Excessive Descent Rate Alert; Forward Looking Terrain Avoidance - Garmin GTN 625 Pilot's Manual

10.3.8.2
Foreword
The purpose of the Excessive Descent Rate (EDR) alert is to provide
notification when the aircraft is determined to be descending upon terrain at an
Getting
Started
excessive rate. The parameters for the alert as defined by TSO-C151c are shown
below.
Xpdr Ctrl
Com/Nav
FPL
Direct-To
Proc
Wpt Info
Map
Traffic
Terrain
Weather
Nearest
10.3.8.3
Services/
Reduced Required Terrain Clearance (RTC) and Reduced Required
Music
Obstacle Clearance (ROC) alerts are issued when the aircraft flight path is
Utilities
above terrain, yet is projected to come within the minimum clearance values in
the FLTA Alert Minimum Terrain and Obstacle Clearance Values table. When an
System
RTC alert and/or a ROC is issued, a threat location indicator is displayed on the
TAWS Page.
Messages
Imminent Terrain Impact (ITI) and Imminent Obstacle Impact (IOI)
Symbols
alerts are issued when the aircraft is below the elevation of a terrain or obstacle
cell in the aircraft' s projected path. ITI and IOI alerts are accompanied by a
Appendix
threat location indicator displayed on the TAWS Page. The alert is annunciated
when the projected vertical flight path is calculated to come within minimum
Index
clearance altitudes in the following table.
10-14

Excessive Descent Rate Alert

6000
5500
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
2000
Figure 10-12 Excessive Descent Rate Alert Criteria

Forward Looking Terrain Avoidance

Garmin GTN 625/635/650 Pilot's Guide
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4000 6000 8000
Descent Rate
10000 12000
190-01004-03 Rev. F