737 Flight Crew Operations Manual
Flight Management, Navigation -
Flight Management Computer
Boeing Proprietary. Copyright © Boeing. May be subject to export restrictions under EAR. See title page for details.
11.32.4 D6-27370-866-EGP
Use of derated climb thrust reduces engine maintenance costs, but increases total
trip fuel.
Fuel Monitoring
The FMC receives fuel data from the fuel quantity indicating system. Fuel
quantity values show on the PERF INIT page and on PROGRESS page 1/3.
The scratchpad message VERIFY GW AND FUEL shows if total fuel quantity
data is invalid. The PERF INIT page FUEL line changes to dashes. The FMC uses
the last valid fuel quantity for performance predictions and VNAV operation. The
flight crew should manually enter estimated fuel weight. Periodic fuel weight
update is required for the remainder of the flight to keep gross weight current. The
FMC does not update the manual fuel weight entry. The scratchpad message
VERIFY GW AND FUEL shows again each 30 minutes if subsequent entries are
not performed. The scratchpad message does not show during descent with Vref
selected.
The scratchpad message CHECK FMC FUEL QUANTITY shows if the FMC has
detected an unexpected drop in fuel quantity.
The FMC continually estimates the amount of fuel that will remain when the
destination airport is reached if the active route is flown. The CDU message
USING RSV FUEL is displayed if the estimate is less than the fuel reserve value
entered on the PERF INIT page. The CDU message INSUFFICIENT FUEL is
displayed if predicted fuel at destination will be 2000 lb. (900 kg) or less.
Loss of FMC Electrical Power
The FMC requires continuous electrical power to operate. When the electrical
power is interrupted for less than ten seconds:
• LNAV and VNAV disengage
• all entered data is retained by the FMC
• the FMC resumes normal operation when power is restored.
If power is lost for ten seconds or more on the ground, all preflight procedures and
entries must be done again when power is restored.
If power is lost for more than ten seconds in flight:
• LNAV and VNAV disengage
• all entered data is retained by the FMC, and when power is restored the
RTE LEGS page is displayed with the scratchpad message
SELECT ACTIVE WPT/LEG.
Before LNAV can engage, the FMC must be instructed how to return to the route.
Select the desired active waypoint and proceed direct or intercept a course to the
waypoint.
September 26, 2013
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