Super 80 Professional – AOM
FLIGHT MANAGEMENT
Section 15 Page 9
Super 80 Professional – Aircraft Operating Manual
Coolsky, 2018
VNAV Mode – Descent
The AFMC will calculate a descent path
when the flight crew has entered an End of
Descent (ED) point. The ED point is a
waypoint altitude constraint that requires a
descent from the cruise altitude. An ED point
may be set by entering an altitude
constraint for a waypoint on the LEGS page,
or by selecting STAR/approach procedure
on the DEP/ARR page.
The AFMC computes the descent path by
starting at the ED point and projecting back
up to the cruise altitude. The point where this
path intersects with the cruise attitude is the
Top of Descent (TD) point.
When reaching the TD point, the AFMC will
command idle thrust and pitch down to
follow the descent path, provided the FGCP
altitude pre-select readout is set to a lower
altitude than the aircraft’s current altitude.
The flight crew may initiate VNAV descent
prior to the TD point by selecting and
executing the DES NOW prompt on the DES
page. The aircraft will not descent below the
altitude set in the altitude pre-select
readout.
The descent path to the first altitude
constraint assumes idle thrust, retracted
speed brakes, decreasing wind speed, and
the AFMC target airspeed. The AFMC
defaults to economy speed above 10,000ft
and 240kts below 10,000ft. The flight crew
may alter the decent profile calculated by
entering forecast winds, anti-ice
requirements (not simulated), or changing
the target speed.
For deviation below the vertical profile, the
FMS will make corrections through throttle
commands. For deviation above the vertical
profile, the FMS will increase the airspeed
(throttles idle) 10 to 15kts above target
airspeed and a DRAG REQUIRED message
will be displayed in the MCDU scratchpad.
FMS Speed Override
The FMS override features allows the flight
crew to manually set the speed while
remaining in VNAV mode. The FMS override
mode is engaged by pushing the FMS OVRD
button on the FGCP. When in the FMS
override mode, the Speed/Mach Select
Knob on the FGCP allows selection of the
desired speed.
When in the FMS override mode:
•
The selected speed is displayed in
the FGCP Speed/Mach Readout.
•
The FMS throttle window annunciates
OVRD followed by the selected
speed.
•
PROGRESS page 1, line 5L will read
OVRD SPD.
To disengage the FMS override mode, push
the FMS OVRD again.
VNAV Engagement
The flight crew may couple the FMS VNAV
mode to the DFGS by pushing the VNAV
button on the FGCP as long as the following
conditions are satisfied:
•
The following FMS data is present:
o
Aircraft GWT, cost index,
cruise altitude.
o
Aircraft position, CADC data,
IAS, Mach, SAT, TAT, pressure
altitude, and vertical speed.
o
Roll and pitch attitudes.
o
FGCP clearance altitude
(altitude preselect readout).
o
Acceleration data.
o
Vertical flight plan.
•
Autopilot and/or Flight Director
engaged.
•
TRP is not in TO, TO FLX, or GA mode.
•
The autothrottles are engaged or will
be engaged within 5 seconds of
VNAV engagement.