cause the autopilot to automatically disengage:
a. Vertical gyro failure.
b. Directional gyro failure.
c. Autopilot power or circuit failure.
d. Torque limiter failure.
illuminate the AP DISC annunciator
annunciator. Pressing the control
wheel AP DISC switch will extinguish
the AP DISC annunciator.
(4) Pitch Sync & Control Wheel Steering (CWS).
The CWS push button located in the control wheel
(FIG. 2-20) allows the pilot to manually change aircraft
attitude, altitude, vertical speed and/or airspeed without
disengaging the autopilot. After completing the manual
maneuver, the CWS pushbutton is released, and the
autopilot will automatically resynchronize to the vertical
mode. Example: with IAS mode selected, the pilot
may depress the CWS pushbutton and manually
change airspeed. Once trimmed at the new airspeed
the CWS pushbutton is released, and the autopilot will
hold this airspeed. If a large pitch attitude change is
made, the pilot should trim the aircraft normally before
releasing the CWS button.
Either pilot's CWS button will permit
changing of the autopilot regardless
of which pilot has control of the
autopilot. However, use of the CWS
will cancel the other pilot's flight
director GA mode.
3-27. INERTIAL NAVIGATION SYSTEM.
a. Description. The Inertial Navigation System
(INS) is a self-contained navigation and attitude
reference system. It is aided by (but not dependent
upon) data obtained from its own TACAN system, the
gyromagnetic compass system. The position and
attitude information computed by the INS is supplied to
the automatic flight control system, weather radar
magnetic indicators. In conjunction with other aircraft
equipment, the INS permits operation under Instrument
Meteorological Conditions (IMC). The INS provides a
visual display of present position data in Universal
coordinates during all phases of flight. When
approaching the point selected for a leg switch, an
ALERT annunciator will illuminate informing the pilot of
an imminent automatic leg switch or the need to
manually insert course change data. The INS may be
manually updated for precise aircraft present position
accuracy by flying over a reference point of known
coordinates. The INS may be updated automatically by
the TACAN system or the GPS. Altitude information is
automatically inserted into the INS computer by an
encoding altimeter whenever the INS is operational.
The Mode Selector Unit (MSU) (FIG. 3-22)
controls system activation and selects operating modes.
The Control Display Unit (CDU) (FIG. 3-23)
provides controls and indicators for entering data into
the INS and displaying navigation and system status
The INS system is protected by the 10-ampere
INS AC POWER and the 5-ampere INS HTR AC
POWER circuit breakers in the mission AC/DC power
cabinet, by the 5-ampere INS CONTROL circuit breaker
in the overhead circuit breaker panel and by the 20-
ampere circuit breaker in the front of the INS battery
b. Controls/Indicators and Functions, INS mode
selector unit. (FIG. 3-22).
(1) READY NAV lamp. Illuminates to indicate
INS high accuracy alignment has been attained. If
attained during ALIGN mode, annunciator remains
illuminated until NAV mode is selected. Annunciator
illuminates momentarily during alignment, if alignment
is accomplished while in NAV mode.
(2) BAT lamp. Illuminates to indicate INS
shutdown due to low battery unit voltage.
(3) Mode select knob. Controls INS activation
and selects operating modes.
(a) OFF. Deactivates INS.
(b) STBY. Moving to STBY from OFF mode:
Starts fast warm-up of system to operating conditions;
activates computer so information may be inserted; all
INS controlled warning flags will indicate warning.