................106 4.7 BRA for directional facilities .......................................................................................108 4.8 General notes for omni-directional and directional facilities .......................................109 4.9 Application to Seville Airport ......................................................................................110 4.9.1 ILS .........................................................................................................................110 ___________________________________________________________________________ 7 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ 4.9.2 NDB.......................................................................................................................111 4.9.3 DME/N ..................................................................................................................111 4.9.4 VOR.......................................................................................................................111 5 Instrument Approach Procedures ........................................................................................112 5.1 General .........................................................................................................................112 5.1.1 Introduction ...........................................................................................................112 5.1.1.1 Scope ..............................................................................................................112 5.1.1.2 Procedure construction ...................................................................................112 5.1.1.3 Fix names........................................................................................................112 5.1.1.4 segment application ........................................................................................112 5.1.1.5 Areas...............................................................................................................113 5.1.1.6 Obstacle clearance ..........................................................................................114 5.1.1.7 Track guidance ...............................................................................................115 5.1.1.8 Vertical guidance............................................................................................115 5.1.1.9 Categories of aircraft ......................................................................................116 5.1.1.10 Bearings, tracks and radials ..........................................................................117 5.1.1.11 Navigation system use accuracy...................................................................118 5.1.1.12 increased altitudes/heights for mountainous areas .......................................118 5.1.1.13 Charting accuracy .........................................................................................119 5.1.1.14 Descent gradients..........................................................................................119 5.1.2 Terminal area fixes ................................................................................................119 5.1.2.1 General ...........................................................................................................119 5.1.2.2 Terminal area fixes .........................................................................................120 5.1.2.3 Tolerance and fix tolerance area for intersecting fixes...................................121 5.1.2.4 Fix tolerance for other types of navigation instruments .................................123 5.1.2.5 Fix tolerance overheading a station ................................................................125 5.1.2.6 operational application of fixes for flight procedures planning .....................127 5.1.2.7 Use of fixes for descent and related obstacle clearance .................................128 5.1.2.8 Protection area for VOR and NDB.................................................................131 5.1.3 Arrival segment .....................................................................................................132 5.1.3.1 standard instrument arrivals............................................................................132 5.1.3.2 Omnidirectional or sector arrivals ..................................................................138 5.1.4 Initial approach segment........................................................................................138 5.1.4.1 General ...........................................................................................................138 5.1.4.2 Altitude selection............................................................................................139 5.1.4.3 Initial approach segments utilizing straight tracks and DME arcs .................140 5.1.4.4 Initial approach segment using a racetrack procedure....................................143 5.1.4.5 Initial approach segment using a reversal procedure......................................144 5.1.4.6 Racetrack and reversal procedure areas..........................................................149 5.1.4.7 Maximum descent/nominal outbound timing relationship for a reversal or racetrack procedure.....................................................................................................153 5.1.4.8 Obstacle clearance ..........................................................................................153 5.1.4.9 Protection area of racetrack and holding procedures......................................153 5.1.5 Intermediate approach segment .............................................................................163 5.1.5.1 General ...........................................................................................................163 5.1.5.2 Altitude/height selection.................................................................................164 5.1.5.3 Intermediate approach segment based on a straight track alignment .............164 5.1.5.4 Intermediate segment within a reversal or racetrack procedure .....................166 ___________________________________________________________________________ 8 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ 5.1.6 Final approach segment .........................................................................................168 5.1.6.1 General ...........................................................................................................168 5.1.6.2 alignment ........................................................................................................168 5.1.6.3 descent gradient ..............................................................................................170 5.1.6.4 obstacle clearance altitude/height (OCA/H)...................................................172 5.1.6.5 promulgation...................................................................................................179 5.1.7 Missed approach segment......................................................................................180 5.1.7.1 General ...........................................................................................................180 5.1.7.2 Climb gradient and MOC ...............................................................................186 5.1.7.3 Straight missed approach................................................................................188 5.1.7.4 Turning missed approach ...............................................................................192 5.1.7.5 Promulgation ..................................................................................................204 5.1.8 Visual manoeuvring (circling) area .......................................................................205 5.1.8.1 Defenition of terms.........................................................................................205 5.1.8.2 Alignment and area.........................................................................................206 5.1.8.3 Obstacle clearance ..........................................................................................207 5.1.8.4 Method for reducing OCA/H..........................................................................208 5.1.8.5 Missed approach associated with the visual manoeuvre ................................209 5.1.8.6 promulgation...................................................................................................209 5.1.9 Minimum sector altitudes (MSA)..........................................................................210 5.1.9.1 Obstacles in buffer area ..................................................................................210 5.1.9.2 Sector orientation............................................................................................210 5.1.9.3 Combining sectors for adjacent facilities .......................................................210 5.1.9.4 Sectors centred on a VOR/DME or NDB/DME.............................................211 5.1.10 ILS .......................................................................................................................212 5.1.10.1 Introduction ..................................................................................................212 5.1.10.2 Initial approach segment...............................................................................215 5.1.10.3 Intermediate approach segment ....................................................................216 5.1.10.4 Precision segment .........................................................................................221 5.1.10.5 Missed approach segment.............................................................................238 5.1.10.6 Simultaneous precision approaches to parallel or near-parallel instrument runways.......................................................................................................................245 5.1.10.7 Promulgation ................................................................................................245 5.2 Application to Seville Airport ......................................................................................248 5.2.1 Non-precision approach.........................................................................................248 5.2.1.1 Initial approach segment.................................................................................248 5.2.1.2 Intermediate approach segment ......................................................................252 5.2.1.3 Final approach segment ..................................................................................253 5.2.1.4 Missed approach segment...............................................................................254 5.2.2 Precision approach.................................................................................................257 5.2.2.1 Initial Approach Segment...............................................................................257 5.2.2.2 Intermediate Approach Segment ....................................................................257 5.2.2.3 Precision Segment ..........................................................................................258 5.2.2.4 Missed Approach after the Precision segment ...............................................260 6 Standard Departure Procedure.............................................................................................262 6.1 General .........................................................................................................................262 6.1.1 Introduction to departure procedures.....................................................................262 6.1.1.1 Consultation....................................................................................................262 ___________________________________________________________________________ 9 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ 6.1.1.2 Standardization ...............................................................................................262 6.1.1.3 Economy.........................................................................................................262 6.1.1.4 Routes .............................................................................................................262 6.1.1.5 Related material..............................................................................................262 6.1.1.6 Abnormal and emergency operations .............................................................263 6.1.2 General concepts for departure procedures ...........................................................263 6.1.2.1 Establishment of a departure procedure .........................................................263 6.1.2.2 Design principles ............................................................................................263 6.1.2.3 Beginning of the departure procedure ............................................................264 6.1.2.4 End of the departure procedure ......................................................................265 6.1.2.5 Minimum obstacle clearance (MOC) .............................................................265 6.1.2.6 Obstacle identification surface (OIS) .............................................................265 6.1.2.7 Procedure design gradient (PDG)...................................................................266 6.1.2.8 Average flight path .........................................................................................266 6.1.2.9 Charting accuracy ...........................................................................................267 6.1.2.10 Additional specific height/distance information...........................................268 6.1.3 Departure routes ....................................................................................................268 6.1.3.1 General ...........................................................................................................268 6.1.3.2 Straight departures..........................................................................................268 6.1.3.3 Turning parameters.........................................................................................272 6.2 Application to Seville Airport ......................................................................................282 6.2.1 General purpose.....................................................................................................282 6.2.2 The design of routes to reporting points................................................................283 6.2.2.1 Runway 09......................................................................................................283 6.2.2.2 Runway 27......................................................................................................285 6.2.3 The design of routes to navigation facilities..........................................................287 6.2.3.1 Runway 09......................................................................................................287 6.2.3.2 Runway 27......................................................................................................288 6.2.4 Notes applicable to the SID’s ................................................................................290 6.2.4.1 Runway 09......................................................................................................290 6.2.4.2 Runway 27......................................................................................................291 Conclusion..............................................................................................................................293 Index appendices ....................................................................................................................294 Appendix A – Obstacle limitation surfaces (OLS).....................................................295 Appendix B – Aerodrome obstacle charts (OAC) ICAO type A ...............................299 Appendix C – Instrument approach charts (IAC) RWY 27 .......................................301 Appendix D – Instrument approach charts (IAC) RWY 27 with protection areas.....303 Appendix E – Standard instrument departure charts (SID).......................................305 Biblography ............................................................................................................................307 ___________________________________________________________________________ 10 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ List of figures Figure 1.1.- Seville Airport ......................................................................................................24 Figure 1.2.- VMC minima controlled airspace .......................................................................31 Figure 1.3.- VMC minima uncontrolled airspace ....................................................................32 Figure 1.4.- Flight phases .......................................................................................................36 Figure 1.5.- Structure of the airspace ......................................................................................38 Figure 1.6.- ADF indicator instrument ....................................................................................39 Figure 1.7.- RMI indicator .......................................................................................................40 Figure 1.8.- The MLS (Microwave Landing System) coverage in diagram form ....................41 Figure 1.9.- DME principle......................................................................................................42 Figure 1.10.- VOR radials.......................................................................................................44 Figure 1.11.- The Horizontal Situation Indicator ....................................................................45 Figure 1.12.- Instrument Landing System ................................................................................46 Figure 1.13.- Coverage volume of the azimuth station ............................................................47 Figure 1.14.- The WSG84 coordinate system definition ..........................................................50 Figure 1.15.- The UMT grid.....................................................................................................51 Figure 2.1.- Sea breeze.............................................................................................................59 Figure 2.2.- Reduction in visibility with reduction in height....................................................61 Figure 2.3.- (A) Visibility after turning on a normal approach (B) Visibility with a modified approach path...........................................................................................................................62 Figure 2.4.- Areas of wind shear associated with an approach path through a warm and cold front ..........................................................................................................................................66 Figure 2.5.- Frequency of velocity and direction of wind for the month of July......................70 Figure 2.6.- Frequency of velocity and direction of wind for the month of January ...............71 Figure 2.7.- Frequency (%) of the intervals with visibility lower than 800, 1 500, 3 000 and 5 000 m – January (1983-1992) ..................................................................................................71 Figure 2.8.- Frequency (%) of the intervals with visibility lower than 800, 1 500, 3 000 and 5 000 m – July (1983-1992).........................................................................................................72 Figure 2.9.- Frequency (%) of base of clouds lower than 30, 60, 150 and 300 m – january (1983-2001) ..............................................................................................................................72 Figure 2.10.- Frequency (%) of base of clouds lower than 30, 60, 150 and 300 m – july (19832001).........................................................................................................................................73 Figure 2.11.- Mean frequency (%) of the intervals of the components of the wind perpendicular to the runway (1983-1992) ...............................................................................73 Figure 3.1- Obstacle limitation surfaces.................................................................................83 Figure 3.2- Inner approach, inner transitional and balked landing surfaces.........................84 Figure 3.3- Obstacle Limitation Surfaces ................................................................................93 Figure 3.4- Runway profile ......................................................................................................95 Figure 3.5- Vertical path of the approach surface - RWY 27 ..................................................97 Figure 4.1- Guidance review process ....................................................................................103 Figure 4.2- Omni directional BRA shape...............................................................................107 Figure 4.3- Directional facilities shape .................................................................................109 Figure 4.4- Directional facilities perspective.........................................................................109 Figure 4.5- ILS LLZ shape .....................................................................................................110 Figure 4.6- NDB shape...........................................................................................................111 Figure 4.7- DME shape ..........................................................................................................111 Figure 4.8- VOR shape...........................................................................................................111 ___________________________________________________________________________ 11 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ Figure 5.1- Segments of instrument approach .......................................................................114 Figure 5.2- Cross-section of straight segment area showing primary and secondary areas 114 Figure 5.3.- Intersection fix tolerance areas..........................................................................120 Figure 5.4.- Final approach fix (FAF) tolerance...................................................................122 Figure 5.5.- Fix tolerance in the intermediate approach segment.........................................123 Figure 5.6.- ILS or “Z” marker coverage ..............................................................................125 Figure 5.7.- Fix area tolerance overhead a VOR...................................................................126 Figure 5.8.- Fix tolerance area overhead an NDB ................................................................127 Figure 5.9.- Assumed fix tolerance area for limiting bearing/radial or DME distance ........129 Figure 5.10.- Distance between fixes .....................................................................................129 Figure 5.11.- Area requiring obstacle clearance ...................................................................130 Figure 5.12.- Stepdown fix with dual OCA/H ........................................................................130 Figure 5.13.- Area where obstacles not need to be considered .............................................132 Figure 5.14.- Arrival segment – protection area (length of the arrival segment greater than or equal to 46 km (25 NM)) ........................................................................................................ 134 Figure 5.15.- Arrival segment – protection area (length of the arrival segment lessthan 46 km (25 NM)) .................................................................................................................................135 Figure 5.16.- DME arc – length of the arrival segment greater than or equal to 46 km (25 NM).........................................................................................................................................135 Figure 5.17.- arc – length of the arrival segment greater less than 46 km (25 NM) .............136 Figure 5.18.- GNSS arrival criteria, IAF beyond 30 NM ARP: 8 NM ½ AW prior to 30 NM from ARP then 5 NM ½ AW....................................................................................................137 Figure 5.19 .- arrival criteria, IAF within 30 NM ARP: 8 NM ½ AW prior to 30 NM from ARP then 5 NM ½ AW ............................................................................................................138 Figure 5.20.- Lead radial for turns greater than 70°.............................................................140 Figure 5.21.- Typical segments (plan view) ...........................................................................142 Figure 5.22.- Initial approach area utilizing straight tracks .................................................142 Figure 5.23.- Entry to procedure turn....................................................................................145 Figure 5.24.- Entry to base turn .............................................................................................146 Figure 5.25.- Example of omnidirectional arrival using a holding procedure in association with a reversal procedure.......................................................................................................146 Figure 5.26.- Types of reversal and racetrack procedures ....................................................148 Figure 5.27.- Application of flight technical tolerance ..........................................................151 Figure 5.28.- Holding/racetrack template with associated construction points ....................158 Figure 5.29.- Holding template ..............................................................................................158 Figure 5.30.- VOR position fix tolerance area.......................................................................159 Figure 5.31.- Construction of the basic area .........................................................................161 Figure 5.32.- Construction of the entry area..........................................................................162 Figure 5.33.- Construction of the entry area; the axis of the template making an angle of 70° with the procedure axis ..........................................................................................................163 Figure 5.34.- Basic area with omnidirectional entry areas ...................................................163 Figure 5.35.- Intermediate approach area within reversal or racetrack procedure with a fix ................................................................................................................................................166 Figure 5.36.- Intermediate approach area within reversal or racetrack procedure with no IF ................................................................................................................................................167 Figure 5.37.- Intermediate approach area within reversal or racetrack procedure based on FAF (not the facility) ..............................................................................................................168 Figure 5.38.- Final straight-in approach alignment ..............................................................169 ___________________________________________________________________________ 12 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ Figure 5.39.- Relationship of obstacle clearance altitude/height (OCA/H) to minimum decision altitude/height (DA/H) for precision approaches ....................................................173 Figure 5.40.- Relationship of obstacle clearance altitude/height (OCA/H) to minimum decision altitude/height (DA/H) for non-precision approaches .............................................174 Figure 5.41.- Relationship of obstacle clearance altitude/height (OCA/H) to decision altitude/height (DA/H) for visual manoeuvring .....................................................................175 Figure 5.42.- Obstacle clearance for final missed approach phase ......................................181 Figure 5.43.- Case where the extension of the missed approach surface covers the initial missed approach phase entirely .............................................................................................181 Figure 5.44.- Determing SOC with an MAPt defined by a naviagation facility or fix...........184 Figure 5.45.- Distance from nominal FAF to earliest and latest MAPt.................................184 Figure 5.46.- Determing SOC with an MAPt defined by a distance from the FAF ...............185 Figure 5.47.- Area for straight missed approach...................................................................189 Figure 5.48.- Area associated with additional track guidance for MAPt defined by a navigational facility................................................................................................................190 Figure 5.49.- Area associated with additional track guidance for MAPt not at a facility.....191 Figure 5.50.- Example of area where the track guidance for missed approach is a continuation of guidance from the facility used on the final approach..................................191 Figure 5.51.- Missed approach turn 15° or less at the MAPt ................................................192 Figure 5.52.- Turn less than 75° at an altitude ......................................................................196 Figure 5.53.- Turn more than 75° at an altitude....................................................................196 Figure 5.54.- Obstacle clearance within turn initiation.........................................................197 Figure 5.55.- Limitation of early turns – additional safeguarding requirement....................199 Figure 5.56.- Turning missed approach with DME as TP fix ................................................200 Figure 5.57.- 180° turning missed approach with DME as TP fix.........................................201 Figure 5.58.- Turning missed approach with TP fix and return to the facility with track back ................................................................................................................................................202 Figure 5.59.- Turning missed approach with TP fix and return to the facility without track back.........................................................................................................................................203 Figure 5.60.- Turning missed approach involving turns over a facility.................................204 Figure 5.61.- Missed approach turn more than 15° at the MAPt ..........................................205 Figure 5.62.- Construction of visual manoeuvring (circling) area........................................206 Figure 5.63.- Visual manoeuvring (circling) area .................................................................207 Figure 5.64.- Visual manoeuvring (circling) area – obstacle clearance ...............................208 Figure 5.65.-Visual manoeuvring (circling) area – prohibition on circling..........................209 Figure 5.66.- Sector orientation .............................................................................................211 Figure 5.67.- Case of VOR/DME subsectors delimited by a DME arc..................................212 Figure 5.68.- Interface – final approach/preceding segment perspective view .....................218 Figure 5.69.- Final approach fix defined by descent fix located at final approach point......219 Figure 5.70.- Precision segment with no final approach fix ..................................................220 Figure 5.71.- Intermediate approach area. ILS approach using reversal or racetrack procedure................................................................................................................................221 Figure 5.72.- Precision segment ............................................................................................222 Figure 5.73.- Illustration of basic ILS surfaces .....................................................................224 Figure 5.74.- System of coordinates.......................................................................................227 Figure 5.75.- Surface equations – basic ILS surfaces............................................................228 Figure 5.76.- Illustration of ILS obstacle assessment surfaces..............................................228 Figure 5.77.- Illustrations of ILS obstacle assessment surfaces – perspective view..............229 ___________________________________________________________________________ 13 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ Figure 5.78.- Typical OAS contours for standard size aircraft .............................................230 Figure 5.79.- Missed approach obstacle after range -900 m.................................................233 Figure 5.80.- Missed approach obstacle before range -900m ...............................................234 Figure 5.81.- Final segment of straight missed approach .....................................................239 Figure 5.82.- Straight missed approach obstacle clearance..................................................240 Figure 5.83.- Turn at a designated altitude............................................................................241 Figure 5.84.- Turn at a designated TP (with TP fix)..............................................................244 Figure 5.85.- Racetrack/holding template with associated construction points ....................251 Figure 5.86.- VOR Position fix tolerance area ......................................................................251 Figure 5.87.- Protection area and buffer of racetrack...........................................................252 Figure 5.88.- Turning Missed Approach Area .......................................................................256 Figure 5.89.- ILS OAS ............................................................................................................260 Figure 6.1.- Procedure design gradient .................................................................................266 Figure 6.2.- Close-in obstacles ..............................................................................................267 Figure 6.3.- Straight departure area without track guidance ................................................269 Figure 6.4.- Straight departure area with track adjustment (track adjustment point not specified).................................................................................................................................270 Figure 6.5.- Straight departure area with a specified track adjusment point ........................270 Figure 6.6.- Straight departure (facility ahead).....................................................................271 Figure 6.7.- Straight departure (facility behind)....................................................................271 Figure 6.8.- Straight departure with offset departure track (track parallel to runway heading) ................................................................................................................................................271 Figure 6.9.- Straight departure with offset departure track (track diverging from runway heading) ..................................................................................................................................272 Figure 6.10.- Straight departure with offset departure track (track crossing runway heading) ................................................................................................................................................272 Figure 6.11.- Turning departure – turn at an altitude ...........................................................276 Figure 6.12.- Turning departure – turn at an altitude ...........................................................277 Figure 6.13.- Turning departure not overheading a facility – turning point tolerance area defined by intersecting radial .................................................................................................279 Figure 6.14.- Turning point not defined by overheading a facility (or RNAV fix).................280 Figure 6.15.- Turning departure – turn at a fix .....................................................................281 Figure 6.16.- Turning departure – turn over a facility ..........................................................281 Figure 6.17.- Turning departure – turn at more than 90°......................................................279 Figure 6.18.- VOR/DME MRN as an alternative intersection ...............................................284 Figure 6.19.- Alternative to reach ROCIO and ONUBIA ......................................................284 Figure 6.20.- Alternative route to SANTA..............................................................................285 Figure 6.21.- Alternative route to ROCIO and ONUBA ........................................................286 Figure 6.22.- Alternative route to OLIVO, CORIA, CLANA..................................................287 Figure 6.23.- Alternative route to VEJER ..............................................................................289 Figure 6.24.- Alternative route to HINOJOSA.......................................................................289 Figure 6.25.- Alternative route to MARTÍN ...........................................................................290 ___________________________________________________________________________ 14 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ List of tables Table 1.1.- Development of domestic traffic.............................................................................20 Table 1.2.- ICAO Airport characteristics.................................................................................25 Table 1.3.- Runway physical characteristics............................................................................25 Table 1.4.- Declared distances .................................................................................................25 Table 1.5.- ICAO airspace classes ...........................................................................................27 Table 2.1.- Base height .............................................................................................................64 Table 2.2.- Navaids...................................................................................................................67 Table 2.3.- Climate summary (1971-2001) ..............................................................................70 Table 3.1- Reference keys from the aerodrome........................................................................75 Table 3.2- Types of obstacle limitation surfaces from the aerodrome .....................................76 Table 3.3- Dimensions and Slopes of Obstacle Limitation Surfaces – Approach Runways ...88 Table 3.4- Dimensions and slopes for obstacle limitation surfaces.........................................92 Table 3.5- Aerodrome geographical Data ...............................................................................94 Table 3.6- Runway physical characteristics.............................................................................94 Table 4.1- Harmonised guidance figures for the omni-directional navigational facilities...107 Table 4.2- Harmonised guidance figures for the directional navigational facilities .............108 Table 4.3- Guidance figures for the ILS LLZ facility .............................................................110 Table 5.1.- Speeds (IAS) for procedures calculations in kilometres per hour (km/h)............117 Table 5.2.- System use accuracy (2SD) of facility providing track guidance and facility not providing track guidance........................................................................................................122 Table 5.3.- Tolerance on which system use accuracies are based .........................................122 Table 5.4.- Total fix tolerance ................................................................................................123 Table 5.5.- Maximum descent to be specified on a reversal or racetrack procedure ............153 Table 5.6.- Calculations associated with the construction of the holding and racetrack template ..................................................................................................................................154 Table 5.7.- Minimum intermediate track length .....................................................................167 Table 5.8.- Lower limit on OCH.............................................................................................170 Table 5.9.- Rate of descent .....................................................................................................171 Table 5.10.- Distance from nominal MAPt to earliest and latest MAPt ................................183 Table 5.11.- Computation of transitional distance.................................................................186 Table 5.12.- MOC and OCA/H for visual manoeuvring (circling) approach ........................208 Table 5.13.- Maximum aircraft dimensions............................................................................213 Table 5.14.- Minimum distances between localizer and glide path interceptions .................217 Table 5.15.- Height loss/altimeter margin..............................................................................225 Table 5.16.- Objects which may be ignored in OCA/H calculations .....................................225 Table 5.17.- Height loss altimeter setting vs. speed ...............................................................236 Table 5.18.- Calculations associated with construction of racetrack and holding template 250 Table 5.19.- Turning Missed Approach area construction ....................................................256 Table 5.20.- OAS related dimensions .....................................................................................259 Table 5.21.- ILS OAS Constants & coordinates.....................................................................259 Table 5.22.- OCA/H................................................................................................................260 Table 5.23.- Turn Area Calculations......................................................................................261 ___________________________________________________________________________ 15 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ List of abbreviations ACAS ACC ACN AD ADF AGL AIP AIS AMSL AOC APP ARP ASL ATC ATM ATS ATSEP ATZ AWO BRA C CAT cm CNS CRM CSB CTA CTR CWY DA DDM DF DGNSS DH DIM DME e.g ELEV EMI FAF FAP FD FL ft GBAS GP HF i.e IAC IAF Airborne Collision And Avoidance System Area Control Centre Aircraft Classification Number Aerodrome Automitac Direction Finder Above Ground Level Aeronautical Information Publication Aeronautical Information Services Above Mean Sea Level Aerodrome Obstacle Chart Approach Aerodrome Reference Point Above Sea Level Air Traffic Control Air Traffic Management Air Traffic Services Air Traffic System Evaluation Program Aerodrome Transit Zone All Weather Operations Building Restricted Area Degree Celsius Category Centimetre Communication Navigation Surveillance Collision Risk Model Carrier And Side Bands Control Zones Control Zone Clearway Decision Altitude Difference In Depth Of Modulation Direction Finder Differential Global Navigation Satellite System Decision Height Dimension Distance Measuring Equipment Example Elevation Electromagnetic Interface Final Approach Fix Final Approach Point Flight Director Flight Level Foot Ground Based Augmentation System Glide Path High Frequency In Other Words Instrument Approach Chart Initial Approach Fix ___________________________________________________________________________ 16 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ IAS ICAO IF IFR IGN ILS IM IMC ISA K kg kHz km km/h kt LLZ m MAPt max MDA/ H MHz MLS MM mm MOC NDB NM NPA OAS OCA/H OES OFZ OLS OM P-RNAV PA PANS-OPS PAPI PSR RADAR RNAV RVR RWY Rx SBAS SID SSR STA STAR TAS THR Indicated Air Speed International Civil Aviation Organisation Intermediate Fix Instrument Flight Rules Instituto Geográfico Nacional Instrument Landing System Inner Marker Instrument Meteorological Conditions International Standard Atmosphere Degree Kelvin Kilogram Kilo Hertz Kilometre Kilometre Per Hour Knot Localizer Metre Missed Approach Point Maximum Minimum Descent Altitude / Height Mega Hertz Microwave Landing System Middle Marker Millimetre Minimum Obstacle Clearance Non Directional Beacon Nautical Mile Non – Precision Approach Obstacle Assessment Surfaces Obstacle Clearance Altitude/Height Obstacle Evaluation Surfaces Obstacle Free Zone Obstacle Limitation Surfaces Outer Marker Precision Area Navigation Precision Approach Procedures For Air Navigation Services – Aircraft Operations Precision Approach Path Indicator Primary Surveillance Radar Radio Detection And Ranging Area Navigation Runway Visual Range Runway Receiver Satellite Base Augmentation System Standard Instrument Departure Secondary Surveillance Radar Straight In Approach Standard Arrival Route True Airspeed Threshold ___________________________________________________________________________ 17 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ TMA TODA TORA TWR Tx UHF UTA UTC UTM VFR VHF VMC VOR WGS Terminal Control Area Take-Off Distance Available Take-Off Run Available Tower Transmitter Ultra High Frequency Upper Control Area Universal Time Conversion Universal Transverse Mercator Visual Flight Rules Very High Frequency Visual Meteorological Conditions VHF- Omnidirectional Range World Geodetic System ___________________________________________________________________________ 18 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ Introduction In the last 10 years the popularity of the low-cost carriers boomed immensely, creating a dazzling increase in passengers. This increase in the number of passengers logically resulted in an increase in flights and a denser air traffic. The higher number of flights had to be dealt with without excessive delays or jeopardizing the human safety; which has always been one of the keystones of air transport. To optimize air transport different steps have been taken. One of them was to deal with the overcrowded airways by switching from conventional navigation to RNAV. In the near future RNAV will be replaced by the newest way of navigation, RNP. Another major step was to increase the safety during the most critical phases, namely departure and arrival, and to keep the delays as low as possible. This was done by precisioninstrumental operations, which make the air transport a safe and well oiled machine. For precision-instrumental operations as well the plane as the aerodrome have to be compliant with the international requirements. This means, for an aerodrome, designing routes in which the plane can fly without encountering obstacles of any kind. The subject of my final project was to assess the feasibility of instrumental operations in Seville Airport. So I had to define the operational requirements to be met by the Seville airport and verify the feasibility of designing instrument approach and departure procedures at both runways. Furthermore I had to assess the aerodrome obstacle surfaces and the radio electric surfaces. Before starting with the design of the surfaces and procedures, I will define some preliminary concepts, necessary for the realization of this final project. ___________________________________________________________________________ 19 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ 1 Preliminary concepts 1.1 Seville Airport 1.1.1 Introduction Seville airport, situated ten kilometres northwest of the capital, embarked on its largest expansion in 1992. In preparation for the Universal Exhibition, the aircraft parking apron was extended and a new terminal was built, as well as a new access road from the National N-IV road and a new control tower to the south of the runway. The design was based on Seville's cultural roots, using three traditional components: the mosque, the palace and the orange trees. An orange grove greets the travellers upon their arrival at the airport before they enter a hall, coloured blue by the effect of the glazed roof tiles, and crowned by a line of arches supported by vaults. Though Seville airport does have some international traffic, it basically deals with domestic traffic, which represents 75 percent of the total. In 2006 a total of 3 870 600 passengers passed through the airport, which carried out 58 565 flight operations and dealt with 11 530 tonnes of cargo. Development of domestic traffic Year N° of passengers Year N° of passengers 1997 1 631 961 2002 2 042 068 1998 1 691 798 2003 2 269 565 1999 1 802 673 2004 2 678 595 2000 2 116 035 2005 3 521 112 2001 2 205 177 2006 3 870 600 Table 1.1.- Development of domestic traffic The mayor players at Seville Airport are: • Air Europa, • Air France, ___________________________________________________________________________ 20 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ • British Airways, • Corsair, • Iberia, • LTU International, • Swiss, • Transavia. Although Seville Airport is not a very big aerodrome, it can offer his clients a rather new range of facilities which includes: 32 check-in desks, 8 gates, 5 air bridges, 6 baggage claim belts, 660 short term parking spaces, 50 long term parking spaces, Bureau de Change, Auto Exchange Machine, Restaurants, Cafeterias, Bars, VIP Lounge, Duty Free Shop, Newsagent/Tobacconist, Chemist Shop, Gift Shop, Tourist Help Desk, Car Rental, Taxi Service/Rank, First Aid, Disabled Access/Facilities. Not only the passenger facilities are well developed, also the cargo handling is well equipped. To give an impression of the cargo handling capabilities, the following facilities are given: Bonded Warehouse, Domestic Cargo Only, EU Border Post, Mechanical Handling, Air-Conditioned Storage, Refrigerated Storage, Animal Quarantine, Fresh Meat Inspection, Livestock Handling, Health Officials, X-Ray Equipment, Express/Courier Centre, Handling Equipment: All 1.1.2 Environment The Seville Airport has committed with the public to ensure that airport activity and development is compatible with and respects its surroundings and the environment. To obtain real benefits –for the environment, the public and the airport– the Seville Airport has driven the implementation of an environmental management system based on the international ISO 14001 standards, which has been reviewed and certified by AENOR, granting it the right to use the AENOR environmental management logo. The Seville airport has undertaken different actions in the area of waste, spill and natural resource consumption management, as well as raising awareness and training all AENA personnel at the airport in the area of the environment. ___________________________________________________________________________ 21 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ Waste management, selective paper and cardboard collection is promoted at the AENA offices and in the part of the airport facilities run by other companies. The management of hazardous waste generated as a result of AENA's activities has been centralised to maintain better control of it. To facilitate this management and offer better service to the customers, the creation of a waste collection point has been established to ensure that waste is stored with guaranteed safety and environmental protection. In the area of spills, AENA has made a large investment that has led to the expansion of the airport sanitation network. All facilities that do not already have this service, due to age or distance, will become fully-equipped with this service. All new connections are being made with devices that separate oils and greases, which will improve the quality of the final dumping into the municipal sanitation network. Periodic analytical controls have been established to ensure the quality of the water that is dumped. The airport has an apron available to the fire fighting service to conduct live fire drills. It has been designed to avoid any risk of contamination to the soil and the water derived from the use of fuels that this practice requires. There are also procedures in place to collect fuel spills on the apron to keep the contaminating spills that occur accidentally from reaching the airport draining network. To reduce the amount of water used to water the green areas, an investment has been made to improve the channelling infrastructure and consumption controls have been increased. Finally, it is important to note the monitoring and control process followed by the companies that carry out their activities on the airport grounds, which, voluntarily, have assumed the environmental protection commitment established by the Seville airport. 1.1.3 History of Seville Airport In 1914 the first plane to fly between the peninsula and Morocco landed at the improvised aerodrome in Tablada - created the previous year for an air show - after the Seville town council provided a piece of land of 240 000 square metres to the Military Aviation Service ___________________________________________________________________________ 22 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ for the construction of an aerodrome. The preparatory works started in 1915 and was used in the same year for pilot training and observers. In 1919 the first commercial flights between Seville and Madrid were carried out. The following year the airborne postal service between Seville and Larache was established and 1921 saw the first Spanish Seville-Larache commercial flight. In 1923 various facilities, hangers, workshops and offices were inaugurated and the construction was approved for a municipal airport in Tablada on the edge of the airfield of the military aerodrome and measuring 750 by 500 metres. In April 1927, the Unión Aérea Española (Spanish Airways Union) established the MadridSeville-Lisbon route. In February 1929, the Seville airport project was approved and, in March, the Tablada aerodrome opened to air navigation and air traffic although this service would have to stop as soon as the airport project was constructed. In 1929, the first Madrid-Seville flight took place and in 1930 it was extended to the Canary Islands. In February 1931 the Berlin-Barcelona route included Seville. In December 1933 LAPE started the Seville-Canaries route. During the Civil War, Seville was the arrival point for African troops whilst Iberia provided air transport services with the Tetuán-Seville-Vitoria, Seville-Salamanca and SevilleLarache-Las Palmas routes. In September 1945, works began on the transoceanic airport of Seville, constructing runways 05-23, 02-20, and 09-27. One year later, it was registered as a customs point and the 05-23 and 02-20 runways were asphalted. In 1948, a direction finder was installed, the runway lighting completed and the runways were named 04-22, 18-36 and 09-27. In 1956, runway 09-27 was extended with the 18-36 runway becoming a taxiway. In 1957, the works on the terminal building and the control tower were carried out. Seville airport was included in the Spanish-American Agreement in order to install a supply base. The facilities were placed close to the start of runway 04, taking it out of service. ___________________________________________________________________________ 23 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ In 1965, ILS was installed. Between 1971 and 1975 the terminal area was remodelled, extending the parking, constructing a new terminal building and developing and preparing new access routes. In 1989, with a view to the 1992 Universal EXPO, the platform was extended, a new access route from the N-IV national motorway was constructed as well as a new terminal building and a new control tower to the south of the runway. On 31 July, the new facilities were inaugurated. Figure 1.1.