OPERATIONS MANUAL

Warning Systems
EGPWS – Terrain Look Ahead Alerting:
This function constructs caution and warning “ribbons” along the predicted flight
path; they have a specific form, and move with the aircraft. When the local terrain,
loaded from the EGPWS database, intersects a ribbon, the respective caution or
warning is triggered. The ribbons rotate vertically with the aircraft flight path angle,
and expand forward with rising groundspeeds. They are, laterally, 0.25 nm wide at
the aircraft, and widen further along the path, 3° to the left and right—greater angles
are used during turns. The caution typically activates 60 seconds before the collision;
30 seconds are given for the warning. To avoid nuisance alerts during takeoff and
approach, the ribbons are modified in the vicinity of the detected target runway.
warning ribbon
caution ribbon
Caution,
terrain!
Caution,
terrain!
CAUTION
Whoop,
whoop,
pull up!
WARNING
PULL UP
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