Complete description of traffic avoidance in air, including different systems and and its operation. Includes pictures and diagrams.

1. TRAFFIC COLLISION
AVOIDANCE SYSTEM
TCAS
Augustine k Jose
Karunya university

2. What is TCAS
 TCAS, and pronounced tee-kas) is an aircraft collision avoidance system designed
to reduce the incidence of mid-air collisions between aircraft. International Civil
Aviation Organization to be fitted to all aircraft with a maximum take-off mass
(MTOM) of over 5,700 kg .

3. Structure

4. OPERATION
 It uses transponder mode c and mode s.
 Interrogates 1030 MHZ Receives reply via 1090 MHZ.
 This interrogation-and-response cycle may occur several times per second.
 The TCAS builds a 3d map of airspace near aircraft ,
 incorporating their range (garnered from the interrogation and response round trip
time), altitude (as reported by the interrogated aircraft), and bearing (by the
directional antenna from the response).

6. 2 types of alerts:
 TA which is a threat advisory that alerts the pilot that another aircraft is close
enough to be a potential threat
 RA is a resolution advisory that means the other aircraft IS a threat (30 seconds to
a possible collision) and issues commands to evade a collision.

7. 7 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

8. 8 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

9. 9 Resolution Advisory
 An RA indicates that an aircraft
 Is a threat
 displayed as a red square
 accompanied by a recommended vertical maneuver.

10. TCAS on a Radar Display
Textbook page 148

11. TCAS on Vertical Speed Indicator

12. TCAS on Vertical Speed Indicator
The red arc indicates the area to avoid, the pilot always
shoots for the green arc.
In this example, the airplane is descending at about 3000
feet per minute.
Textbook page 149

13. TCAS on an EFIS screen
Textbook page 149

14. 14 AFI 11-202 Vol 3
 Response to TCAS Alerts.
 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.

15. 15 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