Japan Airlines flight JL356, a Boeing 747-400D, departed Fukuoka Airport as scheduled passenger flight 356. While descending from cruising altitude for Tokyo International Airport at 10:57 (JST) over the sea approximately 8nm southeast of Hamamatsu City at an altitude of around 39,000ft, the aircraft was shaken abruptly and at that time three passengers and a member of the cabin crew were seriously injured, and 18 passengers and 11 cabin crew sustained minor injuries. There were 556 persons on board flight 356 ? 541 passengers (including three infants), the captain and 14 other crewmembers. The interior of the cabin was partly damaged when the aircraft was shaken abruptly. PROBABLE CAUSE In this accident, while the aircraft was descending, a rapid increase in the aircraft?s pitch angle followed by pitch changes occurred which caused passengers and cabin crew to float up and be seriously injured when they hit their heads etc. against the ceiling and when they fell to the floor and hit their backs etc. Contributing to the occurrence of serious injury when the pitch changes occurred were the facts that the seatbelt signs were not turned on at the time, that some passengers who were seated were not using their seatbelts, and that the cabin attendants had been carrying out their duties. It is considered that the rapid increase in pitch and the subsequent pitch changes occurred through the following process: (1) Airspeed (CAS/Mach number) increased rapidly due to encountering a strong windshear, and the autopilot responded to reduce the aircraft?s speed. (2) The aircraft?s pitch angle increased rapidly. It is considered possible that the speed brakes were used at that time. (3) The autopilot was disengaged, and then oscillatory pitch changes occurred according to the pilot?s control column input when manual control was assumed. Further, it is considered possible that a contributory factor regarding the oscillatory pitch changes was the fact that the pilots had not had sufficient opportunity to experience disconnecting the autopilot and assuming manual control when the Mach number approached Mmo at high altitude, and stick shaker work, or the handling characteristics under those conditions.