Premature Descent Alerting - Garmin GTN 750 Pilot's Manual Upgrade Supplement

11.5.6.3
Foreword
A Premature Descent Alert (PDA) is issued when the system detects that the
Getting
aircraft is significantly below the normal approach path to a runway.
Started
PDA alerting begins when the aircraft is within 15 NM of the destination
Audio &
airport and ends when the aircraft is either 0.5 NM from the runway threshold
Xpdr Ctrl
or is at an altitude of 125 feet AGL while within 1.0 NM of the threshold. During
Com/Nav
the final descent, algorithms set a threshold for alerting based on speed, distance,
and other parameters.
FPL
Direct-To
Proc
Charts
Wpt Info
Map
Traffic
PDA and FLTA aural and visual alerts can be manually inhibited. Discretion
Terrain
should be used when inhibiting terrain alerts and the system should be enabled
when appropriate. When terrain alerting is inhibited, the alert annunciation
Weather
"TER INHB" is shown.
Nearest
11.5.6.4
Inhibit mode deactivates the PDA/FLTA aural and visual alerts. Pilots should
Services/
Music
use discretion when inhibiting terrain alerts and always remember to enable
the system when appropriate. Only the PDA and FLTA alerts are disabled in the
Utilities
inhibit mode. After cycling power, the terrain alerting function will no longer
be inhibited.
System
Messages
Symbols
Appendix
11-18
Index

Premature Descent Alerting

700
600
500
400
300
200
100
Runway
1 2 3 4
Threshold
Distance From Destination Airport (nm)
Figure 11-10 PDA Alerting Threshold
Inhibiting/Enabling PDA/FLTA Alerting
GTN 725/750 Pilot's Guide
PDA Alerting Area PDA Alerting Area
5 6 7 8 9 10 11 12 13 14 15
190-01007-03 Rev. Q