Transcript
10th USA / Europe Air Traffic Management Research and Development Seminar (ATM 2013) 10 June 2013
ADS-B: The Case for London Terminal Manoeuvring Area (LTMA)
©Thales
Busyairah Syd Ali
Agenda • Introduction • System Overview • Data Characteristics • Data Evaluation Framework
©Thales
• Results of Evaluation • Findings • Recommendations • Conclusions
©Thales
Introduction • Motivation - Article 4 of SPI-IR, clauses 3 and 4 - ANSP to ensure surveillance system complies to requirements - Operator to investigate and rectify avionics anomalies
• Hence the need for a framework to evaluate ADS-B performance - Challenges in the data analysis - Errors in the datasets - Recommendations
System overview Source Positioning performance Data : British Airways Onboard avionics performance Data: NATS & BA
Ground station performance
Data Link Mode-S 1090Mhz performance
Data: NATS
Data: NATS
Data characteristics
Ground ADS-B ground stations (ASTERIX CAT021) Airborne Aircraft navigation system (GPS)
Data characteristics Problems identified in the datasets • Duplicate ADS-B messages, as recorded at ground level • GPS clock errors as recorded on board the aircraft • GPS position fluctuations recorded on board the aircraft • Lack of consistent GPS position format output by the aircraft • Uncorrelated time intervals between GPS data (at aircraft level) and ADS-B data (at ground level) Each aircraft is assessed if it is suitable for the quantitative performance analysis. Findings are recorded.
Data evaluation framework
Data evaluation framework: Data correlation Difficulties in data correlation: • Mismatch of update rates between data • Inconsistent update rate of ADS-B data • Lack of ADS-B data • Different decimal precisions • Time stamp differences • Different horizontal position values GPS & ADS-B datasets
Data evaluation framework: Data correlation
Data evaluation framework: ‘Reference’ ‘REFERENCE’ horizontal position derivation The Reference (φREF, λREF) is derived as: φREF = φGPS + Δφ λREF = λGPS + Δλ where, φGPS is GPS latitude, λGPS is GPS longitude, Δφ , Δλ is the function of distance and azimuth based on latency and speed.
Assumption ADS-B Specific COMM
AVIONIC GS
GPS
SBAS, GBAS, RAIM
Results of Evaluation: ADS-B Latency Definition – delay between aircraft position determination by onboard navigation system and position reception by ground station Potential sources for latency : •ADS-B ground station antenna delay •GPS antenna on the ground station (for clock) •Delay in the Flight Management System (FMS) (due to flight duration) •Interfacing between FMS to transponder (ADS-B emitter) •Interfacing between GPS receiver to transponder (ADS-B emitter) •Time error at the ground station •Data link delay (signal in space)
Results of Evaluation: ADS-B Latency Δa
GNSS SIS
Δb
GPS Receiver
Interface
Δc
ADS - B Emitter
Δd
SIS (1090 MHz)
Aircraft
Latency Model = Δa + Δb + Δc + Δd + Δe Δb varies based on DO-260/DO-260A or DO-260B configuration
Δe
ADS - B Station /other Aircraft
Results of Evaluation: ADS-B Latency Aircraft ID
GPS Receiver
ADS-B Emitter
Mean Latency (second)
Standard Deviation (second)
40608F
Thales TLS755 MMR
Honeywell TRA-67A
1.7227
0.4851
405A48
Thales TLS755 MMR
Honeywell TRA-67A
0.6289
0.2430
400A26
Thales TLS755 MMR
Honeywell TRA-67A
1.9050
0.6485
400877
Thales TLS755 MMR
Honeywell TRA-67A
0.6927
0.1615
400878
Thales TLS755 MMR
Honeywell TRA-67A
0.5597
0.2627
40087B
Thales TLS755 MMR
Honeywell TRA-67A
1.7414
0.7008
4008B4
Thales TLS755 MMR
Honeywell TRA-67A
0.5895
0.2760
4008F2
Thales TLS755 MMR
Honeywell TRA-67A
0.6235
0.2584
400935
Thales TLS755 MMR
Honeywell TRA-67A
0.7094
0.2158
Results of Evaluation: ADS-B Latency
Results of Evaluation: ADS-B Horizontal Position Accuracy Analysis Method Horizontal Position Error (HPE) assessment by: comparing the received position with the REFERENCE position
Results of Evaluation: ADS-B Horizontal Position Error (HPE) Aircraft ID
GPS Receiver
ADS-B Emitter
40608F
Thales TLS755 MMR
Honeywell TRA-67A
RMS Position Error (meter) 476.2826
405A48
Thales TLS755 MMR
Honeywell TRA-67A
66.2622
400A26
Thales TLS755 MMR
Honeywell TRA-67A
552.8482
400877
Thales TLS755 MMR
Honeywell TRA-67A
109.4822
400878
Thales TLS755 MMR
Honeywell TRA-67A
113.1374
40087B
Thales TLS755 MMR
Honeywell TRA-67A
14287
4008B4
Thales TLS755 MMR
Honeywell TRA-67A
30.8691
4008F2
Thales TLS755 MMR
Honeywell TRA-67A
48.8772
400935
Thales TLS755 MMR
Honeywell TRA-67A
145.4744
Results of Evaluation: ADS-B Horizontal Position Error (HPE)
Figure: Position error over time for aircraft 40087B
Figure: Position error distribution for aircraft 40087B
Results of Evaluation: ADS-B Horizontal Position Error (HPE)
Figure: Position error over time for aircraft 4008B4
Figure: Position error distribution for aircraft 4008B4
Results of Evaluation: ADS-B Horizontal Position Integrity Analysis Method • Position integrity quality indicator analysis • Verification of integrity quality indicator
Results of Evaluation: ADS-B Horizontal Position Integrity Quality Indicator (FOM) Analysis N
Min
Max
Mean
95676
0
8
5.43
Std. Dev 2.62
Results of Evaluation: ADS-B Horizontal Position Integrity Integrity Quality Indicator (NUC) Verification
Displayed NUC = Actual Surveillance Performance???