- Seville Airport 1.1.3 Technical Information of Seville Airport 1.1.3.1 General The aerodrome locator indicator- name is LEZL-SEVILLA. Because the standard language for this work is English I will also use the English name for Sevilla, which is Seville. The parameters used in the following tables were found in the ICAO-Airport Characteristics Database. Though they are not as detailed as the ones given in the Spanish AIP I still show the general and physical characteristics (see table 1.2 and 1.3) because some data of them ___________________________________________________________________________ 24 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ were used in order to draw the obstacle charts. For all the other calculations I used the ones given in the AIP, because the precision of the elevation and slope of the runway are greater than those in the ICAO document. The general and physical characteristics as found in the AIP can be found back in table 2.5 and 2.6. Airport characteristics State: Spain IATA Code: SVQ Airport: Sevilla/ San Pablo Latitude of ARP: 372505N Alternate Airports: LEMG and LEMD Longitude of 0055356W ARP: City: Sevilla Elevation: 34 m ICAO Code: LEZL Temperature: 35°C Table 1.2.- ICAO Airport characteristics The alternate airports are Malaga Airport (LEMG) and Madrid-Barajas Airport (LEMD). The coordinates for the ARP used in table 1.2 are WSG84 coordinates. Before using them in calculations they will be converted to UTM coordinates (see 2.3.2). Runway Physical Characteristics RWY Length Width Code Strength Slope Runway Profile 09/27 3360 m 045 m PCN100/F/D/W/T +0,26% +0,18% (2800 m) + 0,64% (560 m) 4D Table 1.3.- Runway physical characteristics Declared Distances RWY TORA (m) TODA (m) ASDA (m) LDA (m) 09 3 360 3 420 3 360 3 360 27 3 360 3 460 3 360 3 360 Table 1.4.- Declared distances ___________________________________________________________________________ 25 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ 1.2 Aerodrome Operation and Airspace 1.2.1 ICAO Airspace Classification The world’s navigable airspace is divided into three-dimensional segments, each of which is assigned to a specific class. Most nations adhere to the classification specified by the ICAO. In the beginning of the 90’s ICAO adopted the current airspace classification scheme. The classes are fundamentally defined in terms of flight rules and interactions between aircraft and Air Traffic Control (ATC). Some key concepts are described in Table 1.5. Class A B Limits IFR VFR Radio Use: Obliged ATC clearance: Needed Speed limit: Not applicable Minimum sight: Not applicable Service: Air Traffic CONTROL Separation: All planes Radio Use: Obliged Obliged ATC clearance: Needed Needed Speed limit: Not applicable Not applicable Minimum sight: Not applicable Above 10.000 ft: 8 km horizontal FORBIDDEN Below 10.000 ft: 5 km horizontal Stay out of the clouds C Service: Air Traffic CONTROL Air Traffic CONTROL Separation: All planes All planes Radio Use: Obliged Obliged ATC clearance: Needed Needed Speed limit: Not Applicable 250 kts below 10.000 ft AMSL Minimum sight: Not applicable Above 10.000 ft: 8 km horizontal 300 m vertical clouds Below 10.000 ft: 5 km horizontal 300 m vertical clouds 1500 m horizontal clouds ___________________________________________________________________________ 26 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ Service: Air Traffic CONTROL 1) Air Traffic CONTROL for separation with IFR 2) VFR Traffic information on request Separation: IFR from VFR VFR from IFR IFR from IFR D Radio Use: Obliged Obliged ATC clearance: Needed Needed Speed limit: 250 kts below 10.000 ft 250 kts below 10.000 ft AMSL AMSL Minimum sight: Not applicable Above 10.000 ft: 8 km horizontal 300 m vertical clouds Below 10.000 ft: 5 km horizontal 300 m vertical clouds 1500 m horizontal clouds Service: Air Traffic CONTROL 1) Flight information between VFR and IFR 2) VFR Traffic information on request G Separation: IFR from IFR Not Used Radio Use: Obliged Obliged ATC clearance: Needed Needed Speed limit: 250 kts below 10.000 ft 250 kts below 10.000 ft AMSL AMSL Minimum sight: Not applicable Above 10.000 ft: 8 km horizontal 300 m above clouds Below 10.000 ft: 5 km horizontal 300 m above clouds Below 900m AMSL: 5 km sight Stay out of clouds Service: Air Traffic CONTROL Flight information between VFR and IFR Separation: IFR from IFR Not Equipped Table 1.5.- ICAO airspace classes As indicated in Table 1.5, in an airspace classified as type “A” no VFR flights are permitted. This means that an airspace “A” is quite restrictive. Type “B” is less restrictive than a type “A” and a “C” is also less restricted than a “B”. ___________________________________________________________________________ 27 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ In general an airspace will be more restricted when there is a big traffic density. It can also be that two airspaces are classified as type “A”, then one of the two has only the half of the traffic density of the other. So we know that it depends on the traffic density but also on other circumstances. It can also happen that the classification of the airspace corresponds to the height, this is the case for Seville. Where the airspace from the TMA is divided in class “A”, “D” and “E”. In this TMA there are also CTR’s from which the classification is “D”. For instance if there would be general aviation aircraft flying above Seville they would have to fly lower because that part is less restricting, keeping in mind that general aviation is mostly VFR. 1.2.2 Operation Classification: VFR and IFR-flights 1.2.2.1 General: VFR and IFR All the aircraft flight phases have to be designed in a way that they guarantee the safety level fixed by them. The risk to penetrate the safety threshold originates in each flight phase of the different elements. For instance when we are in the en-route segment the biggest risk is the collision between two different aircrafts. Although pilots have a lot of aids there has to be a sufficient horizontal and vertical separation between them. When the aircraft comes closer to the airport you have two things that must be taken into account. If it is an aerodrome with parallel airways again a certain separation must be hold between aircraft, and not forget that there are always obstacles which are important in take-off conditions but even more important in approach and landing. We have to keep in mind that the main purpose of the navigation and circulation areas is safety. The factors that also can affect the safety in a big way are meteorological conditions. In the beginning of air navigation the pilots always needed to see the exterior part which means that when there was a lot of rain and smog, lots of flights were cancelled. The necessity to have a regularity in the airspace and specific in air transport made that in today’s world a big progress has been made in technical possibilities and navigation operations. These navigation operations are called VFR and IFR. ___________________________________________________________________________ 28 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ Visual flight rules (VFR) are a set of aviation regulations under which a pilot may operate an aircraft in weather conditions sufficient to allow the pilot, by visual reference to the environment outside the cockpit, to control the aircraft's attitude, navigate, and maintain safe separation from obstacles such as terrain, buildings, and other aircraft. The essential collision safety principle guiding the VFR pilot is "see and avoid". Pilots flying under VFR assume responsibility for their separation from all other aircraft and are generally not assigned routes or altitudes by air traffic control. In busier controlled airspace, VFR aircraft are required to have a transponder. Governing agencies establish strict VFR "weather minima" for visibility, distance from clouds, and altitude to ensure that aircraft operating under VFR can be seen from a far enough distance to ensure safety, as can be seen in Figure 1.2. In strictly controlled airspace, air traffic control will separate VFR aircraft from all other aircraft or just from instrument flight rules (IFR) aircraft. In other airspace, a VFR pilot can at his or her discretion request traffic information from air traffic control regarding other aircraft in their vicinity, but the duty of maintaining safe separation still remains with the pilot. The minimum meteorological requirements for VFR are termed visual meteorological conditions (VMC). If they are not met then the flight must operate under IFR; to do so, the pilot must hold an instrument rating and meet recency of experience requirements pertaining to instrument flight, the aircraft must be equipped and type-certified for instrument flight. In some types of airspace, generally at higher altitudes, a flight must operate under instrument flight rules regardless of the meteorological conditions, as aircraft fly at high speeds at higher altitudes and thus the "see and avoid" method of avoiding conflicting traffic is not adequate to ensure safety. Following division gives us a good view of what is possible. • visual • instrumental ƒ approach - non precision (NPA) - APV I and II ___________________________________________________________________________ 29 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ ƒ precision (PA) (CAT I and II/III) departure On the other hand when the meteorological conditions do not permit a separation from the clouds, neither other visibility, then the conditions are called IMC. Meaning instrument meteorological conditions and these cannot be realized with a VFR flight, which is mandatory for an IFR flight. Instrument Flight Rules (IFR) are a set of regulations and procedures for flying aircraft without the assumption that pilots will be able to see and avoid obstacles, terrain, and other air traffic. Since navigation and control of the aircraft under IFR is done by instruments, flying through clouds is allowed; under VFR it is not. Commercial traffic operates under IFR almost exclusively. The most important concept of IFR flying is that it allows continued flight operations in reduced visibility, during which time the ability of a pilot to physically see and avoid collision with other aircraft or obstacles is severely reduced, or even impossible. In controlled airspace, air traffic control (ATC) separates IFR aircraft from obstacles and other IFR aircraft. Generally, in most controlled airspaces, IFR aircraft require an ATC clearance for each part of the flight, typically providing a heading or route, altitude, and clearance limit (the farthest the aircraft can fly without a new clearance). In very busy areas, typically near major airports, clearances may also be required for VFR aircraft, and ATC may also provide separation between IFR and VFR aircraft or even between VFR aircraft. In uncontrolled airspace, IFR aircraft do not require clearances, and they separate themselves from each other by using charted minimum altitudes to avoid terrain and obstacles, standard cruising altitudes to avoid aircraft flying in different directions, and radio reports over mandatory locations. One advantage of IFR is the ability to fly an aircraft in IMC. In such conditions the pilot will control the altitude of the aircraft by watching the flight instruments, and will rely entirely on ATC for separation. Although large airliners and, increasingly, smaller aircraft ___________________________________________________________________________ 30 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ now carry their own terrain- and collision-avoidance systems such as TCAS, these are primarily backup systems. It is important, however, not to confuse IFR with IMC: the vast majority of IFR flying is done under VMC, and in many cases, the pilot will be controlling the aircraft primarily by outside visual references, as with VFR. Under VMC in some types of airspace, ATC will not provide separation between IFR and VFR aircraft, so pilots are responsible for seeing and avoiding other traffic just as they would be under VFR. Figure 1.2.- VMC minima controlled airspace In the case of an IFR flight there is not only the aircraft that has to be taken into account but also the crew and not forget the aerodrome. The aeroplane has to have the navigation equipment on board necessary for the flight that will be carried out and the crew has to be in the possession of an IFR qualification. On the aerodrome has to exist an adequate infrastructure, consisting of a line of radio-aids for the en-route phase and has to be provided with different systems (radio-aids, lighting systems,…) for approach and landing. If one of these three does not correspond with the provided requirements an IFR flight cannot be realized. ___________________________________________________________________________ 31 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ Figure 1.3.- VMC minima uncontrolled airspace 1.2.2.2 Visual flight rules Except when operating as a special VFR flight, VFR flights shall be conducted so that the aircraft is flown in conditions of visibility and distance from clouds equal to or greater than those specified in the Figure 1.3 above. Except when clearance is obtained from an air traffic control unit, VFR flights shall not take off or land at an aerodrome within a control zone, or enter the aerodrome traffic zone or traffic pattern: • when the ceiling is less than 450 m (1 500 ft); or • when the ground visibility is less than 5 km. VFR flights between sunset and sunrise, or such other period between sunset and sunrise as prescribed by the appropriate ATS authority, shall be operated according to the conditions prescribed by such authority. Unless authorised by the appropriate ATS authority, VFR flights shall not be operated: • above FL 200; • at transonic and supersonic speeds. Authorisation for VFR flights to operate above FL 290 shall not be granted in areas where a vertical separation minimum of 300 m (1 000 ft) is applied above FL 290. Except when ___________________________________________________________________________ 32 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ necessary for take-off or landing, or except by permission from the appropriate authority, a VFR flight shall not be flown: • over the congested areas of cities, towns or settlements or over an open-air assembly of persons at a height less than 300 m (1 000 ft) above the highest obstacle within a radius of 600 m from the aircraft; • elsewhere than as specified in the point above, at a height less than 150 m (500 ft) above the ground or water. Except where otherwise indicated in air traffic control clearances or specified by the appropriate ATS authority, VFR flights in level cruising flight when operated above 900 m (3 000 ft) from the ground or water, or a higher datum as specified by the appropriate ATS authority, shall be conducted at a flight level appropriate to the track as specified in the Tables of cruising levels (see ICAO standard). VFR flights shall comply with the provisions of above: • when operated within Classes B, C and D airspace; • when forming part of aerodrome traffic at controlled aerodromes; or • when operated as special VFR flights. A VFR flight operating within or into areas, or along routes, designated by the appropriate ATS authority shall maintain continuous air-ground voice communication watch on the appropriate communication channel of, and report its position as necessary to the air traffic services unit providing flight information service. An aircraft operated in accordance with the visual flight rules which wishes to change to compliance with the instrument flight rules shall: • if a flight plan was submitted, communicate the necessary changes to be effected to its current flight plan, or • when so required, submit a flight plan to the appropriate air traffic services unit and obtain a clearance prior to proceeding IFR when in controlled airspace. 1.2.2.3 Instrument flight rules Rules applicable to all IFR flights Aircraft equipment: ___________________________________________________________________________ 33 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ Aircraft shall be equipped with suitable instruments and with navigation equipment appropriate to the route to be flown. Minimum levels: Except when necessary for take-off or landing, or except when specifically authorised by the appropriate authority, an IFR flight shall be flown at a level which is not below the minimum flight altitude established by the State whose territory is over flown, or, where no such minimum flight altitude has been established: • over high terrain or in mountainous areas, at a level which is at least 600 m (2 000 ft) above the highest obstacle located within 8 km of the estimated position of the aircraft; • elsewhere than as specified above, at a level which is at least 300 m (1 000 ft) above the highest obstacle located within 8 km of the estimated position of the aircraft. Note: The estimated position of the aircraft will take account of the navigational accuracy which can be achieved on the relevant route segment, having regard to the navigational facilities available on the ground and in the aircraft. Change from IFR flight to VFR flight: An aircraft electing to change the conduct of its flight from compliance with the instrument flight rules to compliance with the visual flight rules shall, if a flight plan was submitted, notify the appropriate air traffic services unit specifically that the IFR flight is cancelled and communicate thereto the changes to be made to its current flight plan. When an aircraft operating under the instrument flight rules is flown in or encounters visual meteorological conditions it shall not cancel its IFR flight unless it is anticipated, and intended, that the flight will be continued for a reasonable period of time in uninterrupted visual meteorological conditions. Rules applicable to IFR flights within controlled airspace IFR flights shall comply with the provisions of general part above when operated in controlled airspace. An IFR flight operating in cruising flight in controlled airspace shall be flown at a cruising level, or, if authorised to employ cruise climb techniques, between two levels or above a level, selected from: ___________________________________________________________________________ 34 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ • the Tables of cruising levels in the ICAO standard, or • a modified table of cruising levels, when so prescribed in accordance with the ICAO standard for flight above FL 410, except that the correlation of levels to track prescribed therein shall not apply whenever otherwise indicated in air traffic control clearances or specified by the appropriate ATS authority in Aeronautical Information Publications. Rules applicable to IFR flights outside controlled airspace Cruising levels: An IFR flight operating in level cruising flight outside of controlled airspace shall be flown at a cruising level appropriate to its track as specified in: • the Tables of cruising levels in the ICAO standard, except when otherwise specified by the appropriate ATS authority for flight at or below 900 m (3 000 ft) above mean sea level; or • a modified table of cruising levels, when so prescribed in accordance to the ICAO standard for flight above FL 410. Note: This provision does not preclude the use of cruise climb techniques by aircraft in supersonic flight. Communications: An IFR flight operating outside controlled airspace but within or into areas, or along routes, designated by the appropriate ATS authority shall maintain an air-ground voice communication watch on the appropriate communication channel and establish two-way communication, as necessary, with the air traffic services unit providing flight information service. Position reports: An IFR flight operating outside controlled airspace is required by the appropriate ATS authority to: • submit a flight plan; • maintain an air-ground voice communication watch on the appropriate communication channel and establish two-way communication, as necessary, with ___________________________________________________________________________ 35 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ the air traffic services unit providing flight information service, shall report position for controlled flights. 1.2.3 Aerodrome Airspace 1.2.3.1 Introduction: airspace around the aerodrome The airport is the junction where aeroplanes come to and leave. When the aircraft progress in their en-route phase there are a lot of human, technical and operative actions required to maintain the level of safety required in these operations. When the aeroplane wants to make an approach to the airport, a lot of other additional aids are used to maintain the safety level. These aids go from a physical structure and airspace operation to the classification and design of flight procedures in this airspace. It is important to define to which point the airspace reaches around the entire aerodrome. From this point an aircraft flight can be divided in different parts starting from aerodrome (take-off) to its destination (landing). A schematic plan can be found in Figure 1.4. Figure 1.4.- Flight phases As we can notice a flight can be divided in different flight phases: take-off, climb, en-route, arrival, approach and landing. The requirements for navigation in each of this phases is quiet different. In the take-off phase, when the meteorological conditions are not good enough, the aircraft needs guidance to roll on the runway and guidance to complete the second segment of the take-off. The second segment is situated at a point of 400 feet above the runway elevation. Once this point is reached the aeroplane can follow different standard departure routes (SID) till it reaches the desired point where it can complete the major part of the flight, en-route phase. Going to the aerodrome destination, the aeroplane starts to descend according to specific routes, called arrival routes. These routes guide the pilot to ___________________________________________________________________________ 36 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ specific points, these points can be aerodrome identification points or the points to make a holding pattern. Once the holding pattern is finished the pilot comes into the next flight phase which is the approach. After this phase there is the landing phase corresponding to the end of the flight. If we analyse in detail every phase we can see that the en-route phase is the easiest. It is the most simple in the point of view of the aircraft and ATC, because the aeroplane flies at an established level with a constant velocity and configuration. The ATS activity in this phase is in every form the less demanding at the point of technical mediums, operation and human activity. When the aircraft comes in the vicinity of the airport, in case of arrivals, the flight becomes more critical because the velocity decreases, altitude decreases and the aircraft configuration changes. From the ATS’ point of view there are also more aids required. Because the aircraft requirements change to the flight phase which it enters, the use of the flights from the ATS’ point of view is to structure, classify and design the airspace according to the activity that will take place in it. When the aircraft activity changes in a part of the defined airspace then it can be necessary to change the airspace. The conclusion is that the airspace design, distribute and use is always connected to the operational criterions, holding the safety of operations and try to obtain a smooth way for the flight operations. The part of the airspace where flights are developed in the vicinity of the aerodrome is called the terminal area. This is a general term that describes the airspace around the airport in which transitional services are represented. In this terminal area the following areas are included: • TMA terminal control area; • CTR control zones; • ATZ aerodrome transit zones. 1.2.3.2 Structure of the airspace As we know the airspace in the vicinity of the aerodrome can be structured in CTA’s, controlled areas, when there are technical aids it is called a TMA, terminal control area. In all the other cases the term CTA is used. In general, there can be noticed that the CTA and ___________________________________________________________________________ 37 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ the TMA have similar characteristics meaning to protect the arrival and departure routes around the aerodrome. When an aircraft leaves the en-route flight phase it normally goes directly to the control zone (CTA or TMA). Once in the CTA, or TMA, the aircraft can go to the arrival or departure routes (STAR, SID). There has to be noticed that in the CTA or TMA there is always control service. The arrival routes take the aircraft to a specific point, from which the approach procedure can be initiated. The approach procedures happen in an other specific airspace which is called a CTR, control zone. We see that every type of airspace has a certain form in which specific operations are developed. The definition of each of these airspace’s is the following • CTR Control zone: A controlled airspace extending upwards from the surface of the earth to a specified upper limit. The lateral limits of this zone extend minimum above the 5 nautical miles (1NM = 1,852km) from the centre of the aerodrome or the considered aerodrome in the direction in which the approach operations are realized. Normally the base is of a circular form. • CTA control area: A controlled airspace extending upwards from a specified limit above the earth. The lower limit is established at a height above the terrain or water and cannot be less than 200 metres. In the control areas airways and TMA’s are included. The lateral limits are established above the base necessary for the operations. Figure 1.5.- Structure of the airspace ___________________________________________________________________________ 38 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ 1.3 Navigation Aids 1.3.1 Non-Directional Beacons 1.3.1.1 Evolution of the NDB In the early days of aviation, aircraft were able to fly at any height and on any track they chose. There were so few aircraft that there was little risk of collision. As actual flight technology grew in sophistication, so the number of aircraft grew, with a corresponding need for swift development in the fields of aircraft communication and navigation. Early knowledge of the use of radio waves was put to good use. In fact, as early as the 1930s it was understood that the orientation of a wire-loop antenna in an electromagnetic field radiated from a ground station could provide an indication of direction to the station. This was the operating principle of the first radio direction-finding (DF) systems. So, early aviators used radio stations to mark their routes. The next stage was the spread of large numbers of ground stations, using aerials rotated manually, with the resulting bearings being directly related to the position of the aerial. The next development was for the aircraft to receive the signals, and manually determine their bearings using its own loop aerial. Figure 1.6.- ADF indicator instrument 1.3.1.2 Role of the NDB NDB’ s can be used as a: • holding fix at an airfield; • en route navigation aid; • distance information; • approach aid at an airfield. ___________________________________________________________________________ 39 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ 1.3.1.3 Operating principle An aerial and a receiver combination can be constructed to sense the direction from which a radio signal is coming. Historically, this was carried out by manually rotating the aerial equipment and listening for the signal. Nowadays this is done automatically in the aircraft and the equipment is known as the Automatic Direction Finder (ADF). In the past, the NDB/ADF combined system was sometimes referred to as the Radio Compass, since the ADF operates according to the radio compass principle, its needle indicating the direction from which signals are coming. At VHF and above, the only radiated wave which can be used is the one which travels in a direct line from the transmitting aerial to the receiving aerial. This is called line-of-sight transmission. A potential disadvantage is that obstacles, even low hills, will restrict coverage. The two essential components of the ground equipment of the NDB/ADF system are the transmitter and the aerial. The NDB/ADF system works through an aircraft tuning into a target NDB on its transmitted frequency, thus providing the pilot with the aircraft's relative bearing from that NDB. The aircraft tunes into the target NDB on its transmitted frequency, and the RMI gives the aircraft's relative bearing from the NDB. Figure 1.7.- RMI indicator 1.3.2 Distance measuring equipment 1.3.2.1 Role of the DME • DME combined with VOR The VOR is a standard short range aid which provides pilots with directional information. A VOR on its own, however, cannot establish an aircraft's position: pilots need extra ___________________________________________________________________________ 40 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ information for this. DME stands for Distance Measuring Equipment. Its role may be understood as complementing the VOR by enabling an aircraft to determine its position along a radial. • DME combined with MLS The MLS was conceived as a successor to the ILS: the ILS and the MLS are the two precision approach aids recognised by ICAO. The MLS gives a wider arc of coverage than the ILS, and is expected to overcome siting limitations associated with the ILS. The DME is a component of the Microwave Landing System (or the MLS). The MLS allows approaches over a wide arc, 80° wide and 15° deep, therefore the DME is necessary to provide aircraft with information about distance from touchdown within this wide area. ICAO has defined two basic types of DME. One is the normal or en-route DME (known as a DME/N). The other is a precision DME, developed solely as an aid to final approach and landing, known as a DME/P - the P stands for Precise or Precision. There is no significant difference between the operation of these two DME’ s. DME/Ps are associated with the Microwave Landing Systems. Figure 1.8.- The MLS (Microwave Landing System) coverage in diagram form 1.3.2.2 Operating principle DME uses the same frequency band as Secondary Surveillance Radar (SSR) and TACAN. Radio waves always travel at the same speed. If, therefore, you know the time of transmission and the time of reception, you can calculate the distance covered. The way the DME works depends on this basic principle: that because the speed of radio waves is a ___________________________________________________________________________ 41 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ constant, it is possible to measure the time taken for a radio wave to cover a given distance and use the result to calculate that distance. In other words, distance can be calculated by measuring the time between transmission and reception. To measure the time taken for the signal to travel from the ground to the aircraft requires that the time is known accurately at both the transmitter and the receiver. In practice, the degree of accuracy required is not achievable. To overcome this problem the signal is both transmitted and received by the aircraft. So it is a 'return journey' time that is measured and, since both transmitter and receiver time are measured by the same 'clock', that clock's absolute accuracy is unimportant. The aircraft does not transmit a continuous signal. It transmits a momentary pulse. When the pulse is received by the DME ground equipment (called a transponder), an answering pulse is transmitted. Although the DME and VOR are often combined into a single navigation aid, they are in fact separate pieces of equipment, operating in different frequency bands. Figure 1.9.- DME principle 1.3.3. VHF Omni directional Beacon 1.3.3.1 VOR evolution The VOR (VOR stands for Very High Frequency Omni-Range) is a radio navigation aid now in extensive use, which was adopted by ICAO in 1960 as the standard short range navigation aid. Historically, various operational reasons caused the proliferation of the VOR in preference to other aids such as the NDB. Some of these reasons are: • the need to avoid the considerable amounts of static noise and interference, ___________________________________________________________________________ 42 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ • the need to install more beacons free of frequency overlapping, • the need to have a very simple indication to monitor track deviation. With the increase in air traffic, the need for greater flexibility and for reliability in navigation aids became apparent. One of the disadvantages of the NDB, for example, is that it does not provide accurate track guidance. The VOR, in its replacement role for earlier navigation aids like the radio range, was introduced to provide accurate track guidance and accurately delineate airway centre lines. VOR beacons are sited world-wide, providing guidance along most overland airways. As its name suggests, the VOR operates within the VHF waveband, in fact, between 112 and 118 MHz. The pilot can select a track to or from the VOR - these tracks are referred to as radials. The pilot is then provided with accurate guidance to follow the selected track, irrespective of wind. The VOR produces 360 different tracks which are called radials. They are track lines emanating from the VOR beacon much like rays emerging from the sun. The VOR then provides pilots with information in the form of magnetic bearings . The pilot has on-board equipment that can select a specific track: the pilot can follow one of these tracks exactly, inbound or outbound to the VOR, or check the crossing of one or more tracks along a route. In the case of an NDB, however, the pilot receives information only about bearings from the NDB, and must calculate the heading required in order to maintain the track to the NDB. There are several factors which affect the transmission of radio waves, including ionospheric changes and the time of day. Because of the lack of reflection by the ionosphere, VHF waves propagate only by direct wave transmission - 'line-of-sight' transmission. As a result, they are less susceptible to atmospheric effects than waves in the lower frequency bands. In particular, they are not subject to night effect or sky wave error. ___________________________________________________________________________ 43 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ Figure 1.10.- VOR radials 1.3.3.2 VOR operating principles The VOR transmits two signals, one in constant phase and one whose phase varies according to a set pattern. The radial which an aircraft is on is determined by measuring the received phase difference between these two signals. This measurement is achieved by the receiver in the aircraft (the phase comparison meter), which displays the result as a radial, that is, as the bearing with respect to the VOR. The two signals transmitted by the VOR are in phase for an aircraft which is due north of the VOR. So, for an aircraft on this particular radial there is zero phase difference between the signals. As the aircraft changes its bearing with respect to the transmitter, the phase of the variable signal alters. Each degree of bearing change corresponds to a one degree change of phase. All this information is shown on the HSI. ___________________________________________________________________________ 44 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ Figure 1.11.- The Horizontal Situation Indicator 1.3.4 Instrument Landing System 1.3.4.1 ILS Evolution The function of the ILS is to provide pilots with guidance during approach and landing. The precursor to the ILS was the SBA, which conveyed information to the pilot through audible means rather than electronically. The SBA was a system of radio navigation which provided an aircraft with lateral guidance and marker beacon indication at specific points during its approach. It is no longer in use. The SBA had no glide path, and offered guidance in plan view only, i.e. right and left guidance. The ILS was developed to provide guidance in the vertical plane as well as the horizontal plane. The guidance is presented visually to the pilot by an instrument on the flight deck. 1.3.4.2 Role of the ILS The ILS gives pilots approach and landing guidance and is designed to be particularly effective in certain circumstances. The capability of each individual ILS is defined according to a particular system of categories known, as the "facility performance categories". There are two standard precision landing aids currently recognised by ICAO. The ILS is one of them. The second one is the Microwave Landing System, which has certain advantages over the ILS, such as an ability to be sited at geographical locations unsuitable for the ILS. The ICAO hopes to see the MLS progressively implemented as the primary approach and ___________________________________________________________________________ 45 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ landing aid. Unlike the ILS, which provides a clearly defined approach path above the extended runway centreline by means of the localizer and glide path, the MLS allows approaches anywhere within its horizontal and vertical fan-shaped coverage area, giving it an extensive operational capability. Corresponding broadly to the ILS localizer, the MLS has an azimuth transmitter: corresponding broadly to the ILS glide path, the MLS has an elevation transmitter. It operates in the SHF frequency and is thus free from ground effects. 1.3.4.3 Operating Principle of ILS Figure 1.12.- Instrument Landing System The ILS system consists of three important components: • Localizer: The localizer provides lateral guidance to the aircraft and is normally located at the end of the runway. The installation radiates (108 – 112 MHz) a vertical field with a horizontal polarisation. This field contains two AM-modulated lobes (90Hz and 150Hz) of which the modulation-amplitudes depend on the azimuthposition. The axis of the runway is defined by the equality of those modulations. The 90Hz-modulation dominates on the left of the approach-axis and the 150Hz on the right. The onboard installation compares the DDM (Difference in Depth of Modulation) of these two components. If the aircraft is situated correctly on the axis the DDM = 0 and the indicator is located in the middle of the graduation. The indicator will move to the right or the left if the aircraft deviates from the approach- ___________________________________________________________________________ 46 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ axis. In this case the pilot has to correct his course (“Follow the needle”). The most accurate way to realise this field is by using the method “Null reference”. • Glide slope: The glide slope is installed on one side of the runway touchdown zone. The signal is transmitted on a carrier frequency (328.6 – 335.4 MHz) with a similar technique as the one used for the localizer. The angle that the glide slope makes with the surface is approximately 3°. • Marker Beacons. Marker beacons are installations located at fixed distances from the runway threshold and operate at a frequency of 75 MHz. We can distinguish 3 types of marker beacons: ƒ Outer Marker (OM): 7.2 km from threshold. ƒ Middle Marker (MM): 1.050 km from threshold. ƒ Inner Marker (IM): 450 m from threshold. Figure 1.13.- Coverage volume of the azimuth station 1.3.4.4 Operating principle of MLS The MLS exist of 3 components: • The azimuth station transmits angle and data on one of 200 channels within the frequency range (5031 – 5091 MHz). This station is located around 300m beyond the end of the runway. Figure 1.13 above gives the azimuth coverage. ___________________________________________________________________________ 47 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ • The elevation station transmits signals on the same frequency as the azimuth station. The station is located between runway threshold and the touchdown zone. • Range guidance. MLS uses DME for range guidance and works the same as the navigation DME. 1.3.5 Inertial Navigation System 1.3.5.1 Role of INS INS stands for Inertial Navigation System. The INS is a self-contained aircraft system. It is not a radio navigation aid and does not use ground equipment. The function of the INS is to provide the pilot with a 3-dimensional position fix. INS equipment may be duplicated or, where the INS is the primary reference source, equipment is triplicated (that is, three sets of the equipment are fitted to the aircraft). This is in order to maximise reliability and to minimise the possibility of errors. The system continuously cross-checks the information given by each of these three units. If one set of information is significantly different from the other two, it is discarded. 1.3.5.2 Operating Principles of INS INS works by dead reckoning. This system of navigation works by measuring the amount of movement in each direction from a known starting point. The information provided by the INS consists of measurements relative to the aircraft's starting point. It is vital, therefore, that the aircraft's starting point is entered into the system before take-off. This will normally be the aircraft's stand position. Whilst this information is being entered into the system the aircraft must remain stationary. Once the information has been entered, the system must not be switched off or the reference point will be lost. INS actually measure acceleration and time, and from this information derive ground speed. This in turn enables the distance from the aircraft's starting point to be calculated. The device which measures acceleration is called an accelerometer. In principle, when an aircraft accelerates or decelerates, a mass, or weight, is displaced. The amount of displacement is proportional to the force of the acceleration or deceleration - the acceleration or deceleration displaces the weight due to the effects of inertia. The INS measures the acceleration and uses time to derive the ground speed: the distance from the start point can thus be calculated. ___________________________________________________________________________ 48 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ 1.4 Aeronautical Charts 1.4.1 Coordinate system Since January 1998, all coordinates published for civil aviation navigation purposes should be based upon WGS84. So in this work all the coordinates used will also be WSG84. The coordinates used in AutoCAD though are UTM, so these WSG84 coordinates will have to be converted to UTM. An introduction on the coordinate systems will first be given. 1.4.1.1 WSG84 WGS stands for World Geodetic1 System and defines a fixed frame for the earth which is used for navigation. It represents the best global geodetic reference system for the Earth available at this time for use of mapping and navigation. The latest version of the system is from 1984 and is called WGS84. This version will be valid till 2010. Previous versions were WGS72, WGS64 and WGS60. These improvements were needed because of the evolution in science and the need of more sufficient data. The WGS 84 Coordinate System is a Conventional Terrestrial Reference System (CTRS). The definition of this coordinate system follows the criteria outlined in the International Earth Rotation Service (IERS) Technical Note 21 . These criteria are repeated below: • it is geocentric, the centre of mass being defined for the whole Earth including oceans and atmosphere; • its scale is that of the local Earth frame, in the meaning of a relativistic theory of gravitation; • its orientation was initially given by the Bureau International de l’Heure (BIH) orientation of 1984.0; • its time evolution in orientation will create no residual global rotation with regards to the crust. The WGS 84 Coordinate System is a right-handed, Earth-fixed orthogonal coordinate system and is graphically depicted in Figure 1.13. ___________________________________________________________________________ 49 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ Figure 1.14.- The WSG84 coordinate system definition In Figure 1.13, the origin and axes are defined as follows: • Origin = Earth’s centre of mass; • Z-Axis = The direction of the IERS Reference Pole (IRP). This direction corresponds to the direction of the BIH Conventional Terrestrial Pole (CTP) with an uncertainty of 0.005; • X-Axis = Intersection of the IERS Reference Meridian (IRM) and the plane passing through the origin and normal to the Z-axis. The IRM is coincident with the BIH Zero Meridian with an uncertainty of 0.005 ; • Y-Axis = Completes a right-handed, Earth-Centred Earth-Fixed (ECEF) orthogonal coordinate system. The WGS 84 Coordinate System origin also serves as the geometric centre of the WGS 84 Ellipsoid and the Z-axis serves as the rotational axis of this ellipsoid of revolution. 1.4.1.2 UMT coordinates The Universal Transverse Mercator (UTM) coordinate system is a grid-based method of specifying locations on the surface of the Earth. It is used to identify locations on the earth, but differs from the traditional method of latitude and longitude in several respects. The UTM system is not a single map projection. The system instead employs a series of sixty zones, each of which is based on a specifically defined Transverse Mercator projection. ___________________________________________________________________________ 50 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ Figure 1.15.- The UMT grid • UTM Longitude The UTM system divides the surface of the Earth between 80° S latitude and 84° N latitude into 60 zones, each 6° of longitude in width and centred over a meridian of longitude. Zones are numbered from 1 to 60. Zone 1 is bounded by longitude 180° to 174° W and is centred on the 177th West meridian. Zone numbering increases in an easterly direction. Each of the 60 longitude zones in the UTM system is based on a Transverse Mercator projection, which is capable of mapping a region of large north-south extent with a low amount of distortion. By using narrow zones of 6° in width, and reducing the scale factor along the central meridian to 0.9996, (a reduction of 1:2500) the amount of distortion is held below 1 part in 1,000 inside each zone. Distortion of scale increases to 1.0010 at the outer zone boundaries along the equator. The reduction in the scale factor along the central meridian creates two lines of true scale located approximately 180 km on either side of, and approximately parallel to, the central meridian. The scale factor is too small inside these lines and too large outside of these lines, but the overall distortion scale inside the entire zone is minimized. • UTM latitude The UTM system segments each longitude zone into 20 latitude zones. Each latitude zone is 8 degrees high, and is lettered starting from "C" at 80° S, increasing up the English alphabet until "X", omitting the letters "I" and "O" (because of their similarity to ___________________________________________________________________________ 51 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ the digits one and zero). The last latitude zone, "X", is extended an extra 4 degrees, so it ends at 84° N latitude, thus covering the northern most land on Earth. Latitude zones "A" and "B" do exist, as do zones "Y" and Z". They cover the western and eastern sides of the Antarctic and Arctic regions respectively. A convenient trick to remember is that the letter "N" is the first letter in the northern hemisphere, so any letter coming before "N" in the alphabet is in the southern hemisphere, and any letter "N" or after is in the northern hemisphere. 1.4.2 Aerodrome Obstacle Chart – Type A This chart shall provide the data necessary to enable an operator to comply with the operating limitations. Aerodrome Obstacle Charts — ICAO Type A (Operating Limitations) shall be made available in the manner prescribed in Annex 6, Part 1 for all aerodromes regularly used by international civil aviation, except for those aerodromes where there are no obstacles in the take-off flight path areas. The charts shall depict a plan and profile of each runway, any associated stopway or clearway, the take-off flight path area and obstacles. The profile for each runway, stopway, clearway and the obstacles in the take-off flight path area shall be shown above its corresponding plan. The profile of an alternative take-off flight path area shall comprise a linear projection of the full take-off flight path and shall be disposed above its corresponding plan in the manner most suited to the ready interpretation of the information. A profile grid shall be ruled over the entire profile area exclusive of the runway. The zero for vertical coordinates shall be mean sea level. The zero for horizontal coordinates shall be the end of the runway furthest from the take-off flight path area concerned. Graduation marks indicating the subdivisions of intervals shall be shown along the base of the grid and along the vertical margins. Objects in the take-off flight path area which project above a plane surface having a 1.2 per cent slope and having a common origin with the take-off flight path area, shall be regarded as obstacles, except that obstacles lying wholly below the shadow of other obstacles as defined in and trucks, which may project above the 1.2 per cent plane, shall be considered obstacles but shall not be considered as being capable of creating a shadow. The shadow of ___________________________________________________________________________ 52 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ an obstacle is considered to be a plane surface originating at a horizontal line passing through the top of the obstacle at right angles to the centre line of the take-off flight path area. For the first 300 m (1 000 ft) of the take-off flight path area, the shadow planes are horizontal and beyond this point such planes have an upward slope of 1.2 per cent. If the obstacle creating a shadow is likely to be removed, objects that would become obstacles by its removal shall be shown. The take-off flight path area consists of a quadrilateral area on the surface of the earth lying directly below, and symmetrically disposed about, the take-off flight path. This area has the following characteristics: • it commences at the end of the area declared suitable for take-off (i.e. at the end of the runway or clearway as appropriate); • its width at the point of origin is 180 m (600 ft) and this width increases at the rate of 0.25D to a maximum of 1 800 m (6 000 ft), where D is the distance from the point of origin; • it extends to the point beyond which no obstacles exist • or to a distance of 10.0 km (5.4 NM), whichever is the lesser. 1.4.3 Standard Instrument Departure Chart This chart shall provide the flight crew with information to enable it to comply with the designated standard instrument departure route from take-off phase to the enroute-phase. The aerodrome of departure shall be shown by the runway pattern. All aerodromes which affect the designated standard instrument departure route shall be shown and identified. Where appropriate the aerodrome runway patterns shall be shown. Prohibited, restricted and danger areas which may affect the execution of the procedures shall be shown with their identification and vertical limits. The established minimum sector altitude, based on a navigation aid associated with the procedure, shall be shown with a clear indication of the sector to which it applies. Where the minimum sector altitude has not been established, the chart shall be drawn to scale and area minimum altitudes shall be shown within quadrilaterals formed by the parallels and meridians. Area minimum altitudes shall also be shown in those parts of the chart not covered by the minimum sector altitude. ___________________________________________________________________________ 53 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ The components of the established relevant air traffic services system shall be shown. The components shall comprise the following: • a graphic portrayal of each standard instrument departure route, including: a) route designator; b) significant points defining the route; c) track or radial to the nearest degree along each segment of the route; d) distances to the nearest kilometre or nautical mile between significant points; e) minimum flight altitudes along the route or route segments and altitudes required by the procedure to; f) the nearest higher 50 m or 100 ft and flight level restrictions where established; g) where the chart is drawn to scale and radar vectoring on departure is provided, established radar minimum altitudes to the nearest higher 50 m or 100 ft, clearly identified; h) the radio navigation aid(s) associated with the route(s) including: I. plain language name; II. identification; III. frequency; IV. geographical coordinates in degrees, minutes and seconds; V. for DME, the channel and the elevation of the transmitting antenna of the DME to the nearest 30 m (100 ft); • the name-codes of the significant points not marked by the position of a radio navigation aid, their geographical coordinates in degrees, minutes and seconds and the bearing to the nearest tenth of a degree and distance to the nearest two-tenths of a kilometre (tenth of a nautical mile) from the reference radio navigation aid; • applicable holding patterns; • transition altitude/height to the nearest higher 300 m or 1 000 ft; • the position and height of close-in obstacles which penetrate the obstacle identification surface (OIS). • area speed restrictions, where established; • all compulsory and “on-request” reporting points; • radio communication procedures, including: ___________________________________________________________________________ 54 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ a) call sign(s) of ATS unit(s); b) frequency; c) transponder setting, where appropriate. 1.4.4 Standard Instrument Arrival Chart This chart shall provide the flight crew with information to enable it to comply with the designated standard instrument arrival route from the en-route phase to the approach phase. The aerodrome of landing shall be shown by the runway pattern. All aerodromes which affect the designated standard instrument arrival route shall be shown and identified. Where appropriate the aerodrome runway patterns shall be shown. Prohibited, restricted and danger areas which may affect the execution of the procedures shall be shown with their identification and vertical limits. The established minimum sector altitude shall be shown with a clear indication of the sector to which it applies. Where the minimum sector altitude has not been established, the chart shall be drawn to scale and area minimum altitudes shall be shown within quadrilaterals formed by the parallels and meridians. Area minimum altitudes shall also be shown in those parts of the chart not covered by the minimum sector altitude. The components of the established relevant air traffic services system shall be shown. The components shall comprise the following: • a graphic portrayal of each standard instrument arrival route, including: a) route designator; b) significant points defining the route; c) track or radial to the nearest degree along each segment of the route; d) distances to the nearest kilometre or nautical mile between significant points; e) minimum flight altitudes along the route or route segments and altitudes required by the procedure to the nearest higher 50 m or 100 ft and flight level restrictions where established; f) where the chart is drawn to scale and radar vectoring on arrival is provided, established radar minimum altitudes to the nearest higher 50 m or 100 ft, clearly identified. • the radio navigation aid(s) associated with the route(s) including: a) plain language name; ___________________________________________________________________________ 55 Chapter 1: Preliminary concepts _________________________________________________________________________________________________________________ b) identification; c) frequency; d) geographical coordinates in degrees, minutes and seconds; e) for DME, the channel and the elevation of the transmitting antenna of the DME to the nearest 30 m (100 ft). • the name-codes of the significant points not marked by the position of a radio navigation aid, their geographical coordinates in degrees, minutes and seconds and the bearing to the nearest tenth of a degree and distance to the nearest two-tenths of a kilometre (tenth of a nautical mile) from the reference radio navigation aid; • applicable holding patterns; • transition altitude/height to the nearest higher 300 m or 1 000 ft; • area speed restrictions, where established; • all compulsory and “on-request” reporting points; • radio communication procedures, including: a) call sign(s) of ATS unit(s); b) frequency; c) transponder setting, where appropriate. ___________________________________________________________________________ 56 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ 2 Operational requirements 2.1 General description 2.1.1 Design of procedures When designing a procedure, it must be done in conjunction with the relevant ATS providers, the airport operator and one or more representatives from the major users. This to be sure that the procedure design meets the operational requirements of these groups. Therefore, before starting with the design, it is important to take account of all the requirements involving several groups such as the aircraft operators, air traffic service providers as well the environmental restrictions forced by the authorities. These listed steps can be helpful in designing a procedure. a) explain the purpose of this new design. Why designing a new procedure; b) identification of users. Who is going to use these procedures, what type of aircrafts will use it,… c) define the procedure based upon the navaid availability; d) establish the environmental impact of the proposed procedure; e) evaluate and validate the procedure using appropriate software tools, simulators and flight checks; f) when publishing the procedure, use the standard terminology and declare the speed and altitudes used to calculate the procedure. Procedures must be defined in such a way that there are no ambiguities when the data is coded into a navigation database, regardless of the systems that are installed. Furthermore, in general, procedure design should focus on : a) safety; b) codability; c) flyability; d) repeatability; e) simplicity; f) noise abatement. ___________________________________________________________________________ 57 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ 2.1.2 Navaids Due to the use of navaids, the procedure designer must consider: a) availability of navaids; b) the effects that navaid outages may have on the proposed procedure; c) the impact of the loss of a navaid on the procedure. 