
Garmin G1000 Cockpit Reference Guide for Mooney M20M & M20R
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APPENDIX A
GRS 77 Message Advisories
Alerts Window Message Comments
AHRS TAS – AHRS not receiving
airspeed.
The AHRS is not receiving true airspeed from the air data computer. The AHRS relies
on GPS information to augment the lack of airspeed. Have the G1000 system
serviced.
AHRS GPS – AHRS using backup GPS
source.
The AHRS is using the backup GPS path. Primary GPS path has failed. Have the
G1000 system serviced when possible.
AHRS GPS – AHRS not receiving GPS
information.
The AHRS is not receiving any GPS information and not operating in its normal mode.
Have the G1000 system serviced.
MANIFEST – GRS1 software mismatch.
Communication halted.
The AHRS has incorrect software installed. Have the G1000 system serviced.
BACKUP PATH – AHRS using backup
data path.
The AHRS is using a backup communications data path. Have the G1000 system
serviced when possible.
AHRS SERVICE – AHRS Magnetic-field
model needs update.
The AHRS earth magnetic field model is out of date. Update magnetic field model
when practical.
GEO LIMITS – Too far North/South, no
magnetic compass.
The aircraft is outside geographical limits for approved AHRS operation. Heading is
flagged invalid.
GMU 44 Message Advisories
Alerts Window Message Comments
HDG FAULT – A magnetometer fault
has occurred.
A fault has occurred in the GMU 44. Heading is flagged invalid. AHRS uses GPS for
backup mode operation. Have the G1000 system serviced.
MANIFEST – GMU1 software mis-
match. Communication halted.
The GMU 44 has incorrect software installed. Have the G1000 system serviced.
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