(18) Radio Altitude Display. Radio altitude is
digital displayed. The range capability of the display is
from -20 to 2500 feet AGL. The display resolution
between 200 and 2500 feet is in 10-foot increments.
The display resolution below 200 feet is 5 feet. The
display will be blank at altitudes over 2500 feet AGL.
Dashes are displayed whenever invalid radio altitude
is being received.
(19) DH SET Knob. Sets decision height from
0 to 990 feet. Decision height displays in the DH
window on lower left corner of ADI. The brightness of
the digital radio altitude and decision height display is
controlled by the dimming knob that is concentric with
the DH SET knob. The dimming knob also dims the
distance and course display on the pilot's HSI, and the
altitude alert display.
(20) Expanded Localizer. Raw localizer
displacement data from the navigation receiver (HSI
display) is amplified approximately 7 1/2 times to
permit the expanded localizer pointer to be used as a
sensitive reference indicator of the aircraft's position,
with respect to the center of the localizer. It is
normally used for assessment only, since the pointer is
very sensitive and difficult to fly throughout the entire
approach. During final approach, the pointer serves
as an indicator of the Category II window. Full-scale
deflection of the expanded localizer pointer is equal to
1/4° of beam signal. The expanded localizer is
displayed by the localizer pointer only when a valid
localizer signal is available.
conventional display of aircraft slip or skid, and is used
as an aid to coordinated maneuvers.
(22) Rate Of Turn. Rate of turn is displayed
by the pointer at the bottom of the ADI. The marks at
the extreme left and right sides of the scale represent
a standard rate turn.
(23) ATT TEST Switch. When pressed, the
sphere will show an approximate attitude change of
20° of right bank at 10° pitch-up. The ATT warning
flag will appear. In addition, all mode annunciator
lights except DH will illuminate.
(24) RA TEST Switch. Pressing the RA TEST
button causes the following displays on the radio
altitude readout: all digits display 8's 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.
(25) Decision Height Display. The digital
decision height (DH) display displays decision height
range from 0 to 990 feet in 10-foot increments. The
decision height is set by the DH SET knob in the lower
right corner of the ADI.
(26) 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 moveable 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.
aircraft deviation from glideslope beam center only
when tuned to an ILS frequency and a valid glideslope
is present. The aircraft is below glide path if pointer is
displaced upward. The glideslope dot represents
approximately 0.4° deviation from the beam centerline.
a. Description. The copilot's Attitude Director
Indicator (ADI) combines the attitude sphere display
with computed steering information to provide the
commands required to intercept and maintain a
desired flight path. It also contains an eyelid display,
expanded localizer, glideslope, rising radio altitude bar
and inclinometer. The indicator has go-around and
decision height annunciators. Any warning flag in view
indicates that portion of information is unreliable.
b. Controls/Indicators and Functions. Refer
to Figure 3B-9.
(1) Attitude Sphere. Moves with respect to
the symbolic aircraft reference to display actual pitch
and roll attitude. Pitch attitude marks are in 5°
increments on a blue and brown sphere.
(2) Roll Attitude Index. Displays actual roll
attitude through a movable index and fixed reference
marks at 0, 10, 20, 30, 45, 60, and 90°.
(3) Eyelid Displays. Surrounds the attitude
sphere and provides positive attitude identification by
means of a blue eyelid which always shows the
relative position of the sky, and a brown eyelid which
always shows the relative position of the ground. The
eyelids maintain the proper ground-sky relationship,
regardless of sphere position.
(4) Flight Director Command Cue. The
maintain a desired flight path. The cue moves up or