NAVIGATION AND
COMMUNICATION
AIRPLANE
OPERATIONS
MANUAL
2-18-75
Page
10
Code
01
REVISION 39
Once AIII mode is active, any sensor or equipment condition that
results in a loss of AIII capability causes a boxed "NO AIII" status to
flash for five seconds on the Combiner and on the HCP MODE line.
An amber “AIII” indication is displayed on the F/O’s PFD.
If either the AIII capability is lost ("NO AIII" status) or the airplane
approach or flare performance does not ensure a safe touchdown
within the required touchdown zone, the HGS provides an "APCH
WARN" (Approach Warning) annunciation on the Combiner and a red
“APCH WARN” indication on the F/O's PFD. An approach out-of-
tolerance condition by itself will result in the "APCH WARN"
annunciations, but will not cause the loss of AIII status. If a "APCH
WARN" annunciation is displayed in low-visibility conditions, a missed
approach procedure must be performed.
Flare initiation is indicated with the FLARE annunciation on the
Combiner display and on the F/O’s PFD. The flare maneuver is
designed to transition the airplane from approach attitude to
touchdown attitude while maintaining positioning and performance
requirements that meet touchdown criteria for CAT IIIa landings. This
includes continuing to track the runway localizer and establishing an
acceptable touchdown sink rate while refraining from long landings. In
order to reduce the longitudinal touchdown distance, an “IDLE”
annunciation is displayed on the Combiner while the F/O’s PFD alerts
the crew to adjust thrust settings.
Following touchdown, the display changes to remove unnecessary
symbology in order to assist the landing rollout. This includes changing
the localizer symbol to the Ground Localizer Scale and Index. The
centerline is tracked while the airplane is decelerated to exit the
runway.
IMC MODE
The IMC mode allows FGS Flight Director approaches to be flown in
the same approach display format as the HGS AIII approach mode.
Altitude and airspeed data are displayed as digital values and raw
navigation data is displayed in close proximity to the Flight Path group.
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