ACAS X Next Generation Collision Avoidance

Transcription

1 ACAS X Next Generation Collision Avoidance Robert Klaus 27 October 2015 Sponsor: Neal Suchy, TCAS Program Manager, AJM-233 Distribution Statement A. Approved for public release; distribution is unlimited. This work is sponsored by the Federal Aviation Administration under Air Force Contract #FA C Opinions, interpretations, recommendations and conclusions are those of the author and are not necessarily endorsed by the United States Government.

2 TCAS System Description Air-to-Air Surveillance Range Altitude Bearing coordination TCAS TCAS Transponder-only Traffic Display Cockpit Displays Vertical Maneuver Guidance SPEED ALT L-NAV A/THR FL STD AP1 7 2 Aural Annunciations Traffic Alert (TA) Traffic, Traffic Resolution Advisory (RA) Ex. Descend, Descend Termination of alert Clear of Conflict TCAS uses onboard surveillance and a pilot interface to provide independent collision avoidance protection ACAS X - 2

3 TCAS II Performance Today Safety More than 20,000 TCAS-equipped aircraft world-wide No U.S. commercial air carrier collisions since 1993 mandate Operational Suitability Nuisance alerts have become a challenge as traffic has increased Alerts in NY Terminal Area in Six-Month Period Relative Risk Other 16% Visual 500 Vertical Separation % No TCAS TCAS-No TCAS TCAS-TCAS TCAS dramatically reduces risk, but frequently alerts during many normal, safe operations ACAS X - 3

4 Future Challenges NextGen Incorporates: Satellite-Based Position New Users New Procedures Enables accurate navigation Broadcast to other aircraft Unmanned aerial systems Small, general aviation aircraft Reduced separation for efficiency and capacity Future collision avoidance must safely support and integrate new surveillance, users, and reduced separation procedures with minimal nuisance alerts ACAS X - 4

5 Next Generation Airborne Collision Avoidance System (ACAS X) Lincoln internally-funded project initiated in 2008 FAA TCAS Program Office funding since 2009; FAA Final Investment Decision in 2013 Team members: Lincoln, JHU/APL, MITRE, Aurora Sciences and others ACAS X Goals: Improve safety & unnecessary alerts Support reduced separation operations Extend collision avoidance to UAS Streamline development process Next Generation System Dynamic Uncertainty State Uncertainty ACAS X supports future airborne collision avoidance requirements Additional Surveillance Sources Improved and flexible threat logic Standard Interface ACAS X - 5

6 ACAS X Variants User Group Surveillance Technology Advisories Initial Implementation ACAS X A ACAS X O Current ACAS II users (large aircraft) Users of specific operations (e.g., closelyspaced parallel operations) Beacon Surveillance supplemented with ADS-B Beacon Surveillance supplemented with ADS-B Same set as current TCAS II Procedurespecific alerts for selected aircraft, global alerting against all others Follow-on Implementation ACAS X U Unmanned aircraft Potentially radar, EO/IR, etc. Vertical and horizontal advisories Longer term research X A Active Surveillance X O Operation Specific X P Passive Surveillance X U Unmanned Aircraft System ACAS X - 6 ACAS X P General aviation Passive only Reduced advisory set

7 Outline Overview ACAS X System Review Logic Optimization Process System Development Status and Activities Next Steps ACAS X - 7

8 ACAS X Architecture Potential Surveillance Source Combination Interrogation/Reply 1090ES ADS-B Xa / Xo / Xu Xu Only Surveillance and Tracking Module (STM) Surveils nearby aircraft and provides TRM with tracked target data Threat Resolution Module (TRM) Processes target information from STM to provide evasive maneuver command to pilot if necessary TAs & RAs UAT ADS-B Electro-Optical Primary Radar Standard interface agnostic of input surveillance sources and TRM logic ACAS X - 8

9 Evolution of TCAS to ACAS-X TCAS ACAS-X Supports GPS-based surveillance Accommodates new sensor modalities Enables collision avoidance for new user classes Beacon-only Surveillance Surveillance Enhancements Plug-and-Play Surveillance IF (ITF.A LT G.ZTHR) THEN IF(ABS(ITF.VMD) LT G.ZTHR) THEN SET ZHIT; ELSE CLEAR ZHIT; ELSE IF (ITF.ADOT GE P.ZDTHR) THEN CLEAR ZHIT ELSE ITF.TAUV = -ITF.A/ITF.ADOT; Rule-based Pseudocode Advisory Logic Enhancements Optimized Logic Table Improves robustness Supports new requirements Reduces nuisance alerts Simplifies development Lowers implementation and maintenance cost ACAS X - 9

10 Outline Overview ACAS X System Review Logic Optimization Process System Development Status and Activities Next Steps ACAS X - 10

11 Legacy TCAS Development Encounter models Simple geometries and flight dynamics Limited use due to Modeled encounter classes Vertical geometries Restricted processing capability Manually intensive analysis Flight tests Heavily used for evaluation of system Prototype units flown on: Test aircraft Onboard testing 8+ years Back of revenue airline flights Helped build pilot trust and acceptance Due to the limited simulation capabilities, flight testing was a primary evaluation method ACAS X - 11

