JAPAN AIRLINES FLIGHT 123
Aviation accident is defined by events associated with an aircraft that has the risk of affecting the safety of operations which takes place between the time any person boards the aircraft with the intention of flight until such time as the passengers have disembarked, in which a person is fatally or seriously injured, the aircraft sustains damage or structural failure or the aircraft is missing or is completely inaccessible.
An accident in which the damage to the aircraft is such that it must be written off, or in which the plane is destroyed is called a hull loss accident.
Over the years, there are many aircraft accidents but there are a few major accidents such as the September 11 crash at the World Trade Center in New York in 2001, the Tenerife airport disaster in 1977 which is recorded as the highest death toll, the Japan Airlines Flight 123 in 1985 and others.
Until today, the Japan Airlines Flight 123 in 1985 is the single-aircraft disaster with the highest number of fatalities. In this crash, all 15 crew members, 505 out of 509 passengers died and resulting in a total of 520 deaths on board a Boeing 747. The aircraft suffered an explosive decompression from an incorrectly repaired doubler plates causing the aft pressure bulkhead to fail, which failed in mid flight and destroyed most of its vertical stabilizer, and severed all of the hydraulic lines, making the 747 paralyzed and uncontrollable. The pilots were able to keep the plane flying for several minutes before crashing into a mountain. Amazingly, several people survived the impact, but by the time the rescue teams could get there, all but four had died.
The Boeing 747SR (Short Range) was an aircraft that was designed to be used on short, high-density routes. Due to its lower fuel capacity, it was only capable of carrying over 550 passengers. For Japan Airlines 747SR, on Monday August 12, 1985 began no different than any other day. The aircraft was refuelled and new flight crew boarded, while the cabin crew remained from the previous flight. JAL123 was ready for the flight to Osaka which was 400km away.
In command of the flight was Captain Masami Takahama, who was a Training Captain. The flight took off and minutes later Tokyo ATC was tracking the flight, the emergency transponder code appeared on their screen, which was 7700. This is the emergency complain for aircraft in distress.
The controller noticed that instead of turning back toward Oshima Island, the aircraft was making only a gradual turn to the right. Crossing the Izu Peninsula and leaving it , it then headed out over Suruga Bay in a north-westerly direction. The aircraft had suffered an explosive decompression of its rear vertical tail plane, losing a section of the vertical stabliliser and making all its flying controls useless.
The aircraft impacted near the top of Mount Osutaka, killing all but four people on board. The cause was found to be an improperly repaired rear pressure bulkhead, which had been repaired by Boeing some years before, after the aircraft had been involved in a tail scrape on landing. This caused the explosion at the aft and failing the hydraulic system thus loss of the flying surfaces in the tail, and the control surfaces to a certain extent on the wings. Up until today, this accident is still considered as the worst accident involving a single airliner in the world.
The outcome of the event was that the Japanese public's confidence in Japan Airlines took a dramatic downturn and the number of passengers dropped to one-third. Months after the crash, domestic traffic had decreased. In 1986, for the first time in a decade, fewer passengers boarded JAL's overseas flights during New Years than the previous year.
Without admitting liability, JAL paid ¥780 million to the victims' relatives in the form of "condolence money". Its president, Yasumoto Takagi, resigned, while a maintenance manager working for the company at Haneda killed himself to apologize for the accident.
In 2009, stairs with a handrail were installed to facilitate visitors' access to the crash site. Japan Transport Minister, Seiji Maehara, visited the site on August 12, 2010 to pray for the victims. A book was written by Chirstopher Hood entitled Dealing with Disaster in Japan: Responses to the Flight JAL123. It was about the effect on Japanese society.
The crash also led to the 2006 opening of the Safety Promotion Center at the Tokyo International Airport. The center was created for training purposes to alert employees of the importance of airline safety and their personal responsibility to ensure safety. The center, which has displays regarding air safety, the history of the crash, and selected pieces of the aircraft and passenger effects (including handwritten farewell notes), is also open to the public by appointment made one day prior to the visit.

Aircraft Accident Report, English translation - Aircraft Accident Investigation Commission
Details of the book Dealing with Disaster in Japan: Responses to the Flight JL123 Crash
Details of the book Osutaka: A Chronicle of Loss in the World's Largest Single Plane Crash
Crash of Japan Airlines B-747 at Mt. Osutaka