During the evening on 15 February 2014, and Airbus A320, registered VH-VNQ, was preparing to depart Hobart, Tasmania, for a flight to Melbourne, Victoria. The crew completed pre-departure activities including entry of take-off reference speeds and the flex temperature (for a flex temperature take-off) into the aircraft’s Flight Management Guidance System (FMGS). The crew started engines and taxied for runway 12, but thunderstorms in the area delayed departure.
After holding for about 75 minutes, waiting for the weather to clear, the crew entered runway 12 and backtracked to the threshold. As they backtracked, the crew were able to gain a better appreciation of the weather in the direction of departure, and assessed their departure options. The crew entered their planned departure procedure into the FMGS, but noticed that the navigation display called for a right turn after take-off, contrary to the published procedure which called for a left turn.
The crew attempted to clear the departure anomaly by changing the departure runway to the reciprocal runway, then re-selecting the correct runway. This action failed to clear the anomaly, so the crew elected to continue with the departure and use heading mode to command a left turn at the appropriate time, rather than allow the auto-flight system to guide the aircraft into a right turn. The crew was unaware at the time, but by changing the departure runway in an attempt to clear the anomaly, take-off reference speeds and the flex temperature previously entered into the FMGS, were removed.
As the flex temperature take-off commenced, the crew noticed that flight mode annunciations were not as they would normally appear. An electronic centralised aircraft monitoring system caution then alerted the crew that the thrust levers were not correctly set, and the crew noticed that the take-off reference speeds were not displayed on the primary flight display airspeed indicators. The captain elected to continue the take-off and advanced the thrust levers to the take-off/go around setting, commanding maximum available thrust. The captain also restored previously entered take-off data by pressing the appropriate line select key on one of the multi-purpose control and display units. As the take-of continued, auto-flight modes became active and the crew selected heading mode to manually command a left turn as planned. The flight to Melbourne then proceeded uneventfully.
The operator’s investigation into the incident identified issues relating to the consistency of their before take-off checklist with that published by the aircraft manufacturer, and the status of the FMGS software installed in the flight simulators used by the operator. In response to the incident, the operator implemented a number of initiatives, including alignment of the before take-off checklist with that published by the aircraft manufacturer, implementation of a revised crew briefing format, provision of relevant educational material to flight crew and implementation of a flight simulator software upgrade.
For operators, this incident highlights the need for robust checklists and checklist management procedures that effectively cater for a wide range of operational scenarios, the importance of ensuring that the performance of training equipment accurately reflects the performance of operational equipment, and the importance of consistently accurate FMGS aeronautical data. For flight crew, this incident serves to highlight the importance of careful attention to FMGS aeronautical data and highlights the need for extra caution following an interruption to the normal sequence of events during preparation for departure. The incident also reinforces the importance of Airbus ‘Golden Rules for Pilots’, particularly the first rule: Fly, navigate and communicate (in this order and with appropriate task sharing).