• The upper altitude limit for the alert is modulated with
vertical speed. For descent rates above 500 FPM, the upper
limit is set to the normal 1000 feet AGL. For descent rates
lower than 500 FPM, the upper limit is desensitized
(reduced) to a minimum of 500 feet AGL.
Additionally, both alert levels are desensitized below 150 feet
AGL, to allow for normal beam variations nearer the ground,
and reduce the possibility of nuisance alerts.
If the Aural Declutter feature is disabled, messages are repeated
continuously until the Mode 5 envelope is exited.
Mode 5 alerts can be canceled by pressing the Glideslope
Cancel switch (if installed). The EGPWS will interpret this
switch one of two ways depending on the installation
• A standard glideslope cancel switch allows for manually
canceling Mode 5 alerting any time below 2000 feet AGL.
This is automatically reset when the aircraft descends below
30 feet or climbs above 2000 feet AGL.
• An alternate glideslope cancel switch allows for manually
canceling Mode 5 alerting at any time and any altitude. The
cancel is reset by again pressing the cancel switch, or
automatically if gear or flaps are raised, or the aircraft is on
the ground. Due to the nature of the alternate cancel
switch, this method requires that there be a cockpit
annunciation that glideslope cancel is in effect.
EGPWS Mode 5 alerts are inhibited during backcourse
approaches to prevent nuisance alerts due to false fly up lobes
from the Glideslope. The EGPWC determines a backcourse
approach if either: 1) the aircraft's magnetic track is greater
than 90 degrees from the runways approach course, or 2) a
glideslope inhibit discrete is set.
060-4241-000 • Rev. D - March 2000
MK V & MK VII EGPWS Pilot Guide