2.1.3 Meteo 2.1.3.1 Winds Wind also plays a major role in designing a procedure. Classical procedures design uses wind spirals, on the outside of turns, based upon a wind speed w1 and either the rate of turn or the bank angle and the TAS. Certain features, such as coastlines, villages and hills and valleys can affect the flow of air in a localised situation. Low level turbulence The general term ‘turbulence’ describes small variations in the local wind. Those that travel with the wind are termed gusts, whilst those that result from obstructions are termed eddies. The effects on aircraft are bumpiness possibly accompanied by sudden changes in airspeed attitude or altitude. The effects of turbulence on wind speed in the turbulence layer have already been considered. The most severe type of thermal turbulence occurs when cold polar air passes over a wellheated landmass. Thermal currents (‘thermals’) are generally larger and more noticeable to pilots than mechanical eddies and may well extend to a much greater height. Sea breeze During the day, the land surface temperature rises. This surface heating causes expansion of the air over the land and over the sea. Where the air is cooler the pressure at the same height is lower and the pressure above about 500 ft over the land rises. As a result of this pressure differential air flows out to sea above about 500ft starting as a gentle drift of one or two knots over a depth of two to three thousand feet. Because air is being taken away from the land, the pressure at the land surface begins to drop and as air begins to accumulate above 500 ft over the sea, the pressure at the sea surface rises. With high surface pressure over the 1 w = 2h+47 with h = aircraft altitude in thousands of ft ___________________________________________________________________________ 58 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ sea and low surface pressure over the land, the air at low level now flows from sea to land as a sea breeze, as illustrated at Figure 2.1. Figure 2.1.- Sea breeze Progressively through the day the sea breeze will be deflected by coriolis (geostrophic force) and eventually may turn sufficiently to blow parallel to the coast line. By the time that the eostrophic force exerts its full effect, however, the land is starting to cool and the sea breeze to diminish in strength. Sea breezes tend to reach the maximum speed by late afternoon, by which time the maximum surface heating has had time to work through the system. Sea breezes are most likely to occur under clear skies in the summer and with a slack pressure gradient to give otherwise light winds. In temperate latitudes, sea breezes reach a maximum speed of around 10 kt, although in tropical latitudes the speed may be as high as 20 kt or more. As a rule, sea breezes do not extend more than 10 to 15 miles on either side of the coastline, and the breeze is confined to very low levels, diminishing in speed rapidly above 500 ft to become negligible in most cases by about 1000 ft. From an aviation point of view the primary significance of sea breezes is that they can sometimes cause advection (sea) fog to drift inland to cover coastal airfields. Usually the high land surface temperatures, which caused the sea breeze, will normally disperse the fog and the sea breeze starts again. Convergence, resulting from air being slowed on reaching the coast, or with an existing offshore wind, can form convection cloud creating a sea breeze front. Thunderstorms can also be initiated by sea breezes if ___________________________________________________________________________ 59 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ conditions are suitable. In some cases, because the sea breeze tends to be shallow, wind shear can occur at coastal aerodromes. Land breezes A land breeze is the breeze which blows from land to sea by night. It is effectively a sea breeze in reverse, since by night the ground will be colder than the sea surface. 2.1.3.2 Visibility Visibility is a measure of the transparency of the atmosphere. By definition it is the maximum horizontal distance in a particular direction at which a dark object of certain dimensions can be seen against a light background such as the horizon sky by an average observer. When visibility varies with direction, the lowest value is measured. (Note that it is often possible to see lights, or shiny objects reflecting strong sunlight, at distances which are beyond the stated visibility, especially if they contrast with their surroundings). Visibility reported at night is that value which would be given by day in the same conditions of transparency of the atmosphere. Lights of known intensity are observed, and an allowance made for that intensity. The range at which the light can be seen is thus converted into equivalent daytime visibility. Meteorological visibility as defined is horizontal visibility at the surface. Haze, mist and fog all tend to be layered, so that visibilities at different levels may be very different. Furthermore light coloured objects are unlikely to be seen against a sky background until the range is considerably less than the published visibility. Flight visibility (which is relevant when assessing VFR criteria) is defined as being the visibility forwards from the flight deck. Obscuring matter which will reduce the transparency of the atmosphere, and therefore visibility, may be classified as follows: a) fog; b) mist; c) cloud; d) precipitation; ___________________________________________________________________________ 60 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ e) sea spray; f) smoke; g) sand; h) dust; i) low drifting and blowing snow. 2.1.3.3 Inflight visibility If a mist or fog layer lies well below the aircraft, the distance at which the ground will be visible will increase with height, as shown at Figure . As the aircraft descends, this distance will decrease markedly. Figure 2.2.- Reduction in visibility with reduction in height It is unwise to attempt a visual approach to land if this involves descending into an obscuring layer of fog, mist or haze without visual contact with the runway. Figure 2.3 shows an alternative solution, providing that the final approach angle does not exceed the limitations of the aircraft, the pilot, or the passengers! Because of glare, visibility is better looking down sun rather than looking into sun in mist or fog but conversely, looking towards the moon will give better visibility than looking away from the moon, because of the better contrast. ___________________________________________________________________________ 61 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ Figure 2.3.- (A) Visibility after turning on a normal approach (B) Visibility with a modified approach path 2.1.3.4 Runway visual range During a take-off run or when approaching to land the pilot requires information concerning the distance at which he may expect to see the runway markers or the runway lights as an aid to visual orientation. An assessment of meteorological visibility is, by definition, of limited value to the pilot under these conditions. One way in which the pilot is provided with a more pertinent assessment of the visibility is by passing him the Runway Visual Range, or RVR. RVR is defined as the maximum distance at which the pilot may expect to see the runway lights or runway markers, during a take-off or landing ground roll, from a point five metres above the touchdown point. RVR may be assessed by an observer stationed 76 metres from the centre line of the runway, abeam the touchdown point. The observer sights and counts (in the direction of ___________________________________________________________________________ 62 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ landing) the numbers of the runway markers, runway lights or special reference lights positioned at known intervals that he can see. Using tables, this number is converted to RVR and passed to the pilot. Using this manual system, RVR is assessed and passed to the pilot whenever the meteorological visibility is less than 1500 metres. Instrument Runway Visual Range systems (IRVR) are used at major airports to assess RVR automatically using transmissometers. These instruments measure the atmospheric opacity along the runway using a beamed light source of known intensity which is shining at a photo-electric cell some four feet away. A problem arises with IRVR in that the fog may be patchy and an IRVR meter measures localised visibility. This problem is overcome by positioning one instrument at the touchdown end of the runway, one at the mid-point, and one at the upwind end of the runway. IRVR reports are passed when the visibility falls below 1 500 metres, or when the observed IRVR is at or below the maximum assessable value for the equipment in use, or when shallow fog is forecast or reported. Between zero and 200 metres the RVR is reported in steps of 25 metres; between 200 and 800 metres in steps of 50 metres; and between 800 and 1 500 metres in steps of 100 metres. Using the IRVR system, the touchdown RVR is always reported. Mid-point and stop-end values are also given when they are less than 800 metres and lower than the touchdown RVR. Midpoint and stop-end values are also given (regardless of whether or not they are less than or greater than the touchdown value) whenever they are less than 400 metres or 500 metres, depending on the type of IRVR system in use. RVR is assessed every 30 minutes or as dictated by density of aircraft movements. There are major differences between the RVR and visibility measurements. RVR is concerned with the range at which markers or lights can be seen in a particular direction whereas visibility is the lowest visual range within the 360° of vision. • visibility is a measure of the transparency of the atmosphere. At night lights of known low values of brightness are used. • RVR systems may use high intensity lighting to increase the visual range. ___________________________________________________________________________ 63 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ • visibility is forecast but RVR is not because it can vary over short periods and is also dependent on the intensity of the runway lighting. 2.1.3.5 Cloud classification Cloud is classified in two ways, according to the height of the base, and according to the characteristic appearance. Table 2.1 shows the heights of the base of low, medium and high cloud. High cloud is unlikely to extend above the tropopause. As the height of the tropopause decreases towards the poles so do the tops of the upper cloud levels. Cloud Base height (in feet) Tropical latitudes Temperate latitudes Polar latitudes High 20 000 ft to 60 000 16 000 to 43 000 10 000 to 26 000 Medium 6 500 ft 26 000 6 500 to 23 000 6 500 to 13 000 Low surface to 6 500 surface to 6 500 surface to 6 500 Table 2.1.- Base height 2.1.3.6 Wind shear Background Wind shear is caused by variations in the direction and/or speed of the local wind with changes in height and/or horizontal distance, it is almost always present but normally does not cause undue difficulty to the pilot. It is the abnormal wind shear that is dangerous. Short-term fluctuations in the wind (gusts) are common at low altitudes, and are unlikely to cause prolonged excursions from the intended flight path and target air speed. If these gusts are large and prolonged their effect on an aircraft may be similar to that caused by a wind shear. Wind shear tends to displace an aircraft abruptly from its intended flight profile such that substantial control action is required. Definition of terms used in wind shear Low altitude wind shear This type of wind shear is experienced along the final approach path or during the initial climb-out flight path. ___________________________________________________________________________ 64 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ Types of wind shear The following definitions are used in order to differentiate between three distinct types of wind shear: • vertical wind shear. The change of horizontal wind vector with height (as might be determined by two or more anemometers at different heights on a mast). • horizontal wind shear. The change of horizontal wind vector with horizontal distance (as might be determined by two or more anemometers mounted at the same height but at different locations). • updraught/downdraught shear. Changes in the vertical component of wind with horizontal distance. Vertical wind shear can be present whenever an aircraft climbs or descends through a weather front. The more active the front the greater the risk of wind shear. A front which is moving at 30 kt or more and across which there is a temperature difference of 5°C or more, or at which a sharp change in wind direction occurs, is likely to produce serious wind shear problems. A vigorous cold front is likely to pose the greatest risk. The position of the aerodrome in relation to the surface position of the front is important. When landing (or taking off) at an aerodrome up to 30 nm ahead of a warm front or 20 nm or less behind a cold front the greatest risk of wind shear exists, as shown at Figure 2.4. Crossing a front in level flight can result in horizontal wind shear, which could present a problem at low level, for example during the early stages of a missed approach, where wind shear induced changes in airspeed and/or rates of climb may well be masked by the changing aircraft configuration. A sea breeze front is unlikely to create significant wind shear problems, however the presence of such a front may well distort the outflow of air from a coastal thunderstorm and increase the severity of the wind shear. Strong mean surface winds usually generate greater differences between the gusts and lulls and may therefore result in wind shear. In hotter climates intense surface heating can give rise to updraught/downdraught wind shear. Significant changes in wind direction can also result from air flowing over or around obstacles as large as mountains or as small as ___________________________________________________________________________ 65 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ hangars. Climbing or descending in the lee of high ground when the wind is strong can be particularly hazardous. Figure 2.4.- Areas of wind shear associated with an approach path through a warm and cold front ___________________________________________________________________________ 66 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ 2.2 Application to Seville Airport 2.2.1 Navaids In the procedures that I will design in the next chapters most headings, turns and locations are described by the use of only one navaid. This makes that these navaids are critical to execute the procedures. By malfunction of one of these navaids the procedures cannot be executed and other procedures shall be used. Which navaids are used with the procedures can be found on the charts (see Appendices) and descriptions in the following chapters. The following table shows us the available navaids at Seville Airport. Facility (VAR) ID FREQ HR VOR SVL 113.700 MHz H24 DME SVL CH 84X H24 NDB/LO SPP 420 kHz H24 LLZ 09 ILS CAT I GP 09 ISE 111.100 MHz H24 331.700 MHz H24 CH 48X H24 110.100 MHz H24 334.400 MHz H24 CH 38X H24 ILS/DME 09 LLZ 27 ISV ILS CAT I GP 27 ILS/DME 27 ISV Coordinates 372540.3792N 0054543.9497W ELEV DME 372540.1558N 0054543.8542W 372505.0066N 0054743.8583W 372504.8324N 0055220.8814W 372500.5017N 0055431.3008W 122.57 m (402 ft) 372500.5035N 0055431.2998W 372504.3021N 0055456.2564W 30.92 m (101 ft) 372500.8705N 0055242.5817W 372500.8705N 0055242.5817W Remarks Range 230° / 3000 ft 75 NM, 033° / 6500 ft 60 NM, 194° / 3000 ft 75 NM COV 40 NM 093º MAG / 145 m FM THR 27, COV 25 NM 3º; RDH 16.32 m; a / at 299 m FM to the right on APCH direction. 37.67 m (124 ft) REF DME THR 09 273° MAG / 314 m FM THR 09, COV 25 NM 3°; RDH 15.9 m; a / at 389 m FM THR 27 & 120 m FM RCL to the left on APCH direction. REF DME THR 27. Table 2.2.- Navaids 2.2.2 Noise abatement procedure Motor test higher than idle is not allowed in any stand of the apron. The motor test clearance higher than idle has to be requested to the Centro de Operaciones, who will refuse or approve the proposed procedure. 2.2.3 Speed limits Within Seville TMA, arrival flights to Seville AD under radar control shall adjust their speeds according to the following: ___________________________________________________________________________ 67 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ • maximum IAS 250 kt at FL 120 or lower; • IAS 210 kt at the beginning of the final turn to intercept the ILS localizer course when the aircraft is located within 20 NM of the landing threshold; • IAS 180 kt once the final turn is completed and established on the ILS localizer when the aircraft is located within 20 NM of the landing threshold; • IAS MAX 160 kt when crossing the NDB SPP; • aircraft with cruising IAS lower than the aforementioned shall maintain cruising speed up to the adjusting fix concerned. 2.2.4 Low Visibility Procedures 2.2.4.1 General Departures in low visibility conditions will be cleared at runway 09/27. Low Visibility Procedures (LVP) will be applied subject to the following conditions: a) when the meteorological minimums established below, are defined in terms of: • Runway visual range (RVR) for runway 27, or • General visibility in movement area for runway 09 (and also for runway 27, if RVR is not operative) is equal or below 600 m. b) pilots will be informed about the application of Low Visibility Procedures by ATC and by ATIS with the following text "LOW VISIBILITY PROCEDURE IN OPERATION". c) pilots will be informed by ATC when the application of the procedures are cancelled, this will take place when RVR or visibility is higher than 1000 metres. 2.2.4.2 Ground movement Pilots will proceed to verify at every moment the aircraft position checking that taxiing is being executed under total safety conditions. In case of being disoriented or in doubt, pilots will stop the aircraft and immediately will notify to ATC. a) arrivals: • aircraft, that have already landed, will notify on exiting the runway: "runway vacated"; • at the apron entry, they must wait for the arrival of a "FOLLOW ME" vehicle in order to be guided to the assigned stand, notifying to TWR: "FOLLOW ME" is in sight. ___________________________________________________________________________ 68 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ b) departures: • pilots will request clearance to start-up engines or taxiing, reporting the apron stand number and the apron exit gate they will use; • when the RVR/visibility is below 600 m, the taxiing of only one aircraft at the same time in the movement area will be authorized; • in case of a departing aircraft had to return to apron, the pilot will inform TWR and wait for new instructions for taxiing. 2.2.4.3 Communications failure Whenever an aircraft or vehicle operating in the manoeuvring area experiences a communication failure, it will comply as follows: a) departing aircraft: It will continue by the assigned route to its clearance limit, taking extreme caution to avoid detours. Once that point have been reached, it must maintain the position and wait for the arrival of a "FOLLOW ME" vehicle in order to be guided to the stand or the assigned holding point; b) arriving aircraft: It will hold the position in the first section of the taxiway in which the sensitive area of the ILS remains free and will wait for the arrival of a "FOLLOW ME" vehicle that will lead him to the position of assigned stand; c) vehicle: It will proceed to leave the zone of "not permanency" by the closer point of his position. 2.2.5 Meteo 2.2.5.1 General data Table 2.3 hereunder shows the general data considered with Seville Airport. As a general conclusion you could say that Seville has a Mediterranean climate, with average temperatures of 26º C in the summer and 12º C in the winter. Winters are also mild. It rains only slightly during the autumn (average annual rainfall: 534 mm). Highest temperatures are experienced during the summer. With close to 3000 hours of sunlight annually, Seville's climate can be considered almost as perfect in all seasons. Thanks to this good climate, Seville Airport will be open all year. ___________________________________________________________________________ 69 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ Month Januari Februari March April May June July August September October November December Temperature (°C) Precipitation (mm) Average number of days with Average Av. max Av. min Max Min Av. Max 24h N° days Snow Storm Frost Hours of sun 10.6 12.2 14.7 16.4 19.7 23.9 27.4 27.2 24.5 19.6 14.8 11.8 179 183 224 234 287 312 351 328 250 218 186 154 15.9 17.9 21.2 22.7 26.4 31.0 35.3 35.0 31.6 25.6 20.1 16.6 5.2 6.7 8.2 10.1 13.1 16.7 19.4 19.5 17.5 13.5 9.3 6.9 23.0 27.6 30.4 35.4 39.1 43.0 46.6 44.8 42.6 35.6 30.0 24.5 -4.4 65 -3.2 54 -2.0 38 2.4 57 6.4 34 8.4 13 14.0 2 12.2 6 8.6 23 2.2 62 -1.4 84 -4.8 95 54 48 75 50 32 55 46 58 47 69 109 57 6 6 5 7 4 2 0 0 2 6 6 8 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 1 1 0 0 1 1 1 1 2 1 0 0 0 0 0 0 0 0 0 1 Table 2.3.- Climate summary (1971-2001) 2.2.5.2 Wind Seville experiences mild winds during spring and summer, which is a typical feature of the Mediterranean climate. These calm breezes will not affect or jeopardize airplanes leaving or landing at Seville Airport. Figure 2.5.- Frequency of velocity and direction of wind for the month of July ___________________________________________________________________________ 70 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ Figure 2.6.- Frequency of velocity and direction of wind for the month of January 2.2.5.3 Visibility In Chapter 2.2.4 I already discussed the low visibility procedure. The low visibility procedures start at a visibility below 600 m and are cancelled above a visibility of 1000 m. When the RVR/visibility is below 600 m, the taxiing of only one aircraft at the same time in the movement area will be authorized. The graphs only show the visibility below 800 m so it is difficult to say when exactly low visibility procedures apply. During the winter the visibility can be below 800 m, especially in the morning. During summer though the chance on low visibility is much smaller. Figure 2.7.- Frequency (%) of the intervals with visibility lower than 800, 1 500, 3 000 and 5 000 m – January (1983-1992) ___________________________________________________________________________ 71 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ Figure 2.8.- Frequency (%) of the intervals with visibility lower than 800, 1 500, 3 000 and 5 000 m – July (1983-1992) 2.2.5.4 Clouds The statistics (Figure 2.9 and 2.10) below give the height of the cloud base at Seville Airport, measured from 1983 to 1992. Cloud base is an important meteorological variable for aviation safety, as it determines whether pilots may use Visual Flight Rules (VFR) or must follow Instrument Flight Rules for take-off or landing. Figure 2.9.- Frequency (%) of base of clouds lower than 30, 60, 150 and 300 m – January (19832001) ___________________________________________________________________________ 72 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ Figure 2.10.- Frequency (%) of base of clouds lower than 30, 60, 150 and 300 m – July (1983-2001) 2.2.5.5 Wind shear Figure 2.11 shows the mean frequency of the intervals of the components of the wind perpendicular to the runway of Seville Airport. Wind shear can affect aircraft airspeed during take off and landing in disastrous ways. It is also a key factor governing the severity of thunderstorms. An additional hazard is turbulence often associated with wind shear. Wind shear also generally inhibits tropical cyclone development. Figure 2.11.- Mean frequency (%) of the intervals of the components of the wind perpendicular to the runway (1983-1992) 2.2.6 Flow Though Seville Airport does have some general aviation flights, it mostly deals with commercial flights, carrying passengers and cargo. ___________________________________________________________________________ 73 Chapter 2: Operational requirements _________________________________________________________________________________________________________________ 2.2.6.1 Commercial flights Though Seville airport does have some international traffic, it basically deals with domestic traffic, which represents 75 percent of the total. International destinations are mostly Germany (Dusseldorf and Frankfurt), Italy (Florence, Milan and Rome) and the United Kingdom (Liverpool, London Gatwick and London Stansted). Other airports that have connections with Seville Airport are located in Belgium, France, the Netherlands, Ireland and Portugal. From Seville Airport other countries can be flown to with scheduled flights with stopover. As already stated, most of the flights at Seville Airport are domestic flights and provide connection with other Spanish cities. Hereunder follows a list of the Spanish cities to which you can travel to from the airport: • a Coruña • Madrid-Barajas • Alicante • Palma de Mallorca • Asturias • San Sebastian • Barcelona • Santander • Bilbao • Santiago de Compostela • Fuerteventura • Tenerife North • Gran Canaria • Tenerife South • Santa Cruz de la Palma • Valencia • Lanzarote • Valladolid • Zaragoza In 2006 a total of 3,870,600 passengers passed through the airport, which carried out 58,565 flight operations and dealt with 11,530 tonnes of cargo. 2.2.6.2 General aviation One of the main users, besides the rich and famous people with there own planes, of the platform for general aviation is the Royal Aeroclub of Seville. They operate a Piper, a Cessna 152 and a Cessna 172 for the education of future pilots. ___________________________________________________________________________ 74 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3 Aerodrome Obstacle Limitation 3.1 Aerodrome Obstacle Surfaces The standards for designing the obstacle surfaces can be found in the ICAO Annex 14 and the “Decreto de Servidumbres”, in the design a lot of decisions have to be taken and it can happen that there are small differences between them, for instance the reference key for the aerodrome, principal parameter for the later development of the work, you have: Code Number Aeroplanes reference field length- Code Aeroplanes reference field length- ICAO Letter Decreto de Servidumbres 1 Less than 800 m A 2 100 and over 2 800 m up to but not including 1 200 m B 1 500 m up to but not including 2 100 m 3 1 200 m up to but not including 1800 C 900 m up to but not including 1 500 m 4 1 800 m and over D 750 m up to but not including 900 m E Less than 750 m - - Table 3.1- Reference keys from the aerodrome As you can see, the criterions are slightly different, by coincidence the mayor part of the actual aerodromes use the key (symbol): ‘4’ when you take the ICAO document, or the key ‘A’ when you use the “Decreto de Servidumbres”, so a combination of specifications coincidence with each other. We have to remember that in the case of doubt it would be better to use the “Decreto de Servidumbres”, because it is ‘safer’ than the ICAO Annex 14. Using the “Decreto de Servidumbres” complicates the problem of the obstacle limitation surfaces therefore the old Spanish standard will not be mentioned again. 3.1.1 Runway classification according to operation There exist, as indicated in the next section, different types of aerodrome limitation surfaces; nonetheless, the application of one or other depends, according to the indication in the ICAO Annex 14, on the operational utilisation of the runways. From a similar form, the parameters that define each surface take different values according to the operation that is realised on the respective runway. From this point of view, a runway classification can be realised, afterwards, according to this classification, there can be dealt with the different surfaces applicable to these. _______________________________________________________________________________________________________________________________________________________ 75 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.1.2 Types of surfaces The types of obstacle limitation surfaces of an aerodrome are those who can be found in Table 3.2. In this table all the surfaces for the ICAO standard are mentioned. Surfaces – Annex 14 Strip Approach Inner Approach Transitional Inner Transitional Inner Horizontal Conical Outer Horizontal Balked Landing Take-off Climb Table 3.2- Types of obstacle limitation surfaces from the aerodrome 3.1.3 Surface description 3.1.3.1 Runway strip The runway strip is not really an obstacle limitation surface, it represents an area around the runway in which the existence of obstacles is regulated. Every object situated in the runway strip and a possible danger to the aeroplanes must be considered as an obstacle and be eliminated. An object located in the strip can for instance be the glide path antenna of the instrument landing system. 3.1.3.2 Approach surface This surface defines the volume of airspace that should be kept free from obstacles to protect an aeroplane in the final phase of the approach -to- land manoeuvre. The slope and dimensions will vary with the aerodrome reference code and whether the runway is used for visual, non-precision or precision approaches. It consists of an inclined plane or a combination of planes preceding the threshold. The limits of the approach surface are described in the next chapter. _______________________________________________________________________________________________________________________________________________________ 76 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.1.3.3 Transitional surface As indicated earlier, the transitional surfaces together with the approach surfaces define the part of the airspace that has to be kept free from obstacles to protect the aeroplanes during the final approach manoeuvring phase before the landing. This is for each runway where approach manoeuvres are realised, these manoeuvres can be visual, precision and nonprecision. 3.1.3.4 Inner horizontal surface The purpose of the inner horizontal surface is to protect the airspace for visual circling prior to landing, possibly after a descent through clouds, aligned with a runway other than that in use for landing. In some instances, certain sectors of the visual circling areas will not be essential to aircraft operations, provided procedures are established to ensure that aircraft do not fly in these sectors, the protection afforded by the inner horizontal surface does not need to extend into those sectors. 3.1.3.5 Conical Is a surface sloping upwards and outwards from the periphery of the inner horizontal surface. It indicates the aircraft en circuit that the inner horizontal surface has a value in the conical surface. The purpose of the conical surface is to protect the airspace for visual circling prior to landing, possibly after a descent through clouds, aligned with a runway other than that in use for landing. In some instances, certain sectors of the visual circling areas will not be essential to aircraft operations, provided procedures are established to ensure that aircraft do not fly in these sectors, the protection afforded by the conical surface does not need to extend into those sectors. Similar discretion can be exercised when procedures have been established and navigational guidance provided to ensure that defined approach and missed approach paths will be followed. _______________________________________________________________________________________________________________________________________________________ 77 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.1.3.6 Outer horizontal surface In the experience of some States significant operational problems can arise from the erection of tall structures in the vicinity of airports beyond the areas currently recognised in ICAO Annex 14 as areas in which restriction of new construction may be necessary. The operational implications fall broadly under the headings of safety and efficiency. Safety implications: It is particularly desirable to review carefully any proposal to erect high masts or skeletal structures in aircraft areas for use on wide visual circuits, on arrival routes, on departure or missed approach climb-paths. Marking and lighting is not always sufficient especially in conditions of reduced visibility. Efficiency implications: If tall structures erect in or near areas suitable for instrument approach procedures, increased procedure heights may need to be adopted, with consequent adverse effects on the regularity and on the duration of the approach procedure, such as the denial of useful altitude allocations to aircraft in associated holding patterns. Such structures may furthermore limit desirable flexibility for radar operations. Tall structures would not be of immediate significance if they are proposed to be located in an area already substantially obstructed by terrain or existing structures of equivalent height; and an area which would be safely avoided by prescribed procedures associated with navigational guidance when appropriate. Tall structures can be considered to be of possible significance if they are both higher than 30m above local ground level and higher than 150 m above aerodrome elevation within a radius of 15 000m of the centre of the airport where the runway code number is 3 or 4. This area has to coincide with the other obstacle limitation surfaces. 3.1.3.7 Take-off climb surface This surface provides protection for an aircraft on take-off, by indicating which obstacles should be removed if possible and marked or lighted if removal is impossible. The dimensions and slopes also vary with the aerodrome reference code. In the next chapter slope, dimensions and divergence can be found. These parameters can be used for every existing runway taking the aerodrome reference code into account. _______________________________________________________________________________________________________________________________________________________ 78 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.1.3.8 Obstacle free zone The obstacle free zone (OFZ) is described in the precision approach procedures to protect the missed approach after passing the decision height, when the operation is visual realised. In this serious case for example, using OCA/H, after decided to go on with the landing, the visual references will be needed. The OFZ is defined as the airspace above the inner approach surface, the inner transitional surface, the balked landing surface and a part of the limited strip for these surfaces. This zone is free of fixed obstacles, with exception of the navigation aids, rising and supporting light and fragile, located on the strip to do there task; and the temporary objects like aeroplanes and vehicles when the strip is used for ILS approach category I or II. The OFZ for a CAT I approach, has to be free of these objects when the strip is used for an ILS CAT I approach. The definitions to create an OFZ are the following: a) inner approach surface: The inner approach surface is a rectangular portion of the approach surface immediately preceding the threshold. The surface will be described in detail in the next chapters, also the physical characteristics will be mentioned. b) inner transitional surface: The purpose of the inner transitional surface is to control obstacle limitation for navigation aids, aircraft and other vehicles that must be near the runway and are not allowed to penetrate the surface, except frangible objects. This transitional surface is intended to remain as the controlling obstacle limitation surface for buildings, etc. The inner transitional surface is a surface similar to the transitional surface, but closer to the runway. Because it is a surface that creates more than the transition and starts to fence the axe of the strip because the transition is more restricted. For an other part, like indicated, this surface determines to avoid the existence of obstacles like the navigational aids and the aircraft, decided with obstacles with a particular character. _______________________________________________________________________________________________________________________________________________________ 79 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ When a strip operates in CAT I, II or III, these surfaces have to be free of obstacles, it is important that the aircraft is far enough from the strip because its vertical landing has no vulnerability, especially leaving the strip in take-off. As long as this doesn’t occur, no other aircraft can operate. In many cases this can be a principal capacity restriction when activated in low visibility approach. c) balked landing surface: The definition of this surface is similar to the one of the inner transitional surface. The obstacles to be avoided are installations from the airport and, or aircraft. Their function is to protect the missed approach manoeuvrability under the decision altitude. This surface doesn’t represent in the serviceability of the airport to require other surfaces for take-off and for much more restrictions. This surface consists of a plane situated in a distance specified after the threshold, stretched between the internal transition surfaces. _______________________________________________________________________________________________________________________________________________________ 80 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.2 Aerodrome Obstacle Restriction and Removal The objectives of the specifications in this chapter are to define the airspace around aerodromes to be maintained free from obstacles so as to permit the intended aeroplane operations at the aerodromes to be conducted safely and to prevent the aerodromes from becoming unusable by the growth of obstacles around the aerodromes. This is achieved by establishing a series of obstacle limitation surfaces that define the limits to which objects may project into the airspace. Objects which penetrate the obstacle limitation surfaces contained in this chapter may in certain circumstances cause an increase in the obstacle clearance altitude/height for an instrument approach procedure or any associated visual circling procedure. Criteria for evaluating obstacles are contained in Procedures for Air Navigation Services — Aircraft Operations (PANS-OPS). 3.2.1 Obstacle Limitation 3.2.1.1 Conical Surface The conical surface is sloping upwards and outwards from the periphery of the inner horizontal surface. The limits of the conical surface shall comprise: a) a lower edge coincident with the periphery of the inner horizontal surface; and b) an upper edge located at a specified height above the inner horizontal surface. The slope of the conical surface shall be measured in a vertical plane perpendicular to the periphery of the inner horizontal surface. 3.2.1.2 Inner Horizontal Surface Inner Horizontal Surface is a surface located in a horizontal plane above an aerodrome and its environs. The radius or outer limits of the inner horizontal surface shall be measured from a reference point or points established for such purpose. The shape of the inner horizontal surface need not necessarily be circular. Guidance on determining the extent and elevation of the inner horizontal surface is contained in the Airport Services Manual, Part 6.The height of the inner horizontal surface shall be measured above an elevation datum established for such purpose. _______________________________________________________________________________________________________________________________________________________ 81 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.2.1.3 Approach Surface Approach surface is an inclined plane or combination of planes preceding the threshold. The limits of the approach surface shall comprise: a) an inner edge of specified length, horizontal and perpendicular to the extended centre line of the runway and located at a specified distance before the threshold; b) two sides originating at the ends of the inner edge and diverging uniformly at a specified rate from the extended centre line of the runway; c) an outer edge parallel to the inner edge; d) the above surfaces shall be varied when lateral offset, offset or curved approaches are utilized, specifically, two sides originating at the ends of the inner edge and diverging uniformly at a specified rate from the extended centre line of the lateral offset, offset or curved ground track. The elevation of the inner edge shall be equal to the elevation of the mid-point of the threshold. The slope(s) of the approach surface shall be measured in the vertical plane containing the centre line of the runway and shall continue containing the centre line of any lateral offset or curved ground track. 3.2.1.4 Inner approach surface Inner approach surface is a rectangular portion of the approach surface immediately preceding the threshold. The limits of the inner approach surface shall comprise: a) an inner edge coincident with the location of the inner edge of the approach surface but of its own specified length; b) two sides originating at the ends of the inner edge and extending parallel to the vertical plane containing the centre line of the runway; c) an outer edge parallel to the inner edge. _______________________________________________________________________________________________________________________________________________________ 82 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ Figure 3.1- Obstacle limitation surfaces 3.2.1.5 Transitional surface. Transitional surface is a complex surface along the side of the strip and part of the side of the approach surface, that slopes upwards and outwards to the inner horizontal surface. The limits of a transitional surface shall comprise: a) a lower edge beginning at the intersection of the side of the approach surface with the inner horizontal surface and extending down the side of the approach surface to the inner edge of the approach surface and from there along the length of the strip parallel to the runway centre line; and b) an upper edge located in the plane of the inner horizontal surface. _______________________________________________________________________________________________________________________________________________________ 83 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ The elevation of a point on the lower edge shall be: a) along the side of the approach surface — equal to the elevation of the approach surface at that point; and b) along the strip — equal to the elevation of the nearest point on the centre line of the runway or its extension. Note: As a result of b) the transitional surface along the strip will be curved if the runway profile is curved, or a plane if the runway profile is a straight line. The intersection of the transitional surface with the inner horizontal surface will also be a curved or a straight line depending on the runway profile. The slope of the transitional surface shall be measured in a vertical plane at right angles to the centre line of the runway. Figure 3.2- Inner approach, inner transitional and balked landing surfaces _______________________________________________________________________________________________________________________________________________________ 84 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.2.1.6 Inner transitional surface It is intended that the inner transitional surface be the controlling obstacle limitation surface for navigation aids, aircraft and other vehicles that must be near the runway and which is not to be penetrated except for frangible objects. The transitional surface is intended to remain as the controlling obstacle limitation surface for buildings, etc. The inner transitional surface is a surface similar to the transitional surface but closer to the runway. The limits of an inner transitional surface shall comprise: a) a lower edge beginning at the end of the inner approach surface and extending down the side of the inner approach surface to the inner edge of that surface, from there along the strip parallel to the runway centre line to the inner edge of the balked landing surface and from there up the side of the balked landing surface to the point where the side intersects the inner horizontal surface; and b) an upper edge located in the plane of the inner horizontal surface. The elevation of a point on the lower edge shall be: a) along the side of the inner approach surface and balked landing surface — equal to the elevation of the particular surface at that point; and b) along the strip — equal to the elevation of the nearest point on the centre line of the runway or its extension. Note: As a result of b) the inner transitional surface along the strip will be curved if the runway profile is curved or a plane if the runway profile is a straight line. The intersection of the inner transitional surface with the inner horizontal surface will also be a curved or straight line depending on the runway profile. The slope of the inner transitional surface shall be measured in a vertical plane at right angles to the centre line of the runway. 3.2.1.7 Balked landing surface The balked landing surface is an inclined plane located at a specified distance after the threshold, extending between the inner transitional surface. The limits of the balked landing surface shall comprise: _______________________________________________________________________________________________________________________________________________________ 85 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ a) an inner edge horizontal and perpendicular to the centre line of the runway and located at a specified distance after the threshold; b) two sides originating at the ends of the inner edge and diverging uniformly at a specified rate from the vertical plane containing the centre line of the runway; and c) an outer edge parallel to the inner edge and located in the plane of the inner horizontal surface. The elevation of the inner edge shall be equal to the elevation of the runway centre line at the location of the inner edge. The slope of the balked landing surface shall be measured in the vertical plane containing the centre line of the runway. 3.2.1.8 Take-off climb surface The take-off climb surface an inclined plane or other specified surface beyond the end of a runway or clearway. The limits of the take-off climb surface shall comprise: a) an inner edge horizontal and perpendicular to the centre line of the runway and located either at a specified distance beyond the end of the runway or at the end of the clearway when such is provided and its length exceeds the specified distance; b) two sides originating at the ends of the inner edge, diverging uniformly at a specified rate from the take-off track to a specified final width and continuing thereafter at that width for the remainder of the length of the takeoff climb surface; and c) an outer edge horizontal and perpendicular to the specified take-off track. The elevation of the inner edge shall be equal to the highest point on the extended runway centre line between the end of the runway and the inner edge, except that when a clearway is provided the elevation shall be equal to the highest point on the ground on the centre line of the clearway. In the case of a straight take-off flight path, the slope of the take-off climb surface shall be measured in the vertical plane containing the centre line of the runway. In the case of a take-off flight path involving a turn, the take-off climb surface shall be a complex surface containing the horizontal normals to its centre line, and the slope of the centre line shall be the same as that for a straight take-off flight. _______________________________________________________________________________________________________________________________________________________ 86 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.2.2 Obstacle limitation requirements The requirements for obstacle limitation surfaces are specified on the basis of the intended use of a runway, i.e. take-off or landing and type of approach, and are intended to be applied when such use is made of the runway. In cases where operations are conducted to or from both directions of a runway, then the function of certain surfaces may be nullified because of more stringent requirements of another lower surface. 3.2.2.1 Non-instrument runways The following obstacle limitation surfaces shall be established for a non-instrument runway: • conical surface; • inner horizontal surface; • approach surface; • transitional surfaces. The heights and slopes of the surfaces shall not be greater than, and their other dimensions not less than, those specified in Table 2.3. New objects or extensions of existing objects shall not be permitted above an approach or transitional surface except when, in the opinion of the appropriate authority, the new object or extension would be shielded by an existing immovable object. Circumstances in which the shielding principle may reasonably be applied are described in the Airport Services Manual, Part 6. Because of transverse or longitudinal slopes on a strip, in certain cases the inner edge or portions of the inner edge of the approach surface may be below the corresponding elevation of the strip. It is not intended that the strip be graded to conform with the inner edge of the approach surface, nor is it intended that terrain or objects which are above the approach surface beyond the end of the strip, but below the level of the strip, be removed unless it is considered they may endanger aeroplanes. _______________________________________________________________________________________________________________________________________________________ 87 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ Table 3.3- Dimensions and Slopes of Obstacle Limitation Surfaces – Approach Runways 3.2.2.2 Non-precision approach runways The following obstacle limitation surfaces shall be established for a non-precision approach runway: _______________________________________________________________________________________________________________________________________________________ 88 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ • conical surface; • inner horizontal surface; • approach surface; • transitional surfaces. The heights and slopes of the surfaces shall not be greater than, and their other dimensions not less than, those specified in Table 3.3, except in the case of the horizontal section of the approach surface. The approach surface shall be horizontal beyond the point at which the 2.5 per cent slope intersects: a) a horizontal plane 150 m above the threshold elevation; or b) the horizontal plane passing through the top of any object that governs the obstacle clearance altitude/height (OCA/H); whichever is the higher. New objects or extensions of existing objects shall not be permitted above an approach surface within 3 000 m of the inner edge or above a transitional surface except when, in the opinion of the appropriate authority, the new object or extension would be shielded by an existing immovable object. Circumstances in which the shielding principle may reasonably be applied are described in the Airport Services Manual, Part 6. Because of transverse or longitudinal slopes on a strip, in certain cases the inner edge or portions of the inner edge of the approach surface may be below the corresponding elevation of the strip. It is not intended that the strip be graded to conform with the inner edge of the approach surface, nor is it intended that terrain or objects which are above the approach surface beyond the end of the strip, but below the level of the strip, be removed unless it is considered they may endanger aeroplanes. 3.2.2.3 Precision approach runways The following obstacle limitation surfaces shall be established for a precision approach runway category I: • conical surface; • inner horizontal surface; • approach surface; and _______________________________________________________________________________________________________________________________________________________ 89 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ • transitional surfaces. The following obstacle limitation surfaces shall be established for a precision approach runway category II or III: • conical surface; • inner horizontal surface; • approach surface and inner approach surface; • transitional surfaces; • inner transitional surfaces; and • balked landing surface. The heights and slopes of the surfaces shall not be greater than, and their other dimensions not less than, those specified in Table 3.3, except in the case of the horizontal section of the approach surface . The approach surface shall be horizontal beyond the point at which the 2.5 per cent slope intersects: a) a horizontal plane 150 m above the threshold elevation; or b) the horizontal plane passing through the top of any object that governs the obstacle clearance limit; whichever is the higher. Fixed objects shall not be permitted above the inner approach surface, the inner transitional surface or the balked landing surface, except for frangible objects which because of their function must be located on the strip. Mobile objects shall not be permitted above these surfaces during the use of the runway for landing. New objects or extensions of existing objects shall not be permitted above an approach surface or a transitional surface except when, in the opinion of the appropriate authority, the new object or extension would be shielded by an existing immovable object. Circumstances in which the shielding principle may reasonably be applied are described in the Airport Services Manual, Part 6. Because of transverse or longitudinal slopes on a strip, in certain cases the inner edge or portions of the inner edge of the approach surface may be below the corresponding elevation of the strip. It _______________________________________________________________________________________________________________________________________________________ 90 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ is not intended that the strip be graded to conform with the inner edge of the approach surface, nor is it intended that terrain or objects which are above the approach surface beyond the end of the strip, but below the level of the strip, be removed unless it is considered they may endanger aeroplanes. 