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
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.