737 Flight Crew Operations Manual
Flight Management, Navigation -
Navigation Systems Description
Boeing Proprietary. Copyright © Boeing. May be subject to export restrictions under EAR. See title page for details.
11.20.2 D6-27370-866-EGP
The FMC uses crew entered flight plan information, airplane systems data, and
data from the FMC navigation database and performance database to calculate
airplane present position, and pitch, roll, and thrust commands required to fly an
optimum flight profile. The FMC sends these commands to the autothrottle,
autopilot, and flight director. Map and route information are sent to the respective
pilot’s navigation displays. The EFIS control panels are used to select the desired
information for navigation display. The mode control panel is used to select the
autothrottle, autopilot, and flight director operating modes.
Global Positioning System (GPS)
Two GPS receivers receive GPS satellite positioning signals. The left and right
GPS receivers are independent and each provides an accurate airplane
geographical position to the FMC and other aircraft systems. GPS operation is
automatic.
GPS Displays
POS REF page 2/3 shows the left and right GPS latitude and longitude position.
POS SHIFT page 3/3 shows the left and right GPS position relative to the FMC
position. NAV STATUS page 1/2 shows the GPS currently in use by the FMC for
position calculation.
When the POS (position) switch on the EFIS control panel is selected, the
navigation display shows the left and right GPS symbols. The GPS symbols are
identical and show as a single symbol when the GPS receivers calculate the same
position.
An amber GPS light illuminates to indicate a failure of both GPS sensor units.
Failure of a single GPS sensor causes the light to illuminate when either system
annunciator panel is pushed.
GPS Data
FMC logic selects the position from one of the GPS sensor units as the primary
update to the FMC position. When GPS position data is available, radio updating
can also occur. If all GPS data becomes unavailable, the FMC position will be
determined by radio or inertial (IRS) updating.
GPS navigational information can be manually deselected on the NAV OPTIONS
page 2/2. No other controls are provided because the operation of the GPS is
completely automatic.
September 24, 2015
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