Correct Detection
(HPE < NUC < AL)
Missed Detection
(NUC < AL < HPE)
False Alert
(NUC < HPE < AL)
Results of Evaluation: ADS-B Horizontal Position Integrity Integrity Quality Indicator (FOM) Verification Aircraft ID
40608F 405A48 400A26 400877 400878 40087B 4008B4 4008F2 400935
HPE (meters) 476.2826 66.2622 552.8482 109.4822 113.1374 14287 30.8691 48.8772 145.4744
FOM
Alert Limit (AL) (meters)
Δ=AL-HPE
Integrity Performance Category
7 7 7 7 7 7 6.4 6.9 7
<185.2 <185.2 <185.2 <185.2 <185.2 <185.2 <370.4 <185.2 <185.2
-291.0826 118.9378 -367.6482 75.7178 72.0626 -14101.8 339.5309 136.3228 39.7256
Missed Detection Correct Detection Missed Detection Correct Detection Correct Detection Missed Detection Correct Detection Correct Detection Correct Detection
Verification based on real time ADS-B data
Results of Evaluation: ADS-B Availability ADS-B reports received
81.8% NUC/FOM > threshold
ADS-B reports availability
81.78%
RTCA standard for Non Radar Airspace (NRA) : DO303 5 NM en-route separation: NUC = 4
RTCA standard for Radar Airspace (RAD) : DO318 5 NM en-route separation: NUC = 4
3 NM separation: NUC = 5
3 NM separation: NUC = 5
Results of Evaluation: ADS-B Update Rate Aircraft ID
GPS Receiver
ADS-B Emitter
40608F
Thales TLS755 MMR
Honeywell TRA-67A
Mean Update Rate (second) 9.6
405A48
Thales TLS755 MMR
Honeywell TRA-67A
1.1
400A26
Thales TLS755 MMR
Honeywell TRA-67A
1.4
400877
Thales TLS755 MMR
Honeywell TRA-67A
2.5
400878
Thales TLS755 MMR
Honeywell TRA-67A
1.4
40087B
Thales TLS755 MMR
Honeywell TRA-67A
1.0
4008B4
Thales TLS755 MMR
Honeywell TRA-67A
2.3
4008F2
Thales TLS755 MMR
Honeywell TRA-67A
1.3
400935
Thales TLS755 MMR
Honeywell TRA-67A
1.1
Findings 1. Unlike radar, ADS-B performance is aircraft dependent 2. ADS-B performance for each aircraft may differ due to: - Type of avionics - State of the communication link 3. Common failure modes - GNSS - ADS-B Ground Station
Recommendations 1. Signal jamming due to shared frequency use: - ADS-B - SSR Mode-S - TCAS 2. Quality indicator verification mechanism in the ground station 3. Ground station identification (ID) in ADS-B message 4. Onboard GPS time stamp in ADS-B message
Conclusion • A comprehensive framework for the evaluation of ADS-B performance
• Identified various errors in the datasets which limited the performance evaluation
• Recommendations to improve ADS-B system performance and implementation
Notification
The methods proposed in this paper requires total collaboration between ANSP and airline operators
Acknowledgements • The Lloyd Register Foundation • Malaysian-Imperial Doctoral Programme • NATS UK • British Airways
Thank you…
[email protected] The LRF Transport Risk Management Centre Centre for Transport Studies Imperial College London
