Garmin G3X Touch Pilot's Manual page 335

Activating Vertical Navigation Mode:
 
When a flight plan is active, VNAV data is valid, and the VNAV Key is selected on
the GMC 507 or G3X Touch, VNAV mode is armed in preparation for descent path
capture. 'VNAV' is annunciated in white in the G3X Touch Autopilot Status Box. If
applicable, the appropriate altitude capture mode is armed for capture of the VNAV
Target Altitude (ALTV) or the Selected Altitude (ALTS), whichever is greater.
 
When a descent leg is captured (i.e., vertical deviation becomes valid), VNAV Mode
is activated and tracks the descent profile. An altitude capture mode (ALTS or ALTV)
is armed as appropriate.
 
When approaching the VNAV Target Altitude (or Selected Altitude) the system
automatically transitions to ALTS or ALTV Mode with ALT Mode armed.
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).
190-02472-00 Rev. D
Garmin G3X Touch ™ Pilot's Guide for Certified Aircraft
 
 
 
AFCS
313