3.2.2.4 Runways meant for take-off The following obstacle limitation surface shall be established for a runway meant for takeoff: take-off climb surface The dimensions of the surface shall be not less than the dimensions specified in Table 3.3, except that a lesser length may be adopted for the take-off climb surface where such lesser length would be consistent with procedural measures adopted to govern the outward flight of aeroplanes. When local conditions differ widely from sea level standard atmospheric conditions, it may be advisable for the slope specified in Table 3.3 to be reduced. The degree of this reduction depends on the divergence between local conditions and sea level standard atmospheric conditions, and on the performance characteristics and operational requirements of the aeroplanes for which the runway is intended. New objects or extensions of existing objects shall not be permitted above a take-off climb surface except when, in the opinion of the appropriate authority, the new object or extension would be shielded by an existing immovable object. Circumstances in which the shielding principle may reasonably be applied are described in the Airport Services Manual, Part 6. Because of transverse slopes on a strip or clearway, in certain cases portions of the inner edge of the take-off climb surface may be below the corresponding elevation of the strip or clearway. It is not intended that the strip or clearway be graded to conform with the inner edge of the take-off climb surface, nor is it intended that terrain or objects which are above the take-off climb surface beyond the end of the strip or clearway, but below the level of the strip or clearway, be removed unless it is considered they may endanger aeroplanes. Similar considerations apply at the junction of a clearway and strip where differences in transverse slopes exist. _______________________________________________________________________________________________________________________________________________________ 91 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ Surface and Dimension 1 2 3 of 4 Length of inner edge 60 m 80 m 180 m Distance from runway end 30 m 60 m 60 m Divergence 10% 10% 12.5% Final Width 380 m 580 m 1 200 m Length 1 600 m 2 500 m 15 000 m Slope 5% 4% 2% Take-off Climb Table 3.4- Dimensions and slopes for obstacle limitation surfaces 3.2.3 Objects outside the obstacle limitation surfaces Arrangements should be made to enable the appropriate authority to be consulted concerning proposed construction beyond the limits of the obstacle limitation surfaces that extend above a height established by that authority, in order to permit an aeronautical study of the effect of such construction on the operation of aeroplanes. In areas beyond the limits of the obstacle limitation surfaces, at least those objects which extend to a height of 150 m or more above ground elevation should be regarded as obstacles, unless a special aeronautical study indicates that they do not constitute a hazard to aeroplanes. This study may have regard to the nature of operations concerned and may distinguish between day and night operations. 3.2.4 Other objects Objects which do not project through the approach surface but which would nevertheless adversely affect the optimum siting or performance of visual or non-visual aids should, as far as practicable, be removed. Anything which may, in the opinion of the appropriate authority after aeronautical study, endanger aeroplanes on the movement area or in the air within the limits of the inner horizontal and conical surfaces should be regarded as an obstacle and should be removed in so far as practicable. In certain circumstances, objects that do not project above any of the surfaces enumerated in Table 3.3 may constitute a hazard to aeroplanes as, for example, where there are one or more isolated objects in the vicinity of an aerodrome. _______________________________________________________________________________________________________________________________________________________ 92 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ Figure 3.3- Obstacle Limitation Surfaces _______________________________________________________________________________________________________________________________________________________ 93 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.3 Application to Seville Airport 3.3.1 General In Chapter I the ICAO airport characteristics are given but they are not as detailed as the ones given in the AIP. For further calculations we will use the following data. Aerodrome Geographical Data ARP Latitude: 372504.5168 N ARP Longitude: 0055356.0889 W Distance and direction to the city 10 km SE Elevation: 33.88 m / 111 feet 1 Magnetic variation: 4°W Reference temperature: 35°C Approved traffic: IFR / VFR Table 3.5- Aerodrome geographical Data Each year the coordinates of the ARP move 8,2’ east. In the calculations we do not use this annual change. In the Spanish AIP special data concerning the runways can be found. We will need these values in order to define and draw the obstacle surfaces. Table 3.6- Runway physical characteristics 1 2 The elevation of the ARP is the highest point of the runway profile. In the clearway from both runways is included 50 m of anti-blast area. _______________________________________________________________________________________________________________________________________________________ 94 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ Figure 3.4- Runway profile 3.3.2 Calculations of coordinates from WSG84 to UTM The ARP and the two runway threshold co-ordinates, given in 4.1.1 and 4.1.2, are coordinates in the WGS 84 system. In AutoCAD the UTM- co-ordinates are used, therefore the WGS 84 coordinates had to be converted into UTM-co-ordinates. I used CoordTrans V2.3-Franson to convert the coordinates. It is software that can be downloaded free of any charge. Following results were found: Aerodrome reference point: X: 243557.11416 Y: 4145383.35217 Runway threshold 09: X: 242388.99795 Y: 4145414.19972 Runway threshold 27: X: 245751.25858 Y: 4145325.32286 3.3.3 Calculation of the surfaces Although you could say that runway 09 and 27 are the same runways, there will be a difference in the elevation of the obstacle surfaces. For some surfaces you use the ARP height, which is the same for both runways, but for most of the surfaces the elevation of the threshold is used. These vary due to the slope of the runway. This is the reason why all the calculations will be made for both runways. Before starting the calculations you have to know which classification the runway has. For Seville as well runway 09 as 27 are precision approach category 1 with code number 4. Now the correct column of Table 2.3 can be used. _______________________________________________________________________________________________________________________________________________________ 95 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.3.3.1 Conical Surface For the conical surface the slope is 5% which corresponds to 2.86°. The upper edge of the conical is located 100 m above the inner horizontal surface. For both runways the conical starts at 78.8 metres and the upper edge is located at 178.8 m. The horizontal displacement of the conical can be calculate with these data: (100/5) x 100 = 2 000 m 3.3.3.2 Inner Horizontal The radius of the inner horizontal surface is 4000 m and shall be measured from the threshold of both runways. The inner horizontal surface is located 45 m above the ARP. 45 m + 33.8 m = 78.8 m Because for both runways the ARP elevation is used there will be no difference between the inner horizontal for runway 09 and 27. 3.3.3.3 Approach Surface The length of the inner edge is 300 m and is located at a distance of 60 m from the threshold of each runway. The surface has a uniform divergence of 15% (8.53°). The first section has a length of 3 000 m and a slope of exactly 2% (1.15°), while the second section is 3 600 m long and has a slope of 2.5% (1.43°). The horizontal section has a length of 8 400 m so the total length of the approach surface is 15 000 m. Though this is the same for both runways, the surfaces will start at a different elevation. This means that the upper edges will be located at different elevations. • Runway 09: The surface begins at 33.3 m and extends to an altitude of 183.8 m. The first section has an elevation of 93.8 m. • Runway 27: The surface begins at 25.3 m and extends to an altitude of 175.3 m. The first section has an elevation of 85.1 m. _______________________________________________________________________________________________________________________________________________________ 96 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ Figure 3.5- Vertical path of the approach surface - RWY 27 3.3.3.4 Inner Approach surface The inner approach is 120 m wide and is located 60 m from the threshold. The length of the surface is 900 m and the slope is 2% (1.15°). With these parameters the elevation of the outer edge can be calculated. (900/100) x 2 = 18 m • Runway 09: The outer edge is located 18 m above the threshold. 25.31 + 18 = 43.31 m • Runway 27: The outer edge is located 18 m above the threshold. 33.83 + 18 = 51.83 m 3.3.3.5 Transitional surface For the transitional surface you only need the slope which is 14.3% for all precision approaches. The height of the upper edge is 45 m above the height of the lower edge. This results in an altitude of 73.83 m for the upper edge if we use 33.83 m for the altitude of the lower edge. With this value you can calculate the horizontal displacement from the strip. (45/14.3) x 100 = 315 m 3.3.3.6 Inner Transitional The slope of the inner transitional is 33.3 % (18.42°) for both runways. The upper edge is located in the plane of the inner horizontal surface, corresponding to an altitude of 77.8 m. 77.8 m minus the 33.8 m from the ARP altitude gives us 44 m. 44 m divided by 0.333 gives 132 m, this is the horizontal displacement. _______________________________________________________________________________________________________________________________________________________ 97 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.3.3.7 Balked Landing surface The balked landing surface is located 1 800 m from the threshold and has a length of 120 m. From this point the surface extends to the upper edge with a slope of 3.33% (1.84°) and an uniform divergence of 10% (5.71°). The upper edge for the two runways will be located at different elevations. • Runway 09: First you have to calculate the elevation of the runway 1800 m from the threshold. For this you need the profile of the runway. 25.29 + (18 x 0.16) = 28.17 m The upper edge is located in the plane of the inner horizontal (78.8 m). The horizontal displacement can be calculated as follows: the altitude of the balked landing surface is 50.6 m above the elevation of the runway, with a slope of 3.33%; 50.6 divided by 3.33 gives 15.2. Multiplying this by 100 gives as result 1 520 m. The final width can be calculated by dividing 1 520 by 10 this gives 152, this figure has to be multiplied by two (because there are two sides) what results in , plus 120 gives 424 m. • Runway 27: First you have to calculate the elevation of the runway 1800 m from the threshold. For this you need the profile of the runway. 33.83- (5.6 x 0.64)- ((18-5.6) x 0.16 )= 28.3 m The upper edge is located in the plane of the inner horizontal (78.8 m). The horizontal displacement can be calculated as follows: the altitude of the balked landing surface is 50.6 m above the elevation of the runway, with a slope of 3.33%; 50.6 divided by 3.33 gives 15.2. Multiplying this by 100 gives as result 1 520 m. The final width can be calculated by dividing 1 520 by 10 this gives 152, this figure has to be multiplied by two (because there are two sides) what results in 304, plus 120 gives 424 m. 3.3.3.8 Take-off climb surface The length of the inner edge is 180 m and is located 60 m from the threshold. The surface uniformly extends with a divergence of 12.5% to a final width of 1 200 m. At this point the distance from the threshold is calculated as follows: _______________________________________________________________________________________________________________________________________________________ 98 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ (1 200-180)/2 = 510 m (510/12,5) x 100 = 4 080 m The total length of the take-off climb is 15 000 m and the slope is 2°. With this distance and slope you can calculate the elevation at the end of the divergence and at the end of the surface. • Runway 09: The elevation at the end of the divergence is 106.9 m. (40.8 x 2) + 25.3 = 106.9 m The elevation at the end of the take-off climb surface is 325.3 m. (150 x 2) + 25.3 = 325.3 m • Runway 27: The elevation at the end of the divergence is 115.4 m. (40.8 x 2) + 33.8 = 115.4 m The elevation at the end of the take-off climb surface is (150 x 2) + 33.8 = 333.8 m 3.3.3.9 Strip According to the AIP of Spain the runways 27 and 09 are precision approach runways CAT I. Thus the runway strip extends 60 m from the runway threshold and is 150 m away from the runway centre line. _______________________________________________________________________________________________________________________________________________________ 99 Chapter 3: Aerodrome Obstacle Limitation _______________________________________________________________________________________________________________________________________________________ 3.4 Obstacle assessment Now all the dimensions of the obstacle limiting surfaces are known, they can be drawn in AutoCAD. I made a chart of the obstacle limiting surfaces and an obstacle type A chart for each runway. I divided the map of the obstacle limiting surfaces in 5 different parts in order to show the details of each surface. The map that shows the total surface is plotted in scale 1/120.000. The more detailed charts of the approach and take-off climb surfaces are plotted in scale 1/60.000, while the detailed chart of the conical is plotted in scale 1/80.000. To make a chart where all the values of the surfaces around the runway are readable, I made a fifth chart in scale 1/30.000. The charts can be found in Appendix A. The obstacle type A chart shows the take-off flight path in a vertical and horizontal view. On these views the objects that penetrate this surface are marked. These objects will be called “obstacles”. These maps can be used by pilots in order to avoid the obstacles. The authorities can use these maps to remove as many obstacles as possible or in case they can not be removed, shield, mark and light them. Natural elevation is not considered to be an obstacle. The actual assignment is to check that no objects penetrate the limiting surfaces. This is done by making a template of the two obstacle limitation charts and placing it over the cartography of Seville Airport. Now you have to look for objects that penetrate the most critical surfaces, which is the lowest surface. For this I bought a topographical map of the surrounding of Seville Airport because on my topographical map there were no height indicating lines. After intensive searching I concluded that no obstacles, except natural elevation, penetrate the surfaces. The ICAO Annex 14 states that when no obstacles penetrates the surfaces, no measures have to be taken. _______________________________________________________________________________________________________________________________________________________ 100 Chapter 4: Building restricted areas ______________________________________________________________________________________________________________________________________________________ 4 Building restricted areas 4.1 Introduction Under the European Air Navigation Planning Group (EANPG) the All-Weather Operation Group (AWOG) addressing the sustainability of All Weather Operations (AWO) was presented with a paper highlighting a problem with the determination of Building Restricted Areas (BRAs’). It has been identified by numerous member states that the control of buildings and the approval processes employed may lead to widely ranging allowances of what is permitted. The AWOG set up a Project Team on Building Restricted Areas (PT/BRA) to elaborate respective European Operational Requirements (OR) and develop guidance material in order to ensure signal in space requirements are maintained within specification for the respective Communication, Navigation and Surveillance (CNS) facilities used in support of the AWO. In the context of this guidance material the definition of the word “Building” will be as defined in section 4.3.1. Guidance material by its very nature is for guiding the user and hence the process identified herein allows a two step approach to the decision making process of whether a building causes unacceptable interference. The principle behind this guidance material is to provide a readily accessible, practical standard procedure. This will enable member states to assess building applications to a known process. 4.2 Scope This document establishes guidance material for determining whether the physical presence of a building may have an adverse effect on the availability or quality of CNS signals of the following ICAO recognised facilities: • DME N; • VOR; • Direction Finder; • NDB; • GBAS (VDB & Receiver stations); ___________________________________________________________________________ 101 Chapter 4: Building restricted areas ______________________________________________________________________________________________________________________________________________________ • ILS (Localiser, Glide-path, & Markers); • SBAS (ground monitoring station); • MLS (Azimuth & Elevation); • VHF Communication; • Primary Radar; • SSR. Degradation of the signal in space caused by electromagnetic interference (EMI) is not covered in this guidance material. The obstacle restrictions that are given in this guidance material do not take into account the effect of the proposed buildings upon VFR / IFR aeronautical operations. The criteria for evaluating buildings from an operational point of view are contained within Annex 14 (Aerodromes) and in ICAO Doc. 8168 (PANS OPS). 4.3 Definitions 4.3.1 Building The development of the guidance material has been with the notion of building in mind. However the guidelines developed apply equally well for other objects whether moving or stationary, temporary or permanent causing interference to the radio signals of CNS facilities, such as machines, constructions used for the erection of buildings as well as excavation and spoil or even vegetation. 4.3.2 Building Restricted Area (BRA) In the context of AWO, the BRA is defined as a volume where buildings have the potential to cause unacceptable interference to the signal-in-space in the service volume of CNS facilities for AWO. All CNS facilities have BRA defined which are not limited to actual site boundaries of the facility but extend to significant distances from the facility. ___________________________________________________________________________ 102 Chapter 4: Building restricted areas ______________________________________________________________________________________________________________________________________________________ 4.4 General procedure The general procedure is a two-step process (see Figure 4.1) for the approval of buildings that may adversely affect CNS facilities. The analysis carried out under both processes should be formally recorded. The intention is that Step 1 should be an expedient evaluation and Step 2 should involve in-depth analysis. For Step 1: Use the General Input Screening method for all applications. This screen is to be used by the appropriate authorities (for example: Airport, Planning, Local Official, Government Authorities who conduct the initial review of building applications) in order to ascertain whether approval can be given directly or it should be passed to the appropriate engineering authorities (Air Traffic Safety Electronic Personnel - ATSEP). For Step 2: The ATSEP should carry out detailed analysis. This should cover all aspects of the CNS facility to be protected and the possible effects of the proposed building on the signal in space provided by these facilities. Figure 4.1- Guidance review process 4.4.1 Definitions and explanation applicable to Figure 4-1 4.4.1.1 Step 1 ___________________________________________________________________________ 103 Chapter 4: Building restricted areas ______________________________________________________________________________________________________________________________________________________ • Building application The application for a new building or modification to an existing or planned building. • Infringe surfaces This is where the generic screening method is applied to the proposal to determine if the BRA surfaces are infringed. In case of non-infringement the process is terminated and the application is recorded as approved. 4.4.1.2 Step 2 • Specialist engineering analysis When an infringement of the BRA is identified, the application is handed over to the responsible engineering authorities for the CNS facilities. This is in accordance with the relevant formal approval process. The engineering authority will conduct appropriate analysis based on theory, experience and existing conditions. • Interference to facility performance The results of the ATSEP analysis determine if the interference effects are acceptable or not. Where conflicting analysis or studies arise it is recommended that first consideration be given to altering the proposal. • Application rejection The building applicant is notified of the rejection of the application by the appropriate authority. This does not preclude any modification that may be made to the application. Following rejection of the building proposal it may be possible to modify and re-submit the application. A modified proposal is subjected to the applicable review processes as identified in Figure 4-1. • Application approval Approval for the building application is given when interference effects to facility performance are accepted. ___________________________________________________________________________ 104 Chapter 4: Building restricted areas ______________________________________________________________________________________________________________________________________________________ 4.5 Details of the two-step process 4.5.1 Step 1 The signal in the service volume for all CNS facilities must be protected from unacceptable interference. In order to achieve this, each type of facility must have its own safeguarded surface as defined by a shape of a certain form. The dimensions of the shape are dependent upon individual facility types. Omni-directional facilities are assessed using the shape formed from a cone and cylinder (see Figure 4.2). Directional facilities are assessed using an adapted shape (see Figure 4.3). Local terrain and environmental constraints may modify the application of the shapes. The shapes generated, when applied to different CNS facilities, represent the individual safeguarded surfaces of these individual facilities. Where these shapes overlap, they are identified as being “clustered” (e.g. at an airport). This then forms a 3 dimensional picture, which is represented as one shape and will form the basis of the overall airport BRA map. The facility that requires the most restrictive BRA takes precedence in step 1 and triggers a step 2 review. The appropriate authority applies the BRA map as a template, including elevation information for the screening process. It has been noted that the Critical and Sensitive areas, for particular system installations and runway profiles, need to be tailored by the ATSEP. These tailored areas are based on the guidance found within Annex 10. They are not considered in this document. 4.5.2 Step 2 The appropriate engineering authority that has responsibility for the CNS facilities in question conducts the second step of the review process. This engineering authority conducts an analysis of the building proposal. The analysis is based on, although not limited to the experience and expert knowledge of the engineers undertaking the task. The ___________________________________________________________________________ 105 Chapter 4: Building restricted areas ______________________________________________________________________________________________________________________________________________________ procedure may cover theoretical analysis, numerical simulation and modelling in order to identify significant effects of the proposed building in the current environment. During the analysis work, the engineers involved will gain an understanding as to the extent of the impact on the CNS facilities affected. There are three possible results from the initial analysis of the building application: • the effects are unacceptable. • some effects are identified. Where this is the case or any doubt exists then further detailed analysis will need to be conducted. • negligible effects. The output of these analyses results in an approval or rejection answer to the building application. It is recommended that where a definite answer is not forthcoming then the engineering authority should protect the facility by refusing the application. If the result of the analysis is to reject the application there may be feedback available from the ATSEP. This is in order to allow some comment on the nature of the proposal and the aspects, which in their view are causing the unacceptable effects on the CNS facilities. The rejection of the application does not preclude the applicant from re-submission. This may take the form of a new or modified building application, which is then re-assessed against the conditions extant at time of re-submission. 4.6 Transition to the future ATM system planning The cylinder is referenced to the ground terrain; the cone is referenced to a horizontal plane. Where irregular terrain is present the BRA shape is adapted. The BRA is considered to provide worst case protection. Direction finder figures may require modification if the antenna is installed at a high level. It is recommended that buildings such as windmills, skyscrapers, large excavating works, TV towers and other high towers should be assessed at all times even outside the BRA for omnidirectional facilities. Particular attention should be paid to clusters of buildings such as windfarms and overhead power lines. ___________________________________________________________________________ 106 Chapter 4: Building restricted areas ______________________________________________________________________________________________________________________________________________________ Figure 4.2- Omni directional BRA shape Harmonised guidance figures for the omni-directional navigational facilities Type of navigation facilities DME N Alpha (α) (°) 1.0 Radius (R-cone) (m) 3 000 Radius (r-cylinder) (m) 300 Origin of cone Base of antenna at ground level 1.0 3 000 600 Centre of antenna system VOR at ground level 1.0 3 000 500 Base of antenna at DF ground level 20.0 200 50 Base of antenna at Markers ground level 5.0 1 000 200 Base of antenna at NDB ground level 3.0 3 000 400 Base of antenna at GBAS ground ground level reference receiver 0.9 3 000 300 Base of antenna at GBAS VDB station ground level 3.0 3 000 400 Base of antenna at SBAS ground ground level monitoring station 2 000 300 Base of antenna at VHF Communication 1.0 ground level Tx 2 000 300 Base of antenna at VHF Communication 1.0 ground level Rx 0.25 15k 500 Base of antenna at PSR ground level 0.25 15k 500 Base of antenna at SSR ground level Table 4.1- Harmonised guidance figures for the omni-directional navigational facilities ___________________________________________________________________________ 107 Chapter 4: Building restricted areas ______________________________________________________________________________________________________________________________________________________ 4.7 BRA for directional facilities The directional BRA dimensions for variants of localiser systems will differ significantly, this is due to the aperture and antenna designs. Wide aperture arrays (typically 24 / 25 element) will have additional protection through the use of the medium aperture BRA figures. Hence the guidance figures presented in table 4.2 only represent the BRA figures for medium aperture antenna arrays for facility performance category III facilities. The end fire array glide-path will require a narrower protection zone due to the directivity of the antenna system. Directional DME is assumed to be associated with landing systems. BRA volumes in both directions should be established where DME is used for go around procedures. The directional shape is orientated by the appropriate ATSEP. It is recommended that buildings such as windmills, skyscrapers, large excavating works, TV towers and other high towers should be assessed at all times even outside the BRA for directional facilities. Particular attention should be paid to clusters of buildings such as windfarms and overhead power lines. Harmonised guidance figures for the directional navigational facilities Type of a b c r D H L navigational (m) (m) (m) (m) (m) (m) (m) facility Distance to threshold 500 70 a+ 6 000 500 10 2300 ILS LLZ Distance to threshold 500 70 a+ 6 000 500 20 1500 ILS LLZ 50 70 6 000 250 5 325 ILS GP M-Type 800 Distance to threshold 20 70 a+ 6 000 600 20 1500 MLS AZ 300 20 70 6 000 200 20 1500 MLS EL Distance to threshold 20 70 a+ 6 000 600 20 1500 DME φ (°) 30 20 10 40 40 40 Table 4.2- Harmonised guidance figures for the directional navigational facilities ___________________________________________________________________________ 108 Chapter 4: Building restricted areas ______________________________________________________________________________________________________________________________________________________ Figure 4.3- Directional facilities shape Figure 4.4- Directional facilities perspective 4.8 General notes for omni-directional and directional facilities Where facilities are co-located the most stringent BRA volume applicable should apply. Non-standard installations (for example: height above 7m, mountain-top site, offset localiser) require careful assessment because changes in the radiation pattern will occur and hence more specific shapes may be required. ___________________________________________________________________________ 109 Chapter 4: Building restricted areas ______________________________________________________________________________________________________________________________________________________ More capable antenna arrangements or advanced technology (e.g. wide aperture, out of phase clearance, Doppler techniques) will allow the reduction of the protection zone applied by the ATSEP. The shapes are applicable from ground terrain upwards. Local terrain and environmental constraints (e.g. humped runways) may modify the application of the shapes. 4.9 Application to Seville Airport 4.9.1 ILS In order to determine if a building at Seville Airport is accepted, I draw the ILS (see figure 4.5) template for runway 09 and 27. By placing the template over the exact location of the beacon and looking for infringements of the surface, it can be determined if the application is approved. In case of non-infringement the process is closed and accepted, otherwise it is handed over to the specialized engineering authority for the CNS facility. They shall decide whether to accept the infringement or to decline it. Type of navigational facility ILS LLZ Guidance figures for the ILS LLZ facility a b c r D (m) (m) (m) (m) (m) Distance to threshold 500 70 a+ 6000 500 φ H (m) L (m) (°) 10 2300 30 Table 4.3- Guidance figures for the ILS LLZ facility φ r b a h Figure 4.5- ILS LLZ shape ___________________________________________________________________________ 110 Chapter 4: Building restricted areas ______________________________________________________________________________________________________________________________________________________ 4.9.2 NDB In order to determine if a building at Seville Airport is accepted, I draw the NDB (see figure 4.6) template for runway 09 and 27. By placing the template over the exact location of the beacon and looking for infringements of the surface, it can be determined if the application is approved. In case of non-infringement the process is closed and accepted, otherwise it is handed over to the specialized engineering authority for the CNS facility. They shall decide whether to accept the infringement or to decline it. Figure 4.6- NDB shape 4.9.3 DME/N In order to determine if a building at Seville Airport is accepted, I draw the DME/N (see Figure 4.7) template for runway 09 and 27. By placing the template over the exact location of the beacon and looking for infringements of the surface, it can be determined if the application is approved. In case of non-infringement the process is closed and accepted, otherwise it is handed over to the specialized engineering authority for the CNS facility. They shall decide whether to accept the infringement or to decline it. Figure 4.7- DME shape 4.9.4 VOR In order to determine if a building at Seville Airport is accepted, I draw the VOR (see Figure 4.8) template for runway 09 and 27. By placing the template over the exact location of the beacon and looking for infringements of the surface, it can be determined if the application is approved. In case of non-infringement the process is closed and accepted, otherwise it is handed over to the specialized engineering authority for the CNS facility. They shall decide whether to accept the infringement or to decline it. Figure 4.8- VOR shape ___________________________________________________________________________ 111 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 5 Instrument Approach Procedures 5.1 General 5.1.1 Introduction 5.1.1.1 Scope This Chapter contains criteria common to all types of instrument arrival and approach procedures. Criteria which apply to specific types of all facilities, such as ILS, are located in the chapters which deal with these kinds of guidance. 5.1.1.2 Procedure construction An instrument approach procedure may have five separate segments. They are the arrival, initial, intermediate, final and missed approach segments. In addition, an area for circling the aerodrome under visual conditions is considered. The approach segments begin and end at the designated fixes. However, under some circumstances, certain segments may begin at specified points where no fixes are available (or necessary), e.g. the final approach segment of a precision approach may originate at the point of intersection of the designated intermediate flight altitude/height with the nominal glide path. 5.1.1.3 Fix names The fixes are named according to the segment they precede. For example, the intermediate segment begins at the intermediate fix. Where no fix is available, as mentioned above in 5.1.1.2, “Procedure construction”, the segments begin and end at specified points (e.g. the point where the glide path intersects the nominal intermediate altitude and the point where the glide path intersects the nominal DA/H). This final project discusses the segments in the order in which the pilot would fly them in a complete procedure, that is from arrival through initial and intermediate to a final approach and, if necessary, the missed approach. 5.1.1.4 segment application Only those segments that are required by local conditions need be included in a procedure. In constructing the procedure, the final approach track should be identified first because it is the least flexible and most critical of all the segments. When the final approach has been _________________________________________________________________________________________________________________ 112 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ determined, the other necessary segments should be blended with it to produce an orderly manoeuvring pattern which is responsive to the local traffic flow. See Figure 5.1- Segments of instrument approach. 5.1.1.5 Areas Each segment has an associated area. Normally the area is symmetrical on both sides of the intended track. In principle, this area is subdivided into primary and secondary areas. However, in some cases, only primary areas are permitted. When secondary areas are permitted, the outer half of each side of the area (normally 25 per cent of the total width) is designated as secondary area. See Figure 5.2. Calculating secondary area width at a given point. The width of the secondary areas at any point (p) between two fixes may be obtained by linear interpolation from the widths at these fixes according to the equation below: Wsp = Wsl + Dp/L (Ws2 – Ws1) where: • Ws1 = width of secondary area at first fix; • Ws2 = width of secondary area at second fix; • Wsp = width of secondary area at point p; • Dp = distance of point p from first fix, measured along the nominal track; • L = distance between two fixes, measured along the nominal track. _________________________________________________________________________________________________________________ 113 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.1- Segments of instrument approach Figure 5.2- Cross-section of straight segment area showing primary and secondary areas 5.1.1.6 Obstacle clearance Full obstacle clearance is provided throughout the entire area unless secondary areas are identified. In this case full obstacle clearance is provided in the primary area and in the secondary area the obstacle clearance is reduced linearly from the full clearance at the inner edge to zero at the outer edge. See Figure 5.2. The MOC in the secondary areas may be obtained by a linear interpolation from the full MOC at the outer edge of the primary area to zero, according to the equation below: MOCsy = MOCp x (1- Y/Ws) _________________________________________________________________________________________________________________ 114 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ where: • MOCp= MOC in primary area; • MOCsy= MOC in secondary area for obstacle at distance Y from the outer edge of primary area; • Ws= Width of secondary area; • Y= Distance of obstacle from the outer edge of the primary area, measured perpendicular to the nominal track. 5.1.1.7 Track guidance Track guidance should normally be provided for all phases of flight through the arrival, initial, intermediate, final and missed approach segments. When track guidance is provided, the appropriate segment shall lie within the established coverage of the navigation facility on which the track guidance is based. When track guidance is not provided the obstacle clearance area shall be expanded as prescribed for dead reckoning (DR) segments in Chapter 5.1.4, “Initial approach segment”. Terminal area surveillance radar (TAR), when available, may be used to provide vectors to the final approach. En-route surveillance radar (RSR) may be used to provide track guidance through initial approach segments up to and including the intermediate fix. Criteria for the construction of areas for missed approaches without track guidance are provided in Chapter 5.1.7, “Missed approach segment”. 5.1.1.8 Vertical guidance Optimum and maximum descent gradients are specified depending on the type of procedure and the segment of the approach. At least in the case of the final approach segment for nonprecision approach procedures and, preferably, also for other approach segments where appropriate, the descent gradient(s) used in the construction of the procedure shall be published. Where distance information is available, descent profile advisory information for the final approach should be provided to assist the pilot to maintain the calculated descent gradient. This should be a table showing altitudes/heights through which the aircraft should be passing at each 2 km or 1 NM as appropriate. _________________________________________________________________________________________________________________ 115 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 5.1.1.9 Categories of aircraft Aircraft performance differences have a direct effect on the airspace and visibility required for manoeuvres such as circling approach, turning missed approach, final approach descent and manoeuvring to land (including base and procedure turns). The most significant factor in performance is speed. Accordingly, five categories of typical aircraft have been established to provide a standardized basis for relating aircraft manoeuvrability to specific instrument approach procedures. The criteria taken into consideration for the classification of aeroplanes by categories is the indicated airspeed at threshold (Vat) which is equal to the stall speed Vso multiplied by 1.3 or stall speed Vsig multiplied by 1.23 in the landing configuration at the maximum certificated landing mass. If both Vso and Vsig are available, the higher resulting Vat shall be used. The landing configuration which is to be taken into consideration shall be defined by the operator or by the aeroplane manufacturer. Aircraft categories will be referred to throughout this document by their letter designations as follows: • category A ― less then 169 km/h (91kt) indicated airspeed (IAS) • category B ― 169 km/h (91 kt) or more but less then 224 km/h (121 kt) IAS • category C ― 224 km/h (121 kt) or more but less then 261 km/h (141 kt) IAS • category D ― 261 km/h (141 kt) or more but less then 307 km/h (166 kt) IAS • category E ― 307 km/h (166 kt) or more but less then 391 km/h (211 kt) IAS The ranges of speeds (IAS) in Table 5.1 is to be used in calculating procedures. Permanent change of category (maximum landing mass). An operator may impose a permanent, lower, landing mass, and use of this mass for determining Vat if approved by the State of the operator. The category defined for a given aeroplane shall be a permanent value and thus independent of changing day-to-day operations. _________________________________________________________________________________________________________________ 116 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Aircraft Vat Range of Range of Max speeds Max speeds for speeds for final for visual missed approach initial approach manoeuvring approach speeds (circling) 165/280 130/185 185 185 205 B 169/223 220/335(260*) 155/240 250 240 280 C 224/260 295/445 215/295 335 295 445 D 261/306 345/465 240/345 380 345 490 E 307/390 345/467 285/425 445 425 510 category <169 A Intermediate Final (2051) Note.― Vat Speed at threshold based on 1.3 times stall speed Vso or 1.23 times stall speed Vsig in the landing configuration at maximum certificated landing mass. Table 5.1.- Speeds (IAS) for procedures calculations in kilometres per hour (km/h) Restrictions on category and IAS. Where airspace requirements are critical for a specific category of aircraft, procedures may be based on lower speed category aircraft, provided use of the procedure is restricted to those categories. Alternatively the procedure may be designated as limited to a specific maximum IAS for a particular segment without reference to category. For precision approach procedures, the dimensions of the aircraft are also a factor for the calculation of the OCH. For category DL aircraft, additional OCA/H is provided, when necessary, to take into account the specific dimensions of these aircraft (see ICAO PANSOPS Part II, Section 1, Chapters 1 and 3 and part III, Section 3, Chapter 6 (GBAS Cat I)). 5.1.1.10 Bearings, tracks and radials In planning procedures; degrees true bearing shall be used. However, all published procedures shall be in degrees magnetic in accordance with ICAO. Radials shall also be expressed in degrees magnetic, and shall further be identified as radials by prefixing the letter “R” to the magnetic bearing from the facility, for example, R-027 or R-310. The published radial shall be that radial which defines the desired flight track. In areas of 1 Maximum speed for reversal and racetrack procedures. _________________________________________________________________________________________________________________ 117 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ magnetic unreliability (i.e. in he vicinity of the earth’s magnetic poles) procedures may be established in degrees true. 5.1.1.11 Navigation system use accuracy The system accuracies used in the development of obstacle clearance criteria are based on minimum system performance factors. Where it can be shown that one or more of the parameters affecting these values are confidently maintained better than the minimum, smaller accuracy values may be used. The accuracy values result from the root sum square (RSS) of the system tolerances. When a navigation aid is used to provide track guidance, the tolerance of the intersection fix is based on 2 sigma confidence limits (95 per cent) while the splay of the instrument approach/missed approach procedure areas is based on 3 sigma confidence limits (99.7 per cent). For VOR/NDB tolerances, see Figures 5.11 and 5.13. 5.1.1.12 increased altitudes/heights for mountainous areas When procedures are designed for use in mountainous areas, consideration must be given to induced altimeter error and pilot control problems which results when winds of 37 km/h (20 kt) or more move over such areas. Where these conditions are known to exist, MOC should be increased by as much as 100 per cent. Procedures specialists and approving authorities should be aware of the hazards involved and make proper addition, based on their experience and judgement, to limit the time in which an aircraft is exposed to lee-side turbulence and other weather phenomena associated with mountainous areas. This may be done by increasing the minimum altitude/height over the intermediate and final approach fixes so as to preclude prolonged flight at a low height above the ground. The operator’s comments should also be solicited to obtain the best local information. Such increases should be included in the State’s Aeronautical Information Publication (AIP), Section GEN 3.3.5, “Minimum flight altitude”. (See ICAO Annex 15, Appendix 1 “Contents of Aeronautical Information Publication”). _________________________________________________________________________________________________________________ 118 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 5.1.1.13 Charting accuracy Charting tolerance should be added to the height and location of the controlling terrain feature or obstacle when instrument approach procedures are developed. Vertical tolerance is added to the depicted height or elevation of the object. Horizontal tolerance is added to the perimeter of the controlling terrain feature or obstacle. When the application of these tolerances creates an unacceptable operational penalty, additional survey information should be used to refine the obstacle location and height data. 5.1.1.14 Descent gradients Throughout the document, optimum and maximum descent gradients are specified. The optimum is the operationally preferred descent gradient. This should only be exceeded where alternative means of satisfying obstacle clearance requirements are impracticable. The maximum gradient shall not be exceeded. 5.1.2 Terminal area fixes 5.1.2.1 General Because all navigation facility and waypoints have accuracy limitations, the geographic point which is identified is not precise, but may be anywhere within an area which surrounds the nominal point. The nominal point can be defined by: a) an intersection (see 5.1.2.3, “Fix tolerance and fix tolerance area for intersecting fixes”); b) overheading a facility (see 5.1.2.5, “Fix tolerance overheading a VOR or NDB”); c) an RNAV waypoint; d) other kinds of navigation aids (see 5.1.2.4, “Fix tolerance for other type of navigation instruments”). As an example, Figure 5.3 illustrates the intersection of an arc and a radial from the same VOR/DME facility, as well as the intersection of two radials or bearings from different navigation facilities. The area of intersection formed in this way is referred to in this document as the “fix tolerance area”. _________________________________________________________________________________________________________________ 119 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.3.- Intersection fix tolerance areas 5.1.2.2 Terminal area fixes Terminal area fixes include, but are not limited to: a) the initial approach fix (IAF); b) the intermediate approach fix (IF); c) the final approach fix (FAF); d) the holding. And when necessary, a fix to mark the missed approach point (MAPt), or the turning point (TP). Terminal area fixes should be based on similar navigation systems. The use of mixed type (as VHF/LF) fixes should be limited to those intersections where no satisfactory alternative exists. _________________________________________________________________________________________________________________ 120 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 5.1.2.3 Tolerance and fix tolerance area for intersecting fixes The fix tolerance and fix tolerance area are obtained by using information from either collocated or non-collocated facilities as shown in Figure 5.3. Fix tolerance areas The fix tolerance areas are formed by the boundaries obtained from system use accuracies of the homing and intersecting radials (or arcs as appropriate ) with respect to the nominal fix position. As the system use accuracy is expressed in angles, the size of the fix tolerance area is dependent on the distance of the fix to navigation aids. Fix tolerance The fix tolerance determines the operational acceptability of a fix. Fix tolerance is a distance measured along the nominal track and relative to the nominal fix position. It is defined by the intersection of the nominal track with the earliest and latest limits of the fix tolerance area, measured along the nominal track. The tolerance is expressed as a plus or minus value around the nominal fix. See figures 5.4 and 5.5. Fix tolerance and system use accuracies are based on a 95 per cent probability of containment (2 SD). System use accuracy for VOR, NDB and LLZ System use accuracy is based on a root sum square calculation using the following tolerances: a) ground system tolerance ; b) airborne receiving system tolerance; c) flight technical tolerance. Difference between the overall system use accuracy of the intersecting facility and the along track facility is accounted for by the fact that flight technical tolerance is not applied to the former. See Table 5.2 for system use accuracies and Table 5.3 for the tolerances on which these values are based. _________________________________________________________________________________________________________________ 121 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ System use accuracy of facility NOT providing track System use accuracy of facility providing track VOR1 ILS NDB ±4.5° ±1.4° ±6.2° ±5.2° ±2.4° ±6.9° Table 5.2.- System use accuracy (2SD) of facility providing track guidance and facility not providing track guidance The values in Table 5.2 are the results of a combination, on a root sum square basis, of the following tolerances: VOR ILS NDB a) ground system tolerance ±3.6° ±1°2 ±3° b) airborne receiving tolerance ±2.7° ±1° ±5.4° c) light technical tolerance23 ±2.5° ±2° ±3° Table 5.3.- Tolerance on which system use accuracies are based Figure 5.4.- Final approach fix (FAF) tolerance 1 The VOR values of ±5.2° and ±4.5° may be modified according to the value of a) in Table I-2-2-2, resulting from flight test. 2 Includes beam bends 3 Flight technical tolerance is only applied to navigations aids providing track. It is not applied to fix intersecting navigation aids. _________________________________________________________________________________________________________________ 122 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.5.- Fix tolerance in the intermediate approach segment 5.1.2.4 Fix tolerance for other types of navigation instruments Terminal area radar The total fix tolerance is the result of a combination, on a root sum square (RSS) basis, as in Table 5.4. Parameter TAR RSR within 37 km (20 NM) within 74 km (40 NM) Video map accuracy 1.1 km 0.6 NM 2.2 km 1.2 NM Azimuth accuracy 0.7 km 0.4 NM 1.5 km 0.8 NM Flight technical 0.7 km 0.3 NM 1.4 km 0.7 NM tolerance (5s at 500 (5s at 250 kt) (10s at 500 ( 10s at 250 kt) km/h) km/h) Controller technical 0.6 km 0.3 NM 1.1 km 0.6 NM tolerance ±1.6 km ±0.8 NM ±3.2 km ±1.7 NM tolerance Total fix (RSS’d) Table 5.4.- Total fix tolerance _________________________________________________________________________________________________________________ 123 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Radar fix accuracies need to consider: a) mapping accuracies (normally 150 m (492 ft) or 3 per cent of the distance to the antenna); b) azimuth resolutions of the radar (reduced to some extent to account for the controller interpretation of target centre); c) flight technical tolerance (which recognizes communication lag as well as speed of the aircraft); Controller technical tolerance (which recognizes sweep speed of the antenna and the speed of the aircraft). Radar fixes Radar should not normally be the primary method of fix identification. However, where air traffic control (ATC) can provide the service, terminal area radar (TAR) within the limitations specified in “Terminal area radar” may be used to identify any terminal area fix. En-route surveillance radar (RSR) may be used for initial approach and intermediate approach fixes. Fixes for VOR or NDB with DME VOR/DME fixes use radial and distance information derived normally from facilities with collocated azimuth and DME antennas. However, where it is necessary to consider a VOR/DME fix derived from separate facilities, the fix is only considered satisfactory where the angles subtended by the facilities at the facilities at the fix results in an acceptable fix tolerance area. See Figure 5.3. Where the DME antenna is not collocated with the VOR and NDB providing track guidance, the maximum divergence between the fix, the tracking facility and the DME shall not be more than 23 degrees. For the use of DME with ILS, see 5.1.10.4, “Glide path verification check”. _________________________________________________________________________________________________________________ 124 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ DME The accuracy is ± (0.46 km (0.25 NM) + 1.25 per cent of the distance to the antenna). This value is the RSS total of minimum accuracy, monitor tolerance and flight technical tolerance, the latter two being so small as to be completely dominated by the larger airborne value. 75 MHz marker beacon Use Figure 5.6 to determine the fix tolerance for ILS and “Z” markers during approach procedures. If the facility defines the MAPt, the fixed value of zero is used . Figure 5.6.- ILS or “Z” marker coverage1 5.1.2.5 Fix tolerance overheading a station VOR Fix tolerance areas should be determined using a cone effect area based on a circular cone of ambiguity, generated by a straight line passing through the facility and making an angle of 50 degrees from the vertical. However, where a State has determined that a lesser angle is appropriate, fix tolerance areas may be adjusted. Entry into the cone is assumed to be achieved within such an accuracy from the prescribed track as to keep the lateral deviation abeam the VOR: 1 Note.- This figure is base don the use of modern aircraft antenna systems with a receiver sensitivity setting àf 1000 μ V up to 1800 m (5 905 ft) above the facility. _________________________________________________________________________________________________________________ 125 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ d = 0.2 h (d and h in km) or d = 0.033 h (d in NM, h in thousands of feet). For a cone angle of 50 degrees, the accuracy of entry is ±5°. From the points of entry, tracking through the cone is assumed to be achieved within an accuracy of ±5°. Passage over the VOR is assumed to be indicated within the limits of the cone of ambiguity. See Figure 5. If the facility defines the MAPt or the turning point in the missed approach, fixed values are used (see Chapter 5.1.7). Figure 5.7.- Fix area tolerance overhead a VOR NDB A cone affect area based upon an inverted cone of ambiguity extending at an angle of 40 degrees either side of the facility should be used in calculating the areas. Entry into the cone is assumed to be achieved within an accuracy of ±15° from the prescribed inbound track. From the points of entry, tracking through the cone is assumed to be achieved within an accuracy of ±15°. See Figure 5.8. If the facility defines the MAPt or the turning point in the missed approach, fixed values are used (see 5.1.7.1; “Calculating start of climb”). _________________________________________________________________________________________________________________ 126 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.8.