787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Flight Management, Navigation Chapter 11
Navigation Systems Description Section 20
Copyright © The Boeing Company. See title page for details.
D615Z003-TBC 11.20.1
11.20 Flight Management, Navigation-Navigation Systems Description
Flight Management, Navigation20 Navigation Systems DescriptionNavigation Systems Description
Introduction
[Option – Dual ADF]
Navigation systems include global positioning system (GPS), air data reference
system (ADRS), inertial reference system (IRS), VOR, DME, ILS, ADF, ATC
transponder, weather radar, and the flight management system (FMS). The FMS
is described in the Flight Management System Description section of this chapter.
For additional information on navigation systems displays, refer to:
• Primary Flight Display (PFD)
, Ch. 10, Sec. 10
• Navigation Display (ND)
, Ch. 10, Sec. 10
Global Positioning System (GPS)
Left and right GPS receivers are independent and supply very accurate position
data to the IRS. The IRS in turn supplies a very accurate hybrid GPS-inertial
position to the FMC. In the event that the IRS becomes inoperative, the GPS
supplies position and track data directly to the FMC. All GPS tuning is automatic.
GPS Displays
POS REF page 4/4 displays the left and right GPS-IRU position. The ND
annunciates GPS when the FMC uses GPS position updates.
When POS (position) is selected on the ND drop-down menu, the ND map
displays raw GPS position as left and right GPS symbols. The GPS symbols are
identical and display as a single symbol when the GPS receivers calculate the
same position.
GPS Data
If the IRS becomes inoperative during flight, the FMC automatically uses GPS
data to navigate. No EICAS message is displayed.
Use the GPS NAV prompt on the POS REF page 3/4 to inhibit GPS navigation
data. The EICAS message GPS alerts the crew when data from both GPS systems
are unavailable or when both systems have failed.
GPS position updates should be used during all approaches in which the FMC
database and approach procedures are referenced to the WGS-84 reference datum.
GPS updates should be inhibited for all other approach operations, unless other
appropriate procedures are used.
GPS position updates should be used for all other operations unless a specific state
requires the use of other update provisions within their airspace (e.g. to
accommodate a non-WGS reference datum or other reason).
February 15, 2010
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