TCAS RA downlink: From R&D concept to operational implementation in Europe


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Presentation at Flight Safety Foundation's 64th International Aviation Safety Seminar, Singapore, November 2011
Presenter: Nick McFarlane of Helios
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TCAS RA downlink: From R&D concept to operational implementation in Europe

  1. 1. TCAS RA downlink:From R&D concept to operationalimplementation in EuropeNick McFARLANE (HELIOS), Stanislaw DROZDOWSKI(EUROCONTROL) and Ben BAKKER (EUROCONTROL)Flight Safety Foundation’s 64th International Aviation Safety Seminar
  2. 2. 2Introduction
  3. 3. Collision avoidance – safety nets3STCA & TCAS do not interact directlySTCA - controller TCAS - pilot• Alerts potential or actualinfringement of separationminima• No resolution adviceProvides:• Traffic advisories (TAs)• Resolution advisories (RAs)
  4. 4. FL170FL180SF340E145“Adjust VerticalSpeed” RA“Climb” RA7000 fpm2000 fpm2100 ftFL149600 ftFL170FL180SF340E145“Adjust VerticalSpeed” RA“Climb” RA7000 fpm2000 fpm2100 ftFL149600 ftExample of a TCAS RA4Pilot reports “clear ofconflict” to controllerPilot reports RA tocontrollerController Pilot Controller
  5. 5. Many RAs are not reportedAircraft crew• High workload• Priority is reacting to the RA• Many RAs reported late / not at allController• Responsible for separation until pilotreports the RA• Could provide an instruction contraryto the RA if no pilot report5Correct & timelyLate or not at allOther (e.g. timely butcontent unknown)Collision avoidance will be severely degraded if pilotsfollow ATC clearances contrary to the RARA reporting
  6. 6. TCAS information transmitted via automatic downlink6What is RA downlink?Rationale• Increased controllersituational awareness• Particularly if the pilot not doesnot report the RA• Reduce the probability ofcontradictory instructions• RA shown on controller working position
  7. 7. ContentsOverview of collision avoidance• Incompatibility• Potential mitigationsRA downlink• Background & history• R&D in Europe• Early adopters in Europe• Challenges faced7
  8. 8. 8Overview ofcollision avoidance
  9. 9. Collision avoidance9Strategic Conflict ManagementSeparation ProvisionCollision AvoidanceATC avoidinginstructions & trafficinformationTCAS IItraffic advisories &resolution advisoriesSee & Avoid??STCARA downlinkInteractions are complex and not well understood??
  10. 10. Incompatibility: TCAS & normal operations10FL170FL180SF340E145“Adjust VerticalSpeed” RA“Climb” RA7000 fpm2000 fpm2100 ftFL149600 ftFL170FL180SF340E145“Adjust VerticalSpeed” RA“Climb” RA7000 fpm2000 fpm2100 ftFL149600 ftA basic STCA implementation will also generatean alert in this exampleGeneration of unwanted RAs resulting inincreased pilot and controller workload
  11. 11. Incompatibility between STCA & TCAS11PerformanceDifferences inupdate rate andazimuth resolutionOperationFundamentallydifferent algorithmsPredictabilityDifferent approachto standardisationCommunicationDifferent prioritiesfor ATC/crewEffectivenessDifferences inreliance on humanfactorsCombined behaviour• Not always predictable andwell understoodDesired behaviour• STCA alerts > 30 secondsbefore the TCAS RABut, in certain geometries• STCA alerts later or evenafter the TCAS RALate STCA alerts can cause an RA or have animpact on pilot response to the RA
  12. 12. Incompatibility between STCA & TCAS12FL290FL270FL310A319B767“CrossingClimb” RA“CrossingDescend” RA400 ftATC: “Climbimmediately FL300”Late STCA alert prompts a controller instructionTCAS RA occurs before the instruction takes effect
  13. 13. Potential mitigationsHarmonise STCA• Develop ICAO Manual for STCAPrevent unwanted TCAS RAs• Short-term TCAS improvementsDisplay TCAS RAs to controllers• Remainder of presentation13
  14. 14. 14RA downlink
  15. 15. Two compelling events15Yaizu (Japan)• Mid-air collision narrowly avoided• Injuries to 100 occupantsÜberlingen (Germany)• Mid-air collision• 71 fatalities
  16. 16. RA downlink timeline161990 1995 2000 2005 2010CENA studiesBoston & Baltimore trialsFARADS simulationsPASS monitoringTokyoLuxemburgBudapestPragueBrusselsCardiffBelfastYaizuÜberlingenMode S deploymentATM system upgradesSPIN & SESAR 4.8.3 & 15.4.3?Early adoptionR&DEarly adoption overtakes R&D?
  17. 17. European R&D - PASS• Frequency & types of RAs• Performance & safetyaspects of STCA• TCAS/STCA interactions17Types of RAs in coreEuropean airspaceAdjust vertical speedClimb/descend RA(followed or not by a weakening RA)Preventive RAOther61%24%10% 5%
  18. 18. European R&D - SESAR18Emerging operational concept• Developed with early adopters in Europe• RA display to controllers is equivalent to a pilot report• Until “Clear of Conflict” is displayed on the ControllerWorking Position (CWP), the controller;• shall not attempt to modify the aircraft flight path; and• ceases to be responsible for the separation of theaffected aircraftConcept would require amendment to ICAO PANS-ATM
  19. 19. Early adopters in EuropeCommercially availableImplementation• Some States have implemented• Being considered by othersDivided opinions• Situational awareness of thecontroller is improved• Several open issues19Considering implementationInstalled in the ATC system (operationalor pre-operational trial)Cardiff APPBelfast APPLuxembourgAPP
  20. 20. Current operational concept• Developed within existing ICAO provisions• RA display is for “information only”Presentation of the RA• Different HMI solutions in terms of...• ...display, alerting, filteringTechnical challenges• Latency, accuracy, broadcast rate20Early adopters – challenges
  21. 21. Conclusions & outlookAdoption• Is overtaking R&DChallenges - operational concept• Today: Responsibilities associated withdisplay “for information only”• Future: Emerging European operationalconcept will require amendment to ICAOPANS-ATMChallenges - technical• Latency, accuracy, broadcast rate21