- Fix tolerance area overhead an NDB 5.1.2.6 operational application of fixes for flight procedures planning Minimum usable ground distance to a VOR/DME fix The minimum usable ground distance to a VOR/DME fix can be determined from the following equations. Dm = h1 tan55° where : h1 = height above the facility in thousands of metres; dm = minimum usable DME ground distance in kilometres. or Dm= 0.164 h1 tan55° where: h1 = height above the facility in thousands of feet; dm = minimum usable DME ground distance in nautical miles. Initial/Intermediate approach fix To be satisfactory as an intermediate or initial approach fix, the fix tolerance (along track tolerance (ATT) for RNAV) must not be larger than ±3.7km (±2 NM) with the following exception. When the FAF is a VOR, NDB or VOR/DME fix, the fix tolerance may be increased to not greater than ±25 per cent of the corresponding segment’s length (intermediate or initial, as appropriate). _________________________________________________________________________________________________________________ 127 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Measurements are made from the nominal fix positions along the nominal flight track. See Figure 5.4. Final approach fix for non-precision approaches For use as FAF, the fix shall be located not farther than 19 km (10 NM) from the landing surface. The fix tolerance at the FAF crossing level should not exceed ±1.9 km (10 NM). See Figure 5.5. Missed approach fixes General A missed approach fix may be used in non-precision approaches. The fix tolerance shall not exceed the longitudinal tolerance of the MAPt calculated assuming that the MAPt is defined by a distance from the FAF. Use of 75 MHz marker beacon The use of an ILS 75 MHz marker as an MAPt is limited to the case of ILS approach with glide path unserviceable. Limiting radials/DME distances Where no missed approach track guidance is available a turn point can be defined by the intersection of the nominal track with the limiting VOR radial, NDB bearing or DME distance. Although this is not a fix, the missed approach calculations are made by assuming a fix tolerance area drawn as shown on Figure 5.9. 5.1.2.7 Use of fixes for descent and related obstacle clearance Distance available for descent When applying descent gradient criteria to an approach segment (initial, intermediate or final approach areas), the gradient is calculated between the nominal positions of the related fixes. See figure 5.10. _________________________________________________________________________________________________________________ 128 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.9.- Assumed fix tolerance area for limiting bearing/radial or DME distance Figure 5.10.- Distance between fixes Obstacle clearance after passing a fix It is assumed that descent will begin at the earliest point within the fix tolerance area of the first fix and will end at the nominal position of the second fix. Obstacle clearance appropriate to the segment being entered shall be provided: a) within the fix tolerance area of the first fix; b) between the nominal positions of the two fixes. See Figure 5.11 for an example of an intermediate approach segment. _________________________________________________________________________________________________________________ 129 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.11.- Area requiring obstacle clearance Stepdown fix A stepdown fix permits additional descent within a segment by identifying a point at which a controlling obstacle has been safely overflown. Preferably, only one stepdown fix should be established in the final approach segment, except in the case where the fix can be provided by radar or DME. In this case no more than two stepdown fixes should be specified. See Figure 5.12. Figure 5.12.- Stepdown fix with dual OCA/H The use of the stepdown fix in the final approach segment shall be limited to aircraft capable of simultaneous reception of the flight track and a crossing indication unless otherwise specified. Where a stepdown fix is used in the final approach segment, an OCA/H shall be specified both with and without the stepdown fix. _________________________________________________________________________________________________________________ 130 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ A stepdown fix should meet the criteria which apply to the fix associated with that segment. That is: a) the criteria for the IAF and the IF in the initial and intermediate approach segments respectively; b) the criteria for the FAF in the final approach segment. Where fixes can be provided by a suitable located DME, a series of descending steps on a specified track or within a specified sector converging to the aerodrome of landing may be constructed. This procedure shall be designed to provide obstacle clearance appropriate to the segment in which the fix is located, from the en-route phase of flight through the final approach segment. Obstacle close to a final approach fix or stepdown fix Obstacles which are within the fix tolerance area and are no more than 9.3 km (5.0 NM) past the earliest point of the fix tolerance area need not be considered in establishing the OCA/H or the minimum altitude/height of the following segment provided that these obstacles are found under a plane: a) perpendicular to the vertical plane containing the nominal final approach flight path and on a 15 per cent horizontal gradient; b) passing through the earliest point of the fix tolerance area at an altitude/height equal to the minimum altitude/height required at the fix, minus the obstacle clearance required for the segment preceding the fix. (See Figure 5.13). 5.1.2.8 Protection area for VOR and NDB The value for protection areas are based on the system use accuracies (2 SID) shown in Table 5.2 and are extrapolated to a 3 SD value (99.7 per cent probability of containment). VOR splay: Terminal= 7.8° NDB splay: Terminal= 10.3° _________________________________________________________________________________________________________________ 131 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.13.- Area where obstacles not need to be considered 5.1.3 Arrival segment 5.1.3.1 standard instrument arrivals General This section contains criteria applicable to all standard instrument arrivals. In some cases it is necessary to designate arrival routes from the en-route structure to the initial approach fix. Only those routes which provide an operational advantage shall be established and published. These should take local air traffic flow into consideration. The length of the arrival route shall not exceed the operational service range of the facilities which provide navigation guidance. _________________________________________________________________________________________________________________ 132 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Standard instrument arrival routes (STARs) should be simple and easily understood and only those navigation facilities, fixes or waypoints essential to define the flight path of an aircraft and for Air Traffic Services (ATS) purposes will be included in the procedure. • a STAR should accommodate as many aircraft categories as possible; A STAR should begin at a fix, e.g. radio navigation facility, intersection, distance measuring equipment (DME) fix or waypoint; • a STAR should permit transition from the en-route phase to the approach phase by linking a significant point normally on an ATS route with a point from which an instrument approach procedure is initiated; • a STAR should be designed to permit aircraft to navigate along the routes reducing the need for radar vectoring; • a STAR may serve one or more airports within an terminal area. Airspeed and altitude/level restrictions, if any, should be included. These should be take into account the operational capabilities of the aircraft category involved, in consultation with the operators. Whenever possible, STARs should be designed with DME fixes or waypoints instead of intersections. A DME arc may provide track guidance for all or a portion of an arrival route. The minimum arc radius shall be 18.5 km (10.0 NM). An arc may join a straight track at or before the initial approach fix. In this case, the angle of intersection of the arc and the track should not exceed 120°. When the angle exceeds 70°, a lead radial which provides at least a distance “d” of lead shall be identified to assist in leading the turn (d = r.tan(α)/2 ; r = radius of turn; α = angle of turn). _________________________________________________________________________________________________________________ 133 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Area construction • Arrival routes 46 km or longer (25 NM) When the length of the arrival route is greater than or equal to 46 km (25 NM), en-route criteria apply to the 46 km (25 NM) prior to the initial approach fix (IAF). The area width decreases from 46 km (25 NM) with a convergence angle of 30° each side of the axis, until reaching the width determined by the initial approach criteria. See Figure 5.14. Figure 5.14.- Arrival segment – protection area (length of the arrival segment greater than or equal to 46 km (25 NM)) • Arrival routes less than 46 km (25 NM) When the length of the arrival route is less than 46 km (25 NM), the area width decreases from the beginning of the arrival route with a convergence angle of 30° each side of the axis, until reaching the width determined by the initial approach criteria. See Figure 5.15. • Turn Protection Turns will be protected by using: a) en-route criteria for distances greater than 46 km (25 NM) from the IAF; b) initial approach criteria for distances of 46 km (25 NM) or less from the IAF. _________________________________________________________________________________________________________________ 134 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.15.- Arrival segment – protection area (length of the arrival segment less than 46 km (25 NM)) • Arrival based on a DME arc In case of an arrival based on a DME arc, the previous points apply with the following exceptions: a) the distance is measured along the DME arc; b) the tapering is over a distance of 9,6 km (5,2 NM) measured along the DME arc. The construction method is as follows. From the centre of the DME arc (point O), draw lines OA and OB which intersects the limits at A1,A2, A3, A4 and B1, B2, B3, B4. Then, draw lines joining corresponding points A to B. See figures 5.16 and 5.17. Figure 5.16.- DME arc – length of the arrival segment greater than or equal to 46 km (25 NM) _________________________________________________________________________________________________________________ 135 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.17.- arc – length of the arrival segment greater less than 46 km (25 NM) • Basic GNSS receivers In addition to the general arrival criteria, the following criteria apply. Cross-track tolerance (XTT), along-track tolerance (ATT) and area semi-width for basic GNSS receivers are determined according to the formulae defined in part III of ICAO ANNEX, but that is not of relevance in this work. The area width tapers at an angle of 30° each side of the axis, perpendicular to the point where the 30 NM (56 km) arc from the aerodrome reference point (ARP) intercepts the nominal track. Contrary to the general arrival criteria, the en-route width shall be used when more than 30 NM (56 km) from the ARP. See Figures 5.18 and 5.19. Obstacle clearance The obstacle clearance in the primary area shall be a minimum of 300 m (984 ft). In the secondary area 300 m (984 ft) of obstacle clearance shall be provided at the inner edge, reducing linearly to zero at the outer edge. Procedure altitude/height The procedure altitude/height shall not be less than the OCA/H and shall be developed in coordination with the air traffic control requirements. The arrival segment procedure _________________________________________________________________________________________________________________ 136 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ altitude/height may be established to allow the aircraft to intercept the prescribed final approach segment descent gradient/angle from within the intermediate segment. Figure 5.18.- GNSS arrival criteria, IAF beyond 30 NM ARP: 8 NM ½ AW prior to 30 NM from ARP then 5 NM ½ AW _________________________________________________________________________________________________________________ 137 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.191.- arrival criteria, IAF within 30 NM ARP: 8 NM ½ AW prior to 30 NM from ARP then 5 NM ½ AW 5.1.3.2 Omnidirectional or sector arrivals Omnidirectional or sector arrivals can be provided taking into account the minimum sector altitudes (MSA) (see Chapter 9, “Minimum sector altitudes”), or terminal arrival altitudes (TAA). 5.1.4 Initial approach segment 5.1.4.1 General The initial approach segment starts at the initial approach fix (IAF). In the initial approach the aircraft is manoeuvring to enter the intermediate segment. When the intermediate fix (IF) is part of the en-route structure, it may not be necessary to designate an initial approach segment. In this case the instrument approach procedure begins at the intermediate fix and intermediate segment criteria apply. An initial approach may be made along a VOR radial, 1 This example is based on 5sec roll anticipation, 16 000 ft, 300 kt, 15° AOB, ISA + 10°C, at en-route waypoint 15 000 ft, 250 kt, 25 AOB, ISA + 10°C at IAF. _________________________________________________________________________________________________________________ 138 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ NDB bearing, specified radar vector or a combination thereof. Where no of these is possible, a DME arc or specified heading may be used. Reversal and racetrack procedures as well as holding pattern descents are considered initial segments until the aircraft is established on the intermediate approach track. Where holding is required prior to entering the initial approach segment, the holding fix and initial approach fix should coincide. When this is not possible, the initial approach fix shall be located within the holding pattern on the inbound holding track. Normally track guidance is required except that dead reckoning tracks may be used for distances not exceeding 19 km (10NM). Although more than one initial approach may be established for a procedure, the number should be limited to that which is justified by traffic flow or other operational requirements. 5.1.4.2 Altitude selection Minimum altitudes Minimum altitudes in the initial approach segment shall be established in 100-ft or 50-m increments as appropriated. The altitude selected shall not be below the reversal or racetrack procedure altitude, where such a procedure is required. In addition, altitudes specified in the initial approach segment must not be lower than any altitude specified for any portion of the intermediate or final approach segments. Minimum altitudes for different aircraft categories When different minimum altitudes are specified for different categories of aircraft, separate procedures shall be published. Procedure altitude/height All initial approach segments shall have procedure altitudes/heights established and published. Procedure altitudes/heights shall not be less than the OCA//H and shall be developed in coordination with air traffic control requirements. The initial segment procedure altitude/height should be established to allow the aircraft to intercept the final approach segment descent gradient/angle from within the intermediate segment. _________________________________________________________________________________________________________________ 139 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 5.1.4.3 Initial approach segments utilizing straight tracks and DME arcs Tracks The angle of intersection between the initial approach track and the intermediate track should not exceed 120°. When the angle exceeds 70°, a radial, bearing, radar vector or DME information providing at least 4 km (2NM) of lead (CAT H, 1.9 km (1NM)) shall be identified to assist in leading the turn onto the intermediate track (see Figure 5.20). When the angle exceeds 120°, the use of a racetrack or reversal procedure or dead reckoning (DR) track should be considered. Criteria for such procedures are in 5.1.4.4, “Initial approach segment using a racetrack procedure”, 5.1.4.5 “ Initial approach segment using a reversal procedure” and 5.1.4.3, “Area associated with dead (DR) track procedures”. DME arcs An arc may provide track guidance for all or for a portion of an initial approach. The minimum arc radius shall be 13 km (7 NM)(CAT H, 9.3 km (5 NM)). An arc may join a track at or before the intermediate fix. When joining a track, the angle of intersection of the arc and the track should not exceed 120°. When the angle exceeds 70°, a radial which provides at least 4 km (2 NM)) of lead shall be identified to assist in leading the turn onto the intermediate track. Figure 5.20.- Lead radial for turns greater than 70° Area The initial approach segment has no standard length. The length shall be sufficient to permit the altitude change required by the procedure. The width is divided into: a) a primary area which extends laterally 4.6 km (2.5 NM) on each side of the track; _________________________________________________________________________________________________________________ 140 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ b) a secondary area which adds an additional 4.6 km (2.5 NM) on each side of the primary area. Area splay Where, because of an operational requirement, any portion of the initial approach is more than 69 km (37 NM) from the VOR or 52 km (28 NM) from the NDB providing track guidance, the area will start splaying at these distances at an angle of 7.8° for VOR or 10.3° for NDB. Within this splayed area, the width of the primary area shall remain one half of the total width of the area. (See figure 5.21) For calculating secondary area width at a given point, see 5.1.1.5, “Calculating secondary area width at a given point”. Area associated with dead reckoning (DR) track procedures Where DR track procedures are utilized, the area allocated for the turning portions of the dead reckoning segment shall be calculated to accommodate omnidirectional wind speed (w) derived by the following equation: w =(12h + 87) km/h, where h is altitude in thousands of metres; or w =(2h + 47) kt, where h is altitude in thousands of feet. The area associated with the straight portion shall be expanded to account for the maximum drift from a unrecognized beam wind component of ± 56 km/h (± 30 kt) in addition to ± 5° heading tolerance, since the pilot is expected to have appraised the wind speed within ± 30 kt (± 56 km/h) on the previous segments. The minimum length of the intermediate track being intercepted shall provide sufficient additional distance to accommodate these tolerances and the associated fix tolerances. _________________________________________________________________________________________________________________ 141 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.21.- Typical segments (plan view) Figure 5.22.- Initial approach area utilizing straight tracks _________________________________________________________________________________________________________________ 142 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Obstacle clearance The obstacle clearance in the initial approach primary area shall be a minimum of 300 m (984 ft). In the secondary area, 300 m (984 ft) shall be provided at the inner edge, reducing linearly to zero at the outer edge. (See Figure 5.2.) For calculating obstacle clearance at a given point, see Chapter1, 5.1.1.6, “Obstacle clearance”. Descent gradient The optimum descent gradient in the initial approach is 4.0 per cent. Where a higher descent gradient is necessary to avoid obstacles, the maximum permissible is 8.0 per cent. 5.1.4.4 Initial approach segment using a racetrack procedure General Racetrack procedures are used where sufficient distance is not available in a straight segment to accommodate the required loss of altitude and when entry into a reversal procedure is not practical. Racetrack procedures may also be specified as an alternative to reversal procedures to increase operational flexibility. Shape of a racetrack procedure The racetrack procedure has the same shape as a holding pattern but with different operating speeds and outbound timing. The inbound track normally becomes the intermediate or final segment of the approach procedure. Starting point The racetrack procedure starts at a designated facility or fix. Entry Entry into a racetrack procedure shall be similar to entry procedures for holding patterns as specified in ICAO PANS-OPS Part II, Section 4, Chapter I, 2.1, with the following additional considerations: a) offset entry from Sector 2 shall limit the time on the 30° offset track to 1 min 30 s. After this time the pilot should turn to a heading parallel to the outbound track for _________________________________________________________________________________________________________________ 143 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ the remainder of the outbound time. If the outbound time is only 1 min, the time on the 30° offset track shall be 1 min also; b) parallel entry shall not return directly to the facility without first intercepting the inbound track (when proceeding onto the final approach segment). Restricted entry Where necessary to conserve airspace (or for other reasons), entry may be restricted to specific routes. When so restricted, the entry route(s) shall be specified in the procedure. Outbound time The duration of the outbound flight of a racetrack procedure may be 1 to 3 minutes (specified in ½ min increments) to allow increased descent. This time may vary according to aircraft categories (see Table 5.1) in order to reduce the overall length of the protected area in cases where airspace is not possible, the descent may involve more than one orbit in the racetrack according to descent/time relationship specified in 5.1.4.7 (Table 5.5). Timings for different categories of aircraft Where different timings are specified for different categories of aircraft, separate procedures shall be published. Limitation of length of outbound track The length of the outbound track of a racetrack procedure may be limited by specifying a DME distance or a radial/bearing from a suitable located facility (see 5.1.4.6, “Use of DME or intersected radial/bearing”). 5.1.4.5 Initial approach segment using a reversal procedure General Reversal procedures are used to establish the aircraft inbound on an intermediate or final approach track at the desired altitude. There are two types of reversal procedure: procedure turns and base turns. Both of these consist of an outbound track followed by a turning manoeuvre which reverses direction onto the inbound track. Reversal procedures are used when: _________________________________________________________________________________________________________________ 144 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ a) the initial approach is initiated from a facility (or fix in the case of a procedure turn) that is located on or near the aerodrome; b) a turn of more than 70° would be required at the IF, and a radial, bearing, radar vector, DR track, or DME information is not available to assist in leading the turn on to the intermediate track; c) a turn of more than 120° (90° for ILS, see ICAO PANS-OPS Part II, Section 1, Chapter 1, 1.2.2 “Initial approach segment alignment”) would be required at the IF. Specifics of each reversal procedure are described below. Starting point The starting point for a base turn shall be a facility. The starting point for a procedure turn shall be a facility or a fix. The reversal procedure may be preceded by manoeuvring in a suitable located holding pattern. Entry Entry into a reversal procedure should be form a track within ± 30° of the outbound track (see Figures 5.23 and 5.24). When entry is desired from tracks outside these limits, suitably protected airspace must be provided to allow the pilot to manoeuvre onto the outbound track. This manoeuvring will be in accordance with the entry procedures associated with a suitable located holding pattern, which must be shown on the approach chart (see Figure 5.25). Figure 5.23.- Entry to procedure turn _________________________________________________________________________________________________________________ 145 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.24.- Entry to base turn Figure 5.25.- Example of omnidirectional arrival using a holding procedure in association with a reversal procedure Types of reversal procedures The types of procedures are illustrated in Figure 5.26 and are described as follows. • 45°/180° procedure turns start at a facility or fix consist of: a) a straight leg with track guidance; this straight leg may be timed or may be limited by a radial or DME distance (see 3.5.5, “Outbound time” and 3.5.6, “Limitation of length of outbound tracks”); b) a 45° turn; c) a straight leg without track guidance. This straight leg is timed; it shall be: - 1 minute from the start of the turn for Categories A and B aircraft; - 1 minute and 15 seconds from the start of the turn for Categories C, D and E aircraft; d) a 180° turn in the opposite direction to intercept the inbound track. _________________________________________________________________________________________________________________ 146 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ • 80°/260° procedure turns start at a facility or fix consist of: a) a straight leg with track guidance; this straight leg may be timed or may be limited by a radial or DME distance (see 3.5.5, “Outbound time” and 3.5.6 “Limitation of length of outbound tracks”); b) an 80° turn; c) a 260° turn in the opposite direction to intercept the inbound track. CAUTION: The 45°/180° and the 80°/260° procedure turns are alternatives to each other and the protection zone should be constructed to accommodate both procedures unless one is specifically excluded (see 5.1.4.6; “Area construction”). a) Base turns consist of a specified outbound track which may be timed or may limited by a radial or DME distance (see 5.1.4.6, “Outbound time” and 5.1.4.6, “Limitation of length of outbound tracks”), followed by a turn to intercept the inbound track. The divergence between the outbound and inbound track (φ) shall be calculated as follows: a) for true airspeed (TAS) less than equal to 315 km/h (170 kt): φ= 36/t; b) for TAS exceeding 135 km/h (170 kt): φ= (0.116 × TAS)/t where TAS is in km/h φ= (0.215 × TAS)/t where TAS is in kt where t is the time in minutes specified for the outbound leg, and TAS corresponds to the maximum indicated airspeed (IAS) specified for the procedure. b) Outbound tracks or timing for different aircraft categories. When different outbound tracks or timing are specified for different categories of aircraft, separate procedures shall be published. _________________________________________________________________________________________________________________ 147 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.26.- Types of reversal and racetrack procedures Outbound time Where appropriate, outbound time of reversal procedures shall be specified. Normally it should be specified as a time between 1 and 3 minutes using ½ min increments. It may be varied in accordance with aircraft categories (see Table 5.1) in order to reduce the overall length of the protected area in cases where airspace is critical. Extension of the outbound timing beyond 3 minutes must only be considered in exceptional circumstances. _________________________________________________________________________________________________________________ 148 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Limitation of length of outbound tracks The length of the outbound track of a reversal procedure may be limited by specifying a DME distance or a radial/bearing from a suitably located facility (see 5.1.4.6, “Use of DME or intersecting radial/bearing”). 5.1.4.6 Racetrack and reversal procedure areas General The areas required to accommodate both the racetrack and reversal procedures described in 5.1.4.4 and 5.1.4.5 shall be based on the application of the area parameters specified in 5.1.4.6 below. These may be applied either on an additive tolerance basis or using statistical methods. Area parameters The parameters on which both racetrack an reversal procedures are based are: a) altitude (h): the specified altitude for which the area is designed; b) temperature: International standard atmosphere (ISA) for the specified altitude plus 15°C; c) indicated airspeed (IAS): the highest procedural speed category for which the area is designed (see Table 5.1) d) true airspeed (TAS): the IAS in c) above adjusted for altitude a) and temperature b); e) wind speed (w): omnidirectional for the specified altitude h; w = (12h +87) km/h where h is in thousands of metres w = (2h +47) kt where h is in thousands of feet or provided adequate statistical data are available, the maximum 95 per cent probability omnidirectional wind may be used (see ICAO PANS-OPS Part II, Section 4, Chapter 1, 1.3.6, “Wind velocity”). f) average achieved bank angle: 25° or the bank angle giving a turn rate of 3° per second, whichever is the lesser; Note. — If the TAS is greater than 315 km/h (170 kt), the bank angle will always be 25°. g) fix tolerance area: as appropriate to the type of facility or fix and type of entry; _________________________________________________________________________________________________________________ 149 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ h) flight technical tolerance which is comprised of the following variables (see Figure 5.27): - outbound timing tolerance of ± 10 s; - pilot reaction time of 0 to + 6 s; - establishment of bank angle, + 5 s; - heading tolerance ± 5°. Operational assumptions The operational assumptions associated with procedure design criteria for racetrack and reversal procedures are: a) start of outbound timing — racetrack procedures: - for racetrack procedures using a facility — outbound timing starts from abeam the facility or on attaining the appropriate outbound heading, whichever comes later; - for racetrack procedures using a fix — appropriate outbound timing starts from obtaining the outbound heading; b) outbound track adjustment — racetrack procedures. The outbound track for racetrack procedures will always be adjusted to avoid crossing the nominal inbound track before the final turn; and c) pilot correction for wind effects: - for racetrack procedures, the area should be calculated and drawn for the fastest aircraft category to be accommodated. Although the area based on the slow speed (i.e. 165 km/h (90kt)) aircraft in strong winds may in some places be larger than the area so constructed, it is considered that the normal operational adjustments made by pilot of such aircraft are such that the aircraft will be contained within the area; - for base and procedure turns, however, the area for 165 km/h (90 kt) should be checked. An additional template for these procedures is incorporated in the Template Manual for Holding, Reversal and Racetrack Procedures (Doc 9371). _________________________________________________________________________________________________________________ 150 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.27.- Application of flight technical tolerance _________________________________________________________________________________________________________________ 151 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Area construction a) statistical area construction If statistical methods are used to combine the variables and then to extrapolate distributions to develop areas, the probability level associated with that extrapolation should meet an acceptable level of safety. b) additive tolerance area construction A variety of methods may be used to construct areas. Whichever method is selected, the procedure design criteria specified in 5.1.4.5, “Initial approach segment using reversal procedure”, and the parameters specified in 5.1.4.6, “Area parameters”, apply. Area reduction The area may be reduced under special circumstances. Methods of reduction include: a) reduction of the maximum speed(s) specified for the procedure. Speeds below the minimum value for initial approach given in a aircraft category shall not be specified (see Tables 5.1). If procedures are developed which exclude specific aircraft categories due to speed, this must be stated explicitly; b) restricting use of the procedure to specified categories of aircraft; c) restricting procedure entry to specific track(s); d) use of DME or radial/bearing to limit outbound track (see 5.1.4.6). Use of DME or intersecting radial/bearing If a DME distance or an intersecting radial or bearing is used to limit the outbound leg, the area may be reduced by applying the appropriate adjustments, in this case the limiting distance or radial/bearing shall allow adequate time from the descent specified. The distance on the outbound track is thereby limited by the timing or by reaching the limiting DME distance or radial/bearing, whichever occurs first. Secondary areas Secondary areas shall be added to the outer boundary of all areas calculated using the criteria in 5.1.4.6, “Area construction”. The width of the secondary area is 4.6 km (2.5 NM). _________________________________________________________________________________________________________________ 152 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 5.1.4.7 Maximum descent/nominal outbound timing relationship for a reversal or racetrack procedure General Because of the actual length of the track will vary, it is not possible to specify a descent gradient for the racetrack or reversal procedures. Instead, the maximum descents which can be specified on the outbound and inbound tracks of the procedure are listed in Table 5.5 as a function of nominal outbound time. Note. — Where a 45° procedure turn is specified, an additional 1 minute may be added to the nominal outbound time in calculating the maximum descent outbound. In calculating maximum descents, no descents shall be considered as having taken place during turns. Outbound track:Cat A/B Cat C/D Inbound track: Cat A/B Cat C/D/E Maximum1 245 m/min (804 ft/min) 365 m/min (1197 ft/min) 200 m/min (655 ft/min) 305 m/min (1000 ft/min) Minimum — — 120 m/min (394 ft/min) 180 m/min (590 ft/min) Table 5.5.- Maximum descent to be specified on a reversal or racetrack procedure 5.1.4.8 Obstacle clearance The prescribed minimum altitudes for either the racetrack or the reversal procedure shall not be less than 300 m (984 ft) above all obstacles within the appropriate primary areas. In the secondary area the minimum obstacle clearance shall be 300 m (984 ft) at the inner edge, reducing linearly to zero at the outer edge. See Chapter 5.1.1.6. 5.1.4.9 Protection area of racetrack and holding procedures General 1 Maximum/minimum descent for 1 minute nominal outbound time in m(ft). For maximum descent rate related to a final approach segment, see Chapter 5.1.6.3. _________________________________________________________________________________________________________________ 153 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Note. — The methods described in this paragraph are related to right turn procedures. For left turn procedures, the corresponding areas are symmetrical with respect to the inbound track. The protection area of a racetrack procedure consists of a primary area and a secondary area; the protection area of a holding procedure consists of an area and a buffer area. Since the construction of the primary area of a racetrack and of the area of a holding is the same, they are referred to by the same term hereafter — the basic area of the procedure. Line 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 Parameters K V v R r h w w' E45 t L ab ac g11=g13 g12=g14 Wb Wc Wd We Wf Wg Wh Wo Wp W11=W13 W12=W14 Wj Wk=Wl Wm Wn3 Wn4 XE YE Formula Conversion factor K x IAS V/3600 943.27/V V/(62.83 R) in thousand of metres (12 x h) + 87 w/3600 (45 x w)'/R 60 x T vxt 5xv 11 x v (t - 5) x v (t + 21) x v 5 x w' 11 x w' Wc + E45 Wc + (2 x E45) Wc + (3 x E45) Wc + (4 x E45) Wb + (4 x E45) Wb + (5 x E45) Wb + (6 x E45) ((t + 6)w') + (4 x E45) Wi1 + (14 x w') Wi2 + E45 Wi2 + (2 x E45) Wi2 + (3 x E45) Wi1 + (4 x E45) Wi2 + (4 x E45) ( 2 x r) + ((t + 15) x v) + ((t + 26 + (195/R) x w') 11 x v x cos20° + r (1+ sin20°) + (t + 15)v tan5° + (t + 26 + 125/R)w' Units km/h km/s °/s km 1000 m km/h km/s km s km km km km km km km km km km km km km km km km km km km km km km km Table 5.6.- Calculations associated with the construction of the holding and racetrack template _________________________________________________________________________________________________________________ 154 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ The construction of the basic area of the procedure is made in three steps. The first step is to construct a template or to take a precalculated one from the Template Manual for Holding, Reversal and Racetrack Procedures (Doc 9371), for the appropriate time, speed and altitude. This template caters for all factors which can cause an aircraft to deviate from the nominal pattern except those related to the fix tolerance area. It is applicable to all types of procedures including VOR or NDB overhead, intersection, intersection of VOR radials, VOR/DME and their entries. In case of Seville airport a template will be constructed later on in this chapter. The second step is to draw the basic area of the procedure by moving the template-origin around the fix tolerance area for procedures overhead a facility or at a intersection of VOR radials, or by using it as described 5.1.4.3 for VOR/DME procedures, and by adding areas to protect entries as required. We will use a overhead procedure . Finally, a secondary area of 4.6 km (2.5 NM) is added around the basic area for a racetrack, and a buffer area of 9.3 km (5.0 NM) is added around the basic area for a holding. First step: construction of the template The parameters used in the construction of the template are contained in 5.1.4.6 for the racetrack and in ICAO PANS-OPS Part II, Section 4, Chapter 1, 1.3, “Construction of holding areas”, for the holding procedures. After completion of the calculations indicated in Table 5.6, the template is constructed as follows. Draw a line representing the axis of the procedure and the nominal pattern. Locate point “a” at the procedure fix. (The radius of turn r is given at line 5 and the outbound length L is given at line 11 of Table 5.6.) Influence of the navigation tolerances a) locate points “b” and “c” on the procedure axis (Table 5.6, lines 12 and 13); “b” and “c” represent the earliest (5 s after “a”) and the latest (11 s after “a”) still air positions of the beginning of the outbound turn. _________________________________________________________________________________________________________________ 155 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ b) draw an arc of 180° with a radius r tangent to the procedure axis at “c”, which represents the latest still air outbound turn. Locate points “d”,”e”,”f” and “g” after 45, 90, 135 and 180° of turn from “c”. c) draw an arc of 270° with a radius r tangent to the procedure axis at “b”, which represents the earliest still air outbound turn. Locate points “h”,”o” and “p” after 180, 225 and 270° of turn from “b”. d) from “g” draw two lines at 5° on each side of the nominal outbound leg. Locate points “i1”, “i2”, “i3” and “i4” on these lines (Table 5.6, lines 14 and 15). “i1” and “i3” are plotted (60T - 5) seconds after “g”; “i2” and “i4” should be (60T + 15) seconds after “h”, but for the sake of simplification they are plotted (60T + 21) seconds after “g”. i1 i2 i3 i4 determine the area containing the still air position of the beginning of the inbound turn. e) with a centre at a distance r below “i2” on the perpendicular line to the nominal outbound leg, and a radius r draw an arc of 180° beginning at “i2” and ending at “n2”. Locate points “j” and “k” after 45 and 90° of turn from “i2”. Draw the corresponding arc beginning at “i4” and ending at “n4”. Locate points “l” and “m” after 90 and 135° of turn from “i4”. f) the end of the inbound turn in still air is contained in the area n1 n2 n3 n4 reduced from i1 i2 i3 i4 by a translation of one diameter of nominal turn. Influence of wind The wind effect is calculated for each point by multiplying the wind speed (Table 5.6, line 7) with the flying time from “a” to the point. • Influence of the wind during the outbound turn: a) draw arcs with centres “b”, “c”, “d”, “e” and “f” and radii Wb, Wc, Wd, We and Wf (Table 5.6, lines 16 to 20). b) the area containing the end of the outbound turn is determined by two arcs with centres “g” and “h” and radii Wg and Wh (Table 5.6, lines 21 and 22) and their common tangents. _________________________________________________________________________________________________________________ 156 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ c) the area containing the beginning of the inbound turn is determined by four arcs with the centres “i1”, “i2”, “i3” and “i4” and radii Wi1, Wi2, Wi3 and Wi4 (Table 5.6, lines 25 and 25) and their four common tangents. • Influence of the wind during the inbound turn: a) draw arcs with centres “j”, “k”, “l”, “m”, “n4” and “n3” and radii Wj, Wk, Wl, Wm, Wn3 and Wn4 (Table 5.6, lines 27 to 31). b) draw arcs with centres “o” and “p” and radii Wo and Wp (Table 5.6, lines 23 to 24). Drawing of the template The outline of the template is composed of: a) the spiral envelope of the arcs centred on “c”, “d”, “e”, “f” and “g”; b) the arc centred on “i1” and the common tangent to this arc and the spiral a); c) the common tangents to the arcs centred on “i1” and “i2”; d) the spiral envelope of the arcs centred on “i2”, “j” and “k”, the spiral envelope of the arc centred on “l”, “m” and “n4” and their common tangent; e) the arcs centred on “n3” and “n4” and their common tangent; and f) the tangent to the arc centred on “n3” and to the spiral a). The protection of the outbound leg in the direction of the D axis is represented by the common tangents to the arcs centred on “g”, “i3” and “i4”, called line “3” (see Figures 5.28 and 5.29). _________________________________________________________________________________________________________________ 157 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.28.- Holding/racetrack template with associated construction points Figure 5.29.- Holding template _________________________________________________________________________________________________________________ 158 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ The protection of a turn of more than 180° is represented by: a) the spiral envelope of the arcs centred on “c”, ”d”, “e”, “f” and the tangent to this spiral passing through “a”; b) the spiral envelope of the arcs centred on “h”, “o” and “p” and the tangent to this spiral and to the area drawn in 5.1.4.9; First step; Influence of the wind. VOR position fix tolerance area Manual construction. The VOR position fix tolerance area V1 V2 V3 V4 is determined as follows: a) draw a circle with centre on the VOR and a radius of zV: zV = h tan α where α is 50° or a lesser value, as determined by the appropriate authority, corresponding to the cone effect; b) draw two lines 5° from the perpendicular to the inbound track; c) draw two lines perpendicular to lines 2) at a distance qV on each side of the inboud track: qV = 0.2 h (h in km and qV in km) qV = 0.333 h (h in thousands of feet and qV in NM); d) locate points V1, V2, V3, V4 at the four intersections of lines 3) with the circle 1). Figure 5.30.- VOR position fix tolerance area _________________________________________________________________________________________________________________ 159 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Point “E” This point is used to determine the omnidirectional entry area in the direction of the C and D axis. It is located by its coordinates XE en YE from the outline of the template: a) draw a line perpendicular to the inbound track at a distance XE (Table 5.6, line 32) from the extreme position of the outline of the template in the direction of the C axis (common tangent to the circles centred on “k” and “l”); b) draw a line parallel to the inbound track at a distance YE (Table 5.6, line 33) from the extreme position of the outline of the template in the direction of the D axis (circle centred on “n4”); c) locate point “E” at the intersection of these two lines. Explanation: XE is the greatest displacement along the C axis of an aeroplane making an antry procedure. This occurs for a sector 3 entry at an angle of 90° with the procedure axis and a wind along the C axis (see Figure 5.32). The maximum displacement along the C axis due to wind effect occurs at point Emax, after that portion of turn corresponding to the drift angle. For simplicity this angle has a value of 15° in the formula. XE = 2r + (t + 15)v + (11 + 90/R + t + 15 + 105/R)w' YE is the greatest displacement along the D axis of an aeroplane making an entry procedure. This occurs for a sector 1 entry at an angle of 70° with the procedure axis and a wind along the D axis (see Figure 5.33). The maximum displacement along the C axis due to wind effect occurs at point Emax, after that portion of turn corresponding to the drift angle. For simplicity this angle has a value of 15° in the formula. YE = 11v cos 20° + r sin 20° + r + (t +15) v tan 5° + (11 + 20/R + 90/R + t + 15 + 15/R)w' _________________________________________________________________________________________________________________ 160 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Second step: construction of the basic area and the associated omnidirectional entry area overhead a VOR Figure 5.31.- Construction of the basic area Procedure overhead a VOR a) locate point “A” on the VOR; b) draw around “A” the position fix tolerance area of the VOR given by the template (area V1 V2 V3 V4) and locate points “A1”, “A2”, “A3” and “A4” on the four corners of this area. Construction of the procedure area a) place the template point “a” successively an “A1”, “A2” and “A4” to draw curves “1”, “2” and “4”; b) draw the common tangents to curves “1” and “2”, “2” and “4”, “3” and “4”, “3” and “1”. Construction of the entry area Construction of the entry area assuming omnidirectional entry overhead a VOR or an NDB: a) draw the circle centred on “A” passing through “A1” and “A3”: b) locate point “E” on a series of points along this circle (with the template axis parallel to the inbound track) and for each point draw a curve at the outer limit of the _________________________________________________________________________________________________________________ 161 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ template in the direction of the C and D axis; curve “5” is the envelope of these curves: c) draw the limit of the entry sectors 1 and 3 (line making an angle of 70° with the inbound track). With the template axis on this line draw the entry fix tolerance area E1 E2 E3 E4 given by the template for the VOR or the NDB; d) place the template point “a” on E1 and E3 (with the template axis parallel to the separating line of the sectors 1 and 3) and draw curves “6” and “7” and their common tangent; e) with a centre on “A”, draw the arc tangent to curve “6” until intersecting curve “1”; f) line 8 is symmetric of lines 6 and 7 about the 70° dividing line. Draw common tangents to curves “5”, “6”, “7” and “8” as appropriate. Figure 5.32.- Construction of the entry area _________________________________________________________________________________________________________________ 162 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.33.- Construction of the entry area; the axis of the template making an angle of 70° with the procedure axis Figure 5.34.- Basic area with omnidirectional entry areas 5.1.5 Intermediate approach segment 5.1.5.1 General The intermediate approach segment blends the initial approach segment into the final approach segment. It is the segment in which aircraft configuration, speed, and positioning adjustments are made for entry into the final approach segment. _________________________________________________________________________________________________________________ 163 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ There are two types of intermediate approach segments: a) one which begins at a designated intermediate approach fix (IF); b) one which begins upon completion of a dead reckoning (DR) track, a reversal or a racetrack procedure. In both cases, track guidance shall be provided inbound to the final approach fix (FAF) where the intermediate approach segment ends. See Figure 5.21 for typical intermediate approach segments. 5.1.5.2 Altitude/height selection The minimum altitude/height in the intermediate approach segment shall be established in 100-ft increments or 50-m increments as appropriate. 5.1.5.3 Intermediate approach segment based on a straight track alignment The track to be flown in the intermediate approach segment should normally be the same as the final approach track. Where this is not practicable and the final approach fix in a nonprecision procedure is a navigation facility, the intermediate track shall not differ from the final approach track by more than 30°. Where the turn at the FAF is greater than 10° the final approach area should be widened on the outer side of the turn as described in 5.1.4.7, “TP marked by a facility (NDB or VOR)”. Area This section deals with the construction of the area of an intermediate approach segment based on a straight track alignment. The length of the intermediate approach segment shall not be more than 28 km (15 NM) or less than 9.3 km (5.0 NM), measured along the track to be flown. The optimum length is 19 km (10 NM). A distance greater than 19 km (10 NM) should not be used unless an operational requirement justifies a greater distance. When the angle at _________________________________________________________________________________________________________________ 164 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ which the initial approach track joins the intermediate approach track exceeds 90°, the minimum length of the intermediate approach track is as shown in Table 5.7. In a straight-in approach, the width of the intermediate approach segment tapers from a maximum width of 19 km (5 NM) at the IF to its minimum width at the FAF (or FAP). The segment is divided longitudinally as follows: a) a primary area which extends laterally on each side of the track; b) a secondary area on each side of the primary area. (See Figure I-4-3-2 of Chapter 3.) For calculating secondary area width at a given point, see 5.1.1.5, “Calculating secondary area width at a given point”. Obstacle clearance A minimum of 150 m (492 ft) of obstacle clearance shall be provided in the primary area of the intermediate approach segment. In the secondary area, 150 m (492 ft) of obstacle clearance shall be provided at the inner edge, reducing to zero at the outer edge. See Figure 5.35. For calculating obstacle clearance at a given point, see 5.1.1.6, “Obstacle clearance”. The altitudes/heights selected by application of the obstacle clearance specified shall be rounded upwards to the next 50 m or 100 ft as appropriate. Procedure altitude/height and descent gradient Because the intermediate approach segment is used to prepare the aircraft speed and configuration for entry into the final approach segment, this segment should be flat or at least have a flat section contained within the segment. If a descent is necessary the maximum permissible gradient will be 5.2 per cent. In this case, a horizontal segment with a minimum length of 2.8 km (1.5 NM) should be provided prior to the final approach for Cat C and D aircraft. For procedures specific to Cat A and B aircraft, this minimum length may be reduced to 1.9 km (1.0 NM). This should allow _________________________________________________________________________________________________________________ 165 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ sufficient distance for aircraft to decelerate and carry out any configuration changes necessary before final approach segment. Procedure altitudes/heights in the intermediate segment shall be established to allow the aircraft to intercept a prescribed final approach descent. 5.1.5.4 Intermediate segment within a reversal or racetrack procedure General The intermediate approach segment begins upon interception of the intermediate track. Criteria are the same as those shown in 5.1.4.4, “Intermediate approach segment base on a straight track alignment”, except as specified in the paragraphs below. Area width When used with the reversal or racetrack procedure, the intermediate segment width expands uniformly from the width of the final approach segment at the navigation facility to 9.3 km (5.0 NM) on each side of the track at 28 km (15 NM) from the facility, for a total width of 18.6 km (10 NM). Beyond 28 km (15 NM) the area remains 19 km (10 NM) wide. See Figure 5.36. Figure 5.35.- Intermediate approach area within reversal or racetrack procedure with a fix The intermediate approach area is divided into primary and secondary areas as specified in 5.1.1.5, “Areas”. _________________________________________________________________________________________________________________ 166 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Area length When an IF is available the intermediate approach segment is normally 19 km (10 NM) long. See Figure 5.35. When no IF is available, the intermediate approach area shall extend to the far boundary of the reversal procedure primary area. See Figures 5.36 and 5.37. Figure 5.36.- Intermediate approach area within reversal or racetrack procedure with no IF Turn not at the facility If the reversal or racetrack procedure is predicated on a FAF which is not located at the facility, the intermediate approach area extends 9.3 km (5.0 NM) on each side of the intermediate track at 28 km (15 NM) from the facility, and tapers uniformly to the width of the final approach area at the FAF. See Figure 5.37. Descent gradient The constraints specified for the inbound track in Table 5.35 apply. Interception angle (degrees) 91-96 97-102 103-108 109-114 115-120 Minimum track length 11 km (6 NM) 13 km (7 NM) 15 km (8 NM) 17 km (9 NM) 19 km (10 NM) Table 5.7.- Minimum intermediate track length _________________________________________________________________________________________________________________ 167 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.37.- Intermediate approach area within reversal or racetrack procedure based on FAF (not the facility) 5.1.6 Final approach segment 5.1.6.1 General In the final approach segment, alignment and descent for landing are carried out. The instrument part of the final approach segment begins at the final approach fix, and ends at the missed approach point (MAPt). Track guidance shall be provided for the instrument phase of the final approach segment. Final approach may be made: a) to a runway for a straight-in landing; b) to an aerodrome for a circling approach. The final approach segment should be aligned with a runway whenever possible. All final approaches with a FAF have an optimum length of 9.3 km (5 NM). Other than this, however, the alignment and dimensions of he final approach segment, as well as minimum obstacle clearance (MOC) vary with the location and type of navigation aid. For this reason, criteria specific to each type are contained in the applicable sections. 5.1.6.2 alignment The final approach and its track guidance should be aligned with a runway whenever possible. When this is not possible it may be offset up to 5 degrees without OCA/H penalty (see 5.1.6.4, “Aligned straight-in approach”). Above that value, a category-dependent _________________________________________________________________________________________________________________ 168 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ penalty is applied (see 5.1.6.4, “Non-aligned straight-in approach”). Beyond these limits (or where other requirements can not be met) a circling approach shall be used. Straight-in approach This paragraph contains the alignment criteria for non-precision. The alignment criteria for approaches other than non-precision are found in the applicable sections. Final approach with track not intersecting the extended runway centre line. A final approach which does not intersect the extended centre line of the runway (θ equal to or less than 5°) may also be established, provided such track lies within 150 m laterally of the extended runway centre line at a distance of 1400 m outward from the runway threshold (see Figure 5.38). Figure 5.38.