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.
The ATSB welcomes the significant Airbus safety action to develop improved detection of erroneous airspeed during take-off that will be associated with an alert and display. The addition of an aural alert and more prominent visual alert is expected to more effectively gain the attention of both pilots early in the take-off roll and provide ample opportunity to reject the take-off if needed.
This safety action, which is now available for A330-900 aircraft and is anticipated to become available for other A330 variants in the coming months, will improve the safety of operations for a significant number of larger air transport aeroplanes worldwide. The ATSB encourages operators of A330 aircraft to implement this safety improvement, and for other Airbus aircraft when the relevant service bulletins become available.
Additionally, recognising that the need for improved alerts and guidance for unreliable airspeed indications on take-off is very likely relevant to other aircraft types, the ATSB continues to encourage all manufacturers and operators of larger air transport aeroplanes to examine and address this issue as described in safety advisory notice AO-2018-053-SAN-004.
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.
On 24 April 2025, Airbus published service bulletin SB 27-3250 to provide for improved detection of erroneous airspeed during the take-off roll in A330-900 aircraft.
Following implementation of the service bulletin, the aircraft systems will automatically reject (stop using) an air data reference (ADR) if there is a difference of more than 30 kt between airspeed and groundspeed, and:
Similar modifications and service bulletins are anticipated to become available for A330-200 and A330-800 aircraft in late 2025, and for A330-300 aircraft in late 2026. Similar modifications are planned for the other Airbus fly-by-wire (FBW) aircraft types.
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.
