In civil transport aircrafts (featured with dual/triple redundancy), how does airplane's Airflow angle (AoA/AoSS) sensor measurements read by the pilot? By using voter mechanism as used for airspeeds or individual sensor measurements to pilot and co-pilot?
The A320 is fitted with an air data inertial reference system (ADIRS) made of 3 ADIRUs. ADIRU 1 data (altitude, speed, etc) are shown on Capt side, ADIRU 2 on F/O side. ADIRU 3 can be selected manually.
Each ADIRU contains an air data reference (ADR) and an inertial reference (IR). Each ADR receives the AoA value from a separate AoA probe.
The AoA value is not displayed by default, but it is accessible on the MCDU after selecting the related page. The values are always monitored for validity by FAC/ELAC before being used.
The final value is the mean of valid inputs. If one ADR disagree it is silently discarded. If all ADR disagree, a message is displayed. Any ADR can be shut down using the overhead panel. From this report:
If one ADR has been detected as being faulty, or has been rejected by the flight control computers, and there is an airspeed or angle of attack disagreement between the remaining two ADRs, then a level 2 alert is raised. This activates the master caution and presents an amber NAV ADR DISAGREE message on the ECAM.
The way the discrepancies are managed can lead to rejecting a valid value because the two other ADR are wrong, but agree.
All pictures are from the report.