MD-11 Flight Crew Operations Manual
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FMS -
Controls and Displays
FMS.30.111
Standby MCDU Operation
If at any time the crew does not believe its FMC is working, the MCDU can be
used for STANDBY operation. When the FMC fails to provide valid page data to
the MCDU within 3 seconds of a request, the MCDU will deactivate that FMC and
display the MENU page. During the time between failure of an FMC and
subsequent recovery of the FMC (or pilot select of standby), the MCDU operates
in an INTERIM navigation mode. In this mode the MCDU supplies the last known
valid radio frequencies received from the FMC. Guidance data to the FCC is not
provided. In the full-up standby mode, the MCDU provides navigation, radio
frequencies, and lateral guidance.
During STANDBY navigation, the MCDU provides aircraft position and
groundspeed. The STANDBY aircraft position consists of the aircraft lateral
position updated by using the present position inputs from the IRU. If INERTIAL
ONLY position update is not active, then the aircraft lateral position is not
computed. STANDBY groundspeed is the groundspeed input from the IRU.
Radio frequencies that were tuned by the FMC prior to failure will remain tuned
until the pilot enters new frequencies into the STANDBY NAV RADIO page. If
the MCDU also fails, it will latch a request for the onside radio equipment to
receive tuning frequencies from the offside FMC until the onside MCDU becomes
operational again.
In STANDBY operation the following data is available to other aircraft systems:
• Aircraft present position.
• Current groundspeed.
• Navaid frequencies (VOR, ADF, ILS) and course (VOR).
• ILS runway heading.
• Distance to active waypoint.
• Time to go (to active waypoint).
• Active waypoint identifiers.
• MAP displays.
MCDU lateral guidance provides horizontal control of the aircraft to the defined
lateral flight path. Roll rate and roll magnitude are limited appropriately for
aircraft speed. Lateral guidance performs the following tasks:
• Lateral path construction.
• Current path leg sequencing.
• Steering commands to AFS (horizontal only).
• Crosstrack deviation (display by EIS).
The MCDU pages used for STANDBY operation are as follows:
• STANDBY F-PLAN page displays each leg of the active route, provides
position data for each waypoint, computed course, and distance data for
connecting legs.
October 02, 2006
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