IFF and TCAS

Question 1

What is a challenge?

Answer 1

Transmitted interrogation that initiates and automatic response.

Question 2

What is a reply?

Answer 2

An automatic response to a challenge, providing altitude and four types of pre-assigned operation selected IFF codes

Question 3

What provides altitude information for the IFF system?

Answer 3

Encoding altimeter

Question 4

What frequency does IFF operate in and what is it known as?

Answer 4

IFF operates on the L-Band, 1000-2000 MHz. Airborne transponders receive interrogations on 1030MHz and transmit replies on 1090 MHz.
Challenging stations are opposite.

Question 5

What is mode 1 of IFF?

Answer 5

Military only, 2 digit code.
0-7 followed by 0-3.
32 possible codes.

Question 6

What is mode 2 of IFF?

Answer 6

Military only
4 digit codes, all 0-7
4069 possible codes

Question 7

What is mode 3/A of IFF?

Answer 7

Military and Civilian
4 digit code with 0-7 for each digit.
4096 possible codes

Question 8

What is mode C of IFF?

Answer 8

Military and civilian

Provides pressure altitude

Question 9

What is mode S of IFF?

Answer 9

Military and civilian
Enhanced mode of 3/A and C.
Can contain tail number, status, altitude, heading, indicated speed, vertical rate, and in flight ID.

Question 10

What is mode 4 of IFF?

Answer 10

Military only as encrypted mode

Classified, only transponders with correct code can communicate

Question 11

What is mode 5 of IFF?

Answer 11

Military only as encrypted mode

Lethal?

Question 12

What is ident?

Answer 12

On mode 1, 2, 3/A, distinguishes between two aircraft with the same code. Last 15-30seconds

Question 13

What is 7700?

1277?

Answer 13

7700- Emergency distress code

1277- rescue

Question 14

What is contained on the mission control center?

Answer 14

Indent, emergency, mode4/5 zeroize, IFF monitor indicator.

Question 15

What does the IFF system transponder do?

Answer 15

Receive interrogation signal, transmits reply signal, mount for crypto appliqué

Question 16

What is the crypto appliqué?

Answer 16

Mode 4/5 computer.

KIV-77 (mode 4 and 5)
KIV-119 (mode 4)

Question 17

What is the purpose of TCAS?

Answer 17

Detects presence of nearby intruder aircraft equipped with transponders.

Question 18

When are traffic advisories issued?

Answer 18

20-48 seconds prior to CPA

Question 19

What is TCAS I used for?

Answer 19

Approximate bearing and relative altitude, typically out to 40 mm.

10-30 pax, and helos

Question 20

What is TCAS II used for?

Answer 20

Optimum flight path strategy and resolution advisory.

Aural and visual warnings

Question 21

What is the mode S transponder responsible for?

Answer 21

Automatically transmit 1090MHz squitter message ever second. Reply to mode S from air to air, and mode A, C and S from ground on 1090.
Tx 1030 MHz RA to air to air

Receives 26 VAC synchro reference and 28 VDC primary input pose

Question 22

What is the TCAS processor?

Answer 22

Master control unit of the TCAS system. L-based receiver transmitter

Question 23

What are the 2 types of TCAS antennas?

Answer 23

Directional; 4 element (0, 90, 180, 270)

Omnidirectional; l-band, blade type

Question 24

Why is the purpose of IFF?

Answer 24

Provides identification and altitude information to civil ground station equipment.
Automatic identification of friendly IFF equipped aircraft.