MD-11 Flight Crew Operations Manual
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FMS -
Controls and Displays
FMS.30.107
• FMC POSITION MISMATCH - Present position differs by more than 5
NM or double the RNP distance in NMs. Automatically canceled when
difference is less than 3 NM or double the RNP distance in NMs
respectively.
• GROSS WEIGHT MISMATCH - Gross weight differs by more than
6,818 kgs. Automatically canceled when difference is less than 2,272 kgs.
• THRUST LIMITS MISMATCH - Active thrust differs by more than 1%
N1. Automatically canceled when the difference is less.
NOTE: In some dynamic conditions, vertical and lateral computations
may temporarily disagree and may be evident on the ND. In this
case, the flight director and autoflight system will use the respective
FMC and autopilot for tracking.
While synchronization of data is in progress, the MCDU message PLEASE WAIT
is displayed. The same message is displayed for a power interrupt longer than 4
seconds. In this case, the FMC in question will become the spare and resync itself
to the master while establishing DUAL mode operation. While the PLEASE
WAIT message is displayed, MCDU key inputs from either MCDU will not be
accepted for processing. The message is automatically cleared when
re-synchronization is attained.
When crosstalk or re-synchronization is attempted and fails, each FMC will revert
to a completely INDEPENDENT mode of operation without crosstalk. The
message INDEPENDENT OPERATION is displayed in the MCDU scratchpad
until it is cleared or the FMS reestablishes DUAL mode. If an FMC generates an
automatic reset in INDEPENDENT operation, then the pilot can reenter data
(GW, ZFWCG, F-PLN, radio tuning) or select the offside FMC via the FMS
transfer switch on the source input select panel. The pilot can attempt to
reestablish DUAL mode by selecting the RESET FMC prompt on the SENSOR
STATUS page. If the problem which is causing the FMS to operate independently
no longer exists, then the FMS will reestablish DUAL mode operation. However,
before selecting a RESET FMC prompt, the pilot must decide which FMC F-PLN
to maintain in case they are different. The pilot should select the RESET FMC
prompt for the FMC which is to be resynchronized.
NOTE: In the INDEPENDENT mode each FMC may evolve its own
flight plan. In this case position errors could be encountered, and
will be seen on the EIS ND.
October 02, 2006
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