Figure 3-19. Tacan Control Panel (AN-ARN-136)
system. When employed as the primary means of navigation,
aircraft flight may be controlled manually or by the autopilot.
Indications of aircraft heading and bearing to ground stations
are displayed on the horizontal situation indicators. Magnetic
bearing to a station is displayed by the RMI bearing pointer.
TACAN distance, groundspeed and time-to-station are all
displayed on the TACAN indicator located on the copilot's
instrument panel (fig. 2-30). The TACAN control panel (fig.
3-19) enables selection of the TACAN frequency (channel) to
be used, and provides for self-test of TACAN circuits. At the
present time most TACAN and VORTAC stations are
operated in the X mode. When Y mode stations become
operational, air navigation charts will designate the Y mode
INS TACAN System. The INS TACAN system is
coupled directly to INS circuits. It is dedicated only to
updating the INS, is activated when the INS is operational,
and is controlled only by the INS. The INS TACAN consists
of a range unit and a distance indicator, both located on the
INS equipment rack and both identical to their counterparts
in * the avionics TACAN and an antenna, located on the
underside of the fuselage (fig. 2-1). No controls are required
or provided for the INS TACAN system.
Controls/Indicators and Functions.
TEST switch. Activates system self-test.
Channel indicator. Displays selected TACAN
X-Y switch. Selects X or Y mode for TACAN
VOL control. Adjusts TACAN volume.
Channel selectors. Dual knob for manual
selection of operating channel.
Outer knob. Selects tens and hundreds
part of channel number.
Inner knob. Selects units part of
ON-OFF switch. Activates or deactivates
NM indicator. Displays slant range distance
in nautical miles from aircraft to selected TACAN ground
KT indicator. Displays ground speed in