Pilot's Guide

190-00617-00 Rev. A Garmin G1000 Pilot’s Guide for the Tiger AG-5B
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SYSTEM OVERVIEW
AHRS MODES OF OPERATION
In addition to using internal sensors, the GRS 77
AHRS uses GPS information, magnetic field data and air
data to assist in attitude/heading calculations. In normal
(primary) mode, the AHRS relies upon GPS and magnetic
field measurements. If either external measurement is un-
available or invalid, the AHRS uses air data information
to assist in attitude determination. Four AHRS modes of
operation are available (see table below) and depend upon
the combination of the sensor inputs available. Loss of air
data, GPS, or magnetometer sensor inputs is communi-
cated to the pilot by message advisory alerts.
GPS Input Failure
The G1000 system provides two sources of GPS infor
-
mation. If a single GPS receiver fails, or if the informa
-
tion provided from one of the GPS receivers is unreliable,
the AHRS transitions seamlessly to using the other GPS
receiver. An alert message informs the pilot of the use of
the backup GPS path. If both GPS inputs fail, the AHRS
continues to operate in reversionary ‘No GPS’ mode, so
long as air data and magnetometer inputs are available
and valid.
AHRS Mode
Available AHRS Functions Available Sensor Inputs
Pitch Roll Heading
GPS Input
(At least one)
GMU 44
Magnetometer
GDC 74A
Air Data Computer
Normal/Primary X X X X X X
Reversionary:
No GPS
X X X – X X
Reversionary:
No Magnetometer
X X – X – X
Reversionary:
No Magnetometer
No Air Data
X X – X – –
Air Data Input Failure
A failure of the air data input has no effect on the AHRS
output while AHRS is operating in normal (primary)
mode. A failure of the air data input while the AHRS is
operating in reversionary ‘No GPS’ mode results in invalid
attitude and heading information on the PFD (as indicated
by red ‘X’ flags).
Magnetometer Failure
If the magnetometer input fails, the AHRS transitions
to one of the reversionary ‘No Magnetometer’ modes and
continues to output valid attitude information. However,
the heading output on the PFD is flagged as invalid with
a red ‘X’.
NOTE: Refer to the Annunciations and Alerts
section for specific AHRS alert information.
NOTE: Aggressive maneuvering in any of the
three reversionary modes listed below can
degrade AHRS accuracy.
System Overview.indd 13 7/7/2005 8:49:01 AM