- Final straight-in approach alignment _________________________________________________________________________________________________________________ 169 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Aircraft category Lower limit on OCH (m (ft)) 5° < Θ < 15° 15° < Θ < 30° 105 (340) 115 (380) 115 (380) 125 (410) 125 (410) — 130 (430) — 145 (480) — A B C D E Table 5.8.- Lower limit on OCH Maximum angle. For a straight-in approach, the angle formed by the final approach track and the runway centre line shall not exceed: a) 30° for procedures restricted to Cat A and B aircraft; b) 15° for other aircraft categories. Minimum distance. The distance between the runway threshold and the point at which the final approach track intersects the runway centre line shall not be less than 1400 m (see Figure 5.38). Circling approach The circling approach contains the visual phase of flight after completing an instrument approach, to bring an aircraft into position for landing on a runway that for operational reasons is not suitably located for straight-in approach. In addition, when the final approach track alignment or the descent gradient does not meet the criteria for a straight-in landing, only a circling approach shall be authorized and the track alignment should ideally be made to the centre of the landing area. When necessary, the final approach track may be aligned to pass over some portion of the usable landing surface. In exceptional cases, it may be aligned beyond the aerodrome boundary, but in no case beyond 1.9 km (1.0 NM) from the usable landing surface. 5.1.6.3 descent gradient Gradient/angle limits Minimum/optimum descent gradient/angle. The minimum/optimum descent gradient is 5.2 per cent for the final approach segment of a non-precision approach with FAF (3° for a precision approach or approach with vertical guidance). Descent gradients steeper than the _________________________________________________________________________________________________________________ 170 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ optimum should not be used unless all other means to avoid obstacles have been attempted since these steeper descent gradients may result in rates of descent which exceed the recommended limits for some aircraft on final approach. Rate of descent Aircraft categories Cat A/B Cat C/D/E Minimum 200 m/min (655 ft/min) 305 m/min (1000 ft/min) Maximum 120 m/min (394 ft/min) 180 m/min (590 ft/min Table 5.9.- Rate of descent Maximum descent gradient/angle. The maximum descent gradient is: a) for non-precision procedures with FAF: 6.5 per cent for a non-precision approach for Cat A and B; 6.1 per cent for Cat C,D and E aircraft; b) for a non-precision approach with non FAF, see Table I-4-5-1; c) 3.5° for an approach with vertical guidance; d) for precision approaches: 3.5° for a Cat I precision approach; 3° for CAT II and III precision approaches. Determination of the descent gradient for a non-precision approach with FAF The descent gradient (g) for a non-precision approach with FAF is computed using the equation: g = h/d. the values for h and d are defined as follows: a) for a straight-in approach use: d = the horizontal distance from the FAF to the threshold; h = the vertical distance between the altitude/height over the FAF and the elevation 15 m (50 ft). b) for a circling approach use: d = the distance from the FAF to the first usable portion of the landing surface; h = the vertical distance between the altitude/height over the FAF and the circling OCA/H. c) for an approach where a stepdown fix (SDF)is used in the final segment, two descent gradients are calculated (g1 and g2). 1) in calculating the gradient (g2) between the stepdown fix and the FAF: _________________________________________________________________________________________________________________ 171 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ d1 = the horizontal distance from the FAF to the SDF; h1 = vertical distance between the height of the FAF and the height of the SDF. 2) in calculating the gradient (g2) between the stepdown fix and the approach runway threshold: d2 = the horizontal distance from the SDF to the threshold; h2 = the vertical distance between the altitude/height at the SDF and the elevation 15 m (50 ft). 5.1.6.4 obstacle clearance altitude/height (OCA/H) General This paragraph describes the application of OCA/H for the different types of approach and its relationship to the aerodrome operating minima. The OCA/H is based on clearing obstacles by a specified minimum obstacle clearance (MOC). In some situations, an additional margin is added to the MOC, or an absolute lower limit should be applied, which will override the OCA/H. See 5.1.6.4, “MOC and OCA/H adjustments”, and Figure 5.39, 5.40 and 5.41. Precision approach procedures/approach procedures with vertical guidance (APV) a) OCA/H. In a precision approach procedure (or APV), the OCA/H is defined as the lowest altitude/height at which a missed approach must be initiated to ensure compliance with the appropriate obstacle clearance design criteria. b) reference datum. The OCA is referenced to mean sea level (MSL). The OCH is referenced to the elevation of the relevant runway threshold. _________________________________________________________________________________________________________________ 172 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.39.- Relationship of obstacle clearance altitude/height (OCA/H) to minimum decision altitude/height (DA/H) for precision approaches Non-precision approach procedure (straight-in) a) OCA/H. In a non-precision approach procedure, the OCA/H is defined as the lowest altitude or alternatively the lowest height below which the aircraft can not descend without infringing the appropriate obstacle clearance criteria. _________________________________________________________________________________________________________________ 173 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ b) reference datum. The OCA/H is referenced to mean sea level (MSL). The OCH is referenced to a) aerodrome elevation; b) runway threshold elevation when the threshold elevation is more than 2 m (7ft) below the aerodrome elevation. Figure 5.40.- Relationship of obstacle clearance altitude/height (OCA/H) to minimum decision altitude/height (DA/H) for non-precision approaches _________________________________________________________________________________________________________________ 174 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Visual manoeuvring (circling) procedure a) OCA/H. Same as in the non-precision approach procedure. b) reference datum. The OCA/H is referenced to mean sea level (MSL). The OCH is referenced to the aerodrome elevation. Figure 5.41.- Relationship of obstacle clearance altitude/height (OCA/H) to decision altitude/height (DA/H) for visual manoeuvring _________________________________________________________________________________________________________________ 175 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Aerodrome operating minima OCA/H is one of the factors taken into account in establishing operating minima for an aerodrome in accordance with Annex 6. See Figure 5.39 to 5.41 OCA/H for precision approaches and approach procedures with vertical guidance The determination of OCA/H in precision approaches and approach procedures with vertical guidance is described in ICAO PANS-OPS Part II, Section 1 and Part III, Section 3, Chapters 4 to 6. OCA/H for non-precision approach (straight-in) Aligned straight-in approach The OCA/H for a straight-in, non-precision approach where the angle between the track and the extended runway centre line does not exceed 5 degrees shall provide the following minimum obstacle clearance (MOC) over the obstacles in the final approach area: a) 75 m (246 ft) with FAF; b) 90 m (295 ft) without FAF. The OCA/H shall also ensure that missed approach obstacle clearance is provided. A straight-in OCA/H shall not be published where final approach alignment or descent gradient criteria are not met. In this case, only circling OCA/H shall be published. Non-aligned straight-in approach For a final approach where the track intersects the extended runway centre line, OCA/H varies according to the interception angle. The OCH of the procedure shall be equal to or greater than the lower limits shown in Table 5.8. The calculations used to arrive at these values appear in the Appendix to this chapter. For nominal descent gradients above 5.2 per cent, increase by 18 per cent the lower limits shown in the table for each per cent of gradient above 5.2 per cent. _________________________________________________________________________________________________________________ 176 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ OCA/H for visual manoeuvring (circling) The OCA/H for visual manoeuvring (circling) shall provide the minimum obstacle clearance (MOC) over the highest obstacle in the visual manoeuvring (circling) area as specified in Table 5.12 . It shall also be: a) above the lower limits (also specified in Table 5.12); b) not less than the OCA/H calculated for the instrument approach procedure which leads to the circling manoeuvre. See 5.1.8, “Visual manoeuvring (circling) area”. MOC and OCA/H adjustments In certain cases the MOC and/or the OCA/H must be increased. This may involve: a) an additional margin that is added to MOC; b) a percentage increase in OCA/H; c) applying a lower limit (a minimum value) to OCA/H; as described below. Additional margin applied MOC a) mountainous areas. See 5.1.1.12, “Increased altitude/heights for mountainous areas” for guidance on increased MOC in mountainous areas. b) excessive length of final approach. When a FAF is incorporated in a non-precision approach procedure, and the distance from the fix to the runway threshold for which the procedure is designed exceeds 11 km (6 NM), the obstacle clearance shall be increased at the rate of 1.5 m (5 ft) for each 0.2 km in excess of 11 km (0.1 NM in excess of 6 NM). Where a stepdown fix is incorporated in the final approach segment, the basic obstacle clearance may be applied between the stepdown fix and the MAPt, provided the fix is within 11 km (6 NM) of the runway threshold. These criteria are applicable to non-precision approach procedures only. Percentage increase in OCA/H: Remote altimeter setting. When the altimeter setting is derived from a source other than the aerodrome, and more than 9 km (5 NM) remote from the threshold, the OCA/H shall be increased at a rate of 0.8 m for each kilometre in excess of 9 km (5 ft for each _________________________________________________________________________________________________________________ 177 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ nautical mile in excess of 5 NM) or a higher value if determined by local authority. In mountainous areas or other areas where reasonably homogenous weather can not always be expected, a procedure based on a remote altimeter setting source should not be provided. In all cases where the source of the altimeter setting is more than 9 km (5 NM) from the threshold, a cautionary note should be inserted on the instrument approach chart identifying the altimeter setting source. Remote altimeter setting source (RASS) in mountainous areas: a) the use of RASS in mountainous areas requires additional calculations to determine the correct OCA/H. The calculation uses the formula OCA/H = 2.3x + 0.14z (non SI) OCA/H = 0.4x + 0.14z (SI) where: OCA/H is the RASS increased altitude/height value (m/ft); x is the distance from the RASS to the landing area (km/NM); z is the difference in elevation between the RASS and the landing area (m/ft). These formulas are used where no intervening terrain adversely influences atmospheric pressure patterns. The use of these criteria is limited to a maximum distance of 138 km (75 NM) laterally or an elevation differential of 1770 m (6000 ft) between the RASS and the landing area. b) where intervening terrain adversely influences atmospheric pressure patterns, the OCA/H shall be evaluated in an Elevation Differential Area (EDA). The EDA is defined as the area within 9 km (5 NM) each side of a line connecting the RASS and the landing area, including a circular area enclosed by a 9 km (5 NM) radius at each end of the line. In this case, z becomes the terrain elevation difference (m/ft) between the highest and lowest terrain elevation points contained in the EDA. _________________________________________________________________________________________________________________ 178 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Lower limit (a minimum value) applied to OCA/H a) forecast altimeter setting. When the altimeter setting to be used with procedures is a forecast value obtained from the appropriate meteorological office, the OCA/H shall be increased by a value corresponding to the forecasting tolerance for the location as agreed by the meteorological office for the time periods involved. Procedures which require the use of forecast altimeter setting shall be suitably annotated on the approach charts. b) final approach rack intersecting the extended runway centre line between 5° and 30°. When the final approach track intersects the extended runway centre line between 5° and 30° a lower limit is applied to OCA/H (5.1.6.4, “non-aligned straight-in approach”). c) final approach track intersecting the extended runway centre line at more than 30° or descent gradient exceeding 6.5 per cent. When the final approach track intersects the extended runway centre line at more than 30°, or the descent gradient exceeds 6.5 per cent, the OCA/H for visual manoeuvring (circling) becomes the lower limit and is applied to the approach procedure. d) visual manoeuvring (circling). For visual manoeuvring (circling) a lower limit consisting of the OCA/H for the associated instrument approach procedure is applied (see 5.1.6.4, “OCA/H for visual manoeuvring (circling)”). 5.1.6.5 promulgation Descent gradients/angles for charting. Descent gradients/angles for charting shall be promulgated to the nearest one-tenth of a percentage/degree. Descent gradients/angles shall originate at a point 15 m (50 ft) above the landing runway threshold. For precision approaches different origination points may apply (see RDH in specific chapters). Earth curvature is not considered in determining the descent gradient/angle. Descent angles for database coding. Previous paragraph applies with the exception that descent angles shall be published to the nearest one-hundredth of a degree. FAF altitude-procedure altitude/height. The descent path reaches a certain altitude at the FAF. In order to avoid overshooting the descent path, the FAF published procedure _________________________________________________________________________________________________________________ 179 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ altitude/height should be 15 m (50 ft) below this altitude. The procedure altitude/height shall not be less than the OCA/H of the segment preceding the final approach segment. Both the procedure altitude/height and the minimum altitude for obstacle clearance shall be published. In no case shall the procedure altitude/height be lower than the minimum altitude for obstacle clearance. The designed stabilized descent path shall clear the stepdown fix minimum obstacle clearance altitude. This can be achieved by increasing the descent gradient by: a) increasing the procedure altitude/height at the FAF; b) moving the FAF toward the landing threshold. Publication of OCA/H. An OCA and/or an OCH shall be published for each instrument approach and circling procedure. For non-precision approach procedures, either value shall be expressed in 5-m or 10-ft increments by rounding up as appropriate. 5.1.7 Missed approach segment 5.1.7.1 General Requirements A missed approach procedure shall be established for each instrument approach and shall specify a point where the procedure begins and a point where it ends. The missed approach procedure is initiated: a) at the decision altitude height (DA/H) in precision approach procedures or approach with vertical guidance (APV); or b) at the missed approach point (MAPt) in non precision approach procedures. The missed approach procedure shall terminate at an altitude/height sufficient to permit: a) initiation of another approach; or b) return of designated holding pattern; or c) resumption of en-route flight. Only one missed approach procedure shall be established for each approach procedure. _________________________________________________________________________________________________________________ 180 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Phases of missed approach segment In principle the missed approach segment starts at the MAPt and includes the following three parts (see Figure 5.42): a) initial phase — begins at the earliest MAPt, and extends until the Start of Climb (SOC); b) intermediate phase — extends from SOC to point where 50 m (164 ft) obstacle clearance is first obtained and can be maintained; c) final phase — extends to the point at which a new approach, holding or return to enroute flight is initiated. Turns may be carried out during this phase. Figure 5.42.- Obstacle clearance for final missed approach phase Figure 5.43.- Case where the extension of the missed approach surface covers the initial missed approach phase entirely _________________________________________________________________________________________________________________ 181 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Types of missed approach There are two types of missed approach: a) straight missed approach (includes turns less than or equal to 1.5 degrees); b) turning missed approach. Missed approach area The area considered for the missed approach shall start at the earliest MAPt tolerance, with a width equal to that of the final approach segment at that point. The subsequent size and shape of the area depends on the missed approach procedure, including the point at which the turn is initiated, if applicable, and the extent of the turn. Missed approach point General. A missed approach begins at the missed approach point (MAPt) and only applies to non-precision approaches. For non-precision approaches, the MAPt shall be defined as follows: a) procedures without a FAF — by a navigation facility or fix; and b) procedure with a FAF — the MAPt shall be defined by one of the following three cases: 1) by timing over the distance from the nominal FAF to the nominal MAPt, where the MAPt is not defined by a facility or fix; or 2) by a navigation facility or fix at the MAPt, in which case procedure must be annotated “timing not authorized for defining the MAPt”; or 3) by both timing over the distance from the nominal FAF to the nominal MAPt, as well as a facility or fix at the missed approach point. In this case a single OCA/H, which shall be the higher of the OCA/H for the specified distance and the OCA/H for the facility or fix, shall be published. However, when an operational advantage can be achieved, both may be published. Note. — The optimum location of the MAPt is the runway threshold. However, where obstacles in the missed approach require an MAPt before the threshold, the MAPt may be located closer to the FAF. It should be moved no farther than necessary and normally _________________________________________________________________________________________________________________ 182 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ should not be located before the point where the OCH intersects the path of a nominal 5.2 per cent descent gradient to the runway. Determining earliest and latest MAPt for a MAPt determined by distance. When the MAPt is determined by timing over the distance from the FAF, the total MAPt tolerance (Y) may be determined by taking the values from Table 5.10) and applying them as shown in Figure 5.45. For the refined calculations see the appendix to this chapter. Aircraft category Category A Category B Category C Category D Distance from nominal MAPt to earliest and latest MAPt max { 2463; 0.3897D1 + 1086} max { 2463; 0.2984D + 1086} max { 2463; 0.1907D + 1086} max { 2463; 0.1562D + 1086} Table 5.10.- Distance from nominal MAPt to earliest and latest MAPt Calculating start of climb (SOC) There are two methods for calculating SOC. The method used depends on whether: a) the MAPt is defined by a navigation facility or fix; or b) the MAPt is defined by a specified distance from the FAF. Determing SOC with an MAPt defined by an navigation facility or fix: When the MAPt is defined by a navigation facility or fix (see Figure 5.44), SOC is determined by the sum of: a) the MAPt tolerance; b) the transitional distance (X) MAPt tolerance when MAPt is defines by a navigation facility or fix. When the MAPt is defined by a navigation facility or fix (see Figure 5.44), the MAPt longitudinal tolerance is defined by the sum of: a) the full tolerance of the facility/fix; plus b) a distance (d), allowing for pilot reaction time. This value corresponds to 3 seconds of flight at the maximum final approach speed for the specific aircraft category, plus a tail wind factor of 19 km/h (10kt). 1 D = distance from nominal FAF to nominal MAPt (km). The values in the table are SI units (meters). _________________________________________________________________________________________________________________ 183 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.44.- Determing SOC with an MAPt defined by a naviagation facility or fix Figure 5.45.- Distance from nominal FAF to earliest and latest MAPt _________________________________________________________________________________________________________________ 184 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ If the MAPt is defined by overheading a navigation facility (VOR, NDB or 75 Mhz marker beacon) the fix tolerance is 0 km (NM). Transitional distance with a MAPt defined by a navigation facility or fix. Transitional distance (X) with an MAPt defined by an navigation facility or fix is based on 15 seconds of flight at a TAS based on the highest final approach speed for each aircraft category (see Tables 5.1), at the aerodrome elevation with a temperature of ISA + 15°C and a tailwind of 19 km/h (10 kt). These values are applied as shown in Figure 5.44. Determing SOC with an MAPt defined by an distance from the FAF (simplified method): For determining SOC with an MAPt defined by a distance from the FAF, a simplified method can be used as a estimate for altitudes up to 4 000 m (13 000 ft), see Figure 5.46. In this case SOC is determined by the sum of: a) the distance from the nominal FAF to the nominal MAPt; plus b) transitional distance (X). Figure 5.46.- Determing SOC with an MAPt defined by a distance from the FAF Transitional distance with an MAPt defined by distance. Transitional distance with a MAPt defined by distance is base on 15 seconds of flight at the appropriate TAS, at the aerodrome _________________________________________________________________________________________________________________ 185 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ elevation with a temperature of ISA+15°C and a tailwind of 19 km/h (10 kt). See Table 5.11 for computation of transitional distance (X). Aircraft category Category A Category B Category C Category D Transitional distance (X) max {0.0875D + 2591; 0.3954D + 1604} max {0.0681D + 3352; 0.3246D + 1653} max {0.0567D + 3794; 0.2328D + 1945} max {0.0495D + 4153; 0.2055D + 2073} Table 5.11.- Computation of transitional distance Determining SOC with an MAPt defined by a distance from the FAF (refined method): The refined method shall be used for altitudes over 4 000 m (13 000 ft), and may give an operational advantage in some conditions under 4000 m (13 000 ft). This is shown in the appendix. 5.1.7.2 Climb gradient and MOC Initial phase The initial phase begins at the earliest missed approach point (MAPt) and ends at the start of climb point (SOC). The manoeuvre during this phase requires the concentrated attention of the pilot, especially when establishing the climb and the changes in configuration, and it is assumed that guidance equipment is not utilized during these manoeuvres. No turns may be specified during this phase. Climb gradient in the initial phase. In the initial phase the flight track is horizontal. Obstacle clearance in the initial phase. In the initial missed approach area, the minimum obstacle clearance shall be the same as for the last part of the final approach area except where the extension of the intermediate missed approach surface backwards towards the missed approach point requires less clearance. (See Figures 5.42 and 5.43) Intermediate phase The intermediate phase begins at the SOC. The climb is continued at stabilized speeds up to the first point where 50 m (164 ft) obstacle clearance is obtained and can be maintained. In the construction of this phase it is assumed that advantage may be taken of available _________________________________________________________________________________________________________________ 186 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ navigation guidance. During the intermediate phase, the missed approach track may be changed from that of the initial phase by a maximum of 15°. Climb gradient in the intermediate phase. The nominal climb gradient (tan Z) of the missed approach surface is 2.5 per cent. A gradient of 2 per cent may be used if the necessary survey and safeguarding can be provided. Additional climb gradients of 3, 4 or 5 per cent may also be specified. These may be used by aircraft whose climb performance permits the operational advantage of the lower OCA/H associated with these gradients, with the approval of the competent authority. Note. — In case of non-precision approach, any intermediate values between 2 and 5 per cent may be considered. Obstacle clearance in the intermediate phase In the intermediate missed approach phase, the minimum obstacle clearance shall be 30 m (98 ft) in the primary area, and in the secondary area the minimum obstacle clearance shall be 30 m (98 ft) at the inner edge, reducing linearly to zero at the outer edge. See Section 2, 5.1.1.6, “Obstacle clearance”; The OCA/H for the nominal 2.5 must always be published on the instrument approach chart. If additional gradients are specified in the construction of the missed approach procedure, they and their associate OCA/H values must be published as alternative options. Note. — MOC may be obtained by increasing the OCA/H or by a longitudinal adjustment of the MAPt or both. Final phase The final phase begins at the point where 50 m (164 ft) obstacle clearance is first obtained and can be maintained. It ends at the point at which a new approach, holding or return to enroute flight is initiated. Turns may be carried out during this phase. _________________________________________________________________________________________________________________ 187 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Climb gradient in the final phase. The criteria of the intermediate phase apply. Obstacle clearance in the final phase In the final missed approach phase of a straight missed approach the minimum obstacle clearance shall be 50 m (164 ft) in the primary area, reducing linearly to zero at the outer edge of the secondary area. See Figure 5.42. Turning missed approaches have specific criteria for MOC and for the arrangement and extent of secondary areas (see 6.1.7.4, “Turning missed approach”). Note. — MOC may be obtained by increasing the OCA/H or by a longitudinal adjustment of the MAPt or both. In addition, obstacles may be excluded from consideration by defining a turn. 5.1.7.3 Straight missed approach This sections contains the criteria for a straight missed approach. It includes turns less than or equal to 15 degrees. Area for straight missed approach The straight missed approach area has a width at its origin equal to that of the final approach area at that point. Thereafter is splays at an angle: a) determined by the accuracy of the tracking navigation aid used (10.3° for NDB, 7.8° for VOR) (see Figure 5.47); or b) with a divergence of 15° where no reference to a navigation aid is available. The area extends a sufficient distance to ensure that an aircraft executing a missed approach has reached an altitude at which obstacle clearances for subsequent procedures (such as for en-route or holding) can be observed. The initial phase of the missed approach surface is horizontal, and is based on the lowest assumed flight path at the OCA/H. The start of climb (SOC) for the intermediate and final phases originates immediately beyond the transitional distance (see 5.1.7.1, “Transitional distance with an MAPt defined by a navigation facility or fix” and 5.1.7.1, “Transitional distance with an MAPt defined by distance”). The _________________________________________________________________________________________________________________ 188 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ intermediate and final phases ascend uniformly with the gradient of the missed approach surface, as specified in 5.1.7.2, “Climb gradient and MOC”. Figure 5.47.- Area for straight missed approach Additional track guidance. An operational advantage may be obtained during the development of the missed approach procedure by using suitably located facilities to reduce the dimensions of the final phase. In this case the boundaries of the final phase are continued until they intersect the appropriate boundaries for the facility provided: a) for a VOR ± 1.9 km (± 1.0 NM) with a splay (towards MAPt) of 7.8°; b) for a NDB ± 2.3 km (± 1.25 NM) with a splay of 10.3°. Figures 5.48 and 5.49 show missed approach areas both with and without additional track guidance. _________________________________________________________________________________________________________________ 189 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.48.- Area associated with additional track guidance for MAPt defined by a navigational facility Continuous track guidance. When the track guidance for missed approach is a continuation of guidance from the facility used on the final approach, the missed approach area is a continuation of that area(s) defined for that facility. See Figure 5.50. _________________________________________________________________________________________________________________ 190 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.49.- Area associated with additional track guidance for MAPt not at a facility Figure 5.50.- Example of area where the track guidance for missed approach is a continuation of guidance from the facility used on the final approach _________________________________________________________________________________________________________________ 191 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.51.- Missed approach turn 15° or less at the MAPt Primary and secondary area The general criteria apply. Alignment Wherever practical the missed approach track should be a continuation of the final approach track. Missed approaches involving turns are permitted (see 5.1.7.4, “Turning missed approach”), but should only be employed when an operational advantage may be obtained. Obstacle clearance for the straight missed approach The general criteria apply as stated in 5.1.7.2, “Climb gradient and MOC”. 5.1.7.4 Turning missed approach This section contains the criteria for a turning missed approach for turns of more than 15 degrees. For turns less than or equal to 15 degrees, the criteria for a straight missed approach apply. See 5.1.7.3, “Straight missed approach”, above. Turns may be defined as occurring at: a) an altitude/height; b) a fix or facility; or c) the MAPt. If a turn from the final approach track is specified, turning missed approach areas must be constructed. The criteria in 5.1.7.3, “Straight missed approach” above remain in effect until the following: _________________________________________________________________________________________________________________ 192 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ a) the turning point (TP) for turns specified by altitude/height (see 5.1.7.4, “Turn initiated at a designated altitude/height”); b) the earliest TP for turns at a designated TP (see 5.1.7.4, “Turn initiated at a designated turning point”). To obtain the minimum OCA/H it may be necessary to adjust the designated turn altitude or turning point (TP). The number of variables is such that this may involve a trial and error process. Note. — All calculations in this chapter are made for the 2.5 per cent nominal gradient. See 5.1.7.2 for use of gradient other than 2.5 per cent. Turn parameters This section shows the parameters on which the turn areas are based, together with the variables which represent them in the drawings. a) altitude: Aerodrome altitude plus 300 m (1 000 ft) or the defined turn altitude; b) temperature: ISA+15°C corresponding to a) above; c) indicated airspeed (IAS): The speed for final missed approach is shown in Tables 5.1. However, where operationally required to avoid obstacles, reduced speeds as slow as the IAS for intermediate missed approach may be used, provided the procedure is annotated “Missed approach turn limited to ____km/h (kt) IAS maximum.”; d) true airspeed: The IAS in c) above for altitude a) and temperature b); e) wind: Maximum 95 per cent probability wind on an omnidirectional basis, where statistical wind data is available. Where no wind data is available, an omnidirectional 56 km/h (30 kt) wind should be used; f) average achieved bank angle: 15°; g) fix tolerance: As appropriate for the type of fix. See 5.1.1.2, “Terminal area fixes”; h) flight technical tolerances: c = a distance equivalent to 6 seconds of flight (3-second pilot reaction and 3-seconds bank establishing time) at the final missed approach seed (for maximum published missed approach speed) plus 56 km/h (30 kt) tailwind; i) d0 = Distance to an obstacle; j) dz = shortest distance to an obstacle or datum measured from SOC parallel to the straight missed approach track; _________________________________________________________________________________________________________________ 193 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ k) Oi = obstacle (subscript indicates the specific obstacle); l) tan Z = tangent of the angle of the missed approach surface with the horizontal plane; m) R = rate of turn; n) r = turn radius; o) E = wind effect. Secondary areas In the turn area, the secondary area always applies on the outer side of the turn, as a continuation of the straight missed approach secondary area (see Figures 5.54 to 5.60 for a turn designated at a turn point). The secondary area resume as soon as the aircraft has track guidance. Additional track guidance. After the turn operational advantage may be obtained during the development of the missed approach procedure, by using suitably located facilities to reduce the dimensions of the final missed approach area. Examples of typical turning missed approach areas with additional track guidance are shown in Figures 5.55 and 5.60. Turn initiated at a designated altitude/height A turn is prescribed upon reaching a specified altitude to cope with two kinds of penalizing obstacles: a) an obstacle located in the direction of the straight missed approach and which must be avoided; b) an obstacle located abeam the straight missed approach track and which must be overflown after the turn with the appropriate margin. A turning missed approach at a designated altitude requires a climb to a specified altitude/height before initiating a turn to a specified heading or towards a fix/facility. Areas • Turn initiation area The point where the designated altitude/height is reached is not fixed. It depends on _________________________________________________________________________________________________________________ 194 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ the climb performance of the aircraft and the point from which the missed approach is initiated. The aircraft may reach the designated turn altitude/height: a) as early as the earliest MAPt when the procedure prohibits turning before the MAPt or as early as the earliest FAF when no restrictions are provided; b) after a climb using the minimum required gradient from the SOC to the point where it reaches the specified altitude height. This point is called the Turn Point (TP). Procedure design should take both extremes into account. Therefore the area where the aircraft can initiate its turn is bounded by: a) the distance from the earliest MAPt or earliest FAF to the TP; b) the edges of the secondary areas of the initial and intermediate phases. This area is called the turn initiation area. The line which marks the end of the turn initiation area is defined by KK (see Figures 5.52 and 5.53). • Turn area The turn area's boundaries are constructed to protect aircraft in the two extreme cases described above: a) inner boundary construction: 1) for turns less than 75 degrees, the inner boundary originates at the inner edge of the earliest MAPt (Figure 5.52) and splays at an angle of 15 degrees relative to the nominal track after the turn; 1) for turns more than 75 degrees, the inner boundary originates at the outer edge of the earliest MAPt (Figure 5.53) and splays at an angle of 15 degrees relative to the nominal track after the turn; b) outer boundary construction: 1) on the outer edge of the turn initiation area, add a tolerance to account for pilot reaction time (c: a distance equivalent to 6 seconds of flight (See 5.1.7.4, “Turn parameters”)). This established point A; and 2) from point A, construct the outer boundary _________________________________________________________________________________________________________________ 195 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.52.- Turn less than 75° at an altitude Figure 5.53.- Turn more than 75° at an altitude Obstacle clearance for turns at a designated altitude a) obstacle clearance in the turn initiation area. The straight missed approach obstacle clearance criteria apply up to the TP. This allows the calculation of OCA/H for final approach and straight missed approach segments (OCA/Hfm) (see 5.1.7.3, “Obstacle clearance for the straight missed approach”). An additional obstacle assessment must be made to assure that the obstacle elevation/height in the turn initiation area shall be less than: TNA/H - 50 m (164 ft) _________________________________________________________________________________________________________________ 196 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.54.- Obstacle clearance within turn initiation b) obstacle clearance in the turn area. Obstacle elevation/height in the turn area shall be less than: TNA/H + d0 tan Z - MOC where: _________________________________________________________________________________________________________________ 197 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ • d0 is measured from the obstacle to the nearest point on the turn initiation area boundary; • MOC is 50 m (164 ft) reducing linearly to zero at the outer edge of the secondary areas, if any. Establishment of turn altitude/height The choice of the turn altitude/height (TNA/H) and associated turn point (TP) is an iterative process. The TP must be located so that the obstacle clearance criteria in both the turn initiation area and turn area are satisfied. Once SOC and OCA/Hfm are determined, turn altitude/height (TNA/H) may be computed from the following relationship: TNA/H= OCA/Hfm + dz tan Z where dz is horizontal distance from SOC to the TP. If the latest TP has to be located at or before the SOC calculated for the final and straight missed approach, then the MAPt shall be moved back and, if necessary, the OCA/H increased. Turn altitude/height adjustments If the criteria specified in 5.1.7.4, “Obstacle clearance for turns at a designated altitude” cannot be met, the turn altitude/height shall be adjusted. This can be done in three ways: a) adjust TNA/H without changing OCA/H. This means that the latest TP will be moved and the areas redrawn accordingly; b) move SOC back to increase dz. This means that the MAPt and consequently earliest TP will be moved and the turn areas extended accordingly; c) increase OCA/H. Safeguarding of early turns If the procedure does not prohibit turns before the MAPt, then an additional area outside the final approach area must be considered (see Figure 5.55). In this area obstacle elevation shall be less than: _________________________________________________________________________________________________________________ 198 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ TNA/H + d0 tan Z - 50 m (164 ft) where d0 is measured from the obstacle to the nearest point on the edge of the final approach area. If this criterion cannot be met, then the procedure must prohibit turns before the MAPt and a note must be added on the profile view of the approach chart. Figure 5.55.- Limitation of early turns – additional safeguarding requirement Turn initiated at a designated turning point A designated TP shall be defined by a fix , or by a limiting radial, bearing or DME distance. It is chosen to allow the aircraft to avoid an obstacle straight ahead. The straight missed approach criteria apply up to the earliest TP. This allows the calculation of OCA/H for final and straight missed approach (OCA/Hfm) (see 5.1.7.2 “Climb gradient and MOC”). SOC is then determined. Turning point tolerance area The length of the TP tolerance area is determined by: a) the limits of the fix tolerance area, plus; _________________________________________________________________________________________________________________ 199 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ b) an additional distance c (pilot reaction and bank establishing time) equivalent to 6 seconds of flight at final missed approach (or maximum published missed approach) speed plus 56 km/h (30 kt) tailwind (see Figure 5.56). If the TP is defined by overheading facility (e.g. VOR, NDB) the TP fix tolerance can be taken as ± 0.9 km (± 0.5 NM) up to a height above the facility of: a) 750 m (2 500 ft) for a VOR (with a cone angle of 50°); b) 1 100 m (3600 ft) for an NDB. Figure 5.56.- Turning missed approach with DME as TP fix Construction of the turn area Turns are executed in the final missed approach area. This area begins at point A, which is located at the latest limit of the TP tolerance area (defined above). Its sides begin at the edges of the straight missed approach area. TP defined by a fix or by a limiting radial, bearing or DME distance. _________________________________________________________________________________________________________________ 200 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ a) outer boundary: 1) On the outside edge of the missed approach area, determine point A (see Figure 5.56); 2) From point A, construct the outer boundary b) inner boundary: 1) on the inner edge of the missed approach area, the earliest TP tolerance, determine point K; 2) from point K, draw a line splayed outward at an angle of 15° from the nominal track after the turn. c) particular case: for particular cases (turns more than 90°, return tot FAF), draw the area after that turn as shown in Figures 5.57, 5.58 and 5.59. Figure 5.57.- 180° turning missed approach with DME as TP fix _________________________________________________________________________________________________________________ 201 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.58.- Turning missed approach with TP fix and return to the facility with track back TP marked by a facility (NDB or VOR). When the turning point is marked by a facility (NDB or VOR) the area is constructed as follows. a) inner boundary: the boundary which is associated with tracking outbound from this facility after the turn; b) outer boundary: in order to accommodate the overshoot when turning over a NAVaid, the boundary on the outer side of the turn must be widened as follows: 1) determine the latest TP tolerance (point A); 2) from point A, construct the outer boundary up to the point where its tangent becomes parallel to the nominal track after the turn. from this point the area boundary remains parallel to the nominal track until it intersects the area associated with the NAV-aid (see Figure 5.60). _________________________________________________________________________________________________________________ 202 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.59.- Turning missed approach with TP fix and return to the facility without track back Obstacle clearance in the turn area Obstacle elevation in the turn shall be less than: OCA/Hfm + d0 tan z – Moc Where: • d0 = dz + shortest distance from obstacle to line K-K, • dz = horizontal distance from SOC to earliest TP (line K-K) and MOC is 50 m (164 ft) for turns more than 15° reducing linearly to zero at the outer edge of the secondary areas, if any. _________________________________________________________________________________________________________________ 203 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.60.- Turning missed approach involving turns over a facility Turn specified at the MAPt Where the turn is specified at the MAPt which means that the pilot is supposed to establish the aeroplane on a climbing path and then to turn, the OCA/H will be taken as the turn altitude/height and the turn initiation area will extend from the earliest MAPt to the SOC (see Figure 5.61). 5.1.7.5 Promulgation If safeguarding of early turn is not provided a note must be added on the profile view of the approach chart: “No turn before MAPt”. The OCA/H for the nominal 2.5 per cent must always be published on the instrument approach chart. If additional gradients are specified in the construction of the missed _________________________________________________________________________________________________________________ 204 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ approach procedure, they and their associated OCA/H values must be published as alternative options. Figure 5.61.- Missed approach turn more than 15° at the MAPt 5.1.8 Visual manoeuvring (circling) area 5.1.8.1 Defenition of terms Visual manoeuvring (circling) is the term used to describe the visual phase of flight after completing an instrument approach, which brings an aircraft into position for landing on a runway which is not suitably located for straight-in approach, i.e. one where the criteria for alignment or descent gradient can not be met. Area to be considered for obstacle clearance The visual manoeuvring (circling) area is the area in which obstacle clearance shall be considered for aircraft manoeuvring visually (circling). Prescribed track for visual manoeuvring In those locations where clearly defined visual features permit, and if it is operationally desirable, a specific track for visual manoeuvring may be prescribed ( in addition to the circling area). _________________________________________________________________________________________________________________ 205 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 5.1.8.2 Alignment and area Method for defining the area The size of the visual manoeuvring (circling) area varies with the category of the aircraft. To define the limits of the area: a) draw an arc from the centre of the threshold of each usable runway with a radius appropriate to the aircraft category; b) from the extremities of the adjacent arcs draw lines tangent to the arcs; c) connect the tangent lines. The area thus enclosed is the visual manoeuvring (circling) area. See Figures 5.62 and 5.63. Figure 5.62.- Construction of visual manoeuvring (circling) area Note that Figure 5.62, as an example, the radius for Category E aircraft is used. An operational advantage is gained by casting arcs only from those runways usable by Category E aircraft. In Figure 5.63 all runways are used because they are available to Category A aircraft. However, since the radius for Category A is less than that for Category E the total area for all aircraft is slightly smaller than it would be if Category E criteria were applied completely. _________________________________________________________________________________________________________________ 206 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.63.- Visual manoeuvring (circling) area Parameters The parameters on which visual manoeuvring (circling) radii are based are as follows: a) speed: speed for each category as shown in Tables 5.1; b) wind: ±46 km/h (25 kt) throughout the turn; c) bank: 20° average achieved on the bank angle producing a turn rate of 3° per second, whichever is the lesser bank. Determination method The radius is determined using the formulas in ICAO PANS-OPS Part I, Section 2, Chapter 3, “Turn area construction”, by applying a 46 km/h (25 kt) wind to the true airspeed (TAS) for each category of aircraft using the visual manoeuvring IAS from Tables 5.1. The TAS is based on: a) altitude: aerodrome elevation + 300 m (1000 ft); b) temperature: ISA + 15°. Visibility and lowest OCA/H It is assumed that the minimum visibility available to the pilot at the lowest OCA/H will be as shown in Table 5.12. This information is not required for the development of the procedure, but is included as a basis for the development of operating minima. 5.1.8.3 Obstacle clearance See 5.1.7.4, “OCA/H for visual manoeuvring (circling)”, and Table 5.12. _________________________________________________________________________________________________________________ 207 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Aircraft category A B C D E Minimum obstacle clearance m (ft) 90 (295) 90 (295) 120 (394) 120 (394) 150 (492) Lower limit for OCH above aerodrome elevation m (ft) 120 (394) 150 (492) 180 (591) 210 (689) 240 (787) Minimum visibility km (NM) 1.9 (1.0) 2.8 (1.5) 3.7 (2.0) 4.6 (2.5) 6.5 (3.5) Table 5.12.- MOC and OCA/H for visual manoeuvring (circling) approach 5.1.8.4 Method for reducing OCA/H Area which can be ignored A sector in the circling area where a prominent obstacle exists may be ignored for OCA/H calculations if it is outside the final approach and missed approach areas. This sector is bounded by the dimensions of the ICAO Annex 14 instrument approach surfaces. (See Figure 5.64.) Figure 5.64.- Visual manoeuvring (circling) area – obstacle clearance _________________________________________________________________________________________________________________ 208 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Promulgation When this option is exercised, the published procedure must prohibit the pilot from circling within the total sector where the obstacle exists. (See Figure 5.65.) Figure 5.65.-Visual manoeuvring (circling) area – prohibition on circling 5.1.8.5 Missed approach associated with the visual manoeuvre A missed approach area specific to the visual manoeuvre is not constructed. 5.1.8.6 promulgation The general criteria in ICAO PANS-OPS Part I, Section 1, Chapter 9, “Charting/AIP” apply. The instrument approach chart for a visual manoeuvre shall be identified by the navigation aid type used for final approach lateral guidance, followed by a single letter suffix, starting with the letter A. The suffix letter shall not be used again for any procedures at that airport, at any other airport serving the same city or at any other airport in the same State, serving a city with the same name. The OCA/H values for the procedure shall be the OCA/H for approach or missed approach, whichever is greater and shall be published in accordance with 5.1.6.3 , “OCA/H for visual manoeuvring (circling)”. _________________________________________________________________________________________________________________ 209 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 5.1.9 Minimum sector altitudes (MSA) 5.1.9.1 General Minimum sector altitudes shall be established for each aerodrome where instrument approach procedures have been established. Each minimum sector altitude shall be calculated by: a) taking the highest elevation in the sector concerned; b) adding a clearance of at least 300 m (1 000 ft); c) rounding the resulting value up to the next higher 50-m or 100-ft increment, as appropriate. If the difference between sector altitudes is insignificant (i.e. in the order of 100 m or 300 ft as appropriate) a minimum altitude applicable to all sectors may be established. A minimum altitude shall apply within a radius of 46 km (25 NM) of the homing facility on which the instrument approach is based. The minimum obstacle clearance when flying over mountainous areas should be increased by as much as 300 m (1 000 ft). 5.1.9.1 Obstacles in buffer area Obstacles within a buffer zone of 9 km (5 NM) around the boundaries of any given sector shall be considered as well. If such obstacles are higher than the highest obstacle within the sector, then the minimum sector altitude shall be calculated by: a) taking the highest elevation in the buffer area concerned; b) adding a clearance of at least 300 m (1 000 ft). Rounding the resulting value up to the nearest 50 m (100 ft). 5.1.9.2 Sector orientation The sectors should normally coincide with the quadrants of the compass. However, when topographical or other conditions make it desirable, the boundaries of the sectors may be chosen to obtain the most favourable minimum sector altitudes. See Figure 5.66. _________________________________________________________________________________________________________________ 210 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.66.- Sector orientation 5.1.9.3 Combining sectors for adjacent facilities Where more than one facility provides instrument approaches to an aerodrome, and several minimum sector altitude diagrams are involved, individual diagrams shall be produced and minimum sector altitudes calculated. If such facilities are located less than 9 km (5 NM) apart, the minimum sector altitude for any given sector should be the highest of all altitudes calculated for that specific sector for every facility serving the aerodrome. 5.1.9.4 Sectors centred on a VOR/DME or NDB/DME In sectors centred on a VOR/DME or NDB/DME, it is possible to define an additional boundary (DME arc) within a sector, dividing the sector into two subsectors with the lower MSA in the inner area. The DME arc radius (R) used should be between 19 and 28 km (10 and 15 NM) in order to avoid the use of a subsector of too small a size. The width of the buffer area between the subsectors remains 9 km (5 NM) (see Figure 5.77). _________________________________________________________________________________________________________________ 211 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.67.- Case of VOR/DME subsectors delimited by a DME arc 5.1.10 ILS 5.1.10.1 Introduction Application The ILS criteria detailed in this chapter are related to the ground and airborne equipment performance and integrity required to meet the Category I, II and III operational objectives described in ICAO Annex 10. Procedure construction The procedure from enroute to the precision segment of the approach and in the final missed approach phase conforms with the general criteria. The differences are found in the physical requirements for the precision segment which contains the final approach segment as well as the initial and intermediate phases of the missed approach segment. These requirements are related to the performance of Cat I, II and III systems. _________________________________________________________________________________________________________________ 212 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Standard conditions The following list contains the standard assumptions on which procedures are developed. Provisions are made for adjustments where appropriate. Adjustments are mandatory when conditions differ adversely from standard conditions and are optional when so specified. Maximum aircraft dimensions are assumed to be the following: Aircraft category Wing span (m) A,B C,D DL 60 65 80 Vertical distance between the flight paths of the wheels and the GP antenna (m) 6 7 8 Table 5.13.- Maximum aircraft dimensions Note 1.- OCA/H for Cat DL aircraft is published when necessary. Note 2.- The dimensions shown are those which encompass current aircraft types. They are chosen to facilitate OCA/H calculations and promulgation of aircraft category relate minima. It is assumed that these dimensions are not intended to be used for other purposes than the OCA/H calculations in other ICAO documents. The use of OAS surfaces to calculate OCA/H may result in significant differences between aircraft categories because of small differences in size. For this reason, it is always preferable to use the Collision Risk Model (1.4.9) which will allow for more realistic assessment for both height and position of obstacles. Note 3.