Figure 3-24. INS Mode Selector Unit
pressed second time, allows displays to resume showing
changing current present position.
ROLL LIM key. Allows selection of Roll
Limited steering mode. Press to select mode, key lights.
Roll steering output is limited to 10 degrees. Press
second time to exit mode, key light extinguishes. Roll
steering output returns to normal limit of 25 degrees.
(3.) Data display, left and right. Composed
of lights which illuminate to display numbers, decimal
points, degree symbols, left and right directions, and
latitude or longitude directions.
(4.) INSERT / ADVANCE / HI PREC key.
Allows insertion of loaded data into computer.
Enters displayed data into INS. When pressed
before pressing 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
if AUTO-MAN switch is set to AUTO.
Flashes on and off when passing waypoint, if
AUTO-MAN switch is set to MAN.
extinguish if AUTO is selected or if a course change is
(6.) BAT lamp. Illuminates amber to indicate
loss of 115 VAC power and INS operation on INS
(7.) WARN /amp. Lights red to alert pilot
INS self-test circuits have detected a system fault.
Illumination may be caused by continuous or
Intermittent conditions light
WARN light until reset by TEST switch. If continuous
condition does not degrade attitude operation, light goes
out when mode selector is set to ATT.
Consists of 10 keys for
entering load data into data and FROM-TO 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.
parameters and DISP (on keys 5 and 9) are
associated with loading and display of UTM
coefficients and waypoint move parameters.
(9.) CLEAR key. When pressed, illuminates
and erases data loaded into data displays or FROM-TO
display. Used to cancel erroneous data. After clearing,
data loading can be resumed.