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Flight Management System (FMS) for the Agusta AW139/AB139 Helicopter
The operational mode of the GPS is displayed on line three. Possible
operational modes are displayed as follows:
SELF--TEST
D
INITIALIZATION
D
ACQUISITION
D
NAVIGATION
D
DIFFERENTIAL
D
ALTITUDE AIDING
D
VELOCITY AIDING
D
FAILED.
D
The acquisition mode is used to acquire satellites after power is applied.
The GPS tracks four satellites to acquire position.
After being in the navigation mode, altitude aiding is the mode entered
when fewer than four satellites are being tracked. The GPS uses
altitude from the digital air data computer (DADC) to aid in determining
position in this mode.
When the GPS is operated inside a hangar or other areas where signals
cannot be received, a failure is detected by the GPS. In this case,
cycling the power is necessary to restart the GPS.
The last line of the GPS STATUS page indicates the number of
satellites being tracked and used by the GPS.
PREDICTIVE RECEIVER AUTONOMOUS INTEGRITY MONITORING
In addition to RAIM for current conditions, the GPS receiver predictive
RAIM calculation gives the pilot an indication as to whether the GPS
satellite geometry is satisfactory for approach at the selected or
expected arrival time. YES indicates RAIM is predicted to be within
approach criteria. NO indicates RAIM is predicted to be unacceptable
or unavailable.
A28- - 1146- - 181
REV 3 Mar 2009
Honeywell International Inc. Do not copy without express permission of Honeywell.
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