Although the NAV ADR DISAGREE had more immediate safety implications relating to unreliable airspeed, the ECAM alert priority logic placed this alert below the engine-related faults. As a result, the NAV ADR DISAGREE alert was not immediately visible to the flight crew due to the limited space available on the ECAM display.
The ATSB is satisfied that this proactive safety action, when completed, will address the safety issue by providing flight crew with timely advice of a NAV ADR DISAGREE alert in the presence of multiple ECAM alerts. This change will give flight crew the best opportunity to detect an unreliable airspeed indication event in a high workload situation.
On 10 August 2018, Airbus informed the ATSB that:
… after internal review with our ECAM specialists we have decided to increase the priority of the NAV ADR DISAGREE alert.
The NAV ADR DISAGREE alert will now have a higher priority than the EPR MODE FAULT alerts.
This will insure that in the event scenario, this alert would be directly visible to the crew.
This modification will be introduced in the next FWS [flight warning system] standard for SA family, the version F12, which currently planned for Q1-2019. A worldwide retrofit is anticipated.
