Garmin G1000 Socata TBM 850 - Manual (Page 28)

Garmin G1000 Pilot’s Guide for the Socata TBM 850 190-00709-00 Rev. A 1-18
SYSTEM OVERVIEW
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 mode, the AHRS relies upon GPS and magnetic
field measurements. If either of these external measurements is unavailable or invalid, the AHRS uses air
data information for attitude determination. Four AHRS modes of operation are available (see Figure 1-
13 and Table 1-1) and depend upon the combination of available sensor inputs. Loss of air data, GPS, or
magnetometer sensor inputs is communicated to the pilot by message advisory alerts.
Attitude/Heading Invalid
AHRS
no-GPS
Mode
AHRS Normal
Operation
AHRS no-
Mag Mode
AHRS no-Mag/
no-Air Mode
Heading Invalid
av
ailab
le
av
ailab
le
una
va
ilab
le una
vailab
le
av
ailab
le
una
va
ilab
le
una
va
ilab
le
av
ailab
le
Air Data
Magnetometer Data
una
va
ilab
le
av
ailab
le
GPS Data
Magnetometer Data
Air Data
Figure 1-13 AHRS Operation
Table 1-1 AHRS Operation Modes
AHRS Modes
Available AHRS Functions Available Sensor Inputs
Pitch Roll Heading
GPS Input
(At least one)
GMU 44
Magnetometer
GDC 74B
Air Data Computer
Normal      
Reversionary:
No GPS
   –  
Reversionary:
No Magnetometer
  –  – 
Reversionary:
No Magnetometer
No Air Data
  –  – –
GPS INPUT FAILURE
The G1000 system provides two sources of GPS information. If a single GPS receiver fails, or if the
information provided from one of the GPS receivers is unreliable, the AHRS seamlessly transitions 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 the air data and magnetometer
inputs are available and valid.