The history of the JAPAN AIRLINES flight JAL877 is summarized as below, based on the data from digital flight data recorder (DFDR) and the statements of the pilot in command (PIC), the first officer (FO), flight attendants (FAs) and an injured passenger.

On November 26, 2012 at 14:28 Japan Standard Time (JST, UTC+9), a Boeing 767-300, registered JA610J, operated by Japan Airlines Co., Ltd. as JAPAN AIRLINES flight JAL877, took off from Narita International Airport (Japan) for Shanghai Pudong International Airport (the People’s Republic of China) with a total of 171 people on board : the PIC, the FO, 10 FAs and 159 passengers.

The PIC of JAPAN AIRLINES flight JAL877 took the left seat as the PM (pilot monitoring: pilot mainly in charge of duties other than flying) and the FO was the PF (pilot flying: pilot mainly in charge of flying).

When reaching a cruising altitude of 36,000 ft, the aircraft was flying in the thin clouds. The PIC instructed all FAs over the interphone to serve passengers with extra care for a while against a little shaking ahead, and – 2 – then around 14:45, the PIC turned off the seatbelt sign. The FAs started to prepare for in-flight services and several passengers left their seats for using the lavatories. In the pre-flight briefing, the PIC had already confirmed the Transverse Band*1 on the meteorological satellite imagery (infrared imagery*2) as of 12:00 and other weather information, and planned earlier descent around westward area of Osaka to avoid it

The aircraft encountered the severe turbulence at an altitude of 36,000 ft over Fujinomiya City, Shizuoka Prefecture around 14:54, following some fluctuations in VSI (Vertical Speed Indicator). Until then, the aircraft had flown in a smooth and steady condition at that altitude and the on-board weather radar had not identified any active radar images. At the moment of shaking, the DFDR recorded the significant changes of vertical acceleration (deceleration to +0.7 G one second after acceleration to +1.9 G). The FO immediately turned on the seatbelt sign and started to descend to evade further turbulences.

After the rough-air condition settled down and the seatbelt sign was turned off, a passenger told a FA that he had tried to maintain his posture and sprained his right ankle as the aircraft shook severely just after he came out of the AFT lavatory.

The aircraft landed at Shanghai Pudong International Airport at 17:49 and the injured passenger was transported to the hospital for diagnosis, where fracture of his ankle was identified.

The accident occurred around 14:54 at an altitude of about 36,000 ft over Fujinomiya City, Shizuoka Prefecture (Latitude 35°12’24” N and Longitude 138°34’25” E). No PIREPs*3 were reported about turbulence at nearby airspace where the accident occurred around that time.

It is highly probable that this accident occurred because the aircraft encountered the turbulence and was shaken at the cruising altitude of 36,000 ft. This shaking caused one of the passengers who had been away from his seat to lose his body’s balance and to sustain serious injuries.

It is probable that the turbulence the aircraft encountered was caused by the large VWS formed in a temporally and spatially limited narrow range due to the strong southerly warm wind which flowed into the developing front side of the Low.