Wednesday is the 30th anniversary of the deadliest single-aircraft accident in history: the crash of Japan Airlines Flight 123, which killed 520 passengers and crew.

“In what apparently is the worst single-plane accident ever, the Japan Air Lines Boeing 747, with 524 people aboard, crashed on the north side of Mount Ogura. First reports from the crash site said there weren’t any survivors. Before the crash, the pilot, who sought to land in a nearby U.S. air base, reported ‘unreliable control,’ saying cabin pressure had dropped because of a broken door,” The Wall Street Journal reported Aug. 13, 1985.

Later updates revealed that four people survived, and that the plane had crashed on Mt. Osutaka.

The Boeing 747 SR-100 took off from Tokyo for Osaka at 6:12 p.m., experiencing trouble about 13 minutes into the flight, while over Izu Peninsula, according to a report by Japan’s transport ministry published in June 1987.

An explosion was heard just before the aircraft reached 24,000 feet. The pilot immediately requested to return to Tokyo’s Haneda airport. “The aircraft suddenly plunged into a dive banking to the left to northwest direction, and went out of sight behind the mountain. Thereafter, smoke and flashing lights were seen emanating from behind the mountain,” witnesses said, according to the report. The plane crashed at 6:56 p.m.

About 30 minutes elapsed between the first report of an emergency and the actual crash. As the pilots attempted to control the plane, those aboard spent their final minutes writing messages to their family and loved ones.

Buddhist monks sit in front of rows of coffins at a temporary morgue for victims of Flight 123. Illustration: Associated Press

“The stricken jet rolled and yawed. As passengers cried out and a cloud of condensation filled the windy cabin, Hirotsugu Kawaguchi, a 52-year-old shipping-company executive in seat 22H, took out his black pocket diary and scrawled a message to his family across seven pages,” reporter Bruce Stanley wrote in the WSJ in July 2006.

“'Be good to each other and work hard. Help your mother,' he exhorted his son and two daughters. ‘I'm very sad, but I'm sure I won't make it....I don't want to take any more planes. Please God, help me. To think that our dinner last night was the last time.'"

The remote, mountainous location of the nighttime crash made it difficult for rescue teams to determine the precise location. They were only able to reach the site next morning.

The aircraft was destroyed. “It is considered that passengers and crew members in the fore and mid fuselage were all instantaneously killed by the shock estimated as much as hundreds of G as well as the total destruction of structures of the fore and mid fuselage at the time of crash,” the ministry said in its report.

The four survivors were “able to escape death miraculously,” it said.

U.S. and Japanese investigations concluded that the crash was caused by a flawed repair made by Boeing Co. seven years earlier. The flawed splice and fatigue cracks over time caused the rupture of the aft pressure bulkhead, they said.

Follow this link to read the transport ministry’s report, and this link for the WSJ article published in 2006 about the crash.