gle- needle pointer, if single-needle switch is in the
(a.) VOR 1. Selects VOR 1 bearing
signals for display.
TACAN. Selects TACAN bearing
signal for display.
Indicators and Functions (RMI, fig. 3-9).
Double needle pointer. Indicates bear-
ing selected by double needle switch.
Compass card. Indicates aircraft head-
ing at top of dial.
(3.) Heading index. Reference point for
Warning flag. Indicates loss of com-
(5.) Double needle switch. Selects desired
signal to be displayed by double needle pointer.
ADF. Selects ADF bearing infor-
(b.) VOR. Selects VOR 2 bearing
(6.) Single needle pointer. Indicates bear-
ing selected by single needle switch.
(7.) Single needle switch. Selects desired
signal to be displayed on single needle pointer.
(a.) INS. Selects INS bearing infor-
(b.) VOR-TACAN. Selects signal as
determined by RMI select switch on instrument
panel, either VOR 1 or TACAN.
3-18. HORIZONTAL SITUATION INDICATORS.
Description. The pilot and copilot have sep-
arate HSI instruments on respective instrument
panel sections (fig. 3-10 and 3-11). Each HSI com-
bines displays to provide a map-like presentation of
the aircraft position with respect to magnetic head-
ing. Each indicator displays aircraft heading, course
deviation, and glideslope data. The pilots HSI
allows the desired course and heading to be input to
the autopilot. Course deviation data is supplied to
the HSI by the VOR 1 or VOR 2 systems, the
TACAN, or the INS. Glideslope data is supplied by
the VOR 1 or VOR 2 systems. The HSI displays
warning flags when the VOR, TACAN, INS or glide-
slope signals are lost or become unreliable.
Figure 3-10. Pilots Horizontal Situation Indicator (RD-650B)