Identification and Avoidance Systems

Question 1

What bus powers the IFF when the switch is at NORM?

Answer 1

The 28V DC ESB

Question 2

State the locations of the upper and lower IFF antennae.

Answer 2

Upper: On top of the nose cone.
Lower: Below the jet pipe.

Question 3

State the operation and function of the Crypto switch.

Answer 3

When held in the zero position for more than 2 seconds, the following are erased:
Modes 1, 3A and 4 codes.
Crypto material.

Question 4

Explain the difference between the Single and Twin options of the rear cockpit IFF codes switch (inc. what happens during ejection as a result).

Answer 4

Single: Emergency mode set, CPI activates and IFF codes and crypto erased if front cockpit ejection seat operates.

Twin: These things only happen if both ejection seats operate.

Question 5

How many digits does IFF mode 1 have?

Answer 5

2

Question 6

What is the purpose of IFF mode C, and how does it work?

Answer 6

Uses data from the PDMC to provide an encoded pressure altitude (based off of 1013.25hPa).

Question 7

Which of the following codes can you change in flight?
Mode 1
Mode 2
Mode 3(A)

Answer 7

Mode 1: Yes
Mode 2: No (set by engineers on ground)
Mode 3(A): Yes.

Question 8

State how to squawk ident using the DEP and HUD scratchpad only (i.e. not using the CNI/ IFF formats).

Answer 8

Press IFF on the DEP.

With a flashing cursor on Opticator 2 (i.e. next to the 4 digit code), press mode.

Question 9

State the maximum horizontal and vertical closure rates that TCAS is designed to protect against.

Answer 9

Horizontal: 1200kts
Vertical: 10,000fpm.

Question 10

Within what time range must both the vertical and horizontal tau values fall in order for TCAS II to generate an RA?

Answer 10

15-35 seconds depending on the sensitivity level (altitude dependant).

Question 11

State the order of priority of TCAS classifications (ascending), and how they are displayed on the TCAS display.

Answer 11

Other - Blue/ cyan open (unfilled) diamond.
Proximate - Blue/ cyan filled diamond.
Intruder - Yellow circle.
Threat - Red square.

Question 12

What are the criteria required to activate a Threat on TCAS?

Answer 12

Range and vertical Taus both less than 15-35 seconds (depending on sensitivity level).

Question 13

What are the criteria required to activate an Intruder on TCAS?

Answer 13

Range and vertical Taus both less than 20-48 seconds (depending on sensitivity level).

Question 14

What are the criteria required to activate a Proximate on TCAS?

Answer 14

Contact within 6nm and 1200ft, but does not meet threat or intruder criteria.

Question 15

What are the criteria required to activate an Other on TCAS?

Answer 15

Contact outside 6nm or 1200ft and does not meet the threat or intruder criteria.

Question 16

How far above and below the aircraft does TCAS look for contacts?

Answer 16

+-12,700ft.

Question 17

What horizontal range does TCAS interrogate other transponders out to?

Answer 17

Nominally 30nm.

Question 18

Within what horizontal range will TCAS II start tracking contacts for possible RA actions?

Answer 18

14nm.

Question 19

Will RAs be generated for contacts not transmitting height information?

Answer 19

No.

Question 20

What speeds do the TCAS VSI markers represent?

Answer 20

500fpm
1000fpm
2000fpm
4000fpm
6000fpm

Question 21

How are TCAS contacts without azimuth information displayed?

Answer 21

As text.

Question 22

For a first time RA, what reaction time is factored into the RA?

How much G will it expect you to use to satisfy RA?

What about in response to a subsequent RA that is activated before you are clear of the initial contact?

Answer 22

5 seconds.

0. 75g or 1.25g
1. 5 seconds and 1+-1/3rd G.

Question 23

What TCAS modes will be turned on if the 3A/C text is boxed on the IFF format?

Answer 23

3A
C
S

Question 24

What is the vertical collision space (i.e. ALIM) range that TCAS II intends to protect?

Answer 24

+-300-700ft, depending on SL.

Question 25

What should you transmit to ATC if you have to respond to a TCAS RA?

Answer 25

“[Callsign], TCAS RA”

Question 26

What should you transmit to ATC once clear of a TCAS RA contact?

Answer 26

“[Callsign], Clear of Conflict, returning to FL…”

Question 27

Below what height are TCAS RAs not available?

Answer 27

1000ft (RadAlt)