On the evening of August 12, 1985, in the middle of Japan’s Obon holiday, Japan Airlines Flight 123 took off from Tokyo’s Haneda Airport for Osaka with 524 people aboard — 509 passengers and a crew of 15 — in a high-density Boeing 747SR built for Japanese domestic routes. Twelve minutes into the flight, at cruising altitude over Sagami Bay, the aircraft’s aft pressure bulkhead burst.
The explosive decompression tore away much of the tail fin and severed all four hydraulic systems, leaving the jet without working flight controls. For 32 minutes Captain Masami Takahama, First Officer Yutaka Sasaki and Flight Engineer Hiroshi Fukuda kept the crippled aircraft in the air on engine power alone as it pitched and rolled across the mountains northwest of Tokyo, fighting to turn back toward Haneda. At 6:56 p.m. the 747 struck a ridge of Mount Takamagahara, in Ueno village, Gunma prefecture, about 100 kilometres from Tokyo.
Of the 524 people aboard, 520 were killed. Four passengers — all women seated together toward the rear of the cabin — survived: an off-duty JAL flight attendant, a mother and her eight-year-old daughter, and a twelve-year-old girl. It remains the deadliest accident involving a single aircraft in aviation history. Among the dead was the singer Kyu Sakamoto, whose song “Sukiyaki” had topped the American charts in 1963.
Japan’s Aircraft Accident Investigation Commission found that the bulkhead had been weakened by an improper repair seven years earlier. In June 1978 the same aircraft had struck its tail on landing at Osaka, cracking the bulkhead; the repair was carried out by Boeing’s own technicians, but a splice plate in the repair was joined with a single row of rivets where the design required two, leaving the joint with a fraction of its intended fatigue strength. Flight by flight the weakened bulkhead tore a little further, until on August 12, 1985 it failed outright.
The commission’s report was published in June 1987. The president of Japan Airlines resigned in the aftermath, and the airline accepted responsibility for the accident. In 2006 JAL opened its Safety Promotion Center near Haneda Airport, where wreckage of Flight 123, including the failed bulkhead, is displayed as a permanent lesson to its own staff. A memorial stands at the crash site, on the ridge now known as Osutaka-no-One.
Download the AAIC Investigation Report (English) (55 MB file)