TACAN and CDI Test Procedure

CHAPTER ONE

BASIC INSTRUMENT PROCEDURES

The mode selector switch will normally be positioned to the Receive mode (REC)

and the set is allowed to warm up. When the REC position is used, distance

information is not available. The appropriate channel is selected and the volume is

adjusted to hear the Morse code identification signal, which is broadcast

approximately every 35 seconds. TACAN is UHF, and is limited to "line of sight"

operation between transmitter and receiver.

When the set is not warmed up, the number 2 needle will rotate. In addition, the

course deviation indicator sweeps from side to side while the TO-FROM and OFF

flag indicators fluctuate. With the station selected and identified, place the mode

selection switch in the Transmit and Receive mode (T/R) position. The indicators

should stabilize and the OFF flag will disappear from the DME range window.

TACAN and CDI Test Procedure. This procedure will test the AN/ARN-118 TACAN and

TACAN indications on the BDHI and the ID-249 Course Indicator:

Confirm that both generators are on-line.

Confirm TACAN Control Transfer light is on in the desired (test) cockpit.

Confirm "OBTAIN COURSE AFT/FWD COCKPIT" caution light is NOT ON in test

cockpit.

Set local TACAN channel.

Set TACAN Mode Selector Switch to T/R.

Confirm receipt of a clear, readable Morse code station identifier. Note the DME

indication and the TACAN needle "bearing to" indication (remember these "pretest

indications").

Set the CDI Course Window to "270."

Depress and release the TACAN TEST button.

Confirm that the:

Test light illuminate/ flash.

ii.

DME OFF flag appears.

iii.

TACAN needle points to 270.

iv.

Course Deviation Indicator (CDI) Bar centers.

Expeditiously reset the CDI Course window to 180.

1-12 BASIC INSTRUMENT PROCEDURES