Ahrs Operation - Garmin G3X Touch Pilot's Manual

System Overview

AHRS OPERATION

The Attitude and Heading Reference System (AHRS) performs attitude, heading,
and vertical acceleration calculations for the G3X Touch System, utilizing GPS,
magnetometer, and air data in addition to information from its internal sensors.
Attitude and heading information are updated on the PFD while the AHRS receives
appropriate combinations of information from the external sensor inputs.
The AHRS (GSU 25) corrects for shifts and variations in the Earth's magnetic field by
applying the Magnetic Field Variation Database. The Magnetic Field Variation Database
is derived from the International Geomagnetic Reference Field (IGRF). The IGRF is a
mathematical model that describes the Earth's main magnetic field and its annual rate
of change. The database is updated approximately every 5 years. Failure to update this
database could lead to erroneous heading information being displayed to the pilot.
Magnetometer Data
AHRS no-
AHRS Normal
Mag Mode
Operation
Loss of GPS, magnetometer, or air data inputs is communicated to the pilot by
message advisory alerts. Any failure of the internal AHRS inertial sensors results in loss
of attitude and heading information (indicated by red 'X' flags over the corresponding
flight instruments). If the G3X Touch senses that the magnetic heading measurement
is valid, but possibly outside of the internal accuracy limits, the numeric heading value
on the PFD is displayed in yellow.
12
GPS Data
Air Data
AHRS no-Mag/
no-Air Mode
Heading Invalid
Garmin G3X Touch Pilot's Guide
Magnetometer Data
Air Data
AHRS
no-GPS
Attitude/Heading Invalid
Mode
190-01754-00 Rev. A