General
The flight management computing system shares data with the these systems or components:
*
Air data inertial reference system

*
Global positioning system

*
Navigation radios

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Engine sensors

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Fuel sensors

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FMCF internal databases

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Key entries into the control display units (CDUs).

The FMCS uses the data from the airplane systems to do these functions:
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Navigation

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Flight planning

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Performance management

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Guidance and control

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Thrust management

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Display and system control

*
Datalink interface.

FMCS Components
The FMCS has these components:
*
Flight management computing function (FMCF) (2) one in each AIMS cabinet

*
CDUs (3)

*
FMC selector

EFFECTIVITY
BEJ ALL

* Instrument source select panel (ISSP) navigation source switches (2).
Also, the mode control panel (MCP) has an interface with the FMCS, but is not an FMCS component.
Flight Management Computing Function
Each FMCF has these two software partitions:
*
Flight management function (FMF) partition

*
Navigation function partition.

The FMF partition supplies these functions:
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Flight planning

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Lateral navigation (LNAV) guidance commands

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Vertical navigation (VNAV) guidance commands

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Thrust guidance commands

*
Performance data

*
Display control

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ND MAP display

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Manual, route, and procedure selection of navigation radios

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BITE and fault monitoring.

The navigation function partition supplies these functions:
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Position calculation

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Navaid selection for radio position calculation

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Navigation radio tuning command outputs.

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FMCS -GENERAL DESCRIPTION

The FMCFs use performance and navigation data bases and sensor inputs to calculate guidance commands. When the flight crew uses the MCP to select the LNAV and VNAV modes, the FMCF sends this data:
*
LNAV and VNAV guidance commands to the autopilot flight director computers (AFDCs)

*
Thrust guidance commands and thrust limit data to the thrust management computing function (TMCF)

*
Display and fault data to the primary display and central maintenance computing functions in the AIMS cabinets.

Automatic Dependent Surveillance Function
The automatic dependent surveillance function (ADSF) is a sub-function of the FMCF. The purpose of the ADSF is to let air traffic control (ATC) monitor the airplane in the air.
ATC sends automatic dependent surveillance (ADS) requests from the ground to the airplane. The ADSF in the airplane sends airplane position, heading, airspeed, and other data to the ground. ATC uses this data to manage air traffic. The ADSF is automatic and does not require flight crew action.
CDU -General
There are three CDUs in the flight deck. The CDUs are the primary control and display interface unit for the FMCF. The flight crew uses the left and right CDUs to enter flight plan data and interface with the FMCF and other systems. If the left or right CDU fails, the center CDU is the backup.
All CDUs can select a maintenance page format on a multifunction display (MFD) in the primary display system (PDS).
All CDUs can control the satellite communication (SATCOM) system.
The center CDU is the interface for the passenger address/ cabin interphone (PA/CI) controller.
The CDU supplies these functions when the FMCFs fail:
*
Backup navigation radio tuning

*
Calculates LNAV guidance commands

*
Backup map data.

FMC Selector and Instrument Source Select Panel
The FMC selector is on the first officer display switching panel. It determines the active FMCF.
The FMC selector and ISSP switches supply analog inputs to the overhead panel ARINC 629 system (OPAS). The OPAS changes these inputs and sends them to the AIMS cabinet on the systems ARINC 629 buses.
The NAV ISSP switch determines the source of navigation display data.
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777 AIRCRAFT MAINTENANCE MANUAL

FMCS -GENERAL DESCRIPTION

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FMCS -FLIGHT DECK COMPONENT LOCATIONS

FMCS Component Locations -P8 and P9 Panels
The FMCS components on the P9 forward aisle stand and P8 aft aisle stand panels are:
　
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