Garmin G1000 Pilot's Manual page 354

AUTOMATIC FLIGHT CONTROL SYSTEM
If it is desired to start a descent to the VNV Target Altitude prior to reaching the planned TOD, a non-path
descent can be flown while under VNV guidance. Pitch Hold, Vertical Speed, and Flight Level Change modes
can be used for non-path descents. Flight Level Change Mode is used for this example.
Non-path descent:
1) Command a non-path descent using Flight Level Change Mode:
a) Using the ALT Knob, set the Selected Altitude below the current aircraft altitude to 5,000 feet.
b) Press the FLC Key before the planned TOD during a vertical profile level leg (tracked using Altitude Hold Mode).
The Airspeed Reference defaults to the current aircraft airspeed. Vertical Path Tracking and Selected Altitude
Capture Mode is armed automatically.
2) Reduce power to allow descent in Flight Level Change Mode. The autopilot maintains the Airspeed Reference.
3) As the aircraft nears the Selected Altitude, the flight director transitions to Selected Altitude Capture Mode,
indicated by the green 'ALTS' annunciation flashing for up to 10 seconds.
The green 'ALT' annunciation flashes for up to 10 seconds upon reaching 50 feet from the Selected Altitude; the
autopilot transitions to Altitude Hold Mode and levels the aircraft.
4) When the next TOD is reached, Vertical Path Tracking becomes active (may require acknowledgment to allow
descent path capture).
5) As the aircraft nears the VNAV Target Altitude, the flight director transitions to VNAV Target Altitude Capture
Mode, indicated by the green 'ALTV' annunciation flashing for up to 10 seconds.
The green 'ALT' annunciation flashes for up to 10 seconds upon reaching 50 feet from the VNAV Target Altitude;
the autopilot transitions to Altitude Hold Mode and levels the aircraft at the vertical waypoint.
7-36 Garmin G1000 Pilot's Guide for Cessna Nav III 190-00498-01 Rev. A