- Current Category E aircraft are not normally civil transport aircraft and their dimensions are not necessarily related to Vai at maximum landing mass. For this reason, they should be treated separately on an individual basis. a) category II flown with flight director; b) missed approach climb gradient 2.5 per cent; c) ILS sector width 210 m at threshold; d) glide path angle: 1) minimum: 2.5°; 2) optimum:3.0°; 3) maximum: 3.5° (3° for Cat II/III operations). e) ILS reference datum height 15 m (50 ft); f) all obstacle heights are referenced to threshold elevation; g) for Cat II and III operations the Annex 14 inner approach, inner transitional and balked landing surfaces have not been penetrated. Where the Cat II OCA/H is higher than the level of the inner horizontal surface, but below 60 m, the inner _________________________________________________________________________________________________________________ 213 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ approach and balked landing surfaces should be extended to the Cat II OCA/H level to accommodate Cat III operations. Obstacle clearance altitude/height (OCA/H) The ILS criteria enable an OCA/H to be calculated for each category of aircraft. See 5.1.1.9, “Categories of aircraft”. Where statistical calculations were involved, the OCA/H values were designed against an overall safety target of 1 x 10-7 (1 in 10 million) per approach for risk of collision with obstacles. The OCA/H ensures clearance of obstacles from the start of the final approach to the end of the intermediate missed approach segment. Additional material is included to allow operational benefit to be calculated for the improved beam holding performance of autopilots meeting national certification standards (as opposed to flight directors) in Cat II, and for improved missed approach climb performance in Cat I, II and III. Benefit may also be calculated for aircraft with dimensions other than the standard size assumed in the basic calculations. An OCA/H is not associated with Cat III operations. These are supported by the obstacle limitation surfaces defined in Annex 14, in association with overlapping protection from the Cat II criteria. Methods of calculating OCA/H General. Three methods of calculating OCA/H are presented, which involve progressive increases in the degree of sophistication in the treatment of obstacles. Standard conditions are assumed to exist unless adjustments for non-standard conditions have been made. First method. The first method involves a set of surfaces derived from the ICAO Annex 14 precision approach obstacle limitation surfaces and a missed approach surface described in 5.1.10.3, “definition of basic ILS surfaces”. From this point forward, these are termed “basic ILS surfaces”. Where the standard conditions exist and where the basic ILS surfaces are free of penetration , the OCA/H for Cat I and Cat II is defined by aircraft category margins, and _________________________________________________________________________________________________________________ 214 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ there are no restrictions in Cat III operations. If the basic ILS surfaces are penetrated, then the OCA/H is calculated. Second method. The second method involves a set of obstacle assessment surfaces (OAS) above the basic ILS surfaces (see 5.1.10.4, “Definition of obstacle assessment surfaces (OAS). If the OAS are not penetrated- and provided the obstacle density below the OAS I operationally acceptable (see 5.1.10.4, “Effect of obstacle density on OCA/H”)- the OCA/H for Cat I and Cat II is still defined by the aircraft category margins, and Cat III operations remain unrestricted. However, if the OAS are penetrated, then an aircraft category-related margin is added to the height of the highest approach obstacle, or to the adjusted height of the largest missed approach penetration, whichever is greater. This value becomes the OCA/H. Third method. The third method, using a collision risk model (CRM), is employed either as an alternative to the use of the OAS criteria (second method) or when the obstacle density below the OAS is considered to be excessive. The CRM accepts all objects as an input and assesses, for any specific OCA/H value, both the risk due to individual obstacles and the accumulated risk due to all obstacles. It is intended to assist operational judgement in the choice of an OCA/H value. ILS with glide path inoperative The ILS with glide path inoperative is a non-precision approach procedure. The principles of ICAO PANS-OPS Part I, Section 2, Chapter 1, “LLZ only”, apply. 5.1.10.2 Initial approach segment General The initial approach segment must ensure that the aircraft is positioned within the operational service volume of the localizer on a heading that will facilitate localizer interception. For this reason, the general criteria which apply to the initial segment ( see 5.1.4.3, “Initial approach segment”) are modified in accordance with 5.1.3.4, “Initial approach segment alignment” and 5.1.10.2, “Initial approach segment area”. For RNAV initial approach segments, the criteria in the applicable RNAV chapters apply. _________________________________________________________________________________________________________________ 215 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Initial approach segment alignment The angle of interception between the initial approach track and the intermediate track should not exceed 90°. In order to permit the autopilot to couple on to the localizer, an interception angle not exceeding 30° is desirable. When the angle exceeds 70° a radial, bearing, radar vector, or DME or RNAV information providing at least 4 km (2 NM). Initial approach segment area The area is as described in the general criteria (see 5.1.3.4 “Area”). The difference is that the intermediate approach fix (IF) must be located within the service volume of the ILS localizer course signal, and normally at a distance not exceeding 46 km (25 NM) from the localizer antenna. 5.1.10.3 Intermediate approach segment General The intermediate approach segment for ILS differs from the general criteria in that: a) the alignment coincides with the localizer course; b) the length may be reduced; c) in certain cases the secondary areas may be eliminated. The primary and secondary areas at the FAP are defined in terms of the ILS surfaces. Consequently, the general criteria in 5.1.3.4, “Intermediate Approach Segment” are applied except as modified or amplified in the paragraphs below with regards to alignment, area length and width, and for obstacle clearance. For RNAV initial approach segments, the criteria in the applicable RNAV chapters apply. Intermediate approach segment alignment The intermediate approach segment of an ILS procedure shall be aligned with the localizer course. _________________________________________________________________________________________________________________ 216 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Intermediate approach segment length The optimum length of the intermediate approach segment is 9 km (5 NM). This segment shall allow interception with the localizer course and with the glide path. Segment length should be sufficient to permit the aircraft to stabilize and establish on the localizer course prior to intercepting the glide path, taking into consideration the angle of interception with the localizer course. Minimum values for distance between localizer and interception of glide path are specified in Table 5.14; however, these minimum values should only be used if usable airspace is restricted. The maximum length of the segment is governed by the requirement that it be located wholly within the service volume of the localizer signal and normally at a distance not exceeding 46 km (25 NM) from the localizer antenna. Intercept angle with localizer (degrees) 0 – 15 16 – 30 31 - 60 61 - 90 or within a racetrack or reversal procedure Cat A/B Cat C/D/E 2.8 km (1.5 NM) 3.7 km ( 2.0 NM) 3.7 km ( 2.0 NM) 3.7 km ( 2.0 NM) 2.8 km (1.5 NM) 3.7 km (2.0 NM) 4.6 km (2.5 NM) 5.6 km (3.0 NM) Table 5.14.- Minimum distances between localizer and glide path interceptions Intermediate approach segment area width The total width at the beginning of the intermediate approach segment is defined by the final total width of the initial approach segment. It tapers uniformly to match the horizontal distance between the OAS X surfaces at the FAP (see 5.1.10.4, “Definition of obstacle assessment surfaces (OAS)”). For obstacle clearance purposes the intermediate approach is usually divided into a primary area bounded on each side by a secondary area. However, when a DR track is used in the initial approach segment, the primary area of the intermediate approach segment extends across its full width and secondary areas are not applied. _________________________________________________________________________________________________________________ 217 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ The primary area is determined by joining the primary initial approach area with the final approach surfaces (at the FAP). At the interface with the initial approach segment the width of each secondary area equals half the width of the primary area. The secondary area width decreases to zero at the interface with the final approach surfaces. See Figure 5.68, 5.69, 5.70. Figure 5.68.- Interface – final approach/preceding segment perspective view _________________________________________________________________________________________________________________ 218 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.69.- Final approach fix defined by descent fix located at final approach point _________________________________________________________________________________________________________________ 219 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.70.- Precision segment with no final approach fix Where a racetrack or reversal manoeuvre is specified prior to intercepting the localizer course the provisions in 5.1.4.4., “Turn not at the facility” apply, the facility being the localizer itself and the FAF being replaced by the FAP. (See Figure 5.71) _________________________________________________________________________________________________________________ 220 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.71.- Intermediate approach area. ILS approach using reversal or racetrack procedure. Intermediate approach segment obstacle clearance The obstacle clearance is the same as defined in 5.1.5, “Intermediate approach segment) except where the procedure permits a straight-in approach in which the aircraft is stabilized on the localizer course prior to crossing the IF. In this case, obstacles in the secondary areas need not be considered for the purpose of obstacle clearance. 5.1.10.4 Precision segment General The precision segment is aligned with the localizer course and contains the final descent for landing as well as the initial and intermediate phases of the missed approach segment. See Figure 5.72. _________________________________________________________________________________________________________________ 221 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.72.- Precision segment Origin The precision segments starts at the final approach point (FAP), that is, the intersection of the nominal glide path and the minimum altitude specified for the preceding segment. The FAP should not normally be located more than 18.5 km (10.0 NM) before threshold, unless adequate glide path guidance beyond the minimum specified in ICAO Annex 10 is provided. Descent fix A descent fix may be located at the FAP to overcome certain obstacles located before the FAP as an alternative to increasing the glide path (GP) angle. When so located, it becomes the final approach fix. The extension of the precision surfaces into the precision segment is then terminated. The descent fix should not normally be located more than 18.5 km (10.0 NM) before threshold, unless adequate GP guidance beyond the minimum specified in Annex 10 is provided. The maximum fix tolerance is ±0.9 km (±0.5 NM). Where DME is used to identify the fix, the range shall be stated in tenths of kilometres (nautical miles). Obstacle clearance at the descent fix. When a descent fix is provided, the precision approach surfaces start at the earliest point of the FAF tolerance area (see Figure 5.69). The provisions of 5.1.2.7, “Obstacle close to a final approach fix or stepdown fix” which allow obstacles close to the fix to be ignored, apply in the area below the 15 per cent gradient within the precision surfaces. Where a descent fix is not provided at the FAP, no curtailment of the precision surfaces is permitted (see Figure 5.70). I the precision surfaces are extended into the preceding segment, they shall not be extended beyond the intermediate approach segment. _________________________________________________________________________________________________________________ 222 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Glide path verification check A fix (outer mark or DME) is necessary so as to permit comparison between the indicated glide path and the aircraft altimeter information. The fix shall not have a fix tolerance exceeding ±0.9 km (0.5 NM). When DME is used to identify the fix, the range shall be stated in tenths of kilometres (nautical miles). Missed approach The missed approach point is defined by the intersection of the nominal glide path and the decision altitude/height (DA/H). The DA/H is set at or above the OCA/H. Termination The precision segment normally terminates at the point where the final phase of the missed approach commences (see 5.1.7.1, “Phase of missed approach segment”) or where the missed approach climb surface Z (starting 900 m past threshold) reaches a height of 300 m (984 ft) above threshold, whichever is lower. Obstacle clearance of the precision segment application of basic ILS surfaces General. The area required for the precision segment is bounded overall by the basic ILS surfaces defined below. In standard conditions there is no restriction on objects beneath these surfaces (see 5.1.10.1, “Standard conditions”). Objects or portions of objects that extend above these surfaces must be either: a) minimum mass and frangible; b) taken into account in the calculation of the OCA/H. Definition of basic ILS surfaces. These surfaces to be considered correspond to a subset of ICAO Annex 14 obstacle limitation surfaces as specified for precision approach runway code numbers 3 or 4 (see Figure 5.73). These are: a) the approach surface continuing to the final approach point (FAP) (first section 2 per cent gradient, second section 2.5 per cent as described in Annex 14); b) the runway strip assumed to be horizontal at the elevation of the threshold.; c) the missed approach surface. This is a sloping surface which: _________________________________________________________________________________________________________________ 223 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 1) starts at a point 900 m past the threshold at threshold elevation; 2) rises at a 2.5 per cent gradient; 3) splays so as to extend between the transitional surfaces. It extends with constant splay to the level of the inner horizontal surface. Thereafter, it continuous at the same gradient but with a 25 per cent splay until the termination of the precision segment; d) the extended transitional surfaces, which continue longitudinally along the sides of the approach and missed approach surfaces and up to a height of 300 m above threshold elevation. Figure 5.73.- Illustration of basic ILS surfaces Determination of OCA/H with basic ILS surfaces Where the basic ILS surfaces are not penetrated, the OCA/H for category I and II is defined by the margins specified in Table 5.15, and category III operations are not restricted. Obstacles may be excluded when they are below the transitional surface defined by ICAO Annex 14 for runways with code numbers 3 and 4, regardless of the actual runway code number (i.e., the surfaces for code numbers 3 and 4 are used for the obstacle assessment on runways with code numbers 1 and 2). If the basic ILS surfaces listed above are penetrated by objects other than those listed in Table 5.16, the OCA/H may be calculated directly by applying height loss/altimeter margins to obstacles (see 5.1.10.4, “Determination of OCA/H with OAS or basic ILS surfaces”). _________________________________________________________________________________________________________________ 224 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Aircraft category1 (Vat) A – 169 km/h (90kt) B – 223 km/h ( 120 kt) C – 260 km/h (140 kt) D – 306 km/h (165 kt) Margin using radio altimeter Metres Feet 13 18 22 26 Margin using pressure altimeter Metres Feet 42 59 71 85 40 43 46 49 130 142 150 161 Table 5.15.- Height loss/altimeter margin Maximum height above threshold GP antenna Aircraft taxiing A/C in holding bay or in taxi holding position at a range between threshold and -250 m A/C in holding bay or in taxi holding position at a range between threshold and -250 m (Cat I only) 17 m (55 ft) 22 m (72 ft) 22 m (72 ft) Minimum lateral distance from runway centre line 120 m 150 m 120 m 15 m (50 ft) 75 m Table 5.16.- Objects which may be ignored in OCA/H calculations The obstacles in Table 5.16 may only be exempted if the following two criteria are met: a) the localizer course sector has standard width of 210 m (see 5.1.10.1, “Standard conditions”); b) the Category I decision height is not less than 60 m (200 ft) or the Category II decision height is not less than 30 m (100 ft). An object that penetrates any of the basic ILS surfaces and becomes the controlling obstacle, but must be maintained because of its function with regards to air navigation requirements, may be ignored under certain circumstances in calculating the OCA/H, with the following provision. It must be established by the appropriate authority that the portion which penetrates the surface is of minimum mass and frangible mounted and would not adversely affect the safety of aircraft operations. Obstacle clearance of the precision segment using obstacle assessment surface (OAS) criteria 1 For Category E aircraft refer directly to the equations given in “Height loss (HL)/altimeter margins for a specific speed at threshold”. _________________________________________________________________________________________________________________ 225 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ General This section describes the OAS surfaces, the constants which are used to define these surfaces, and the conditions under which adjustments may or must be made. The OAS dimensions are related to: a) the ILS geometry (localizer-threshold distance, glide path angle, ILS RDH, localizer sector width); b) the category of ILS operation; c) other factors, including aircraft geometry, missed approach climb gradient. Thus, a table of OCA/H values for each aircraft category may be calculated for Cat I and II ILS operations at the particular airfield. Additional material is included to enable appropriate authorities to assess realistic benefits for claims of improved performance and associated conditions. See 5.1.10.4, “Adjustments of OAS constants”. Note that the OAS are not intended to replace ICAO Annex 14 surfaces as planning surfaces for unrestricted obstacle growth. The obstacle density between the basic ILS surfaces and the OAS must be accounted for (see 5.1.10.4, “Effect of obstacle density on OCA/H”). Frame reference Positions of obstacles are related to a conventional x, y, z coordinate system with its origin at threshold. See Figure 5.74. The x-axis is parallel to the precision segment track: positive x is distance before threshold and negative x is distance after threshold. The y-axis is at right angles to the x-axis. Although shown conventionally in Figure 5.74, in all calculations associated with OAS geometry, the y coordinate is always counted as positive. The z-axis is vertical, heights above threshold being positive. All dimensions connected with the OAS are specified in metres only. The dimensions should include any adjustments necessary to cater for tolerances in survey data (see 5.1.1.13, “Charting accuracy”). _________________________________________________________________________________________________________________ 226 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.74.- System of coordinates OAS constants- specification For Category I and II operations the constants A, B and C for each sloping surface are listed in Attachment I to Part III. They are tabulated for all combinations of localizer/threshold distance and glide path angle between 2 000 m and 4 500 m and 2.5 and 3.5 degrees in increments of 200 m and 0.1 degree. For intermediate values of localizer threshold distance or glide path, the next lower distance or angle must be used. Where the localizer threshold distance or the glide path angle are outside the range of values for which data is tabulated, that data tabulated for the appropriate maximum/minimum values must be used. For ease of reference, all the relevant data for each localizer- threshold distance/glide path angle combination is located on individual pages. Definition of obstacle assessment surfaces (OAS) The OAS consist of six sloping plane surfaces (denoted by letters W, X, Y and Z) arranged symmetrically about the precision segment track, together with the horizontal plane which contains the threshold (see Figures 5.76 and 5.77). The geometry of the sloping surfaces is defined by four linear equations of the form z = Ax + By + C. In these equations x and y are position coordinates and z is the height of the surface at that position (see Figure 5.75). For each surface a set of constants (A, B and C) are obtained from the ICAO PANS-OPS CD-ROM for the operational range of localizer threshold distances and glide path angles. Separate sets of constants are specified for Category I and II. These constants may be modified by the programme (see 5.1.10.4, “Adjustments of OAS constants”). The category I OAS are limited by the length of the precision segment and, except for the W and X surfaces, by a maximum height of 300 m. The Category II OAS are limited by a maximum height of 150 m. _________________________________________________________________________________________________________________ 227 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.75.- Surface equations – basic ILS surfaces Figure 5.76.- Illustration of ILS obstacle assessment surfaces _________________________________________________________________________________________________________________ 228 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.77.- Illustrations of ILS obstacle assessment surfaces – perspective view Where the ICAO Annex 14 approach and transitional obstacle limitation surfaces for code numbers 3 and 4 precision approach runways penetrate inside the OAS, the ICAO Annex 14 surfaces become the OAS (i.e. the surfaces for code numbers 3 and 4 are used for obstacle assessment on runways with code numbers 1 and 2). The ICAO Annex 14 inner approach, inner transitional and balked landing obstacle limitation surfaces protect Category III operations, provided the Category II OCA/H is at or below the top of those surfaces which may be extended up to 60 m if necessary) (see Figure 5.73). Calculation of OAS heights To calculate the height z of any of the sloping surfaces at a location x’, y’, the appropriate constants should be first obtained from the ICAO PANS-OPS CD-ROM. These values are then substituted in the equation z = Ax’ + By’ + C. If it is not clear which of the OAS surfaces is above the obstacle location this should be repeated for the other sloping surfaces. The OAS height is the highest of the plane heights (zero is all the plane heights are negative). OAS template construction Templates, or plan views of the OAS contours to map scale, are sometimes used to help identify obstacles for detail survey (see Figure 5.78). The OAS data in the ICAO PANSOPS CD-ROM includes the coordinates of the points of intersection: _________________________________________________________________________________________________________________ 229 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ a) of the sloping surfaces at threshold level. The intersection coordinates are labelled as C, D and E (Figure 5.77); b) at 300 m above threshold level for Cat 1; c) at 150 m for Cat II. Figure 5.78.- Typical OAS contours for standard size aircraft _________________________________________________________________________________________________________________ 230 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Adjustments of OAS constants General. The following paragraphs describe the adjustments that the ICAO PANS-OPS CDROM programme makes to the OAS constants. These adjustments are mandatory when the standard conditions are not met. Optional adjustments may be made when so specified. For examples of calculations see the Instrument Flight Procedures Construction Manual. Reasons for adjusting constants. The constants may be modified to account for the following: a) missed approach climb gradient; b) dimensions of specific aircraft; c) the height of the ILS reference datum; d) improved beam holding performance due to use of autopilots certified for category II operations; e) certain Category I localizers having a sector width greater than the nominal 210 m at threshold. Specific aircraft dimensions. An adjustment is mandatory where aircraft dimensions exceed those specified in 5.1.10.1, “Standard conditions” and is optional for aircraft with smaller dimensions. The ICAO PANS-OPS CD-ROM adjust the OAS coefficients and template coordinates for the standard dimensions of Category A, B, C, D and DL aircraft automatically. It will do the same for specific aircraft dimensions in any category. It uses the following correction formula to adjust the coefficient C for the W, W*, X and Y surfaces: W surface: Cw corr = Cw – (t-6) W* surface: Cw* corr = Cw* - (t-6) Where: X surface: Cx corr = Cx – Bx . P Y surface: Cy corr = Cy – By . P P = [ t/Bx or S + (t-3)/Bx, whichever is the maximum] – [ 6/Bx or 30 + 3/Bx, whichever is the maximum] And s = semi-span _________________________________________________________________________________________________________________ 231 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ t = vertical distance between paths of the GP antenna and the lowest part of the wheels. Height of the ILS reference datum (RDH). This is based on a reference datum height (RDH) of 15 m. An adjustment to the OAS constants is mandatory for an RDH less than 15 m, and is optional for an RDH greater than 15 m. The ICAO PANS-OPS CD-ROM adjusts the OAS coefficients and template coordinates by correcting the tabulated values of the coefficient C for the W, W*, X and Y surfaces as follows: C corr = C + (RDH – 15) Where: C corr = corrected value of coefficient C for the appropriate surface; C = tabulated value. Modification for Cat I localizers with course width greater than 210 m at threshold. Where the ILS localizer sector width at threshold is greater than the nominal value of 210 m, the collision risk model (CRM) method described in 1.4.9 shall be used. Use of autopilot (autocoupled) in Cat II. The Cat II OAS may be reduced to reflect the improved beam holding of autopilots where these are certificated for the operation by the appropriate authority. This reduction is achieved in the ICAO PANS-OPS CD-ROM by the use of modified A, B, C constants for the X surface and the introduction of an extra surface (denoted by W*) (see Figure 5.78c). the use of these reduced surfaces should not be authorized for non-autocoupled approaches. Missed approach climb gradient. If equipment is capable of missed approach climb gradients better than the nominal 2.5 per cent, the Y and Z surfaces may be adjusted. This is done by using the desired missed approach climb gradient in the ICAO PANS-OPS CDROM. The programme then adjust the Y an Z coefficients. Determination of OCA/H with OAS or basic ILS surfaces General. The OCA/H is determined by accounting for all obstacles which penetrate the basic ILS surfaces and the OAS surfaces applicable to the ILS category of operation being _________________________________________________________________________________________________________________ 232 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ considered. The exemptions listed in 5.1.10.4, “Determination of OCA/H with basic ILS surfaces” for obstacles penetrating the basic ILS surfaces may be applied to obstacles penetrating the OAS, providing the criteria listed in that paragraph are met. The surfaces which apply to each category of operations are: a) ILS Cat I: ILS Cat I OAS; b) ILS Cat II: ILS Cat II OAS and those portions of ILS Cat I which lie above the limits of ILS Cat II; c) ILS Cat III: Same as ILS Cat II. Calculation of OCA/H values with OAS. Accountable obstacles, as determined below, “OCA/H Calculation steps” are divided into approach and missed approach obstacles. The standard method of categorization is as follows: Approach obstacles are those between the FAP and 900 m after threshold. Missed approach obstacles are those in the remainder of the precision segment (see Figure 5.79). However, in some cases this categorization of obstacles may produce an excessive penalty for certain missed approach. Where desired by the appropriate authority, missed approach obstacles may be defined as those above a plane surface parallel to the plane of the glide path and with origin at -900 m (see Figure 5.80), i.e. obstacle height greater than [(900 + x) tanθ]. Figure 5.79.- Missed approach obstacle after range -900 m _________________________________________________________________________________________________________________ 233 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.80.- Missed approach obstacle before range -900m OCA/H Calculation steps a) determine the height of the highest approach obstacle. b) convert the heights of all missed approach obstacle (hma) to the heights of equivalent approach obstacles (ha) by the formula given below, and determine the highest equivalent approach obstacle. c) determine which of the obstacles identified in steps a) and b) is the highest. This is the controlling obstacle. d) add the appropriate aircraft category related margin (Table 5.15) to the height of the controlling obstacle. ha = (hma cot Z + (xz +x))/(cot Z / cotθ) where: ha = height of equivalent approach obstacle hma = height of missed approach obstacle Θ = angle of glide path (elevation angle) Z = angle of missed approach surface x = range of obstacle relative to threshold (negative after threshold) xz = distance from threshold to origin of Z surface (900 m) Adjustments for high airfield elevations and steep glide path angles Height loss (HL)/altimeter margins. These margins in Table 5.15 shall be adjusted as follows: _________________________________________________________________________________________________________________ 234 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ a) for airfield elevation higher than 900 m (2 953 ft), the tabulated allowances shall be increased by 2 per cent of the radio altimeter margin per 300 m (984 ft) airfield elevation; b) for glide path angles greater than 3.2° in exceptional cases, the allowances shall be increased by 5 per cent of the radio altimeter margin per 0.1° increase in glide path angle between 3.2° and 3.5°. Procedures involving glide paths greater than 3.5° or any angle when the nominal rate of descent (Vat for the aircraft type x the sine of the glide path angle) exceeds 5 M/sec (1 000 ft/min), are non-standard. They require the following: a) increase of height loss margin (which may be aircraft type specific); b) adjustments of the origin of the missed approach surface; c) adjustments of the slope of the W surface; d) re-survey of obstacles; e) the application of related operational constraints. Such procedures re normally restricted to specifically approved operators and aircraft, and are associated with appropriate aircraft and crew restrictions. They are not to be used as a means to introduce noise abatements procedures. Exceptions and adjustments to values in Table 5.15. Values in Table 5.15 are calculated to account for aircraft using normal manual overshoot procedures from OCA/H on the nominal approach path. The values in Table 5.15 do not apply to Cat III operations. The values do not consider the lateral displacement of an obstacle nor the probability of an aircraft being displaced. If consideration of these joint probabilities is required, then the CRM shall be used. Values in Table 5.15 may be adjusted for specific aircraft types where adequate flight and theoretical evidence is available, i.e. the height loss value corresponding to a probability of 1 x 10-5 ( based on a missed approach rate 10-2). Radio altimeter verification. If the radio altimeter OCA/H is promulgated, operational checks shall have confirmed the repeatability of radio altimeter information. _________________________________________________________________________________________________________________ 235 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Height loss (HL)/altimeter margins for a specific speed at threshold. If a height loss/altimeter margin is required for a specific Vat, the following formulae apply (see also Table 5.17): Table 5.17.- Height loss altimeter setting vs. speed Use of radio altimeter: Margin = (0.096 Vat – 3.2) metres where Vat in km/h Margin = (0.177 Vat – 3.2) metres where Vat in kt Use of pressure altimeter: Margin = (0.068 Vat + 28.3) metres where Vat in km/h Margin = (0.125 Vat + 28.3) metres where Vat in kt _________________________________________________________________________________________________________________ 236 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Where Vat is the speed at threshold based on 1.3 times stall speed in the landing configuration at maximum certificated landing mass. Note.- The equations assume the aerodynamic and dynamic characteristics of the aircraft are directly related to the speed category. Thus, the calculated height loss/altimeter margins may not realistically represent small aircraft with Vat at maximum landing mass exceeding 165 kt. Effect of obstacle density on OCA/H. To assess the acceptability of obstacle density below the OAS, the CRM described in 5.1.10.4, “Obstacle clearance of the precision segment – application of collision risk model (CRM)” may be used. This can provide assistance by comparing aerodrome environments and by assessing risk levels associated with given OCA/H values. It is emphasized that it is not a substitute for operational judgement. Obstacle clearance of the precision segment – application of collision risk model (CRM) General. The CRM is a computer programme that establishes the numerical risk which can be compared to the target level of safety for aircraft operating to a specified OCA/H height. A description of the programme and instructions on its use, including the precise format of both the data required as input and the output results, are given in the Manual on the Use of the Collision Risk Model (CRM) for ILS Operations. Input. The CRM requires the following data as input: a) aerodrome details: name, runway threshold position and runway orientation in threshold elevation above MSL, details of proceeding segment; b) ILS parameters: category, glide slope angle, localizer-threshold distance, localizer course width, height of ILS reference datum above threshold; c) missed approach parameters: decision height (obstacle clearance height) and missed approach turn point; d) aircraft parameters: type, wheel height (antenna to bottom of wheel), and wing semi-span, aircraft category (A, B,C,D or DL) missed approach climb gradient; e) obstacle data: obstacle boundaries (either as x and y coordinates relative to the runway threshold or as map grid coordinates) and obstacle height (either above _________________________________________________________________________________________________________________ 237 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ threshold elevation or above MSL). For density assessment, all obstacles penetrating the basic ILS surfaces must be included. Output and application. The output of the programme is: a) the overall risk of the collision with obstacles for aircraft operating to a specified OCA/H; b) the minimum OCA/H which will provide the target level of safety. The user, by rerunning the CRM with the appropriate parameters, can asses the effect on the safety of operations of any alteration in the parameters, typically varying the glide path angle or remaining obstacles. 5.1.10.5 Missed approach segment General The criteria for the final missed approach are based on those for the general criteria. Certain modifications have been made to allow for the different areas and surfaces associated with the precision segment and for the possible variation in OCA/H for that segment with aircraft category. Area construction is according to the navigation system specified for the missed approach. The datum used for calculation of distances and gradients in obstacle clearance calculations is termed “start of climb” (SOC). It is defined by the height and range at which the plane GP’ – a plane parallel with the glide path and with origin at -900 m at threshold level – reaches the altitude OCA/H – HL. OCA/H and HL must both relate to the same category of aircraft. If obstacles identified in the final missed approach segment result in an increase in any of the OCA/H calculated for the precision segment, a higher gradient of the missed approach surface (Z) may be specified in addition if this will be provide clearance over those obstacles at a specified lower OCA/H (see 5.1.7.2, “Climb gradient in the final phase”). _________________________________________________________________________________________________________________ 238 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Straight missed approach General. The precision segment terminates at the point where the Z surface reaches a height 300 m above threshold. The width of the Z surface at the distance defines the initial width of the final missed approach area which splays at an angle of 15 degrees from that point, as shown in Figure 5.81. There are no secondary areas. Figure 5.81.- Final segment of straight missed approach Straight missed approach obstacle clearance. (See Figure 5.82). Obstacle elevation/height in this final missed approach area shall be less than (OCA/Hps – HL) + do tan Z Where: a) OCA/H of the precision segment (OCA/Hps) and HL (Table II-1-1-2 value) both relate to the same aircraft category. b) Do is measured from SOC parallel to the straight missed approach track; c) Z is the angle of the missed approach surface with the horizontal plane. If this requirement cannot be met, a turn shall be prescribed to avoid the obstacle in question. If a turn is not practical, the OCA/H shall be raised. _________________________________________________________________________________________________________________ 239 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.82.- Straight missed approach obstacle clearance Turning missed approach General. Turns may be prescribed at a designated turning point (TP), at a designated altitude/height, or “as soon as practicable”. The criteria used depend on the location of the turn relative to the normal termination of the precision segment (see 5.1.10.4, “Termination”) and are as follows: a) turn after normal termination of the precision segment. If a turn is prescribed after normal termination of the precision segment, the general criteria of 5.1.7.4, “Turn initiated at a designated altitude/height” and 5.1.7.4, “Turn initiated at a designated turning point” apply with the following exceptions: 1) OCA/H is replaced by (OCA/H – HL) as in 5.1.10.5, “Straight missed approach obstacle clearance”; 2) because SOC is related to OCA/H, it is not possible to obtain obstacle clearance by the means used in non-precision approaches (that is, by independent adjustment of OCA/H or MAPt); b) turn before normal termination of the precision segment. If a turn is prescribed at a designated altitude/height which is less than 300 m above threshold, or at a designated TP such that the earliest TP is within the normal termination range. Note.- Adjustments to designated TP location or to the designated turn altitude may involve redrawing the associated areas and recalculating the clearances. This can exclude some obstacles or introduce new ones. Thus, when it is necessary to obtain the minimum value of _________________________________________________________________________________________________________________ 240 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ OCA/H – particularly when constraints due to obstacles are very high – it may be necessary to adjust the designate TP or turn altitude by trial and error. Turn at a designated altitude/height less than 300 m above threshold The general criteria apply (see 5.1.7.4, “Turn initiated at a designated altitude/height”) as amplified and modified by the contents of this section. Construction of the turn initiation area and the subsequent turn are illustrated in Figure 5.83. Figure 5.83.- Turn at a designated altitude Turn altitude/height The general criteria apply, modified as follows. The precision segment terminates (and the final missed approach segment begins) at the TP. This allows the calculation of OCA/Hps and (OCA/Hps –HL). SOC is then determined, and turn altitude/height (TNA/H) is computed from the following relationship: TNA/H = OCA/Hps – HL + dz tanZ _________________________________________________________________________________________________________________ 241 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Where: dz is the horizontal distance from SOC to the TP and OCA/Hps = OCA/H calculated for the precision segment. If the TP is located at the SOC, the chart shall be annotated “turn as soon as practicable to … (heading of facility)” and shall include sufficient information to identify the position and height of the obstacles dictating the turn requirement. Areas Turn initiation area. (See Figure 5.83). The turn initiation area is bounded by the 300 m Category I Y surface contour, and terminates at the TP. Note.- The earliest TP is considered to be at the beginning of the 300 m Category I Y surface contour (“point D”) unless a fix is specified to limit early turns. Turn boundary construction. Turn boundaries are constructed as specified in ICAO PANSOPS Part I, Section 2, Chapter 3, “Turn area construction”. Obstacle clearance a) obstacle clearance in the turn initiation area. Obstacle elevation/height in the turn initiation area shall be less than: 1) turn altitude/height – 50 m (164 ft); 2) turn altitude/height – 30 m (98 ft) for turns 15° or less, except that obstacles located under the Y surface on the outer side of the turn need not be considered when calculating turn altitude/height. b) obstacle clearance in the turn area. Obstacle elevation/height in the turn area and subsequently shall be less than: turn altitude/height + do tan Z – MOC where: do is measured from the obstacle to the nearest point on the turn initiation area boundary and MOC is: 1) 50 m (164 ft) for turns more than 15°; _________________________________________________________________________________________________________________ 242 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 2) 30 m (98 ft) for turns 15° or less, reducing linearly to zero at the outer edge of the secondary areas, if any. Turn altitude/height adjustments. If the criteria specified in 5.1.10.5, “Obstacle clearance”, above can not be met, the turn altitude/height shall be adjusted. This can be done in two ways: a) adjust turns altitude/height without changing OCA/H: this means that the TP will be moved and the areas redrawn accordingly; b) raise turn altitude/height by increasing OCA/H: this results in a higher turn altitude over the same TP. The turn areas remain unchanged. Safeguarding of early turns. Where the published procedure does not specify a fix to limit turns for aircraft executing a missed approach from above the designated turn altitude/height, an additional check of obstacles shall be made. The general criteria of 5.1.7, “Missed Approach segment”, Figure 5.55 apply with the following modifications: a) the limit of the final approach area is replaced by the line DD’ of the OAS surfaces and its extension; b) the FAF is replaced by the FAP; c) the earliest MAPt is replaced by the line D”D” ‘earliest limit of the turn initiation area); d) if the criteria can not be met, then the procedure must be added on the profile view of the approach chart. Turn at a designated TP with earliest TP before normal termination of precision segment Where a turn is specified at a designated TP, and the earliest TP is before the normal termination range of the precision segment, the precision segment terminates at the earliest TP. This allows the calculation of OCA/Hps and (OCA/Hps – HL); SOC is then determined. Turn area. The turn area is constructed as specified in ICAO PANS-OPS Part I, Section 4, Chapter 6, 6.4.6.3, “Construction of the turn area” except that it is based on the width of the 300 m OAS Y surface contours at the earliest and latest TP (see Figure 5.84). _________________________________________________________________________________________________________________ 243 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.84.- Turn at a designated TP (with TP fix) Obstacle clearance. Obstacle elevation/height shall be less than: (OCA/Hps – HL) + do tan Z – MOC where: • do = dz + shortest distance from obstacle to line K-K, • dz = horizontal distance from SOC to the earliest TP and MOC is: • 50 m (164 ft) for turns more than 15° and • 30 m (98 ft) for turns 15° or less. _________________________________________________________________________________________________________________ 244 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ If the obstacle elevation/height exceeds this value, the OCA/H must be increased, or the TP moved to obtain the required clearance. 5.1.10.6 Simultaneous precision approaches to parallel or near-parallel instrument runways Note.- Guidance material is contained in the Manual on Simultaneous Operations on Parallel or Near-Parallel Instrument Runways (Doc 9643). General When it is intended to use precision approach procedures to parallel runways simultaneously, the following additional criteria shall be applied in the design of both procedures: a) the maximum intercept angle with the final approach course is 30°. The point of intercepting final approach course should be located at least 3.7 km (2.0 NM) prior to the point of intercepting the glide path; b) the minimum altitudes of the intermediate approach segments of the two procedures differ by at least 300 m (1000 ft); c) the nominal tracks of the two missed approach procedures diverge by at least 30°. Associated missed approach turns shall be specified as “ as soon as practicable”. Obstacle clearance The obstacle clearance criteria for precision approaches, as specified in the designated chapters apply for each of the parallel precision procedures. In addition to these criteria, a check of obstacles shall be made in the area o the far side of the parallel runway in order to safeguard early turns required to avoid potential intruding aircraft from the adjacent runway. This check can be made using a set of separately defined parallel approach obstacle assessment surfaces (PAOAS). 5.1.10.7 Promulgation General The instrument approach chart for an ILS approach procedure shall be identified by the title ILS Rwy XX. If category II and/or III minima are included on the chart, the title shall read _________________________________________________________________________________________________________________ 245 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ ILS Rwy XX CAT II or ILS Rwy XX CAT II & III, as appropriate. If more than one ILS approach is published for the same runway, the Duplicate Procedure Title convention shall be applied, with the approach having the lowest minima being identified as ILS Z RWY XX. If more than one ILS approach is published for the same runway and some segments of the two approaches are not equal, the Duplicate Procedure Title convention shall be applied. As an example, when considering two ILS approaches to the same runway that have different missed approach procedures, the Duplicate Procedure Title convention shall be applied. When two different approaches to the same runway are published, the approach having the lowest minima should be identified as ILS Z Rwy XX. When a final approach fix is identified at the FAP, a warning shall be appended to the procedure stating that descent on the glidepath below the FAF altitude is not permitted until passing the FAF. Promulgation of OCA/H values Promulgation of OCA/H for Cat I and II approach procedures The OCA or OCH values, as appropriate, shall be promulgated for those categories of aircraft for which the procedure is designed. The values shall be based on the following standard conditions: a) Cat I flown with pressure altimeter; b) Cat II flown autocoupled with radio altimeter; c) standard aircraft dimensions (see 5.1.10.1, “Standard conditions”); d) 2.5 per cent missed approach climb gradient. Additional values of OCA/H may be agreed upon between operators and the appropriate authority and be promulgated, provided that modifications have been carried out using the guidelines and algorithms defined in 5.1.10.4, “Radio altimeter verification” is met. Promulgation of Category III approach procedures _________________________________________________________________________________________________________________ 246 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Category III operations may be permitted subject to the appropriate Category II OCA/H being below the height of the ICAO Annex 14 inner horizontal surface. Category III operations may also be permitted with a Category II OCA/H between the height of the inner horizontal surface and 60 m provided the ICAO Annex 14 Category II inner approach, inner transitional and balked landing surfaces are extended to protect that OCA/H. Turn at a designated altitude/height (missed/approach) If the TP is located at the SOC, the chart shall be annotated “turn as soon as practicable to … (heading or facility)” and shall include sufficient information to identify the position and height of the obstacles dictating the turn requirement. Turn at a designated TP (missed approach) Where the procedure requires that a turn be executed at a designated TP, the following information must be published with the procedure: a) the TP, when it is designated by a fix; or b) the intersecting VOR radial, NDB bearing or DME distance where there is no track guidance (see 5.1.2.6, “Missed approach fixes”). Procedures involving glide paths greater than 3.5° or any angle when the nominal rat of descent exceeds 5m/sec (1 000 ft/min), are non-standard and subject to restrictions (see 5.1.10.4, “Height loss (HL)/altimeter margins”. They are normally restricted to specifically approved operators and aircraft, and are promulgated with appropriate aircraft and crew restrictions annotated on the approach chart. Additional gradient for the final missed approach segment If obstacles identified in the finale missed approach segment result in an increase in any of the OCA/H calculated for the precision segment, a higher gradient of the missed approach surface (Z) may be specified in addition if this will provide clearance over those obstacles at a specified lower OCA/H (see 5.1.7.2, “Climb gradient in the final phase”). _________________________________________________________________________________________________________________ 247 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 5.2 Application to Seville Airport In the following chapters the approach procedures for a specific runway at Seville Airport will be designed. For runway 27, an ILS precision approach and a VOR non-precision approach will be designed. At the end, the approach procedures, both precision as non-precision, will be drawn in AutoCAD and plotted on one instrument approach chart. 5.2.1 Non-precision approach The non-precision approach designed in this part is a VOR approach with a FAF. All the segments will be located according to the general theory described in 5.1. 5.2.1.1 Initial approach segment The initial approach fix can be designed in two ways: using a racetrack or using a reversal procedure. For the initial approach segment of the non-precision I have chosen to use a racetrack procedure, because this is used where sufficient distance is not available in a straight segment to accommodate the required loss of altitude and when entry into reversal procedure is not practical. Starting point The racetrack procedure starts at the IAF. The IAF is located on the VOR (SVL) at an minimum altitude of 2 000 ft. Entry The entry into the racetrack is similar to the entry into the holding pattern. These apply to the general design methods described in 5.1.4.4, “Initial approach segment using a racetrack procedure”. If no calculation is included, the general design methods apply. Restricted Area The restricted area will not be necessary. Shape/Outbound time The racetrack and holding procedure will be designed with the following criteria. ___________________________________________________________________________ 248 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ • maximum speed of 426 km/h (230 kt) IAS; • duration of outbound leg is 1 minute; • temperature is ISA + 15°C; • altitude is 610 m (2 000 ft); • conversion factor K = 1.06. Limitation of length of outbound track If a DME distance or an intersecting radial or bearing is used to limit the outbound leg, the area may be reduced by applying the appropriate adjustments, however this is not obligatory. No limitations will be used, thus the outbound track will be 1 minute. Construction of the protection area of the racetrack and holding procedures Hereunder follow the calculations and AutoCAD drawings that are used to construct the protection area. All are designed to the theory described in 5.1. Table 5.18 gives us the formulas to calculate the parameters used in the holding/racetrack protection area construction. The calculations were made for the criteria specified above and a correction factor K of 1.06. After calculating the parameters the template will be designed according to the construction criteria explained in 5.1.4. Figure 5.87 shows the completed template. The VOR position fix tolerance area is determined as follows: • A circle with centre on the VOR and radius zV zV = h x tan50° = 609.6 x tan50° = 726.50 m • qV = 0.2 x h = 0.2 x 0.6096 = 0.12192 km ___________________________________________________________________________ 249 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Line 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 Parameters K V v R r h w w' E45 t L ab ac g11=g13 g12=g14 Wb Wc Wd We Wf Wg Wh Wo Wp W11=W13 W12=W14 Wj Wk=Wl Wm Wn3 Wn4 XE YE Formula Value Units Conversion factor 1.06 K x IAS 450.12 km/h V/3600 0.13 km/s 943.27/V 2.10 °/s V/(62.83 R) 3.42 km in thousand of metres 0.61 m (12 x h) + 87 94.32 km/h w/3600 0.03 km/s (45 x w)'/R 0.56 km 60 x T 60.00 s vxt 7.50 km 5xv 0.63 km 11 x v 1.38 km (t - 5) x v 6.88 km (t + 21) x v 10.13 km 5 x w' 0.13 km 11 x w' 0.29 km Wc + E45 0.85 km Wc + (2 x E45) 1.41 km Wc + (3 x E45) 1.98 km Wc + (4 x E45) 2.54 km Wb + (4 x E45) 2.38 km Wb + (5 x E45) 2.94 km Wb + (6 x E45) 3.51 km ((t + 6)w') + (4 x E45) 3.98 km Wi1 + (14 x w') 4.35 km Wi2 + E45 4.91 km Wi2 + (2 x E45) 5.47 km Wi2 + (3 x E45) 6.03 km Wi1 + (4 x E45) 6.23 km Wi2 + (4 x E45) 6.60 km ( 2 x r) + ((t + 15) x v) + ((t + 26 + (195/R) x w') 20.91 km 11 x v x cos20° + r (1+ sin20°) + 7.23 km (t + 15)v tan5° + (t + 26 + 125/R)w' Table 5.18.- Calculations associated with the construction of racetrack and holding template When the VOR position fix tolerance area is calculated and drawn it is possible to draw the basic area, entry area and omnidirectional entry area. The omnidirectional entry area gives protection to entries from each sector. Finally, a secondary area of 4.6 km (2.5 NM) is added around the basic area for a racetrack, and a buffer of 9.3 km (5.0 NM) for a holding. ___________________________________________________________________________ 250 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.85.