(4) Double Needle Pointer. Indicates #2
ADF or #2 VOR bearing as selected by double needle
(5) Single Needle Pointer. Indicates #1 ADF
or VOR/TACAN bearing as selected by single needle
(6) Double Needle Switch. Selects desired
signal to be displayed on double needle pointer.
(a) ADF Position. Selects #2 ADF
(b) VOR Position. Selects #2 VOR
(7) Single Needle Switch.
(a) ADF Position. Selects #1 ADF
VOR/waypoint bearing information.
a. Description. The pilot's Horizontal Situation
Indicator (HSI) combines numerous displays to provide
a presentation of the aircraft position. Refer to Figure
3B-6. The indicator displays aircraft displacement
relative to VOR, localizer, glideslope beam, GPS,
TACAN, and selected heading, with respect to
magnetic north. Any warning flag in view indicates
that portion of the HSI display is unreliable. Display
brightness is controlled by a dimming knob that is
concentric with the DH SET knob and located on the
Function. Refer to Figure 2-9 Sheet 1.
(1) COURSE Knob. Positions the course
(2) HEADING Knob. Positions the heading
bug to a pre-selected heading.
c. Controls/Indicators and Function.
(1) Distance Display (DIST). Provides digital
displays of DME/TACAN, waypoint or GPS distance.
DME/TACAN and waypoint distance is displayed in
1/10-mile increments. GPS distance is displayed in
whole mile increments. The display will show dashes
when the distance input data is invalid or absent.
Displays gyro stabilized magnetic compass information
on a dial that rotates with the aircraft throughout 360°.
The azimuth ring is graduated in 5° increments.
(3) Lubber Line. Fixed heading marks
located at the fore (upper) and aft (lower) position.
(4) Heading Bug. The notched orange
heading bug is positioned on the rotating heading dial
by the heading knob, to select and display a
preselected compass heading. Once set to the
desired heading, the heading bug maintains its
position on the heading dial. The difference between
the bug and the fore (upper) lubber line index is the
amount of heading select error applied to the flight
director computer. In the heading mode the ADI will
display the proper bank commands to turn to and
maintain this selected heading.
(5) COURSE Display. Provides a digital
readout of selected magnetic course.
(6) Course Pointer. The yellow course
pointer is positioned on the heading dial by the remote
course knob, to a magnetic bearing that coincides with
the selected course being flown. The course pointer is
also positioned by the RNAV or VLF modes of
operation. The course pointer rotates with the heading
dial to provide a continuous readout of course error to
(7) Bearing Pointer. Indicates ADF or NAV
relative bearing as selected by the bearing pointer
(8) ADF Annunciator. When illuminated,
indicates ADF bearing information is being displayed.
(9) Bearing Pointer Source Switch. The
bearing pointer source switch, located on the pilot's
HSI, provides for selecting between ADF and NAV
bearing information as presented by the bearing
pointer. Each push of the select switch alternates
selection of ADF or NAV. Upon power-up or following
long-term power interruption, NAV is displayed.
(10) NAV Annunciator. When illuminated,
indicates NAV bearing information is being displayed.