6-19
190-01004-03 Rev. P
GTN 625/635/650 Pilot’s Guide
Proc
6.12.1 Flying the LPV Approach
1. Within 31 NM of the destination, the GTN switches from en
route mode to terminal mode and the CDI scale transitions
from 2.0 to 1.0 NM, full scale deflection.
2. As you approach the IAF, a waypoint message appears on the
bottom of the screen.
3. As the distance (DIST) to the IAF approaches zero, the message
is replaced by a turn advisory that counts down 10 seconds
prior to the turn.
4. As you approach the FAF, the GTN will begin to automatically
rescale in an angular fashion. This will allow the LPV approach
to be flown in an identical fashion to a standard ILS. At
2.0 NM from the FAF, CDI scaling is tightened from 1.0 NM to
the angular full scale deflection (typically the angular full-scale
deflection is 2.0°, but will be as defined for the approach).
5. Sixty seconds prior to reaching the FAF, the unit will check the
required Horizontal Alarm Limit (HAL) and Vertical Alarm Limit
(VAL) to ensure the GPS position integrity is within limits to
complete the LPV precision approach. In the event the HAL
or VAL limits are exceeded, the approach will be downgraded
to a non-precision approach indicated by “LNAV” on the
moving map, a message that the approach is downgraded
(“APPROACH DOWNGRADE - GPS approach downgraded. Use
LNAV minima.”), and the glideslope indicator will be flagged.
You may continue the approach using LNAV non-precision
minimums if there are LNAV minimums for this approach. In
the rare event the GPS integrity cannot meet the non-precision
HAL limits, the unit will send a message to the pilot to abort
the approach (“ABORT APPROACH - GPS approach no longer
available.”). The unit will revert to terminal limits to support
navigation to the missed approach when the message is
acknowledged. After the aircraft has passed the FAF, a loss of
WAAS integrity will cause the approach to abort instead of
downgrade.
6. Capture the glideslope as you would an ILS glideslope.
Summary of Contents for GTN 625
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