TM 55-1510-219-10
Figure 3-22. Mode Selector Unit (C-IV-E)
b.
Controls and Indicators.
(1)
Mode selector unit (fig. 3-22).
CONTROL
FUNCTIONS
Mode select
Controls INS activation and se-
knob
lects operating modes.
OFF
Deactivates INS.
STBY (ground
To STBY from OFF mode.
use only)
Starts fast warmup of system to
operating conditions; activates
computer so information may be
inserted; all INS-controlled
warning flags will indicate warn-
ing.
To STBY from any other mode:
INS operates as if in attitude reference mode; all
INS warning flags and lamps, except ATTITUDE and
PLATFORM HEADING, will indicate warning.
ALIGN (ground
To ALIGN from STBY mode.
use only, parked)
Starts automatic course align-
ment mode (if fast-warmup heat-
ers are off); fine alignment will
not start until present position is
inserted into CDU.
To ALIGN from OFF mode:
Leveling starts after fast-warmup heaters are off.
To ALIGN from NAV mode:
INS is not downmoded but will allow automatic
shutdown if overtemperature is detected.
NAV
Activates normal navigation
mode after automatic alignment
is completed; must be selected
before moving aircraft.
To NAV from STBY mode:
Causes INS to automatically sequence through
STBY and ALIGN to NAV mode, if present position is
inserted and aircraft is parked.
Used to shorten time in STBY and to bypass battery
test, if stored heading is valid.
ATT
Activates attitude reference
mode. Used to provide only INS
attitude signals. Shuts down
computer and CDU leaving only
BAT and WARN lamps opera-
tive. Once selected, INS align-
ment is lost.
BAT lamp
Lights to indicate INS shutdown
due to low battery unit voltage.
READY NAV
Lights to indicate INS high accu-
lamp
racy alignment is attained. If at-
tained during ALIGN mode,
3-43