12 ACAS X Logic Optimization Process Model-Driven Development Performance Objectives Safety and Suitability Results of previous evaluations 22+ Performance metrics Modify STM to Update trackers and noise models Tune TRM to Optimize online and offline costs Preferences and Issues Iterate until goals achieved (currently 3 month cycle) 5 Candidate Logic versions Human Evaluation Aggregate metrics Individual encounters Simulate Performance Safety and operational models Real world data Real World Evaluation Validate Modeling and Simulation 2 Year Cycle Formal FAA Flight Test Most Recent Logic version ACAS X - 12

13 Performance Simulation Evaluation Models Aircraft Trajectories Pilot Response Model Climb, Climb Airspace Encounter Models U.S. and European Critical encounters Operational Data TCAS encounter data Full aircraft tracks from airspace Sensor Models STM/TRM Flight test data Each candidate is evaluated across eight different evaluation models Validity of results dependent on models employed throughout the simulation process Last update process considered 14,171 logic variants over billion encounters Procedure-Specific Models Current procedures Level ~500 feet Level-off Future scenarios Stressful Encounters Encounter geometries that are difficult to resolve ACAS X - 13

14 Safety and Operational Performance Relative Risk* Alert Rate More Safe Less Safe TCAS v ACAS X Relative Alert Rate TCAS v7.1 Overall Alerts Climb/Descend ACAS X 47% Safer than v7.1 (Overall Relative Risk) 41% fewer Alerts than TCAS v7.1 58% fewer Climb/Descend alerts than TCAS v7.1 ACAS X - 14 *Relative to risk without collision avoidance

15 Outline Overview ACAS X System Review Logic Optimization Process System Development Status and Activities Next Steps ACAS X - 15

16 ACAS Xa/Xo Program Activities 2013 Flight Test 1. Tested look-up logic table method 2. Multiple optimized logic tables 3. Collected performance data 4. Validated simulation vs. actual performance 5. Solicited initial pilot feedback Outcome Initiated RTCA MOPS 2015 Flight Test 1. End-to-end system performance of STM/TRM 2. Master and slave coordination 3. System performance with ADS-B failures 4. ACAS Xo designation and undesignation 5. Validated simulation vs. actual performance Outcome Proceed to Op Eval RTCA SC-147/EUROCAE WG75 Standards Development Initiated in December, 2013 MOPS on track for 2018 completion ICAO Standards/Annex 6 & Annex 10 changes part of published work program ACAS X - 16

17 Collision Avoidance for Unmanned Aircraft Systems (UAS) Airborne collision avoidance for manned aircraft Airborne collision avoidance for unmanned aircraft Assumes high vehicle performance Works only with cooperative (transponder / ADS-B equipped) traffic Assumes flight crew will see and avoid non-cooperative traffic Provides only vertical maneuvers Uses active coordination on 1030/1090 MHz Must work for low performance vehicles May only use ADS-B for cooperative traffic Uses alternate surveillance to track noncooperative traffic Must support horizontal maneuvers May require maneuver coordination via alternate link ACAS Xu developed to provide UAS Collision Avoidance capability ACAS X - 17

18 ACAS Xa vs. ACAS Xu ACAS Xa ACAS Xu Cooperative Surveillance ADS-B validated by active surveillance ADS-B validated by active surveillance Non-cooperative Surveillance Does not provide protection for non-transponder equipped intruders Tracked output from primary radar, EO, IR or other sensor Threat logic Tuned for aircraft meeting TCAS performance assumptions (2,500 fpm climb/descent) Accommodates range of vehicle vertical performance Nucleus function switches between vertical and horizontal tables based on surveillance quality and vehicle performance Advisories Traffic Alerts Standard TCAS Vertical RAs Either manual or automated RA response TA or Self Separation Alert Vertical Resolution Advisories Horizontal Resolution Advisories Automatic RA response Coordination Standard TCAS coordination over 1030 MHz Supports TCAS coordination over 1030 MHz Responsive coordination over 1030 MHz Active Coordination over 1090 MHz ADS- B ACAS X - 18

19 ACAS X - 19 ACAS Xu Flight Test Video

20 2016 Flight Test Plan Implementation of full integrated STM and TRM Track correlation of separate surveillance sources Improved validation algorithms TRM that switches to horizontal advisories when vehicle is climb limited Show plug-and-play versatility of STM/TRM At least two different avionics vendors Fly encounters against manned and unmanned Likely partnership with NASA, General Atomics Potential for additional airframe partners Timeline: Flight Test Plan and code freeze (December 2015) Flight Test in October 2016 ACAS X - 20

21 Outline Overview ACAS X System Surveillance and Tracking Module Threat Resolution Module Logic Optimization Process Next Steps ACAS X - 21

22 Program Timelines ACAS X A ACAS X o 2013 R & D Standards Development /safety assessment Draft FAA Guidance Guidance published Operational Use August 2013 Proof-of-concept Flight Test FY2015 Full System Flight Test FY2017 Operational Evaluation FY18 initial MOPS FAA TSO & AC Complete ACAS X R & D U TBD RTCA Standards Development /safety assessment FAA Guidance Nov/Dec 2014 Proof-of-concept Flight Test FY2016 Full System Flight Test FY20 MOPS Complete ACAS X - 22

23 Summary ACAS X supports NextGen collision avoidance requirements Flexibility to accommodate new user classes Plug and Play surveillance Procedure-specific alerting ACAS Xa will enter operational use in 2020 with significant benefits 47% reduction in risk ratio 58% fewer corrective alerts ACAS Xu will begin RTCA standards development in Jan 2016 with final ACAS Xu MOPS by flight test will demonstrate mature system with expanded functionality Exploring application to small UAS ACAS X - 23