What happened
On February 10, 2008, an Air China Limited Boeing 737-300, registration B2906, was operating a scheduled flight from Beijing Capital International Airport to Kansai International Airport. While descending through approximately 31,400 feet near Matsue City, Shimane Prefecture, the aircraft encountered sudden and violent turbulence.
At approximately 19:19 JST, the aircraft's airspeed increased rapidly, causing the autopilot to disengage. Following the disengagement, the pilot flying executed manual control inputs to manage the airspeed, which resulted in significant fluctuations in vertical acceleration, ranging from 2.2G to 0.0G. During this period of intense shaking, a passenger walking in the aft cabin aisle lost her balance. The passenger struck her abdomen against a seat, resulting in one serious injury.
The investigation
The JTSB investigation examined flight data from the Digital Flight Data Recorder (DFDR), air traffic control communications, and interviews with the crew and passengers. Investigators analyzed the aircraft's flight path, the behavior of the autopilot during the event, and the specific control column movements made by the crew. The investigation also reviewed meteorological charts, including Significant Weather Prognostic Charts and vertical wind shear analysis, to determine the environmental conditions at the time of the incident.