Methods and systems are disclosed for preventing aircraft collisions with
forward looking terrain avoidance (FLTA) functionality based on a terrain
avoidance profile used to evaluate potential terrain threats based on the
projected flight path of an aircraft in flight, and a clear terrain
profile to determine whether the terrain threat has been cleared. If the
terrain avoidance profile conflicts with terrain, a collision threat may
exist whereby the pilot is notified and a terrain avoidance maneuver is
executed. During the terrain avoidance maneuver the clear terrain profile
extends in a direction substantially parallel with the horizon at or near
the present altitude of the aircraft to check whether it is safe to
return to the previous flight path angle or otherwise end the
terrain-avoiding maneuver. When the clear terrain profile no longer
conflicts with the terrain threat, a terrain clear indicator is then
issued to the pilot.