What happened
On 29 December 2012, an Airbus A340-300E, registration ZS-SXF, was operating an international scheduled flight from Dakar, Senegal, to Johannesburg, South Africa. While descending through approximately 20,676 feet, the aircraft encountered a period of intense, sudden air turbulence lasting about eight seconds.
At the time of the event, two cabin crew members were working in the rear galley, attempting to secure service trolleys and overhead bins. The turbulence was powerful enough to throw the crew members into the air, causing them to collide with the aircraft's interior furnishings. One crew member suffered a suspected dislocated knee. Following the incident, the pilot-in-command requested a priority landing at O.R. Tambo International Airport. Upon arrival, paramedics met the aircraft at the parking bay, where the injured crew members were stabilized and transported to a hospital in Kempton Park.
The investigation
The investigation focused on the environmental conditions and the actions of the flight deck crew. Data retrieved from the Quick Access Recorder (QAR) confirmed that the aircraft experienced significant vertical accelerations, peaking at +1.551g and -0.121g. While the weather radar did not show moisture or turbulence in the clouds directly ahead of the flight path, the surrounding region was experiencing isolated thunderstorms.
Investigators also reviewed the cockpit's communication and safety procedures. Although the 'Fasten Seat Belt' sign had been activated roughly 100 nautical miles before landing, the pilot flying did not issue a specific verbal command for the cabin crew to take their seats and secure their harnesses. The investigation noted that the turbulence appeared to have a much more violent impact on the aft section of the aircraft than in the cockpit.