Traffic Collision Avoidance System (TCAS)

Question 1

What is the purpose of TCAS?

Answer 1

To prevent mid air collisions

Question 2

Does the TCAS need ground stations to function?

Answer 2

TCAS is independent from the ground

Question 3

What is TCAS based on?

Answer 3

SSR transponder signals and mode S

Question 4

What does TCAS 1 give us?

Answer 4

• monitors traffic 40miles around the plane
• bearing and altitude
• can give a Traffic Advisory warning

Question 5

Can TCAS 1 give Resolution Advisories?

Answer 5

TCAS 1 cannot give resolution advisories it is all up to the pilot

Question 6

Which version of TCAS is mostly used in commercial aviation?

Answer 6

TCAS 2

Question 7

What improvement does TCAS 2 have from TCAS 1?

Answer 7

TCAS 2 can give Resolution Advisories

Question 8

What is Preventative RA?

Answer 8

To tell pilots not to deviate from their current vertical speed

Question 9

What does CPA stand for?

Answer 9

Closest Point of Approach

Question 10

Is TCAS based on time?

Answer 10

Yes

Question 11

What improvement does TCAS 3 have over TCAS 2?

Answer 11

Gives TA/RA with horizontal and vertical maneuvers (turn right climb/turn left descend)

Question 12

Which TCAS version uses mode S for additional info in the transponder reply?

Answer 12

TCAS 4

Question 13

How does TCAS 4 help generate a horizontal resolution to the RA?

Answer 13

TCAS 4 encodes its own position

Question 14

What are the possible on board equipment of TCAS?

Answer 14

• Dedicated instrument
• VSI
• PFD/MFD
• EHSI

Question 15

What happens in Standby mode?

Answer 15

• TCAS does not interrogate
• transponder only responds to discrete
• used on ground, outside of runway

Question 16

Which mode does the transponder reply to all ground and TCAS interrogations but the TCAS is still on stand by?

Answer 16

Transponder mode

Question 17

What happens in Traffic Advisory mode?

Answer 17

• Issues proper interrogations and performs all tracking functions
• Only TA, no RA

Question 18

Which mode is TA and RA active and is mandatory for commercial aviation?

Answer 18

Automatic

Question 19

The aircraft interrogates at which frequency?

Answer 19

1030MHz

Question 20

Is a mode C or S needed for TCAS?

Answer 20

Yes

Question 21

How do you get distance?

Answer 21

The time it took from interrogation and response

Question 22

How do you get altitude?

Answer 22

Reported by the interrogated aircraft (mode C or S)

Question 23

How do you get the bearing?

Answer 23

Using the directional antenna

Question 24

How many targets can the TCAS keep track of?

Answer 24

30 targets

Question 25

If the symbol is a white/cyan diamond thats not coloured in, what is it?

Answer 25

Non-threat

Question 26

What symbol and colour is a proximate traffic?

Answer 26

Coloured in white/cyan diamond

Question 27

What does a yellow/amber circle signify?

Answer 27

Intruder, TA, 40s away

Question 28

What symbol is shown if an aircraft is 25s away and an RA is given?

Answer 28

Red square

Question 29

How does TCAS auto negotiate a mutual avoidance maneuver?

Answer 29

Using mode S transponder

Question 30

Which has priority, TCAS RA or ATC?

Answer 30

TCAS RA

Question 31

Are both mode S antennas directional or omnidirectional?

Answer 31

Directional

Question 32

Is the bottom TCAS antenna only directional?

Answer 32

No it can be omnidirectional

Question 33

What is the purpose of the Whisper Shout Technique?

Answer 33

To reduce synchronous garble

Question 34

How does the Whisper Shout Technique work?

Answer 34

- Talk to nearby airc. first then sending a specific P2 pulse in the next Tx so they don't reply - Low power first, then at 24/s max power of 250W

Question 35

What is our sensitivity level at 5000-10000ft?

Answer 35

SL at 5

Question 36

What is the TAU TA and RA?

Answer 36

TA=40s | RA=25s

Question 37

What is DMOD and what are the TA and RA?

Answer 37

DMOD is the slow encroachment of an aircraft behind or beside you TA at 0.75NM RA at 0.55NM

Question 38

What is the Altitiude threshold above and below the aircraft?

Answer 38

TA is 850ft above and below | RA is 600ft above and below

Question 39

During mode S surveillance, the extended squitter interrogation happens every how many seconds?

Answer 39

Every 5s and increases once per second the closer it is

Question 40

Does mode S surveillance need directional antenna to get bearing and distance?

Answer 40

No it does not need the directional antenna to get bearing and distance