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
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
Set the CDI Course Window to "270."
Depress and release the TACAN TEST button.
Confirm that the:
Test light illuminate/ flash.
DME OFF flag appears.
TACAN needle points to 270º.
Course Deviation Indicator (CDI) Bar centers.
Expeditiously reset the CDI Course window to 180º.
1-12 BASIC INSTRUMENT PROCEDURES