(6.) Digital COURSE counter. Provides a
digital readout of selected magnetic course.
(7.) HDG flag. Indicates loss of reliable
(8.) Lubber line marks. Fixed heading
marks located at the fore (upper) and aft (lower)
(9.) Course pointer. The yellow course
pointer is positioned on the heading dial by the
course knob to select a magnetic bearing that coin-
cides with the desired VOR or TACAN radial or
INS or localizer course. The course pointer rotates
with the heading dial to provide a continuous read-
out of course error to the computer.
DIST display. Provides digital display
of station distance.
(Il.) Heading bug. The notched orange
heading bug is positioned on the rotating heading
dial by the heading knob, and displays preselected
compass heading. The bug rotates with the heading
(12.) Bearing pointer. The bearing pointer
provides magnetic bearing to a selected TACAN or
VOR station or INS waypoint.
(13.) Glideslope pointer/scale. The glide
slope pointer displays glide slope deviation. The
pointer is in view only when tuned to a localizer fre-
quency. If the aircraft is below glide slope path, the
pointer is displayed upward on the scale. Each dot
on the scale represents approximately 0.4 degree dis-
NAV flag. Indicates that information
derived from the selected navigational source (VOR,
TACAN or INS) is invalid and should not be used.
(15.) To-from pointers. The to-from point-
ers aligned on the course pointer, are located 180
degrees apart. One always points in the direction of
the station, along the selected VOR or TACAN
radial or toward INS waypoint.
(16.) Heading knob. Positions the heading
bug to a preselected compass heading.
(17.) Course deviation dots. In VOR,
TACAN or INS operation, each dot represents a 5
degree deviation from the centerline (° 10 degrees).
In ILS operation, each dot represents 1 degree devi-
ation from the centerline. In INS operation, each
dot represents a 3.75 nautical miles deviation from
(18.) Aircraft symbol. The fixed miniature
aircraft symbol corresponds to the longitudinal axis
of the aircraft and lubber line markings. The symbol
shows aircraft position and heading with respect to
a radio course and the rotating heading (azimuth)
(19.) Course knob. Positions the course
switch fig. 2-29). Selects desired source of data for
display on copilots HSI.
(a.) VOR 1. Selects data from VOR
(b.) VOR 2. Selects data from VOR
(c.) TACAN. Selects data from
(d.) INS. Selects data from INS.
3-19. PILOTS ATTITUDE DIRECTOR INDICA-
a. Description. The pilots attitude director
indicator (ADI) (fig. 3-12) 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, glide slope, radio
altitude display, rate-of-turn indicator, mode annun-
ciators, go-around and decision height annunciators,
and inclinometer. Any warning flag in view indi-
cates that portion of information is unreliable.
b. Controls/Indicators and Functions.
Attitude sphere. Moves with respect to
the symbolic aircraft reference to display actual
pitch and roll attitude. Pitch attitude marks are in 5
degree increments on a blue and brown sphere.
(2.) Roll attitude index. Displays actual
roll attitude through a movable index and fixed
scale reference marks at 0, 10, 20, 30, 45, 60 and 90
(3.) GA (go-around) annunciator. Illumi-
nates when go-around mode has been selected.
(4.) SPD annunciator. Illuminates when
airspeed is being held by the flight director, in the
(5.) ALT annunciator. Illuminates when
altitude is being held by the flight director.
(6.) HDG annunciator. Illuminates when
heading is being held by the flight director, in the
NAV ARM, BC ARM mode.