TM 55-1510-222-10
Figure 3-23. INS Control Display Unit (7564978-021)
any numerical key, alternates display of normal and
high precision data.
(5) ALERT lamp. Illuminates amber to alert pilot
1.3 minutes before impending automatic course leg
change. Extinguishes when switched to new leg, if
AUTO-MAN switch is set to AUTO. Flashes on and off
when passing way-point, if AUTO-MAN switch is set to
MAN. Annunciator will extinguish if AUTO is selected
or if a course change is inserted.
(6) BAT lamp. Illuminates amber to indicate loss
of 115 VAC power and INS operation using INS battery
power.
(7) WARN lamp. Illuminates red to alert pilot INS
self test circuits have detected a system fault.
Illumination
may
be
caused
by
continuous
or
intermittent condition. Intermittent conditions illuminate
WARN annunciator until reset by TEST switch. If
continuous
condition
does
not
degrade
attitude
operation,
annunciator
extinguishes
when
mode
selector is set to ATT.
(8) Keyboard. Consists of 10 keys for entering
load data into data and TO-FROM displays. N, S, E,
and W (on keys 2,8,6 and 4) indicate direction of
latitude and longitude. TAC and DISP (on keys 7 and
9) enable loading and display of TACAN station data.
MV/P and DISP (on keys 3 and 9) are associated with
loading and display of magnetic variation and magnetic
heading. R/B and DISP (on keys 5 and 9) are
associated with loading and display of UTM coefficients
and way-point move parameters.
(9) CLEAR key. When pressed, illuminates and
erases data loaded into data displays or TO-FROM
display. Used to cancel, erroneous data. After
clearing, data loading can be resumed.
(10) WYPT CHG key. When pressed, enables
numbers in TO-FROM display to be changed. If
INSERT/ADVANCE key is pressed, computer will use
navigation leg defined by new number in all navigation
computations. If INSERT/ADVANCE key is not
pressed, computer will continue using original numbers
in all navigation computations; but distance/time
information, based on new leg, may be called up and
read in data displays (in case of way-points). When not
in TACAN mix mode, TACAN station number is inserted
to display DIS/TIME information.
(11) AUTO-MAN TEST switch. This is a dual
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