Lufthansa Airbus Industrie A340-300 accident

The transport aircraft encountered severe turbulence at flight level 310 while in IMC during an international flight. Convective SIGMETs for an area of thunderstorms with tops to flight level 410 were in effect at the time and location of the accident. The FDR data showed aircraft disturbances in vertical acceleration, lateral acceleration, altitude, magnetic heading, and vertical speed. The autopilot and auto-throttle parameters remained engaged throughout the event. The captain side stick pitch, first officer side stick pitch, and first officer side stick roll parameters showed no movement during the disturbance. The captain side stick roll parameter moved -1 degree during 2057:07 and then returned to 0 degrees. The rudder pedal position and rudder parameters showed less than one degree of movement during the event sequence, and the pitch and elevator parameters registered excursions of less than 1.5 degrees. The altitude reached a minimum value of 30,884 feet msl, the aircraft stabilized at 31,000 feet. The aircraft landed at 2207 at the destination airport, approximately I hour and 10 minutes after the encounter with severe turbulence. Food service was in progress in the cabin, and the "fasten seat belt" light was on at the time of the turbulence encounter. The FA statements revealed that 7 FA's hit the cabin ceiling and then the floor, one FA hit the ceiling then an armrest, and 2 FA's were tossed through a galley. Three food serving carts were lifted from the floor, and numerous food service items were tossed about the cabin. Some of the passengers were out of their seats, and some, who were seated, did not have their seat belts secured per the "Fasten Seat Belt" light. The 18,593-hour captain/check airman with 4,093 hours in the accident aircraft, was the non-flying pilot (PNF) during the event, the 2,759-hour first officer was the pilot flying (PF). Reviews of the flight and duty time records disclosed no evidence of any activities that would have prevented the flight crewmembers from obtaining sufficient rest in the 72 hours before the accident flight. Company interviews revealed that the departure flight was delayed 4 hours and 7 minutes as a result of a change of airplanes. The Flight Crew Manual states in part: every cloud related to a severe thunderstorm represents a serious danger, and AVOID - AVOID - AVOID since weather can exceed the performance capabilities and/or structural limits of the airplane.

Verbatim NTSB analysis and probable cause from the NTSB dataset