Garmin G500 Pilot's Manual page 30

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NOTE: Fastest AHRS alignment is achieved with the aircraft stationary and
with all AHRS inputs valid (3-D GPS position, magnetometer, and air data).
During initial power up on the ground, no GPS position and/or magnetic
anomalies are common. If the aircraft is taxied prior to AHRS alignment,
alignment may be delayed until after a valid 3-D GPS position is available.
NOTE: During in-flight alignment of the AHRS, minimize aircraft
maneuvering. The AHRS will align with shallow banking and pitch angles
(less than 20 degrees of roll or 5 degrees of pitch). AHRS alignment may
not be possible during more aggressive maneuvers.
Heading Considered Unreliable
When the AHRS signals that a heading is unreliable or in recovery, indications
are displayed on the PFD. These indications are automatically removed once the
heading alignment is corrected.
NOTE: Depending on the AHRS type and the magnitude of the heading error,
the displayed indication may change directly from unreliable to reliable.
AHRS Signal
Heading unreliable
Heading recovery in progress
Heading reliable
Current Heading Unreliable
1-8
The current heading value changes from
white to amber.
The Align Aircraft (ALN) indication
appears to the left of the heading.
Current heading value turns white.
Table 1-3 AHRS Signals and Indications
Align Heading
Align Heading
Figure 1-9 AHRS Heading Indications
Garmin G500/G600 Pilot's Guide
Displayed Indication
Heading Recovery in Progress
190-00601-02 Rev. J