HORIZONTAL SITUATION INDICATOR (HSI)
HORIZONTAL SITUATION INDICATOR (HSI) DISPLAYS AND ANNUNCIATORS
Heading display on the HSI has 3 selectable modes: Full compass, Arc, and Map mode.
Modes are selected by pushing the HSI button.
FULL COMPASS MODE
Displayed on initialization.
360-degree compass view
Present heading is indicated by a fixed lubber
line at the top of the heading scale with a digital heading readout directly above the lubber line.
ARC MODE
90 degrees of compass view.
Weather is displayed when the WX button is pushed.
When the heading bug goes beyond the display range
is displayed and shows the shortest direction to the heading select bug.
MAP MODE
90 degrees of compass view.
Weather is displayed when the WX button is pushed.
Flight plans are displayed
Cannot be used for preview mode.
SELECTED HEADING DIGITAL READOUT AND BUG
Displays the digital value for the aircraft selected heading.
Cyan heading select bug is positioned by rotating the HDG SEL knob.
Pushing the PUSH SYNC button on the HDG SEL knob synchronizes the heading bug and readout to the current aircraft heading.
When the aircraft selected heading (or the referenced aircraft heading) is invalid, the bug is removed, and digital readout is replaced with
DRIFT ANGLE BUG
Represented by an inverted solid white triangle displayed on the outside edge of the heading scale.
The difference between the aircraft heading and the aircraft ground track is the drift angle.
The drift angle bug is placed on the edge of the heading scale and aligned to the drift angle with respect to the lubber line.
When the drift angle is 0 degrees, the drift bug fits inside the heading bracket notch.
PRIMARY NAV SOURCE ANNUNCIATOR
Selected using the V/L or FMS buttons.
The V/L(VOR/LOC) button selects the available SRN (short-range navigation) source, displayed in green.
The associated annunciators are
The FMSbutton selects FMS as the source, displayed in magenta.
With dual FMS systems installed the identifier will show
When both sides have the same NAV source selected, digital readout for all information turns amber.
PRIMARY NAV DISTANCE IDENTIFIER
Displays the NAV source station identifier.
The next magenta TO waypoint identifier is displayed.
PRIMARY NAV DISTANCE READOUT
Distances of 100 NM or more, the digits are displayed with 1 NM resolution
Distances of less than 100 NM, the digits are displayed with 0.1 NM resolution
PRIMARY NAV ESTIMATED TIME ENROUTE
Time is always displayed in minutes.
HEADING SOURCE ANNUNCIATORS
Selected by the IRS reversion buttons.
Not displayed when the on-side IRS source and magnetic heading are selected.
COURSE SELECT/DESIRED TRACK POINTER AND READOUT
Green for VOR and LOC navigation and the label is
When VOR or LOC is selected, the track pointer is positioned by turning the CRS knob.
When the PUSH DIR button in the center of the CRS knob is pushed, the course select value is set to the course that minimizes the lateral deviation.
Magenta for FMS navigation and the label is
Value of the desired track is supplied by the FMS.
Course deviation bar moves laterally and shows lateral deviation.
If both sides have the same navigation source selected the pointer, deviation bar, and digital readout turn amber.
TO/FROM INDICATOR
Magenta for FMS, Green for VOR or LOC. Turns amber if both sides are selected to the same source.
Pointer indicates the aircraft is flying to or away from the selected navigation source.
For a TO indication the triangle is located above the nose of the aircraft symbol.
The FROM indication is a triangle pointer on the tail of the aircraft symbol.
COURSE DEVIATION INDICATOR (CDI) AND LATERAL DEVIATION SCALE
Only displayed when a navigation source is active.
Deviation bar moves left or right to show the deviation from the selected NAV source.
When the back course mode is selected, or when tuned to a localizer frequency and the selected course is more than 100 degrees from the aircraft heading, the course deviation automatically reverses to properly sense deviation with respect to the course centerline.
When lateral deviation data is invalid, the CDI is removed and
is displayed in the CDI scale area.
BEARING POINTERS
Source is either VOR, ADF, or FMS.
Source is selected using the
buttons on the guidance panel.
GROUNDSPEED
Displayed in the upper left corner of the HIS just below the airspeed tape.
When the IRS is invalid the digits are replaced with
DME SOURCE ANNUNCIATOR
DME source is selected by pushing the V/L button.
DME source annunciation reflects the short-range navigation source selection.
VOR1/LOC1 displays
VOR2/LOC2 displays 
When primary NAV source is FMS, the last selected VOR/LOC is used for the DME distance display.
When the same source is used, the DME data is displayed in amber.
DME STATION IDENTIFIER, DISTANCE, AND TTG READOUT
DME source station identifier is displayed directly below the DME source annunciator.
Distance to go to the waypoint identified by the DME station identifier is shown in nautical miles.
TTG to the waypoint identified by the DME station identifier is shown in minutes.
When DME is in DME hold mode
is displayed in the front of the distance readout.
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