Japan Air Lines Flight 123 was a scheduled domestic passenger flight from Tokyo to Osaka, Japan. On August 12, 1985, the Boeing 747 flying the route suffered a severe structural failure and decompression 12 minutes into the flight. After flying under minimal control for a further 32 minutes, the 747 crashed in the area of Mount Takamagahara, 100 kilometres (62 mi; 54 nmi) from Tokyo.

The aircraft, featuring a high-density seating configuration, was carrying 524 people. The crash killed all 15 crew members and 505 of the 509 passengers on board, leaving only four survivors. An estimated 20 to 50 passengers had survived the initial crash, but died a few hours later while awaiting rescue due to their serious injuries. The crash of Flight 123 is the deadliest single-aircraft accident in aviation history.

Japan's Aircraft Accident Investigation Commission (AAIC),^: 129 assisted by the U.S. National Transportation Safety Board, concluded that the structural failure was caused by a faulty repair by Boeing technicians following a tailstrike incident seven years earlier. When the faulty repair eventually failed, it resulted in a rapid decompression that ripped off a large portion of the tail and caused the loss of all on-board hydraulic systems, disabling the aircraft's flight controls.

Background

Aircraft

The accident aircraft, a Boeing 747SR-46 with registration JA8119 (serial number 20783, line number 230), was built and delivered to Japan Air Lines in 1974 (prior to them changing their name to "Japan Airlines").