KLM MD-11 - AP;FD Altitude Control

MD-11 Flight Crew Operations Manual
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Automatic Flight -
Description and Operation
Auto.10.8
• The pitch thumbwheel on the FCP is rotated to select the desired vertical
speed in the V/S-FPA display window except when the AP is engaged in
land mode, dual FD approach mode below 1500 feet, or takeoff/GA mode
below 400 feet.
• The V/S-FPA changeover button on the FCP is pushed to V/S from FPA
while operating in the flight path angle mode. The vertical speed
reference will be the vertical equivalent to the displayed flight path angle
at the time of FPA to V/S changeover selection.
Engaging the AP/FD vertical speed mode sets the ATS to control speed. The FMA
annunciates V/S in the vertical control window and THRUST in the speed control
window.
During an altitude intercept, if the aircraft is in the altitude capture phase of the
intercept (FMA annunciates ALT HOLD), manually adjusting the vertical speed
wheel (V/S) will cancel the altitude capture. Dashes in the V/S-FPA window will
be replaced by the existing V/S, and the V/S may then be adjusted if desired. The
capture mode will not re-engage until the V/S wheel has come to rest for two
seconds. Repeated adjustments of the wheel at intervals of less than two seconds
will defeat the capture function. The target altitude will continue to be displayed,
but the autopilot may no longer be able to intercept it.
AP/FD Altitude Control
Altitude control consists of a capture mode and a hold mode. The AFS controls
altitude to the FCP altitude display window value automatically whenever the
FMS PROF is not engaged.
When the FMS PROF mode is engaged, altitude is controlled by the FMS altitude
targets in PROF climb or the FMS steering commands in PROF descent. The final
altitude capture is always the FCP selected value.
The capture mode provides a transition phase between any other cruise mode and
the FCP-selected, baro-corrected altitude or FMS PROF constraint altitude.
Capture is always armed except when in takeoff or go-around modes below
400-feet RA and in the glideslope engage mode.
Capture will engage automatically when a 0.05-g circular path to the selected
altitude is intercepted. The pilot may intervene with V/S control at any time during
the altitude capture maneuver, if it is deemed necessary.
If the altitude display window setting on the FCP is changed when the aircraft is
within 250 feet of target altitude, a 0.09-g circular path will be commanded when:
• The aircraft is within the 0.05-g path with a high rate of climb or
• The aircraft is past the 0.05-g path with the correct rate of climb.
Changing the altitude display window setting on the FCP while in the altitude
capture phase, cancels the capture mode, triggers the mode in control prior to
capture, and rearms altitude capture.
October 02, 2006