Garmin G500, Pilot'S Manual, Page: 423 / 440

190-01717-10 Rev. H Pilot’s Guide 9-21
Abnormal Operations
NO COMPARE ANNUNCIATIONS
A no compare monitor determines when data to the second ADC or AHRS source is
unable to be used for comparison.
9.4 HSI Failure Modes
NOTE
TAWS/terrain alerting is unavailable in the absence of a certified GPS
source.
The HSI continues to display limited navigation information during magnetometer
and GPS failures. If the magnetometer input fails, the AHRS transitions to backup
No-Magnetometer mode and continues to output valid attitude information.
If the aircraft is airborne, the PFD heading output reverts to GPS track. Magnetic
heading is replaced by GPS track information and HSI compass card orients to GPS
track. The following TXi system conditions exist:
•
SVT turns off and automatically re-enables when heading is restored
•
Map orientations change from HDG UP to TRACK UP
•
When heading is restored orientations change back to HDG up
•
When heading fails heading bug remains
•
GDU continues driving autopilot heading error output using track in place of
heading
No compares generate an
advisory annunciation over the
affected instrument(s) driven by
ADC and AHRS units.