3-10
Climb-out/Enroute
If VNAV is engaged when the next altitude constraint in the flight
plan is above the current aircraft altitude, the system will hold the
current aircraft altitude (and not climb to that constraint) and the
IFD will display the cyan advisory message, “VNAV Holding Alt”.
If the system has concluded that it cannot make the next vertical
constraint for any reason, a yellow R6 caution message, “VNAV
Unable Constraint” is issued. In this case, additional pilot input
may be required if the entered vertical constraint is to be met.
If VNAV is terminated for some reason other than an overt pilot
action, a cyan advisory message, “VNAV Terminated” is
displayed. Likewise, whenever VNAV is pressed on the autopilot
control panel but conditions are invalid for VNAV (e.g. Primary
Nav source not FMS, autopilot not in NAV, no down-path altitude
constraints in the flight plan, etc), a cyan advisory message,
“VNAV Unavailable” is displayed.
The autopilot modes annunciator indication is a green “
VNAV
”.
There is no armed (cyan) VNAV mode.
ALTITUDE CAPTURE MODE
Altitude captures can be performed using IAS, VS, VNAV or
PITCH.
To perform an indicated airspeed-based altitude capture, set both
the IAS bug and the ALT bug to the desired values and press the
“IAS” button on the autopilot control panel. The system has a
Alt-Always-Armed design that means the “ALT” button will
automatically arm after pressing just the “IAS” button. The system
will light the IAS button in green and turn the IAS bug solid and
light the ALT button in cyan and turn the ALT bug solid.
To perform a vertical speed-based altitude capture, set both the
VS bug and the ALT bug to the desired values and press the “VS”
button on the autopilot control panel. The system has a Alt-
Always-Armed design that means the “ALT” button will
automatically arm after pressing just the “VS” button. The system
will light the VS button in green and turn the VS bug solid and
light the ALT button in cyan and turn the ALT bug solid. A pilot
throttle input may be required to sustain the target vertical speed.
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