060-4314-000 • Rev. C - May 2004
MK VI & MK VIII EGPWS Pilot Guide
21
Mode 5 provides two levels of alerting for when the aircraft de-
scends below glideslope, resulting in activation of EGPWS alert
lights and aural messages.
MODE 5
Excessive
Deviation
Below Glides-
lope
The first level alert occurs when below 1000 feet Radio Altitude
and the aircraft is 1.3 dots or greater below the beam. This
turns on alert lights and is called a “soft” alert because the audio
message “GLIDESLOPE” is enunciated at half volume. Twenty
percent increases in the glideslope deviation cause additional
“GLIDESLOPE” messages to be enunciated.
The second level alert occurs when below 300 feet Radio Altitude
with 2 dots or greater glideslope deviation. This is called a “hard”
alert because a louder “GLIDESLOPE, GLIDESLOPE” message is
enunciated every 4 seconds continuing until the “hard” envelope
is exited. The alert lights remain on until a glideslope deviation
less than 1.3 dots is achieved.
To avoid unwanted Below Glideslope alerts when capturing the
localizer between 500 and 1000 feet AGL, alerting is varied in the
following ways:
• Below Glideslope alerts are enabled only if;
• Localizer is within ± 2 dots, if available
• Landing gear and flaps are selected,
• Glideslope Cancel is not active,
• A front course approach is determined
• 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.
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