Vnav Target Altitude Capture Mode (Altv) - Garmin G3X Touch Pilot's Manual

If the altimeter's barometric setting is adjusted while VNAV mode is active, the
autopilot increases/decreases the descent rate by up to 500 fpm to re-establish the
aircraft on the descent path (without commanding a climb). For large changes, it may
take several minutes for the aircraft to reestablish on the descent path. If the change
is made while nearing the VNAV waypoint, the aircraft may not reestablish on the
descent path in time to level off at the VNAV Target Altitude. In this case, the autopilot
will revert to Pitch Hold mode upon passing the VNAV waypoint, and Selected Altitude
Capture (ALTV) mode will be automatically armed.
AUTOMATIC REVERSION TO PITCH HOLD MODE
Several situations can occur while VNAV Mode is active which cause the
AFCS to revert to Pitch Hold Mode:
• Vertical deviation exceeds 200 feet during an overspeed condition.
• Vertical deviation becomes invalid (the Deviation Indicator is removed
from the PFD).
Following a reversion to Pitch Hold Mode, VNAV Mode and the appropriate
altitude capture mode become armed to allow for possible profile recapture.

VNAV TARGET ALTITUDE CAPTURE MODE (ALTV)

VNAV Target Altitude Capture is analogous to Selected Altitude Capture
Mode and is armed automatically after the VNV Key (GMC 305) or VNAV is
selected if the VNAV Target Altitude is to be intercepted before the Selected
Altitude. The annunciation 'ALTV' indicates that the VNAV Target Altitude is to
be captured. Refer to Section 2.3 (Vertical Navigation) for more information
on setting up the VNAV target altitude.
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Garmin G3X Touch Pilot's Guide
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AFCS
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