(e)
(f)
(g)
A
747-400 MAINTENANCE MANUAL
Global Positioning System (GPS)
1) The FMC uses autonomous GPS data (in addition to traditional navigational sensors) for position updating.
2) Universal Time Code (UTC) from the MMRs is used as the primary clock source for performance predictions and time stamping of ATS messages. UTC is shown on the POS INIT page.
3) The CDU POS pages display the GPS position, GPS velocity, FMC position and FMC update mode.
4) The GPS function is enabled by option code and a hardware program pin.
Required Navigation Performance (RNP)
1) A default value of required navigation performance (RNP), based on phase of flight, is shown on the CDU. Manual entry of RNP is allowed. The FMC computes an actual navigation performance (ANP) that is an estimate of FMC navigation accuracy. When the ANP exceeds the RNP, a message will be shown on EICAS.
FMC Airline Operational Communications (AOC)
1) The FMC can receive and display uplink data of flight plan information, en route wind information, and descent forecast data. In addition, the FMC can receive uplink messages containing position report triggers. The CDU displays a message on the scratchpad when an uplink message is received.
2) The FMC can initiate downlink reports in response to an uplink request or in response to a position report waypoint trigger condition. The flight crew can manually initiate a downlink request for flight plan information, en route wind information, or descent forecast data.
3) The AOC function is enabled by option code and hardware program pin.
Required Time of Arrival (RTA)
1) The FMC can calculate a VNAV cruise speed target adjustment to arrive at a pilot specified fix and time (RTA). If it is not possible to be at the fix at the specified time, the CDU will display a message in the scratchpad.
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747-400
MAINTENANCE MANUAL
(3)
The performance function uses data contained in the performance data base along with other data, affecting the airplanes performance, to provide the optimal values for speed and thrust. It also creates the most optimal flight path profile. The guidance and thrust management functions incorporate these performance outputs making them realizable in actual flight.
(4)
The guidance function uses performance and navigation data to compute pitch and roll commands which are sent to the Automatic Flight Director System (AFDS) to maintain airplane control, referenced to a defined flight path.
(5)
The thrust management function uses the performance function outputs to compute thrust limits for display on the EICAS and for throttle commands for control of airplane thrust through each leg of the flight path.
(6)
The FMC transmits both dynamic and map background data to be displayed on the EFIS. This data includes airplane track, ground speed, computed winds, active flight plan, waypoints, navaids, airports and vertical and lateral deviations from the perscribed path.
D. Navigation and performance data bases.
(1)
Two data bases exist within the FMC, the navigation data base (NDB) and the performance data base (PDB). The performance data base is loaded along with the loading of the operational program through the use of a data loader. The NDB is also loaded through a data loader but is loaded separately.
(2)
The NDB contains data pertaining to the airplane's flight path. This data includes all of the VORTAC, VOR/DME, VOR, DME and TACAN navaids as well as airport data including airport reference point, runway threshold position, runway heading, length and elevation, and ILS facilities for specific geographical areas. This data will be subjected to updating on a 28 day basis.
(3)
The PDB contains data pertaining to airplane configuration. This data includes engine thrust and fuel flow, airplane drag polars and operational limits. It also includes certain derived data such as speed schedules. The supplier will retain the capability to code revisions to the PDB for updating or in the case of a change in airplane or engine configuration.
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