MD-11 Flight Crew Operations Manual
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Warning and Alerting -
Description and Operation
Warn.10.18
When bank angle exceeds the warning limits, voice warning BANK ANGLE are
generated twice, and then suppressed unless the roll angle increases by an
additional 20%.
Airport Envelope Modulation
The airport envelope modulation feature provides improved alert/warning
protection at some key locations throughout the world while improving margins
against nuisance warnings at others. Near certain airports, modes 4 and 5 are
expanded to provide warnings consistent with normal approaches. Near other
airports, modes 1, 2, and 4, are desensitized to prevent nuisance warnings that
result from unusual terrain or approach procedures.
Enhanced Ground Proximity Warning System (EGPWS)
The EGPWS combines basic GPWS functions with the enhanced features
including terrain clearance floor, terrain awareness, and optional peaks and
obstacles. The enhanced features are independent of, and have no affect upon, the
other modes of the GPWS.
Terrain Clearance Floor
The Terrain Clearance Floor (TCF) alert function adds an additional element of
protection to the basic GPWS by creating an increasing terrain clearance envelope
around the airport runway. TCF alerts are based on current aircraft location,
destination runway center point position and radio altitude.
A Runway Field Clearance Floor (RFCF) alert function is available. RFCF alerts
are based on current aircraft location, destination runway center point position and
height (MSL, not AGL) above destination runway.
When the TCF or RFCF envelope is penetrated:
• TOO LOW TERRAIN voice warning is generated twice.
• Amber GROUND PROX message is displayed on PFD.
• Additional TOO LOW TERRAIN voice warning will be generated for
every additional loss of altitude (AGL or MSL) of approximately 20%.
TCF is active during takeoff, cruise, and final approach. The TCF alerts add to the
existing Mode 4 protection by providing alerts based on insufficient terrain
clearance including landing configuration.
Terrain Awareness
The terrain awareness features add a terrain "look ahead" capability of the GPWS.
The features include terrain alerting and standard terrain display.
October 02, 2006
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