(a) NM Displays slant range distance in
nautical miles from aircraft to ground station.
(b) KT Displays groundspeed in knots.
(c) MIN Displays time to TACAN
station in minutes.
c. Normal Operating Procedures.
(1) Equipment Startup.
It is assumed the Avionics Master Power
switch is on, and that normally used
avionics circuit breakers remain pressed.
1. TACAN control panel Turn VOL
ON / OFF knob ON.
2. VOR ADF / TACAN ADF Switch
Select TACAN ADF.
3. RMI Selector for #1 Needle (yellow)
4. HSI Switches Press TACAN.
(2) Self-test Procedure.
1. Course knob on HSI Set 180
2. TACAN control panel Hold test
HSI course indicator centers on a 180 ± 2 TO
indication. Using course knob, increase selected
course. Deviation bar will move to left. Decrease
selected course: deviation bar will center and move to
right of center. Full-scale deflection will be 10 + 1.
In OSA aircraft, the RMI and HSI bearing pointers will
indicate approximately a 180 magnetic bearing. In
aircraft, only the RMI bearing pointer will indicate the
(3) Normal Operation.
1. VOR ADF / TACAN ADF Switch
Select TACAN ADF.
2. RMI selector for #1 needle single
(yellow) Select VOR.
3. HSI switches Press TACAN.
4. Mode switch (X / Y) As required.
6. Wait 5 seconds for signal acquisition
and lock-on. If bearing signal lock-on
does not occur, the TACAN remains
in the bearing search mode. If
bearing lock-on is not obtained,
perform an in-flight self-test to ensure
correct operation of the system.
Anytime the course indicator's flag is
in view, in OSA aircraft, the HSI
bearing pointer will drive to the park
or 3 o'clock position. The course
information may be inaccurate and
should be disregarded. ANG aircraft
are not equipped with an HSI bearing
pointer, however, the bearing, course
deviation, and TO/FROM information
presented may also be inaccurate
and should be disregarded.
On the RMI, there is no warning flag to
indicate failure to receive the station.
Instead, the RMI needle will drive to the
park or 3 o'clock position. Always
crosscheck the RMI with the HSI course
indicator for a possible warning flag.
identification signal is correct for the
ground station selected.
8. Course Knob (HSI) Set course
desired. Verify proper TO or FROM
pointer indication. Intercept course
as required. In OSA aircraft, verify
intercept heading by reference to the
RMI and HSI bearing pointers. In
ANG aircraft, verify intercept heading
by reference to RMI using RMI only
9. Course Deviation Bar (HSI) Read
deviation from selected course. The
heading and the course pointer, when
the course deviation bar is centered
and the aircraft is tracking the
selected course, will show the wind