alignment. Movement during alignment requires
(a) Transient stops.
Action to be taken during a transient
stop depends upon time available
parking coordinates (latitude and
Realignment - INS operating.
(Recommended if sufficient time and accurate
parking coordinates are available.)
INS can be downmoded to perform a
calibration. Alignment to produce an
alignment state number of 5 can be
accomplished in approximately 17
minutes. During the 17 minute
period, an automatic azimuth gyro
recalibration is determined on basis
of difference between inertial present
position before downmoding and
inserted present position. To obtain
further refinement of azimuth gyro
drift rate, calculated on basis of
newly computed error data, INS can
be left in alignment mode for a
longer period, allowing the alignment
state number to attain some value
lower than 5.
Data selector - STBY, then to ALIGN.
Present position coordinates - Insert,
according to procedure: Geographic Present Position
Insertion or UTM Present Position Insertion.
Realignment - INS shutdown.
Perform complete alignment procedures.
Perform position update using parking coordinates
in accordance with procedure: Insertion of Geographic
Waypoint Coordinates. If parking coordinates are not
available, proceed as follows:
Continue operation in NAV, if INS accuracy appears
Perform position update using best estimate of
INS can be downmoded to standby
running. INS is downmoded to
standby as follows:
Downmoding to standby:
Mode selector - STBY.
Do not leave INS operating unless
aircraft or ground power and cooling
air are available to system.
Mode selector - OFF.
position data computed at time INS
is downmoded. This value is
inserted for next alignment and
difference is used to determine
azimuth gyro drift rate.
(1) General. INS contains self-testing features
which provide one or more warning indications when a
failure occurs. The WARN annunciator in the CDU
provides a master warning for most malfunctions
occurring in the navigation unit. Malfunctions in the
MSU or CDU will normally be obvious because of
abnormal indications of displays and annunciators. A
battery unit malfunction will shut down INS when battery
power is used.
(2) Automatic IN: shutdown.
(a) Overtemperature. An overtemperature in
navigation unit will cause INS to shut down (indicated by
blank CDU displays) when mode selector is at STBY or
annunciator in CDU will illuminate and will not
extinguish until mode selector is rotated to OFF. The
cooling system should be checked and corrected if
faulty. If cooling system is satisfactory, navigation unit
should be replaced.
(b) Low battery charge. A low battery unit
charge will cause INS to shut down when INS is
operating on battery unit power. Both WARN
annunciator on CDU and BAT annunciator inMSU