Cirrus SR2x

SYSTEM OVERVIEW
SYSTEM
OVERVIEW
FLIGHT
INSTRUMENTS
AHRS OPERATION
NOTE: Aggressive maneuvering in reversionary mode can degrade AHRS accuracy.
The Attitude and Heading Reference System (AHRS) performs attitude, heading, and vertical acceleration
calculations for the system, using 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.
EIS
Y
E
S
GPS Data Available and Reliable?
N
O
AUDIO PANEL
& CNS
FLIGHT
MANAGEMENT
HAZARD
AVOIDANCE
Mag Data Available and Reliable?
Y
E
S
AHRS Normal
Mode
Y
E
S
AHRS no-Mag
Mode
N
O
Air Data Available and Reliable?
N
O
AHRS no-Mag/
no-Air Mode
Mag Data AND Air Data
Available and Reliable?
Y
E
S
AHRS no-GPS
Mode
N
O
AHRS coast-on-gyros
until invalid
AFCS
Heading Invalid Heading Invalid Attitude/Heading Invalid
Figure 1-20 AHRS Operation
ADDITIONAL
FEATURES
APPENDICES
INDEX
Loss of GPS, magnetometer, or air data inputs is communicated to the pilot by message advisory alerts (refer
to Appendix A for specific AHRS alert information). Any failure of the internal AHRS inertial sensors results
in loss of attitude and heading information (indicated by red ‘X’ indications over the corresponding flight
instruments).
Two GPS inputs are provided to the AHRS. If GPS information from one of the inputs fails, the AHRS uses
the remaining GPS input and an alert message is issued to inform the pilot. If both GPS inputs fail, the AHRS
can continue to provide attitude and heading information to the PFD as long as magnetometer and airspeed
data are available and valid.
If the magnetometer input fails, the AHRS continues to output valid attitude information. If GPS-based track
information is available while magnetometer input has failed, the HSI displays the ground track instead of
heading using HSI Track Mode. In this mode, a magenta ‘TRK’ annunciation and track readout appear on the
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Pilot’s Guide for the Cirrus SR2x with Cirrus Perspective by Garmin
190-00820-11 Rev. A