TACAN

Question 1

What frequency does TACAN use?

Answer 1

UHF

Question 2

What does TACAN provide?

Answer 2

High accuracy bearing and distance to or from a station utilising DME equipment.

Question 3

What are the two separate but related systems for TACAN?

Answer 3

• DME

- Bearing measuring equipment.

Question 4

What are TACAN radials?

Answer 4

Magnetic bearings from a station

Question 5

How many fixed TACANs are there in Australia?

Answer 5

11

Question 6

What information does the TACAN navigation system provide?

Answer 6

1) Magnetic radial from the selected TACAN station
2) Relative bearing to the selected TACAN station
3) Course Deviation
4) To-from indication
5) Coverage from 5,000 ft is 60 NM, from FL 200 is 180 NM.
6) Aural identification of the TACAN station transmitted every 37.5 seconds

Question 7

What does the TACAN ground station comprise of?

Answer 7

1) A cylindrical tower with a domed crown

2) DME array at the base, sometimes enclosed within a shelter.

Question 8

What does the inner cylinder carry?

Answer 8

A reflector

Question 9

What does the outer cylinder carry?

Answer 9

Nine directors, which rotate together at 15 revs per second.

Question 10

What is the theory of operation of the TACAN?

Answer 10

• TACAN sends out one Primary Reference Burst and 9 Secondary reference bursts during one revolution of the outer cylinder.
• From this, an accurate radial can be determined.

Question 11

What does the external aircraft TACAN system comprise?

Answer 11

1) Antenna
2) Transmitter
3) Dual Receivers

Question 12

What does the A/C antenna do?

Answer 12

Operates at similar frequencies and has a similar function

Question 13

What does the transmitter do?

Answer 13

Interrogates the DME

Question 14

What do the dual receivers do?

Answer 14

Process the TACAN pulse pairs and ensure correct signal spacing

Question 15

What is used to select the TACAN mode of operation on the PC-21?

Answer 15

UFCP

Question 16

Does TACAN use frequencies or channels ?

Answer 16

Channels

Question 17

What is used as the primary TACAN display?

Answer 17

• The HSI
• A desired radial can be selected using the course knob and the relative position of the TACAN aid displayed used the Bearing pointers.

Question 18

How many channels are there on the TACAN system?

Answer 18

252 channels

Question 19

What are the limitations of the TACAN navigations system?

Answer 19

1) No voice transmission capability
2) Interrogation from a maximum of 100 aircraft
3) LOS operations
4) Limited Range
5) Azimuth Cone of Confusion
6) Shielding by other A/C/ terrain
7) Slant range error when overhead the TACAN.

Question 20

What are the range limits of TACAN?

Answer 20

• 60 NM for A/C < 5000 ft

- 180 for A/C operating at 20,000 ft.

Question 21

What is the Azimuth Cone of Confusion?

Answer 21

• The space where TACAN azimuth information is not available which varies from 70 to 100 deg wide.
• Cone is about 15 NM across at 40,000 ft.

Question 22

What is a TACAN check board?

Answer 22

• Displays information about the TACAN relative to A/C position near the holding point for each of the runways
• Allows the pilot to check the accuracy of TACAN equipment prior to getting airborne.

Question 23

What does A-A mode provide for the TACAN?

Answer 23

Distance between A/C when flying in formation.