Terrain Alerts; Pop-Up Alerts; Forward Looking Terrain Avoidance - Garmin GPS 400W,GNC 420W Pilot's Manual & Reference

TERRAIN Alerts

TERRAIN alerts are issued when flight conditions
meet parameters that are set within the TERRAIN
system software algorithms. When an alert is issued,
visual annunciations are displayed. Annunciations
appear in a dedicated field in the lower left corner of
the display.
TERRAIN Annunciation Field
TERRAIN Annunciation and Pop-Up

Pop-up Alerts

On any page except the TERRAIN Page, when a
terrain or obstacle alert is issued, a pop-up window is
displayed with the appropriate alert.
To acknowledge the pop-up alert and return to
the currently viewed page:
Press the CLR key.
To acknowledge the pop-up alert and quickly
display the TERRAIN Page:
Press the ENT key.
TERRAIN Pop-Up Alert
Alert

Forward Looking Terrain Avoidance

The Forward Looking Terrain Avoidance alert, or
FLTA, is used by the TERRAIN system and is com-
posed of two elements: Reduced Required Terrain Clear-
ance (RTC) Avoidance and Imminent Terrain Impact
(ITI) Avoidance.
RTC/ITI TERRAIN Severity Levels
"TERRAIN ADVISORY" advisory—Estimated
potential impact in approximately 60 seconds
after pop-up alert and annunciation. Similarly, an
"OBSTACLE ADVISORY" alert is also provided.
"TERRAIN AHEAD" alert (flashing)—Estimated
potential impact in approximately 30 seconds
after pop-up alert and annunciation. Similarly, an
"OBSTACLE AHEAD'' alert is also provided.
• Reduced Required Terrain Clearance (RTC) Avoidance
— Provides alerts when the aircraft flight path
is above terrain, yet is projected to come within
minimum clearance values outlined in the fol-
lowing Minimum Terrain Clearance Values table.
When an RTC alert is issued, a potential impact
point is displayed on the TERRAIN Page as shown
in the previous Terrain Altitude/Color figure.
2 - NAV PAGES
Terrain Alerts
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