ILS/TCN Panel Operation

ILS/TCN Panel Operation

TACAN (Tactical Air Navigation) SYSTEM

The TACAN system functions to give precise air-to-ground bearing and distance information at ranges up to approximately 300 miles (depending on aircraft altitude) from an associated ground or shipboard transmitting station. It determines the identity of the transmitting station and indicates the dependability of the transmitted signal.

When operating in conjunction with aircraft having air-to-air capability, the A/A mode provides line of sight distance between two aircraft operating their TACAN sets 63 channels apart. Up to five aircraft can
determine line of sight distance from a sixth lead aircraft in the A/A mode, provided their TACAN sets are set 63 channels apart from the lead aircraft. The limit of operation is four times the distance between the lead aircraft and the nearest aircraft. The lead aircraft will indicate distance from one of the other five, but it cannot readily determine which one. Before operating in the A/A mode, the frequencies used by each aircraft must be coordinated. TACAN information except in A/A mode is presented on the horizontal situation indicator (HSI), the attitude director indicator (ADI), and the head-up display. In A/A mode, both distance and bearing are received if cooperating aircraft (such as refueling tanker aircraft) have bearing transmission capability.


The controls for TACAN operation are on the ILS/TCN control panel on the left console, on the steering mode panel on the main instrument panel, and on the HSI. The controls on the ILS/TCN control panel are the function selector knob, the volume control knob, the channel selector knob and the XY switch. The controls on the steering mode panel consist of the steering mode knob. The controls on the HSI are the course set and the heading set knob.

Function Selector Knob

The function selector knob is a three-position rotary knob used for selecting TACAN modes of operation. The mode positions are marked A/A, T/R and REC.

Function Selector Knob
T/R TACAN receives bearing signals from the TACAN ground station, and in addition, the TACAN interrogates the TACAN ground station to establish distance from the aircraft to the ground station. The bearing and distance information is displayed on the HSI.
REC TACAN receives bearing signals from the TACAN ground station for bearing display on the HSI, and also for steering display on the ADI and HUD. TACAN distance readout is shuttered on the HSI.
A/A TACAN interrogates other aircraft which contain a TACAN in the A/A mode and is tuned 63 channels apart from the channel setting of the interrogating aircraft. Bearing and distance information is received from a cooperating aircraft if it has bearing transmission capability. If the cooperating aircraft is not equipped with bearing transmission equipment, only distance information is received and the HSI No. 1 bearing pointer will rotate clockwise at 30 degrees per second.
Volume Control Knob
The volume control knob is used to turn the tacan on and off and for volume adjustment of the station identity tone signal.
Channel Selector Knob
The channel select or knob provides for selection of 126 TACAN channels. The control consists of an outer knob used to select the units digit of the channel counter (0 to 9) and an inner knob used to select the tens and hundreds digits (00 to 12).
XY Switch
The XY switch is a toggle-type with positions of X and Y. Placing the switch to the X position provides capability for 126 channel operation. Placing the switch to the Y position adds an additional 126 channel capability to the TACAN system.

Operational information on this page taken from TO 1F-15A-1, Change 1 – 15 August 1984