Cockpit Reference Guide

Garmin G1000 Cockpit Reference Guide for the Cessna Nav III
190-00384-08 Rev. A
SECTION 6 – AUTOMATIC
FLIGHT CONTROL
6-10
Vertical Navigation Modes (VPTH, ALTV)
NOTE: Pressing the CWS Button while Vertical
Path Tracking Mode is active does not cancel
the mode. The autopilot guides the aircraft back
to the descent path upon release of the CWS
Button.
NOTE: VNAV flight director pitch modes are
available only in conjunction with GPS roll
modes.
NOTE: The Selected Altitude takes precedence
over any other vertical constraints.
Vertical Navigation (VNAV) flight control is available
for enroute/terminal cruise and descent operations when
VNAV has been enabled and a VNAV flight plan (with at
least one vertical waypoint) or direct-to with a vertical
constraint has been activated. Refer to the Navigation
section for more information on VNAV flight plans. The
flight director may be armed for VNAV at any time, but no
target altitudes are captured during a climb.
The Command Bars provide vertical profile guidance
based on specified altitudes (entered manually or loaded
from the database) at waypoints in the active flight plan
or vertical direct-to. The appropriate VNAV flight control
modes are sequenced by the flight director to follow the
path defined by the vertical profile. Upon reaching the
last waypoint in the VNAV flight plan, the flight director
transitions to Altitude Hold Mode and cancels any armed
VNAV modes.
Vertical Path Tracking Mode (VPTH)
NOTE: If another pitch mode key is pressed while
Vertical Path Tracking Mode is selected, Vertical
Path Tracking Mode reverts to armed.
When a vertical profile (VNAV flight plan) is active and
the VNV Key is pressed, Vertical Path Tracking Mode is
armed in preparation for descent path capture. ‘VPTH’ (or
‘/V’ when Glidepath or Glideslope Mode is concurrently
armed) is annunciated in white in addition to previously
armed modes. If applicable, the appropriate altitude
capture mode is armed for capture of the next VNAV
Target Altitude (ALTV) or the Selected Altitude (ALTS),
whichever is greater.
Figure 6-10 Vertical Path Tracking Armed Annunciations
Prior to descent path interception, the Selected Altitude
must be set below the current aircraft altitude by at least
75 ft. For the flight director to transition from Altitude
Hold to Vertical Path Tracking Mode, acknowledgment is
required within five minutes of descent path capture by:
• Pressing the
VNV Key
• Adjusting the Selected Altitude
If acknowledgment is not received within one minute of
descent path interception, the white ‘VPTH’ annunciation
and the
VNV Key annunciator light start to flash. Flashing
continues until acknowledged or the descent path is
intercepted. If the descent is not confirmed by the time of
interception, Vertical Path Tracking Mode remains armed
and the descent is not captured.