the RA test button causes the following displays on the
radio altitude readout: all digits display 8 then dashes,
and then the preprogrammed test altitude as set in the
radio altimeter R/T unit, until the test button is released
at which time the actual altitude is displayed. The DH
display during the test displays all 8's with the altitude
display and then displays the current set altitude for the
remainder of the test. RA test is inhibited as a function
of APR CAP.
Decision height (DH) display. The
digital DH display, presents decision height range from 0
to 990 feet in 10 foot increments. The decision height is
set by the knob in the lower right corner of the ADI.
Symbolic miniature aircraft. Serves
as a stationary symbol of the aircraft. Aircraft pitch and
roll attitudes are displayed by the relationship between
the fixed miniature aircraft and the movable sphere.
The symbolic aircraft is flown to align the command cue
to the aircraft symbol in order to satisfy the commands
of the selected flight director mode.
Displays aircraft deviation from glideslope beam center
only when tuned to an ILS frequency and a valid
glideslope signal is present. The aircraft is below
glideslope if pointer is displaced upward. The glideslope
dot represents approximately 0. 4 degree deviation
from the beam centerline.
3-18. COPILOT'S GYRO HORIZON INDICATOR (GH-
Description. The copilot's gyro horizon
indicator (fig. 3-11) is a flight aid which indicates the
aircraft's attitude. The attitude given is in relationship to
an artificial horizon. There are no front panel fuses or
circuit breakers provided for the copilot's gyro horizon
indicator. b. Indicators and Functions.
Bank angle scale. Indicates aircraft
bank angle from zero to 90 degrees with marks at 10,
20, 30, 45, 60, and 90 degrees.
Bank angle pointer. Indicates aircraft
indicating zero-degree bank.
Horizon line. Affixed to sphere,
remains parallel to the earth's horizon at all times.
G flag. Presence announces loss of
Sphere. Indicates orientation with
earth's axis at all times.
Inclinometer. Assists the copilot in
making coordinated turns.
Miniature aircraft. Indicates attitude
of aircraft with respect to the earth's horizon.
3-19. TURN AND SLIP INDICATORS.
Description. The pilot and copilot have
identical turn and slip indicators (fig. 3-12) protected by
two 5-ampere circuit breakers placarded TURN & SLIP
PILOT and TURN & SLIP COPILOT on the overhead
circuit breaker panel (fig. 2-6).
Controls/Indicators and Functions.
markers indicate two-minute turn rate when covered by
turn rate indicator.
Turn rate indicator. Deflects to
indicate rate of turn.
acceleration (side slip) of aircraft.
3-20. GYROMAGNETIC COMPASS SYSTEMS.
systems provide accurate directional information for the
aircraft at all latitudes of the earth. As a heading
reference, two modes of operation are used: directional
gyro (FREE) mode, or slaved (SLAVE) mode. In polar
regions of the earth where magnetic heading references
are not reliable, the system is operated in the FREE
mode. In this mode, the system furnishes an inertial
heading reference, with latitude corrections introduced
manually. In areas where magnetic heading references
are reliable, the system is operated in the SLAVE mode.
In this mode, the directional gyro is slaved to the
magnetic flux detector, which supplies long-term
magnetic reference to correct the apparent drift of the
gyro. Magnetic heading information from both systems
is applied to various aircraft systems through pilot and
copilot COMPASS No. 1 No. 2 switches.