520 Die in Crash. In 1985, 520 people died when pilots on Japan Airlines flight 123 lost most control over the plane. It crashed into a mountainside, making it the deadliest crash ever. Why Planes Crash Video - weather.com
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.
August 12, 1985. Japan Airline Flight 123. Domestic flight between Tokyo and Osaka. It crashed into two ridges of Mount Takamagahara in Ueno, Gunma Prefecture, 100 kilometers from Tokyo. The crash site was on Osutaka Ridge, near Mount Osutaka. There were 4 survivors out of a total of 524 passengers and crew.
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.