Heading and navigation source annunciators
Partial compass displays.
Lightning sensor system data
EHSI Controls, Indicators, and Functions (fig. 3-
Course/desired track display. The course
(CRS)/desired track (DTRK) display provides a digital
digital readout of the course selected by the course
pointer (yellow) or the desired track when navigation with
information supplied by the INS. Course (CRS) or
desired track (DTRK) are displayed in white letters with
the numerical course displayed in yellow.
Single-needle bearing pointer. The
single-needle bearing pointer (blue circle) indicates the
relative bearing to the selected navaid. The navigation
source is indicated by the single-needle pointer source
annunciator. When the bearing pointer navigation
source is invalid or a localizer frequency has been
chosen, the bearing pointer will be removed from the
heading source annunciator will display MAG1 or MAG2
when slaved or DG1 or DG2 when free, to show which
gyrocompass system is providing heading information to
Heading marker. The notched blue
heading marker is positioned on the heading dial by the
respective heading selection knob on the remote
instrument controller panel, which is located on the
pedestal extension (fig. 2-14). Once set to the desired
heading, the heading marker will maintain its position on
the heading dial. The difference between the heading
marker and the lubber line index is the amount of
heading select error applied to the flight director
computer. In heading mode, the EADI pitch and roll
command cue will display the proper bank commands to
turn to and maintain this selected heading. Pulling on
the heading select knob (pedestal extension, fig.
2-14) will set the heading marker to aircraft heading.
Lubber line. Aircraft heading is read from
the heading dial under the lubber line.
Double-needle bearing pointer. The
double-needle bearing pointer (green diamond) indicates
the relative bearing to the selected navaid. The
navigation source is indicated by the double-needle
pointer source annunciator. When the bearing pointer
navigation source is invalid or a localizer frequency has
been chosen, the bearing pointer will be removed from
DME hold annunciator. Illumination of the
amber DME hold (H) annunciator indicates that hold has
been selected on the VOR navigation receiver control
panel that is supplying navigation information to the
Navigation source annunciator. The
navigation source that is being used by the EHSI is
indicated by the illumination of a navigation source
annunciator. Possible annunciations are VOR1, VOR2,
ILS1, ILS2, TCN, and INS. All the annunciations are
white, except INS which is annunciated in blue to show
that it is a long range navigation system. The navigation
source will annunciate amber if the pilot and copilot
select the same navigation source. The navigation
source will annunciate amber if the pilot has selected
VOR2 or if the copilot has selected VOR1.
Distance display. The distance display
indicates the distance in nautical miles to the selected
DME station or INS waypoint. When short range
navigation information is being used the distance will be
displayed in a 0 to 399.9 nautical mile format. When
long range navigation (INS) information is being used
the distance will be displayed in a 0 to 3999 nautical mile
DME distance is supplied to the EFIS by
channels # 1 and # 2 of the three channel TACAN/DME
unit. Channel # I provides the TACAN distance data
when TACAN is the selected navigation source or DME
distance data when NAV1 is the selected navigation
source. Channel # 2 provides distance data when NAV2
is the selected navigation source.
Previ ew course pointer navigation source
annunciator. The preview course pointer navigation
source annunciator displays which navigation source is
being used by the preview course pointer.
Glideslope deviation pointer, annunciator,
and scale. The glideslope deviation pointer shows
aircraft deviation from the center of the glideslope beam.
The G annunciator on the glideslope deviation pointer
indicates that the information being presented is
glideslope deviation. Deviation from the center of the
glideslope beam is measured by the glideslope scale.
The distance between two dots is equal to a 0.35 degree
deviation. The glideslope display will not be present on
the EHSI unless a valid ILS frequency has been tuned.