- Racetrack/holding template with associated construction points Figure 5.86.- VOR Position fix tolerance area . ___________________________________________________________________________ 251 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.87.- Protection area and buffer of racetrack Obstacle clearance The minimum altitude for the racetrack procedure is not less than 300 m (984 ft). above all obstacles in the initial areas. The normal reduction in MOC for secondary areas applies to the general criteria, described in 5.1.4. 5.2.1.2 Intermediate approach segment This is the segment which blends the initial approach segment into the final approach segment. The intermediate approach segment will begin at an designated intermediate approach fix (IF). Starting point The intermediate segments begins upon intersection intermediate approach track and ends at the FAF, which is located on the 5.4 NM from the threshold. ___________________________________________________________________________ 252 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Area length The optimum length of the intermediate approach segment is 19 km (10 NM), however I use a intermediate approach area within the racetrack procedure. So the length will be the same as the racetrack leg length. Area width The intermediate segment expands uniformly from the width of the final approach, which is 1.85 km (1 NM) on each side of the FAF for a VOR, to 9.3 km (5 NM) on each side of the track at the IF. This area is divided in a primary an secondary area. Descent gradient Because the intermediate approach segment is used to prepare the aircraft speed and configuration for entry into the final approach segment, this segment should be flat or at least have a flat section contained within the segment. The maximum permissible gradient will be 5.2 per cent and a horizontal section with a minimum length of 2.8 km (1.5 NM) is provided. Obstacle clearance The minimum obstacle clearance is 150 m (492 ft) in the primary area. In the secondary area, 150 m (492 ft) of obstacle clearance is provided at the inner edge, reducing to zero at the outer edge. 5.2.1.3 Final approach segment In the final approach segment, alignment and descent for landing are carried out. Final approach will be made to the runway using a straight-in landing. Starting point The final approach segments begins at the FAF and ends at the MAPt. Descent gradient The minimum/optimum descent gradient is 5.2 per cent for the final approach segment of a non-precision approach with FAF. This has to be used when possible. ___________________________________________________________________________ 253 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Area width The width of the area, when a VOR is used, is 1.85 km (1 NM) on each side of the track and expands uniformly with 7.8° towards the MAPt. Obstacle clearance altitude/height (OCA/H) The OCA/H for a straight-in, non-precision approach where the angle between the track and the extended runway centre line does not exceed 5 degrees, provides 75 m (246 ft), with FAF, minimum obstacle clearance (MOC) over the obstacles in the final approach area. The OCA/H also ensures that missed approach obstacle clearance is provided. OCA = highest obstacle in area + MOC = 328 ft + 246 ft = 574 ft 5.2.1.4 Missed approach segment A missed approach procedure shall be established when an aircraft is caused to abort a landing after it has already started the landing approach. A turning missed approach will be designed. The missed approach segments consists of: • initial phase; • intermediate phase; • final phase. Initial phase The initial phase begins at the missed approach point and ends at the start of the climb point. Intermediate phase The intermediate phase is that phase during which the climb is continued and stabilized and speeds up to the first point where 50 m (164 ft) obstacle clearance is obtained and can be maintained. ___________________________________________________________________________ 254 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Final phase The phase begins at the point where 50 m (164 ft) obstacle clearance is first obtained and can be maintained. It extends to the point at which a new holding is initiated. MAPt The MAPt should normally be located on the threshold, but because obstacles are located in the missed approach segment, the MAPt is located before the threshold. The MAPt is located at an height equal to that of the OCA/H. The MAPt is defined by a distance 7.41 km (4.00 NM) from the FAF. SOC The SOC can be derived from Table 5.19. For a FAF which is located 7.41 km (4.00 NM) from the MAPt, a nominal ‘MAPt to FAF’ distance of 4.5 km (2.43 NM) can be derived. Gradient The climb gradient of the missed approach surface is 2.5 per cent. Turn Point The turn point is located at a designated altitude of 2 000 ft. Protection area of the turn point missed approach This section shows the parameters on which the turn area is based, together with the variables which represent them in the drawings. The turn is made for the following values: Altitude: The defined turn altitude = 6096 m (2 000 ft) Temperature: ISA + 15°C Indicated airspeed (IAS): 425 km/h (230 kt) Conversion factor K for IAS to TAS: 1,0567 ___________________________________________________________________________ 255 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Parameter Formula ― IAS Value Unit 425.96 km/h TAS TAS x K 450.11 km/h C 6 seconds (TAS+56)x(6÷3600) 0.84 km R 542÷TAS 1.2 Deg/s r (TAS)/62.8R 5.95 km E 1.4/R 1.16 km Table 5.19.- Turning Missed Approach area construction where: • R is the rate of turn; • r is the turn radius; and • E is the wind effect. Obstacle clearance The minimal obstacle clearance in the initial phase is the same as in the approach segment, which is an OCA of 574 ft. In the intermediate segment the minimum obstacle clearance is 30 m (98 ft) at the inner edges and reduces to zero at the outer edge. In the final missed approach phase the MOC is 50 m (164 ft) in the primary area and reducing to zero at the outer edge of the secondary area. Figure 5.88.- Turning Missed Approach Area ___________________________________________________________________________ 256 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ 5.2.2 Precision approach The procedure from en route to the precision segment of the ILS approach and in the final missed approach phase conforms with the general criteria specified in chapter 5.2. The differences are found in the physical requirements for the ILS precision segment which contains the final approach segment and the initial/intermediate phases of the missed approach segment. In stead of using a turn point at a designated height/altitude, I will now use a turn point at a designated point. 5.2.2.1 Initial Approach Segment The area is the same as the one used for non-precision approach (see 5.2.1.1). The difference is that the IF must be located within the service volume of the ILS localizer course signal, and normally at a distance not exceeding 46 km (25 NM) from the localizer antenna. 5.2.2.2 Intermediate Approach Segment The intermediate approach segment for ILS differs from the general criteria in that: • the alignment coincides with the localizer course • the length may be reduced • in certain cases the secondary areas may be eliminated Alignment The intermediate approach segment for an ILS procedure shall be aligned with the localizer course. Segment length The optimum segment length is 9 km (5 NM). The maximum length is governed by the requirement that it be located wholly within the service volume of the localizer signal and normally at a distance not exceeding 46 km (25 NM) from the localizer antenna. Area width The total width at the beginning of the segment is defined by the final width of the initial approach segment. The primary area expands uniformly to 9.3 km (5M) at 28 km (15 NM) . At the interface with the initial approach segment the width of each secondary area equals ___________________________________________________________________________ 257 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ half the width of the primary area and decreases to zero at the interface with the final approach surface. Obstacle clearance The obstacle clearance is the same as for the non-precision intermediate approach segment. (See 5.1.1.2). 5.2.2.3 Precision Segment The precision segment is aligned with the localizer course and contains the final descent for landing as well as the initial and intermediate phases of the missed approach segment. Start and ending point The precision segment starts at the FAP and ends where the final phase of the missed approach commences. The FAP should not be located more than 18.5 km (10.0 NM) before threshold. In this case the FAP is located 10.56 km (5.7 NM) from the ILS. Descent fix The descent fix should not be located more than 18.5 km (10.0 NM) before threshold. The maximum fix tolerance is ±0.9 km (±0.5 NM). Calculating OCA/H There are three methods for calculating the obstacle clearance: • application of basic ILS surfaces; • using OAS criteria; • application of CRM. The basic ILS surfaces correspond to some Annex 14 obstacle limitation surfaces, these are already specified and drawn in chapter 3 (Appendix A). In standard conditions there is no restriction on objects beneath these surfaces. The CRM will not be applied, this procedure is further described in chapter 5.1.10.4 and in ICAO Doc 9274, Manual on the Use of the Collision Risk Model (CRM) for ILS Operations. ___________________________________________________________________________ 258 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ I decided to determine the obstacle clearance using the OAS criteria. This section describes the constants and conditions to determine these surfaces. The OAS dimensions are related to: • the ILS geometry (localizer-threshold distance, glide path angle, ILS RDH, localizer sector width); • the category of ILS operations; • other factors such as aircraft geometry and missed approach climb gradient. Elevation ARP [m] 33.88 Elevation THR [m] 33.88 3 Angle GP [°] Distance LLZ/THR [m] 3674 Height ILS [m] 3.87 Slope Missed Approach [°] 2.5 I ILS Category Table 5.20.- OAS related dimensions Though recently software was made available by ICAO to calculate the OAS parameters, I will still use the OAS parameters found in ICAO PANS-OPS (1993). Hereunder the OAS model will be calculated and drawn in AutoCAD. A 0.028500 0.028249 -0.025930 -0.025930 W X Y Z X Y C 281 49 D -286 135 ILS Constants OAS B 0.000000 0.186246 0.000000 0.204119 Coordinates OAS E C'' -900 10 807 205 63 D'' 5 438 877 C -8.01 -17.06 -22.50 -20.14 E'' -15 900 3 588 Table 5.21.- ILS OAS Constants & coordinates With the parameters shown in Table x-x-b the OAS model can be drawn, Figure X shows us the finished AutoCAD OAS model. ___________________________________________________________________________ 259 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Figure 5.89.- ILS OAS The obstacles in the OAS are divided in two categories, approach and missed approach. In my case there are 2 objects located in the approach sector, one of 153 m (499 ft) located 6780 m from the ILS and one of 99.4 m (326 ft) located 6460 m from the ILS. The OCA/H is different for each aircraft category, because the added margin to ha is different for each category. Table X shows the OCA/H for each altitude. Aircraft Category OCA/H (ft) A B C D 289 310 318 329 (187) (199) (207) (218) Table 5.22.- OCA/H 5.2.2.4 Missed Approach after the Precision segment The criteria for the final missed approach are based on those for the general criteria with certain modifications to allow for the different areas and surfaces associated with the ILS precision segment and the possible variation in OCA/H for that segment with aircraft category. I have chosen to make a turning missed approach using a TP at a specified DME distance. Turn point The TP is chosen at 1574 m (8.5 NM) distance, this results is the fact that the TP is located in the precision area. Turn initiation area The turn initiation area is bounded by the 300 m Category 1 Y surface contour, except that it terminates at the range of the TP. ___________________________________________________________________________ 260 Chapter 5: Instrument Approach Procedure _________________________________________________________________________________________________________________ Turn radius and protection area of the turned missed approach The turn area is constructed as specified in the general criteria (see 5.1). Table 5.23 gives us the formulas to calculate the parameters used in the turning missed approach area construction. The calculations were made for: Parameter IAS TAS c 6 seconds R r E • maximum speed of 426 km/h (230 kt) IAS; • duration of outbound leg is 1 minute; • temperature is ISA + 15°C; • altitude is 610 m (2 000 ft); • conversion factor K = 1.06. CALCULATIONS USING SI UNITS Formula IAS x K (TAS+56)x(6÷3600) 542÷TAS TAS ÷ 62.8R 1.4÷R Value Unit 425.96 km/h 450.11 km/h 0.84 km 1.2 deg/s 5.95 km 1.16 km Table 5.23.- Turn Area Calculations where: • R is the rate of turn; • r is the turn radius; and • E is the wind effect. With these values the outer turn boundary can be drawn, this can be found in Appendix D. Obstacle clearance Obstacle elevation/height shall be less than: (OCA/Hps - HL) + d0 tan Z - MOC with MOC = 50 m (164 ft) ___________________________________________________________________________ 261 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ 6 Standard Departure Procedure 6.1 General 6.1.1 Introduction to departure procedures A departure procedure designed in accordance with this section provides obstacle clearance immediately after take-off until the aircraft intercepts an en-route segment. Departure procedures include, but are not limited to, standard departure routes and associated procedures (ICAO Annex 11, Appendix 3). 6.1.1.1 Consultation A departure procedure may also be required for air-traffic control, airspace management or other reasons (e.g. noise abatement) and the departure route or procedure may not be determined by obstacle clearance requirements alone. Departure procedures should be developed in consultation with the operators, ATC and other parties concerned. 6.1.1.2 Standardization The specifications contained in this section are based on conventional navigation equipment and operating practices and have been formulated with a view to achieving a reasonable degree of standardization. Exceptions should be permitted alone after joint consideration by the State authority and the operators concerned. For RNAV departures, refer also to the requirements in ICAO PANS-OPS Part III “RNAV procedures and satellite-based procedures”. 6.1.1.3 Economy In the interest of efficiency and economy, every effort should be made to ensure that procedures are designed, consistent with safety, to minimize both the time taken in executing a departure and the airspace required. 6.1.1.4 Routes Departure procedures may be published as specific routes or as omnidirectional departures. 6.1.1.5 Related material ___________________________________________________________________________ 262 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ For the construction of obstacle clearance areas associated with turns, reference should be made to the standard techniques contained in ICAO PANS-OPS Part I Section 2, Chapter 3, “Turn area construction”. Navigation aid characteristics and fix tolerances are specified in 5.1.2, “Terminal area fixes”. 6.1.1.6 Abnormal and emergency operations The design of procedures in accordance with this section assumes normal operations and that all engines are operating. It is the responsibility of the operator to conduct an examination of all relevant obstacles and to ensure that the performance requirements of ICAO Annex 6 are met by the provision of contingency procedures for abnormal and emergency operations. Where terrain and/or obstacles considerations permit, the contingency procedure routing should follow that of the departure procedure. It is the responsibility of the state to make available the obstacle information described in ICAO Annexes 4 and 6, and any additional information used in the design of departures in accordance with this section. 6.1.2 General concepts for departure procedures 6.1.2.1 Establishment of a departure procedure For each runway at aerodromes where instrument departures are expected to be used, a departure procedure shall be established and promulgated. A departure procedure should be designed to accommodate all aircraft categories where possible. Where departures are limited to specific categories, the departure chart shall clearly identify the applicable categories. 6.1.2.2 Design principles Departures may be designed as straight departures or turning departures. An omnidirectional departure procedure may be designed that permits a turn in any direction after reaching a specified altitude/height. ___________________________________________________________________________ 263 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ A straight departure may permit a turn of 15° or less. An aircraft will maintain the runway direction until reaching a minimum height of 120 m (294 ft) above the runway/FATO before commencing a turn. A turning departure will specify a turn either at a turn point or an altitude/height. The standard procedure design gradient (PDG) is 3.3 per cent. The PDG begins at a point 5 m (16 ft) above the departure end of the runway (DER). The standard PDG provides an additional clearance of 0.8 per cent of the distance flown from the DER, above an obstacle identification surface (OIS). The OIS has a gradient of 2.5 per cent. Where an obstacle penetrates the OIS, a steeper PDG may be promulgated to provide obstacle clearance of 0.8 per cent of the distance flown from the DER. Before any turn greater than 15° may be executed, a minimum obstacle clearance of 90 m (295 ft) must be reached. Alternatively, 0.8 per cent of the distance from the DER may be used, if this value is higher. This minimum obstacle clearance must be maintained during subsequent flight. 6.1.2.3 Beginning of the departure procedure For aeroplanes the departure procedure begins at the departure end of the runway (DER), which is the end of the area declared suitable for take-off (i.e. the end of the runway or clearway as appropriate.) Since the point of lift-of will vary, and in order to protect for turns prior to the DER, the protected area begins at a point 600 m from the start of runway. This is based on the assumption that the minimum turn height of 120 m (394 ft) above the elevation of the DER could be reached 600 m from the start of runway. ___________________________________________________________________________ 264 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Note.— The elevation of the DER is the elevation of the end of the runway or the elevation of the end of the clearway, whichever is higher. 6.1.2.4 End of the departure procedure The departure procedure ends at the point where the PDG reaches the minimum altitude/height authorized for the next phase of flight (i.e. en-route, holding or approach). 6.1.2.5 Minimum obstacle clearance (MOC) The minimum obstacle clearance (MOC) in the primary area is 0.8 per cent of the distance flown from the DER. The MOC is zero at the DER. The MOC is provided above an obstacle identification surface or, where an obstacle penetrates the OIS, above the elevation of the obstacle. In addition to the above prior to the commencement of a turn of more than 15 degrees, MOC of 90 m (295 ft) is required. Where mountainous terrain is a factor, consideration shall be given to increasing the minimum obstacle clearance (see 5.1.1.12, “Increased altitudes/heights for mountainous areas”). 6.1.2.6 Obstacle identification surface (OIS) The obstacle identification surface (OIS) is a sloping surface used to identify obstacles in the departure area. For straight departures the origin of the OIS is 5 m (16 ft) above the DER. For omnidirectional departures several OIS are considered as described in ICAO PANS-OPS Part I Chapter 4, “Omnidirectional Departures”. The OIS gradient is 2.5 per cent. Survey of OIS The OIS should be surveyed at regular intervals to validate obstacle information so that the minimum obstacle clearance is assured and the integrity of departure procedures is safeguarded. The competent authority should be notified whenever an object is erected that penetrates the OIS. ___________________________________________________________________________ 265 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Note.— Yearly checks are considered to meet the requirements for “regular intervals.” Distances to obstacles should be referenced to the DER. 6.1.2.7 Procedure design gradient (PDG) The procedure design gradient (PDG) Is the published climb gradient measured from the origin of the OIS (5 m (16 ft) above DER). Provided no obstacles penetrate the OIS the procedure design gradient (PDG) is the OIS gradient plus 0.8 per cent. Where the 2.5 per cent OIS is penetrated, the departure route should be adjusted to avoid the penetration. If this is not possible then the PDG may be increased to provide the minimum obstacle clearance above the penetration (0.8 per cent of the distance from the DER). (See Figure 6.1.) Figure 6.1.- Procedure design gradient A PDG in excess of 3.3 per cent and the altitude to which the increased gradient extends shall be promulgated. ___________________________________________________________________________ 266 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Where the PDG is increased to avoid a penetrating obstacle, the PDG shall be reduced to 3.3 per cent at the point past the critical obstacle where obstacle clearance of 0.8 per cent of the distance from the DER can be provided. (See Figure 6.1.) An increased gradient that is required to a height of 60 m (200 ft) or less, (normally due to low, close-in obstacles) shall not be promulgated (see Figure 6.2). The position and elevation/height of close-in obstacles penetrating the OIS shall be promulgated. Figure 6.2.- Close-in obstacles 6.1.2.8 Average flight path When close conformance to the nominal track is important (for noise abatement/ATC constraints, etc.), actual flight track data may be used to determine the average flight path. Guidance material (based on statistical data) on how to establish an average flight path is given in ICAO PANS-OPS Part I, Section 4, Chapter 3, Appendix. The aircraft performance used to determine the average flight path must be used for obstacle clearance calculation purposes. 6.1.2.9 Charting accuracy Charting accuracy must be taken into account by applying vertical and horizontal tolerances, as described in 5.1.1.13, “Charting accuracy”. When the application of these tolerances creates an unacceptable operational penalty, additional survey information should be used to refine the obstacle location and height data. ___________________________________________________________________________ 267 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ 6.1.2.10 Additional specific height/distance information Whenever a suitably located DME exists, or when suitably located RNAV fixes can be established, additional specific height/distance information intended for obstacle avoidance should be published in order to provide a means of monitoring aircraft position relative to critical obstacles. 6.1.3 Departure routes 6.1.3.1 General There are two basic types of departure route: straight and turning. Track guidance shall be provided: a) within 20.0 km (10.8 NM) from the departure end of the runway (DER) for straight departures; b) within 10.0 km (5.4 NM) after completion of turns for turning departures. Surveillance radar may be used to provide track guidance. 6.1.3.2 Straight departures General A departure in which the initial departure track is within 15° of the alignment of the runway centre line is a straight departure. Wherever practical, the departure track should be extended runway centre line (see Figure 6.3). Types of straight departure Straight departures are divided into two main categories, depending upon availability of initial track guidance: a) straight departure without track guidance: 1) departure with no track adjustment; 2) departure with track adjustment (track adjustment point not specified); 3) departure with track adjustment (track adjustment point specified). b) straight departure with track guidance: 1) facility ahead or behind; 2) offset (track parallel/track offset/track crossing). ___________________________________________________________________________ 268 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Figure 6.3.- Straight departure area without track guidance Track adjustment In the construction of areas it is assumed that any track adjustment will take place no further along the track than a point at which the PDG reaches 120 m (394 ft) above the elevation of the DER, or at a specified track adjustment point. Straight departure without track guidance Departure with no track adjustment The area begins at the DER and has an initial width of 300 m. It is centred on the runway centre line and splays at an angle of 15° on each side of the extended runway centre line (see Figure 6.3). The area terminates at the end of the departure procedure as specified in 6.1.2.4, “End of the departure procedure.” Departure with track adjustment The initial departure track may be adjusted by 15° or less. When adjusted, the splay of the area boundary on the side of the track adjustment is increased by the track adjustment angle, starting at the DER. ___________________________________________________________________________ 269 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ On the side opposite the track adjustment, the boundary is adjusted by the same amount at a point where the PDG reaches 120 m (394 ft). This distance is nominally 3.5 km/1.9 NM from the DER for a 3.3 per cent PDG (see Figure 6.4). Figure 6.4.- Straight departure area with track adjustment (track adjustment point not specified) Track adjustment point specified. If a track adjustment point is specified (see Figure 6.5): a) the splay of the area boundary on the side of the track adjustment is increased by the track adjustment angle, from the earliest tolerance of the track adjustment point; b) the splay of the area boundary on the side opposite the track adjustment is reduced by the track adjustment angle from the latest tolerance of the track adjustment point. Figure 6.5.- Straight departure area with a specified track adjustment point ___________________________________________________________________________ 270 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Straight departure with track guidance General The area is constructed as described in 6.1.3.2, “Straight departure without track guidance” and extended to the point where boundaries intercept the area associated with the navigation aid providing the track guidance (see Figures 6.6 to 6.10). Figure 6.6.- Straight departure (facility ahead) Figure 6.7.- Straight departure (facility behind) Figure 6.8.- Straight departure with offset departure track (track parallel to runway heading) ___________________________________________________________________________ 271 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Figure 6.9.- Straight departure with offset departure track (track diverging from runway heading) Figure 6.10.- Straight departure with offset departure track (track crossing runway heading) Areas associated with a navigational aid The areas associated with a navigational aid other than a localizer consist of appropriate portions of trapezoids specified in ICAO PANS-OPS Part II, Section 2, Chapters 4 and 6. The general principle of secondary areas is applied. 6.1.3.3 Turning parameters General ___________________________________________________________________________ 272 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ A departure incorporating a turn of more than 15° is a turning departure. Turns may be specified at an altitude/height, or at a fix or at a facility. Straight flight is assumed until reaching a height of at least 120 m (394 ft) above the elevation of the DER. No provision is made for turning departures which require a turn below 120 m (394 ft) above the elevation of the DER. Where the location and/or height of obstacles makes it impossible to construct turning departures which satisfy the minimum turn height criterion, departure procedures should be developed on a local basis in consultation with the operators concerned. The areas considered in the design of turning departures are defined as: a) the turn initiation area; b) the turn area. The turn initiation area is an area within which the aircraft conducts a straight climb in order to reach the MOC required prior to the beginning of a turn (90 m (295 ft)). The turn area is the area in which the aircraft is considered to be turning. Turn initiation area For aeroplanes, the turn initiation area starts at a point 600 m from the start of runway. Where the departure chart prohibits turns prior to the DER the turn initiation area starts at the DER. The turn initiation area terminates at the TP. The TP may be defined by: a) the earliest fix tolerance of the TP fix (turn at designated turn point); b) the position at which the PDG reaches the specified turn altitude/height. The TP may be located no closer to the DER than the distance required at the PDG to reach the higher of 120 m (394 ft) or the specified turn altitude/height. The turn initiation area is identical to the area associated with a straight departure with no track guidance as described in 6.1.3.2, “Straight departure without track guidance.” (See Figures 6.11 and 6.12.) Turn area ___________________________________________________________________________ 273 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ The turn area is constructed in the same manner as the turning missed approach area (see 5.1.7.4, “Turning missed approach”). The inner and outer boundaries of the turn area are constructed as specified in 5.1.7.4, “Turn area construction”. Turn parameters The parameters on which turn areas are based area: a) altitude: 1) turn designated at an altitude/height: turn altitude/height; 2) turn at a designated turning point: aerodrome elevation plus 10 per cent of the distance from the DER to he TP (i.e. allowing for a 10 per cent climb). b) temperature: ISA + 15°C corresponding to a) above; c) indicated airspeed: the speed tabulated for “final missed approach” in Table 5.1 for the applicable aircraft category, increased by 10 per cent to account for increased aircraft mass at departure. However, where operationally required to avoid obstacles, reduced speeds not less than 1.1 times the IAS tabulated for “intermediate missed approach” in Table 5.1 may be used, provided the procedure is annotated “Departure turn limited to _ km/h (kt) IAS maximum”. In order to verify the operational effect of a speed limitation, the speed should be compared with the statistical speed. d) true airspeed: the IAS in c) above adjusted for altitude a) and temperature b); e) wind: maximum 95 per cent probability wind on an omnidirectional basis, where statistical wind data are available. Where no wind data are available, an omnidirectional 56 km/h (30 kt) wind should be used; f) bank angle: 15° average achieved ; g) fix tolerance: as appropriate for the type of fix; h) flight technical tolerances: a distance equivalent to 6 seconds of flight (3 second pilot reaction and 3 second bank establishing time) at the specified speed. (See c) above. This value is represented by the letter c in this chapter); i) secondary areas: secondary areas are applied where track guidance is available. Turn at a specified altitude/height General ___________________________________________________________________________ 274 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ A turn may be prescribed upon reaching a specified altitude/height to accommodate the situation where there is: a) an obstacle located in the direction of the straight departure that must be avoided; b) an obstacle located abeam the straight departure track that must be overflown after the turn. Turning altitude or height calculations A turn altitude/height is selected which results in a turning point that ensures that the aircraft avoids the straight ahead obstacle or overflies the abeam obstacle with the required MOC. Turn height (TNH) is computed by: TNH = drPDG + 5 m (16 ft) where: dr is the horizontal distance from DER to the TP; PDG is the procedure design gradient. Obstacle clearance calculation a) turn initiation area. The minimum obstacle clearance in the turn initiation area is calculated using the horizontal distance from the DER measured along the nominal track, at the designated PDG. (See 6.1.2.5, “Minimum obstacle clearance”.) Note that a turn may be commenced at the specified turn altitude, and that nominal aircraft performance will often result in this altitude being reached before the end of the turn initiation area (TP). Therefore, the minimum obstacle clearance for turning must also be provided above all obstacles in the turn initiation area. This criterion will be met if the maximum obstacle elevation in the turn initiation area is: maximum obstacle elevation/height = TNA/H – 90 m (295 ft) b) turn area. The minimum obstacle clearance in the turn area is calculated as follows. 1) Obstacles locate before the TP (k-line). MOC is the greater of the minimum MOC for turning (90 m (295 ft) and 0.008 (dr + d0) where: dr is the distance measured along the departure track corresponding to the point on the turn initiation area boundary where the distance d0 is measured, and ___________________________________________________________________________ 275 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ d0 is the shortest distance from the turn initiation area boundary to the obstacle. 2) obstacles located after the TP (k-line). MOC is the greater of the minimum MOC for turning (90 m (295 ft)), and 0.008 (dr + d0) where: dr is the horizontal distance from DER to the K-line, and d0 is the shortest distance from the turn initiation area boundary to the obstacle. (See Figures 6.11 and 6.12.) Figure 6.11.- Turning departure – turn at an altitude ___________________________________________________________________________ 276 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ The maximum permissible elevation/height of an obstacle in the turn area can be computed by: Maximum obstacle elevation/height = TNA/H + d0PDG – MOC Turn at a designated TP General A designated TP is selected to allow the aircraft to avoid an obstacle straight ahead. The straight departure criteria apply up to the earliest TP. Figure 6.12.- Turning departure – turn at an altitude ___________________________________________________________________________ 277 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Turn point tolerance The longitudinal limits of the TP tolerance are: a) earliest limit, the end of the turn initiation area (K-line); b) latest limit, determined by: 1) K-line plus; 2) TP fix tolerance plus; 3) flight technical tolerance c, where c is calculated in accordance with 6.3.3 h). Where the TP is defined by passage over a navigation aid, the fix tolerance is computed at the elevation of the DER plus 10 per cent of the distance from the DER to the TP (i.e. allowing for a 10 per cent climb gradient). Where the TP is defined by a DME distance, the maximum angle that a line joining the TP and the DME may make with the nominal departure track shall not be more than 23°. (See 5.1.2.4, “Fixes for VOR or NDB with DME” and Figure 5.3.) Construction a) inner boundary. The inner boundary of the turn area is constructed in accordance with Section 2, Chapter 3, “Turn area construction”. b) outer boundary. The outer boundary of the turn area: 1) begins at the latest TP tolerance (see also Figures 6.13, 6.14, 6.15 and 6.16); 2) continues along the wind spiral or bounding circles constructed in accordance with ICAO PANS-OPS Part I, Section 2, Chapter 3, “Turn area construction”; and up to the point (P) where the tangent becomes parallel to the nominal track after the turn. Examples of turns with track guidance after the turn, flying to or from a facility are provided in Figures 6.15 and 6.16 respectively. c) for turns more than 90° the area after the turn is constructed as shown on Figure 6.17. ___________________________________________________________________________ 278 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Figure 6.17.- Turning departure – turn at more than 90° Figure 6.13.- Turning departure not overheading a facility – turning point tolerance area defined by intersecting radial ___________________________________________________________________________ 279 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Figure 6.14.- Turning point not defined by overheading a facility (or RNAV fix) Obstacle clearance in the turn area In order to ensure that the minimum obstacle clearance in the turn area has been provided, use the following equation to check the maximum height of an obstacle in the turn area above the elevation of the DER: Maximum height of obstacle = PDG(dr + d0) + H – MOC where: d0 = shortest distance from obstacle to line K-K (see Figures 6.15) dr = horizontal distance from DER to line K-K (earliest TP) PDG = promulgated procedure design gradient H = OIS height at DER (5 m or 16 f) MOC = the greater of 0.008 (dr + d0) and 90 m (295 ft) ___________________________________________________________________________ 280 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Figure 6.15.- Turning departure – turn at a fix Figure 6.16.- Turning departure – turn over a facility ___________________________________________________________________________ 281 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ 6.2 Application to Seville Airport 6.2.1 General purpose In this chapter I will design a series of standard instrument departure (SID) for Seville Airport, these are designed and published to expedite clearance delivery and to facilitate transition between take off and en-route operations. The SID provides a standard route from the terminal to the en-route structure. Further the transitions which connect the end of the SID with one of several en-route possibilities will be drawn. My SID for runway 09 will provide a transition to following reporting points: • HIJ1R • SANTA1R • ONUBA1R • CLANA1R • VJF1R • MAR1R • VIBAS1R while the SID for runway 27 will provide a transition for these reporting points: • HIJ1R • SANTA1G • ONUBA1G • CLANA2G • VJF1G • MAR1G • VIBAS1G These two SID’s will be drawn on SID charts with AutoCAD, they are included in Appendix E. ___________________________________________________________________________ 282 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ 6.2.2 The design of routes to reporting points This subchapter will only give the information related to the routes to reporting points (these are indicated with a triangle on the charts). For routes to other navigation facilities, see 6.2.3. Both the runway and notification point are fixed, they can not be moved in space. So I will have to design the routes between this 2 points. It is also important that each route is provided with some kind of guidance, preferably VOR(/DME) guidance. We also have to keep in mind that the SID should be simple without unnecessary routes, and off course the shortest possible route. This can be achieved with one (or few) central cross points. Also we have to take different restrictions into account: • (P) prohibited areas : cannot be used; • (R) restricted areas : can be used under some circumstances; and • (D) danger areas : can be used, be should be avoided where possible. 6.2.2.1 Runway 09 The cross point for runway 09 is a central VOR/DME (SVL), however another VOR/DME should be possible to play the role of this central VOR/DME. For example MRN could be used to fly to the southern notification points. Using this VOR/DME station would raise the distance and flying time to reach the southern notification points. VOR/DME SVL station is very well located because the pilot just has to climb until reaching 3 DME SVL to intercept it. From this central station the following notification points can be easily reached by the means of straight tracks: • VIBAS: RDL-094 SVL; • CORIA: RDL-223 SVL; • CLANA: RDL-223 SVL; • ARROS: RDL-302 SVL; • SANTA: RDL-302 SVL. Note that CORIA/CLANA and ARROS/SANTA are located on the same radial. ___________________________________________________________________________ 283 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ 18 70 78 Figure 6.18.- VOR/DME MRN as an alternative intersection Notification points ROCIO and ONUBIA can’t be reached with straight tracks from SVL because the turns would be to sharp. To reach them you have to first fly on RDL-223 SVL then turn right intercepting RDL-284 MRN. This track leads to notification point ROCIO. To reach ONUBIA you have to turn left over ROCIO, intercepting RDL-260 SVL. All these track are all aligned with a VOR radial (since they begin overhead the VOR), thus the VOR provides the track guidance, this is important to draw the protection areas (see 6.2.4). Figure 6.19.- Alternative to reach ROCIO and ONUBIA ___________________________________________________________________________ 284 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ 6.2.2.2 Runway 27 Northern part For the northern part of the SID of runway 27, ARROS will be used as central cross point. ARROS will be reached by climbing on runway heading until reaching 600 ft and then turning right intercepting RDL-302 SVL. ARROS should be crossed at 1 500 ft or above. Notification point SANTA can now be reached by a straight track from RDL-302 SVL. SANTA could also be reached by first flying RDL-277 SVL over LAMAR and the turning right intercepting RDL-302 SVL, however when two reporting points are located near each other it is more practical to use the nearest to the station (ARROS in this case) as an intersection. Since they do not differ much in heading and distance from the VOR station there will be no significant loss of time. Otherwise an extra track would be needed and this would only complicate the problem with no significant advantage. RD L-3 02 SV L Figure 6.20.- Alternative route to SANTA Southern part For the southern part LAMAR will be used as a central cross point. LAMAR will be reached by climbing on runway heading until reaching 600 ft and then turning right intercepting RDL-277 SVL. LAMAR should be crossed at 1 500 ft or above. From this cross point following notification points can be reached: • • • ROCIO: RDL-260 SVL; ONUBA: RDL-260 SVL; CORIA: RDL-223 SVL; ___________________________________________________________________________ 285 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ • • CLANA: RDL-223 SVL; OLIVO: 15 DME ARC SVL. None of these can be reached with a straight track. In order to reach ROCIO you have to make a left hand turn over LAMAR intercepting RDL-260 SVL. When flying straight ahead over ROCIO, intercepting RDL-260 SVL, notification point ONUBA will be reached. These two notification points could also be reached flying straight ahead after departure and directly intercepting RDL-260 SVL, not using cross point LAMAR. In my charts I still used LAMAR as a crossing point in order to reach ROCIO and ONUBA. ONA B A 1G RDL287 M AR Figure 6.21.- Alternative route to ROCIO and ONUBA To intercept CORIA and CLANA you have to turn left over LAMAR intercepting RDL-359 JRZ. Then intercept RDL-223 SVL leading first to CORIA and then to CLANA. In theory OLIVO, CORIA and CLANA could be reached with a straight track without using LAMAR flying left directly after departure. In reality this can not be realised because the turn would be to sharp. Notification point OLIVO is reached by intercepting DME arc 15 SVL. OLIVO should be crossed at 4 000 ft or above. This is a difficult manoeuvre because on little distance an almost 180° turn is performed. This is the only way to intercept OLIVA because otherwise no guidance is provided. ___________________________________________________________________________ 286 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ BA1G L RD L22 3 SV L ONA V 260 S R D L- 1 70 Figure 6.22.- Alternative route to OLIVO, CORIA, CLANA After reaching OLIVO fly onto RDL-287 MAR until VOR/DME station MARTÍN and then intercept RDL-075 MAR that leads to notification point VIBAS. 6.2.3 The design of routes to navigation facilities In some cases I used another VOR/DME station as endpoint of the departure route and start of the en-route navigation. 6.2.3.1 Runway 09 As endpoint of the departure route I used the following VOR/DME stations: • HINOJOSA: RDL-028 SVL; • MARTÍN: RDL-122 SVL; • JEREZ: RDL-202 SVL; • VEJER: RDL-009 VJF. ___________________________________________________________________________ 287 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ When flying to HINOJOSA, MARTÍN and JEREZ VOR/DME station SVL will provide track guidance. For VEJER track guidance will first be provided by VOR/DME station JEREZ and the last leg of the route will be guided by VOR/DME station VEJER. To get to HINOJOSA fly radial 028 over VOR/DME station SVL. This is a straight line and shortest route so no other possibility is useful. This is the same for MARTÍN, you just have to fly RDL-122 SVL. To reach JEREZ and VEJER, you have to turn right over SVL to intercept RDL-202 SVL. By turning left over JRZ intercepting RDL-171 JRZ and afterwards intercepting RDL-009 VJF VOR/DME station VEJER can be reached. As an alternative you could fly straight to VEJER, not passing JEREZ. This is not done in order to keep the number of routes as low as possible. 6.2.3.2 Runway 27 To end the departure route I used the following VOR/DME stations: • HINOJOSA: RDL-225 HIJ; • MARTÍN: RDL-287 MAR; • JEREZ: RDL-359 JRZ; • VEJER: RDL-179 JZR. To reach HINOJOSA you have to turn right over reporting point ARROS and intercept RDL-225 HIJ. A straight route to HINOJOSA , not passing ARROS, is not possible because the number of routes should be as low as possible. ___________________________________________________________________________ 288 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ 43 7 48 Figure 6.23.- Alternative route to VEJER Figure 6.24.- Alternative route to HINOJOSA Reaching MARTÍN is done by slightly turning left over reporting point OLIVO intercepting RDL-287 MAR. Flying directly to MARTÍN is not possible because the turn would be to sharp and it would also create to many routes. To get to JEREZ you have to turn right over LAMAR intercepting RDL-359 JZR. VOR/DME VEJER station is easily reached from JEREZ, you just have to fly straight ahead intercepting RDL-179 JZR. ___________________________________________________________________________ 289 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Figure 6.25.- Alternative route to MARTÍN 6.2.4 Notes applicable to the SID’s Each SID is prone to some restrictions, as shown below. A restriction which is applicable to all the SID’s is that the IAS MAX is 250 kt until leaving FL 120. 6.2.4.1 Runway 09 HINOJOSA ONE ROMEO departure (HIJ1R) Climb on runway heading until reaching 3 DME SVL. Turn left direct to VOR/DME SVL. Proceed on RDL-028 SVL, direct to VOR/DME HIJ. SANTA ONE ROMEO departure (SANTA1R) Climb on runway heading until reaching 3 DME SVL. Turn left to intercept and follow RDL-302 SVL direct to ARROS. Direct to SANTA. ONUBA ONE ROMEO departure (ONUBA1R) Climb on runway heading until reaching 3 DME SVL. Turn right to intercept and follow RDL-223 SVL, direct to cross 12 DME SVL at 3 500 ft or above. Turn right to intercept and follow RDL-284 MRN, direct to ROCIO. Proceed on RDL-260 SVL direct to ONUBA. 4% minimum climb gradient until reaching 3 500 ft. CLANA ONE ROMEO departure (CLANA1R) ___________________________________________________________________________ 290 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ Climb on runway heading until reaching 3 DME SVL. Turn right to intercept and follow RDL-223 SVL, direct to cross 12 DME SVL at 3 500 ft or above. Direct to cross CORIA at FL70 or above. Direct to CLANA. 4% minimum climb gradient until reaching 3 500 ft. VEJER ONE ROMEO departure (VJF1R) Climb on runway heading until reaching 3 DME SVL. Turn right to intercept and follow RDL-202 SVL, direct to cross 12 DME SVL at 3 500 ft or above. Direct to VOR/DME JRZ. Proceed on RDL-171 JRZ until intercepting and following RDL-009 VJF. Direct to DVOR/DME VJF. 4% minimum climb gradient until reaching 3 500 ft. MARTÍN ONE ROMEO departure (MAR1R) Climb on runway heading until intercepting and following RDL-122 SVL. Direct to DVOR/DME MAR. VIBAS ONE ROMEO departure (VIBAS1R) Climb on runway heading until intercepting and following RDL-094 SVL. Direct to VIBAS. 6.2.4.2 Runway 27 HINOJOSA ONE GOLF departure (HIJ1G) Climb on runway heading until reaching 600 ft. Turn right to follow RDL-302 SVL direct to ARROS. Turn right to follow RDL-225 HIJ, direct to VOR/DME HIJ. NOTE: Traffic bound for airway UN-858 shall cross VOR/DME HIJ at FL245 or above and proceed on RDL-359 HIJ direct to PARKA. SANTA ONE GOLF departure (SANTA1G) Climb on runway heading until reaching 600 ft. Turn right to follow RDL-302 SVL, direct to ARROS. Direct to SANTA. ___________________________________________________________________________ 291 Chapter 6: Standard Departure Procedure _________________________________________________________________________________________________________________ ONUBA ONE GOLF departure (ONUBA1G) Climb on runway heading until reaching 600 ft. Turn right to follow RDL-277 SVL, direct to cross LAMAR at 1500 ft or above. Turn left to follow RDL-260 SVL, direct to ROCIO. Direct to ONUBA. CLANA TWO GOLF departure (CLANA2G) Climb on runway heading until reaching 600 ft. Turn right to follow RDL-277 SVL, direct to cross LAMAR at 1500 ft or above. Turn left to follow RDL-359 JRZ. Turn right to intercept and follow RDL-223 SVL direct to cross CORIA at FL70 or above. Direct to CLANA. VEJER ONE GOLF departure (VJF1G) Climb on runway heading until reaching 600 ft. Turn right to follow RDL-277 SVL, direct to cross LAMAR at 1500 ft or above. Turn left to follow RDL-359 JRZ direct to VOR/DME JRZ. Direct to DVOR/DME VJF. MARTÍN ONE GOLF departure (MAR1G) Climb on runway heading until reaching 600 ft. Turn right to follow RDL-277 SVL, direct to cross LAMAR at 1500 ft or above. Turn left to proceed on arc 15 DME SVL to cross OLIVO at 4000 ft or above. Turn left to follow RDL-287 MAR, direct to DVOR/DME MAR. VIBAS ONE GOLF departure (VIBAS1G) Climb on runway heading until reaching 600 ft. Turn right to follow RDL-277 SVL direct to cross LAMAR at 1500 ft or above. Turn left to proceed on arc 15 DME SVL to cross OLIVO at 4000 ft or above. Turn left to follow RDL-287 MAR direct to DVOR/DME MAR. Proceed on RDL-075 MAR direct to VIBAS. ___________________________________________________________________________ 292 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ Conclusion The main object of this final project was to investigate if instrumental operations at Seville Airport are possible. The most important about this was not the result, whether instrumental operations are possible or not, but how we came to this result. Before I started working on the final project I already knew that instrumental operations at Seville Airport were possible, because in the AIP of Seville Airport it is stated that VFR as well as IFR flights are approved. Before constructing the instrument approach and departure procedures I had to study the surroundings of the strip. To avoid accidents due to obstacles, it important that urban construction regulations specify maximum height of buildings and artificial objects (antennas, pylons, etc), and that these and natural obstacles (trees) are frequently monitored. Seville Airport is excellently positioned because no obstacles penetrate the obstacle limiting surfaces. Before starting the design of the approach procedure I first had to study all the theory about this subject. After this I realised that there were several ways to construct the approach procedure. Depending on the existing navigation aids provided in the surrounding area of Seville Airport I decided to design a non-precision approach procedure using a VOR station with FAF and a precision approach using ILS. Also for the design of the standard instrument departures I first had to study the theory before deciding what kind of procedure I was going to use. The most difficult part of designing the routes was to locate the reporting points and to decide which navigation facilities I was going to use. The constructing of the actual routes was quite simple, you only had to keep in mind that the plane could not cross prohibited areas and that there are some restrictions to the maximum banking angle of a plane. A great part of my final project was drawing all these surfaces and routes in AutoCAD. I had never learnt how to use this drawing program so in the beginning I had some difficulties with creating the charts but after a process of trial and error I managed to draw the things I wanted. ___________________________________________________________________________ 293 Feasibility of instrumental operations in Seville Airport _________________________________________________________________________________________________________________ APPENDICES The following appendices are included in this final project, all these drawings are designed in AutoCAD 2007. APPENDIX A – OBSTACLE LIMITATION SURFACES (OLS) ................................................................................295 1. Total view .........................................................................................................................................295 2. Central part view ..............................................................................................................................296 3. Western part view ............................................................................................................................297 4. Eastern part view .............................................................................................................................298 APPENDIX B – AERODROME OBSTACLE CHARTS (OAC) ICAO TYPE A............................................................299 1. Runway 09 .......................................................................................................................................299 2. Runway 27 .......................................................................................................................................300 APPENDIX C – INSTRUMENT APPROACH CHARTS (IAC) RWY 27 ....................................................................301 1. Non-precision approach ...................................................................................................................301 2. Precision approach ..........................................................................................................................302 APPENDIX D – INSTRUMENT APPROACH CHARTS (IAC) RWY 27 WITH PROTECTION AREAS .............................303 1. Non-precision approach ...................................................................................................................303 2. Precision approach ..........................................................................................................................304 APPENDIX E – STANDARD INSTRUMENT DEPARTURE CHARTS (SID)...............................................................305 1. Runway 09 .......................................................................................................................................305 2. Runway 27 .......................................................................................................................................306 ___________________________________________________________________________ 294 Feasibility of instrumental operations in Seville Airport __________________________________________________________________________________________________________ Bibliography Literature Aircraft Operations (2006). Procedures for Air Navigation Services Doc 8168, Volume II Construction of Visual and Instrument Flight Procedures, Fifth edition (s.l.). Manual, ICAO. Building restricted areas (2004). European guidance material on managing building restricted areas EUR Doc 015, First edition (s.l.). Manual, ICAO. Airport Service Manual (s.d.). Part 6 Control of Obstacles Doc 9137, Second edition (s.l.). Manual, ICAO. PDF-files Annex 4 (2005). Aeronautical Charts, Annexes to the Convention On International Civil Aviation, Volume I (s.l.). Manual, ICAO. 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