1. TCAS Basics Capt Craig Hinkley

2. 2 TCAS HISTORY  1956 - Two planes collided over the Grand Canyon  1974 - Alternative airborne version using transponders  Beacon-Based Collision Avoidance System (BCAS)  1981 - The FAA chose to pursue the onboard design  BCAS was renamed TCAS  1986 - While TCAS still in development, collision occurred  1993 - Congress mandate all carrier acft operating w/in US  1997 - Final major change to the TCAS logic, version 7

3. 3 TCAS Basics  TCAS I - Aircraft with 10 to 30 seats  Traffic Advisory Only  TCAS II - Aircraft with more than 30 passenger  Traffic Advisory  Resolution Advisory  Mode S – Detailed flight parameter information  ATC Ground Based Radars  Other Mode S equipped aircraft  Provides coordinated RAs

4. 4 TCAS Basics  TCAS II is designed to provide collision avoidance  horizontally at any rate up to 1200 knots  vertically up to 10,000 feet per minute (fpm)  TCAS II computes closure rates using relative bearing, distance and speed to estimated time to conflict and calculate Resolution Advisories

5. 5 TCAS Basics Conflicting Aircraft EquipmentTCAS II Response No transponderNo TCAS indications Transponder w/out AltTA Only Transponder w/ AltTA/RA Transponder w/ Mode SCoordinated RA 1 1 2 2 3 3

6. 6 TCAS Basics  TCAS monitors traffic and categorizes into 1 of 4 groups:  Other  Proximate  TA (Intruding)  RA (Threat)

7. 7 Other Traffic  Other traffic is any aircraft  beyond 6 NM and 1,200 feet  displayed as an open diamond

8. 8 Proximate Traffic  Proximate traffic is an aircraft that is  within both 6 NM and 1,200  displayed as a filled diamond

9. 9 Traffic Advisory  A TA indicates that an aircraft  is a potential threat  RA may be necessary w/in, approx, the next 25 sec  most commonly displayed as a yellow circle

10. 10 Resolution Advisory  An RA indicates that an aircraft  Is a threat  displayed as a red square  accompanied by a recommended vertical maneuver.

11. 11 TCAS BASICS  When an RA occurs, the pilot has 5 seconds to assess the situation and maneuver the aircraft to the green or recommended area on the display.  If the TCAS displays an increase rate or reversal RA, the pilot should comply within 2.5 seconds utilizing 1/3 g Acceleration.  RAs requiring altitude excursion rarely exceed 300-500 ft.  Except between “slow” and “fast” movers

12. 12 AFI 11-202 Vol 3  5.29.1. Response to TCAS Alerts.  5.29.1.5. If a TCAS RA requires maneuvering contrary to ATC instructions, right-of-way rules, cloud clearance requirements, or other VFR/IFR flight rules, pilots are expected to follow the TCAS RA.

13. 13 Common Problem Areas  Pilots not following RA  Incorrect reaction to “Adjust Vertical Speed”  Conflicting ATC - RA instructions  Turns based off TCAS display  Level-off with 1000 ft separation  RA against VRF traffic

14. 14 Common Problem Areas Pilots Not Following RA

15. 15 Pilots Not Following RA  It is important pilots follow all RAs even when there is:  An opposite avoiding instruction by the controller  Conflict close to the top of the operating envelope  Traffic information from the controller  Visual acquisition

16. 16 Common Problem Areas Incorrect Reaction To “Adjust Vertical Speed”

17. 17 “Adjust Vertical Speed”  Incorrect Reaction

18. 18 “Adjust Vertical Speed”  Correct Reaction

19. 19 “Adjust Vertical Speed”  Two factors contributing to the misinterpretation of “Adjust Vertical Speed” RAs have been identified:  The aural message "Adjust Vertical Speed, Adjust" does not specify the sense of the required maneuver  The RA display on the vertical speed tape and on the semi-circular VSI on the PFD may sometimes be difficult to interpret "Adjust Vertical Speed" RA always requires a REDUCTION of the vertical speed.

20. 20 Common Problem Areas Conflicting ATC - RA Instructions

21. 21 Conflicting ATC - RA Instructions  ATC  Detect the conflict (possible delays)  Asses the situation  Formulate a solution  Communicate to the pilot (possible delays)  TCAS  Automatically detects any risk of collision  Calculates the necessary maneuver  Communicates the solution directly to the flight crew.  All in less than one second.

22. 22 Conflicting ATC - RA Instructions  Following ATC – Disregarding RA

23. 23 Conflicting ATC - RA Instructions  Following ATC – Disregarding RA

24. 24 Common Problem Areas Turns Based Off TCAS Display

25. 25 Turns Based Off TCAS Display  Incorrect Turn

26. 26 Turns Based Off TCAS Display

27. 27 Turns Based Off TCAS Display  Delayed Turn

28. 28 Turns Based Off TCAS Display

29. 29 Turns Based Off TCAS Display  Actual Track Vs TCAS Track

30. 30 Common Problem Areas Level-Off With 1000 ft Separation

31. 31 Level-Off w/ 1000 ft Separation  RA calculated based on vertical + horizontal convergence

32. 32 Level-Off w/ 1000 ft Separation  Excessive Climb Rate

33. 33 Level-Off w/ 1000 ft Separation  Altitude Bust

34. 34 Level-Off w/ 1000 ft Separation Recommendation to prevent 1000 ft RA “Vertical rate should be reduced to less than 1000 fpm in the last 1000 ft before reaching the cleared flight level. This will reduce the number of RAs generated in such geometries.”

35. 35 Common Problem Areas RA Against VRF Traffic

36. 36 RA against VRF traffic  Poor Altitude Control

37. 37 RA against VRF traffic  TA Vs RA w/ 500 ft Separation

38. 38 Common Problem Areas  Pilots not following RA  Incorrect reaction to “Adjust Vertical Speed”  Conflicting ATC - RA instructions  Turns based off TCAS display  Level-off with 1000 ft separation  RA against VRF traffic

39. 39 Review of RA Reaction  5 seconds to recognize and maneuver  2.5 seconds to respond to an increase or reversal  Required altitude excursion rarely exceeds 300-500 feet  Report to ATC as soon as practical

40. 40 Ten Fundamental Dos and Don’ts 1.TCAS must be operated in RA mode to provide full safety benefit 2.Pilots must follow all RAs promptly and accurately 3.Pilots must never maneuver in the opposite sense of an RA 4.Pilots must report RAs to controllers as soon as possible 5.Controllers must not interfere with pilots’ reactions to RAs 6.Vertical speed must be reduced in response to “Adjust Vert Spd” 7.TCAS traffic displays must not be used for self-separation 8.Vertical speed must be reduced when approaching cleared FL 9.VFR pilots must operate their altitude reporting transponder 10.Pilots and controllers must be recurrently trained on TCAS ops