What happened
On October 27, 2007, a Japan Airlines International Boeing 767-300, registration JA611J, was operating a scheduled flight from Hangzhou Xiaoshan International Airport to Narita International Airport. While descending toward Narita, the aircraft encountered extreme atmospheric instability.
At approximately 17:30 JST, at an altitude of roughly 10,500 feet, the aircraft entered a period of intense turbulence. Flight data recorders captured severe vertical accelerations, with peaks exceeding +3.3G, and a significant leftward roll of nearly 67 degrees. During this 19-second window of violent motion, the aircraft's stick shaker and stick nudger were activated.
While the crew managed the aircraft through the disturbance and landed safely at Narita, the turbulence caused one passenger to suffer a serious injury. The passenger's seatbelt became unfastened during the shaking, causing them to be thrown upward and strike the seatback in front of them.
The investigation
The JTSB investigation examined flight data from the DFDR, CVR, and QAR, alongside interviews with the flight crew and cabin attendants. Investigators analyzed the aircraft's flight path, which had been adjusted to avoid significant weather radar echoes, and reviewed the weather patterns associated with an approaching typhoon in the Kanto region.
The investigation also focused on the cabin environment, specifically how the seatbelt remained unfastened despite the crew's prior efforts to ensure all passengers were secured. Physical evidence, including the passenger's personal belongings and the seatbelt mechanism, was reviewed to determine the mechanics of the unfastening.