1. Traffic Alert and Collision Avoidance System TCAS
Chapter 20
Traffic Alert and Collision Avoidance System
TCAS

2. TCAS The heart of the TCAS system is the transponder.
Aircraft with Mode C transponders will respond to interrogations with altitude information.
Aircraft with Mode S transponders will respond to interrogations with address information.
If another aircraft is within range, it will respond to the interrogation, the first aircraft will measure the time difference to compute the range of the other aircraft.
Because TCAS operates aircraft-to-aircraft, it is not dependent on ground stations.
The TCAS system issues 2 types of alerts: a TA which is a threat advisory that alerts the pilot that another aircraft is close enough to be a potential threat; a 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.

3. TCAS on a Radar Display
Textbook page 148

4. TCAS on Vertical Speed Indicator

5. 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

6. TCAS on an EFIS screen
Textbook page 149

7. TCAS Warnings
Textbook page 152

8. TCAS System Block Diagram
Textbook page 150

9. TCAS System Components
Textbook page 151

10. TCAS I was developed to accommodate the general aviation (GA) community and the regional airlines. This system issues ‘Traffic Advisories’(TAs) to assist pilots in visual acquisition of intruder aircraft. TCAS I is mandated on aircraft with 10 to 30 seats, although TCAS II may be installed instead.
TCAS II Provides the information of TCAS I, and also analyzes the projected flight path of approaching aircraft and issues ‘Resolution Advisories’ (RAs) to the pilot to resolve potential mid-air collisions. TCAS II is required internationally in aircraft with more than 30 seats or weighing more than 15,000 kg.

12. Nov 1, 2004 – May 31, 2005

13. Ueberlingen July 2002

14. ADS-B Automatic Dependant Survailance- Broadcast

15. Sec. 91.113 — Right-of-way rules: Except water operations.
(b) General. When weather conditions permit, regardless of whether an operation is conducted under instrument flight rules or visual flight rules, vigilance shall be maintained by each person operating an aircraft so as to see and avoid other aircraft. When a rule of this section gives another aircraft the right-of-way, the pilot shall give way to that aircraft and may not pass over, under, or ahead of it unless well clear.

16. Review Q & A Chapter 20 TCAS
20.1 A TCAS aircraft transmits an interrogation once per ____.
Answer: second.
20.2 How does an intruder aircraft with an ATCRBS (early type) transponder reply to TCAS interrogation?
Answer: Only a TA
20.3 How does an intruder aircraft with a Mode S transponder reply to TCAS interrogations?
Answer: Both a TA and RA
20.4 How does TCAS determine the direction of a threat?
Answer: From its directional antenna
20.5 How does TCAS determine the distance of a threat?
Answer: By using Tau and using the range rate.
20.6 How does TCAS determine whether the other aircraft is a threat?
Answer: By using range rate
20.7 What is the concept of “Tau”?
Answer: Compensation for varied speeds and performance
20.8 Name the 2 kinds of warnings issued by TCAS.
Answer: TA (Threat Advisory) and RA (Resolution Advisory).
20.9 Does a Threat Advisory (TA) command the pilot to maneuver out of the way?
Answer: No.
What does a Resolution Advisory (RA) do?
Answer: Issues evasive maneuvers
20.11 If 2 TCAS aircraft are closing, what prevents them from climbing, and flying into each other?
Answer: Coordinated Resolution Advisories
What is the technique of “whisper-shout”?
Answer: Buffering of replies to prevent alert overload
How does the directional antenna reduce the number of replies for each interrogation?
Answer: By only responding to interrogations in the active quadrant.

17. Conectors