This section sets out a few operational safety topics with respect to commercial air transport, principally involving large aeroplanes. These topics are illustrated with the latest reports published by the BEA and certain reports from foreign investigations which the BEA was involved in as accredited representative.
Aside from major accidents, turbulence is the cause of the greatest number of serious injuries in commercial air transport every year. The immediate consequences can include long-term incapacitating injuries. Turbulence can also cause the crew to react by taking unusual pitch attitudes, exposing them to the risk of an in-flight loss of control. The accidents and serious incidents registered by the BEA are equally divided between turbulence associated with convective phenomena and clear-sky turbulence. In all cases, anticipation remains a major challenge, and notably raises the question of ground and on-board systems.
1. Turbulence en route, cabin crew member seriously injured, emergency landing at destination
On 25 July 2021, after circumnavigating what they thought to be the last storm cell, the crew of the Boeing 737 registered SE-RPE bound for Nice indicated that they could now head towards the waypoint requested by the controller. On turning, the crew suddenly saw on the weather radar and had in sight, storm cloud developments immediately behind the cell they had just circumnavigated. Flight through this zone was short but very turbulent. During this phase, a cabin crew member who was busy securing equipment in the aft galley, was seriously injured and another cabin crew member was slightly injured. The investigation highlighted that in France, meteorological information is not displayed on the controllers’ radar screens.
2. Turbulence in descent, cabin crew member seriously injured
On 5 December 2021, during the flight, and in particular, the minutes preceding the accident, the crew of the Airbus A350 registered F-HNET had effectively identified the risk of turbulence and had asked all the occupants, including the cabin crew, to remain seated with their seatbelts fastened. The first zones of turbulence were flown through without incident. On passing FL 100, outside of clouds and thinking that the turbulence was behind them, the captain authorised the cabin crew at the rear of the cabin to finish preparing the cabin for landing. A few minutes later, a sudden brief turbulence caused injuries to three cabin crew, with one of them sustaining serious injuries. This zone of turbulence was probably generated by a convective cell close by. The crew may not have been able to detect or may have underestimated the distance or extent of the zone of influence of this cell.
On 3 May 2017, during a flight between Taipei (Taïwan) and Kuala Lumpur, the crew of the Airbus A330 registered 9M-XXS were surprised by moderate turbulence which they had not detected with the on-board radar. The aeroplane first took a bank angle of 8°. The captain, PM on this leg, disconnected the autopilot and tried to bring the wings level. For around 90 s, the dual inputs made by the captain and the co-pilot in roll and pitch resulted in the aeroplane taking high angles of attack (to MAX), a reduction in Mach (0.64) and an increase in altitude to over 42,000 ft. On top of the higher-than-recommended altitude (REC MAX = 415) and a high angle of attack, the cyclic dual inputs made by the two flight crew at the frequency of the Dutch-roll, resulted in a very dynamic situation in roll. The maximum roll angle reached 98°. The crew finally managed to return to normal attitudes. Five passengers were injured during the incident. The report insists on the importance of selecting an appropriate ND range in order to correctly display the radar information. The report also highlights the early disengagement of the automatic systems in the event of turbulence and the dual inputs by the two crew members on the sidesticks as contributing factors to the momentary loss of control at high altitude.
