CREW
AWARENESS
AIRPLANE
OPERATIONS
MANUAL
2-04-30
Page
26
Code
01
REVISION 38
AOM-145/1114
EGPWS FEATURES
The EGPWS incorporates GPWS functions with added features
including the Terrain Clearance Floor, Terrain Look Ahead Alerting
and Terrain Awareness Display. Airplanes equipped with EGPWS
version 216 incorporates additional features like Peaks Mode, Runway
Field Clearance Floor, Obstacle Alerting and Geometric Altitude.
TERRAIN CLEARANCE FLOOR
The Terrain Clearance Floor (TCF) provides a terrain clearance
circular envelope around the airport runway, alerting the pilot of a
possible premature descent for non-precision approaches regardless
of the airplane's configuration. The TCF is active during takeoff, cruise
and final approach and is based on current airplane position, nearest
runway and radio altitude.
This alert mode complements the Mode 4 by providing an alert based
on insufficient terrain clearance even when the airplane is in the
landing configuration.
TCF alerts display “GRND PROX” on the PFD and the aural message
"TOO LOW TERRAIN" sounds. This message sounds once when
initial envelope penetration occurs and will repeat at every additional
20% decrease in radio altitude. The “GRND PROX” annunciator
remains on until the TCF envelope is exited.
In the EGPWS version 216, the TCF alert provides an envelope
extension for runway sides, which is limited to a minimum value of
245 ft beside the runway, within 1 NM to 2.5 NM from runway end.
This feature provides improved alerting when it is determined that the
airplane is landing to the side of the runway.
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