ads-b: the case for london terminal manoeuvring area (ltma) · -260/do-260a or do -260b...

ADS-B: The Case for London Terminal Manoeuvring Area (LTMA)

Busyairah Syd Ali

©Thales

10th USA / Europe Air Traffic Management Research and Development Seminar (ATM 2013)

10 June 2013

Agenda

• Introduction

• System Overview

• Data Characteristics

• Data Evaluation Framework

• Results of Evaluation

• Findings

• Recommendations

• Conclusions

©Thales

©Thales

• 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

Introduction

System overview

Source Positioning performance

Data : British Airways

Onboard avionics performance

Data: NATS & BA

Ground station performance

Data: NATS

Data Link Mode-S 1090Mhz performance

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

GS GPS

AVIONIC

SBAS, GBAS, RAIM

Results of Evaluation: ADS-B Latency

Definition – delay between aircraft position determination by on-board 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)


Latency Model = Δa + Δb + Δc + Δd + Δe

Δb varies based on DO-260/DO-260A or DO-260B configuration

Aircraft

GNSS

SIS

GPS Receiver

ADS - B

Emitter SIS (1090 MHz) ADS - B

Station /other Aircraft

Interface

Δ b Δ c Δ d Δ a

Δ e

Aircraft

GNSS

SIS

GPS Receiver

ADS - B

Emitter SIS (1090 MHz) ADS - B

Station /other Aircraft

Interface

Δ b Δ c Δ d Δ a

Δ e


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


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


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 RMS Position Error (meter)

40608F Thales TLS755 MMR Honeywell TRA-67A 476.2826

405A48 Thales TLS755 MMR Honeywell TRA-67A 66.2622


400877 Thales TLS755 MMR Honeywell TRA-67A 109.4822


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



Figure: Position error over time for aircraft 40087B

Figure: Position error distribution for aircraft 40087B


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


Quality Indicator (FOM) Analysis

N Min Max Mean Std. Dev

95676 0 8 5.43 2.62


Integrity Quality Indicator (NUC) Verification

Correct Detection (HPE < NUC < AL)

Missed Detection (NUC < AL < HPE)

False Alert (NUC < HPE < AL)

Displayed NUC = Actual Surveillance Performance???


Integrity Quality Indicator (FOM) Verification

Aircraft ID HPE (meters)

FOM Alert Limit (AL)

(meters)

Δ=AL-HPE Integrity Performance Category

40608F 476.2826 7

Results of Evaluation: ADS-B Availability

RTCA standard for Non Radar Airspace (NRA) : DO303

RTCA standard for Radar Airspace (RAD) : DO318

5 NM en-route separation: NUC = 4 3 NM separation: NUC = 5

5 NM en-route separation: NUC = 4 3 NM separation: NUC = 5

ADS-B reports received 81.8%

NUC/FOM > threshold

ADS-B reports availability 81.78%

Results of Evaluation: ADS-B Update Rate

Aircraft ID GPS Receiver ADS-B Emitter Mean Update Rate (second)

40608F Thales TLS755 MMR Honeywell TRA-67A 9.6





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


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

The methods proposed in this paper requires total collaboration between ANSP and airline

operators

Notification

Acknowledgements

• The Lloyd Register Foundation

• Malaysian-Imperial Doctoral Programme

• NATS UK

• British Airways

[email protected] The LRF Transport Risk Management Centre Centre for Transport Studies Imperial College London

Thank you…

ADS-B: The Case for London Terminal Manoeuvring Area (LTMA)AgendaIntroductionSystem overviewData characteristicsData characteristicsData evaluation frameworkData evaluation framework: Data correlation Data evaluation framework: Data correlation Data evaluation framework: ‘Reference’Results of Evaluation: ADS-B LatencyResults of Evaluation: ADS-B LatencyResults of Evaluation: ADS-B LatencyResults of Evaluation: ADS-B LatencyResults of Evaluation: �ADS-B Horizontal Position AccuracyResults of Evaluation: �ADS-B Horizontal Position Error (HPE)Results of Evaluation: �ADS-B Horizontal Position Error (HPE)Results of Evaluation: �ADS-B Horizontal Position Error (HPE)Results of Evaluation: �ADS-B Horizontal Position IntegrityResults of Evaluation: �ADS-B Horizontal Position IntegrityResults of Evaluation: �ADS-B Horizontal Position IntegrityResults of Evaluation: �ADS-B Horizontal Position IntegrityResults of Evaluation: ADS-B AvailabilityResults of Evaluation: ADS-B Update RateFindingsRecommendations ConclusionNotificationAcknowledgementsThank you…

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