10-30
GTN 625/635/650 Pilot’s Guide
190-01004-03 Rev. P
Terrain
Flight Phase
Minimum Clearance Altitude (feet)
Level Flight
Descending
En Route
700
500
Terminal
350
300
Approach
150
100
Departure
100
100
Table 10-15 FLTA Alert Minimum Terrain and Obstacle Clearance Values
During final approach, FLTA alerts are automatically inhibited when the
aircraft is below 200 feet AGL while within 0.5 NM of the approach runway or
below 125 feet AGL while within 1.0 NM of the runway threshold.
10.6.6.4 Premature Descent Alerting
A Premature Descent Alert (PDA) is issued when the system detects that the
aircraft is significantly below the normal approach path to a runway.
PDA alerting begins when the aircraft is within 15 NM of the destination
airport and ends when the aircraft is either 0.5 NM from the runway threshold
or is at an altitude of 125 feet AGL while within 1.0 NM of the threshold. During
the final descent, algorithms set a threshold for alerting based on speed, distance,
and other parameters.
700
600
500
400
300
200
100
Height Above Terrain (Feet)
Distance From Destination Airport (nm)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
PDA Alerting Area
PDA Alerting Area
Runway
Threshold
Figure 10-20 PDA Alerting Threshold
PDA and FLTA aural and visual alerts can be manually inhibited. Discretion
should be used when inhibiting TAWS and the system should be enabled when
appropriate. When TAWS is inhibited, the alert annunciation “TAWS INHB” is
shown.
Summary of Contents for GTN 625
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