1985 ♦ August 12 – Japan Airlines Flight 123, a Boeing 747, crashes into Mount Osutaka after catastrophic failure of the pressure hull severs all hydraulic lines and renders the aircraft uncontrollable, killing 520 of 524 people on board. To date, it is the worst single-aircraft disaster in history.
flygcforum.com - On Monday, August 12, 1985, the Boeing 747-146SR that made this route, registered JA8119, suffered mechanical failures 12 minutes into the flight and 32 minutes later crashed into two ridges of Mount Takamagahara in Ueno, Gunma Prefecture, 100 kilometers (62 mi) from Tokyo.
The crash of Japan Airlines Flight 123, on August 12, 1985 is the single-aircraft disaster with the highest number of fatalities: 520 died on board. The aircraft suffered an explosive decompression from an incorrectly repaired aft pressure bulkhead, which failed in mid flight, destroying most of its vertical stabilizer, severing all of the hydraulic lines, making the 747 virtually uncontrollable. Pilots were able to keep the plane flying for half an hour before crashing into a mountain.
This picture recovered from the crash site of Japan Airlines Flight 123, shows the cabin before tragedy struck. A total of 509 people were killed. There were 4 survivors. There was an explosive decompression on board caused by a faulty repair performed seven years earlier. The plane crashed 32 minutes later.