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2 - NAV PAGES
49
190-00357-00 Rev E
Forward Looking Terrain Avoidance
The unit will issue terrain alerts not only when the
aircraft altitude is below the terrain elevation but also
when the aircraft is projected to come within minimum
clearance values of the terrain. This alerting, called
Forward Looking Terrain Avoidance (FLTA), is also
provided for obstacles. Any potential impact points will
be depicted on the display.
FLTA Severity Levels
“TERRAIN AHEAD” alert (flashing)—Similarly, an
“OBSTACLE AHEAD’’ alert is also provided.
“TERRAIN ADVISORY” advisory—Similarly, an
“OBSTACLE ADVISORY” alert is also provided.
Phase of Flight Level Flight Descending
En Route 700 ft. 500 ft.
Terminal 350 ft. 300 ft.
Approach 150 ft. 100 ft.
Departure 100 ft. 100 ft.
Minimum Terrain Clearance Values
NOTE: During the final approach phase of flight, FLTA
alerts are automatically inhibited when the aircraft is
below 200 feet AGL while within 0.5 NM of the ap-
proach runway or is below 125 feet AGL while within
1.0 NM of the runway.
Premature Descent Alerting (PDA)
TheTERRAINsystemissuesaPrematureDescent
Alert(PDA)whenthesystemdetectsthattheaircraft
is significantly below the normal approach path to a
runway.
PDA ends when the aircraft is either:
• 0.5 NM from the runway threshold
OR
• is below an altitude of 125 feet AGL while within
1.0 NM of the threshold.
CAUTION — The above annunciation and pop-up
terrain alert are displayed during a PDA alert.
PDA Severity Levels
Terrain Alerts