User Guide

190-00494-00 Rev. B
Garmin G1000 Pilot’s Guide for the Cessna Citation Mustang
7-17
AFCS
If the Altimeter’s barometric setting is adjusted while Vertical Path Tracking is active, the flight director
increases/decreases the descent rate by up to 500 fpm to re-establish the aircraft on the descent path (without
commanding a climb). Adjusting the altimeter barometric setting creates discontinuities in VNV vertical
deviation, moving the descent path. For large adjustments, it may take several minutes for the aircraft to re-
establish on the descent path. If the change is made while nearing a waypoint with a VNV Target Altitude,
the aircraft may not re-establish on the descent path in time to meet the vertical constraint.
Automatic Reversion to Pitch Hold Mode
Several situations can occur while Vertical Path Tracking Mode is active which cause the flight director
to revert to Pitch Hold Mode:
• Vertical deviation exceeds 200 feet during an overspeed condition.
• Vertical deviation experiences a discontinuity that both exceeds 200 feet in magnitude and results in
the vertical deviation exceeding 200 feet in magnitude. Such discontinuities are usually caused by
flight plan changes that affect the vertical profile.
• Vertical deviation becomes invalid (the Vertical Deviation Indicator is removed from the PFD).
• A display enters Reversionary Mode (this does not apply to an active vertical direct-to).
Unless VNV is disabled, Vertical Path Tracking Mode and the appropriate altitude capture mode become
armed following the reversion to Pitch Hold Mode to allow for possible profile recapture.
Non-Path Descents
Pitch Hold, Vertical Speed, and Flight Level Change modes can also be used to fly non-path descents
while VNV flight control is selected. If the
VS or FLC Key is pressed while Vertical Path Tracking Mode is
selected, Vertical Path Tracking Mode reverts to armed along with the appropriate altitude capture mode
to allow profile re-capture.
Figure 7-16 Flight Level Change VNV Non-Path Descent
To prevent immediate profile re-capture, the following must be satisfied:
• At least 10 seconds have passed since the non-path transition was initiated
• Vertical deviation from the profile has exceeded 250 feet, but is now less than 200 feet
Pressing the
VNV Key twice re-arms Vertical Path Tracking for immediate profile re-capture.