In the Airbus A330, there was no auditory alert associated with nil or unreliable airspeed from two or more sources during take-off (a high workload, critical phase of flight). Comparatively, other critical failures provide both visual and auditory indications.
In addition to other proactive safety actions (AO-2018-053-PSA-01), on 5 August 2021 Airbus advised:
Airbus has launched and is developing an improvement of detection of erroneous airspeed during the take-off roll. This improvement includes the detection of multiple and consistent erroneous airspeeds. It is planned to be available on A330 from end of 2022.
Airbus further advised that the system design was not yet complete but would be associated with ‘alert/display’ and that the manufacturer was reviewing the potential for it to be available on other aircraft types. The flight crew procedure will not change as a result of the improved alerting.
The ATSB welcomes the Airbus safety action to develop improved detection of erroneous airspeed during take-off that will be associated with an alert and/or display. The ATSB will monitor the progress of this development.
On 14 December 2022 Airbus advised that a system modification improving the detection of erroneous airspeed during the take-off roll and, in particular, detecting multiple and consistent erroneous airspeeds has been finalised. It is expected to be implemented in new A330 computers, commencing 2024, and retrofitted to existing aircraft worldwide. Similar modifications are planned to be implemented for the other Airbus fly-by-wire aircraft types.
The ATSB acknowledges the update and will continue to monitor this safety action.
On 7 February 2024, Airbus advised that certification of changes to the A330-900 is expected in early 2025, with certification of changes to other A330 variants to follow in 2025 and 2026.
The ATSB acknowledges the update and will continue to monitor this safety action.
The Australian Transport Safety Bureau encourages all manufacturers and operators of larger air transport aeroplanes to consider what types of unreliable airspeed events can occur, how the information is presented to flight crews, and what responses are the safest in different phases of the take-off and in a range of potential situations. Aircraft alerting systems, flight crew procedures, and flight crew training should be designed to provide sufficient assurance that flight crews become aware of and understand how to appropriately respond to unreliable airspeed on take-off in a timely manner.
A copy of the Safety Advisory Notice is available here.
