The crash of Japan Airlines Flight 123 forty years ago remains the world’s worst aircraft accident involving a single airliner. Stephen Skinner looks back at the events of that tragic day and the subsequent investigation

Japan Airlines Boeing 747SR-46, JA8119 (c/n 20783), was delivered to the airline in February 1974. The SR had been developed after a request from Japanese airlines and had modifications to its structure to cope with the greater number of flight cycles

WERNER FISCHDICK COLLECTION

Japan Airlines was unusual in using nine Boeing 747SRs (Short Range), capable of carrying 550 passengers and a flight crew of 12 on short-haul domestic flights. In addition to the high-density seating, these 747SRs had strengthened wings and undercarriages owing to the greater number of take-offs and landings (or cycles) required by short-haul flights. Japan Airlines was, at that time, the largest 747 operator in the world, with 38 in service.

One such example, JA8119 (c/n 20783), was delivered in February 1974. Its service life was uneventful until a landing at Osaka/Itami Airport on June 2, 1978. It touched down, lifted off, and then, in an excessively nose-high attitude, touched down again on its tail, striking and scraping the tarmac. All aircraft have tail skids designed to absorb the impact of such events; however, in this instance, JA8119 received severe damage to its underside, resulting in the removal of skin panels and cracking of its rear pressure bulkhead. The 747 was grounded for a month while Boeing engineers supervised repairs, replacing the lower part of the rear fuselage and mending the damaged rear pressure bulkhead. Following a test flight, JA8119 returned to service.

A busy flight

Seven years later, on Monday, August 12, 1985, JA8119 had completed its fourth service of the day and returned to Tokyo/Haneda Airport at 1717hrs local time. The large number of passengers speedily disembarked, and the 747 was readied for its next service as JL123 to Osaka. The three-day traditional religious festival of Bon Odori was starting the next day, and many passengers were travelling on the short one-hour flight to Osaka to be united with their families. As a result, the 747 was booked almost to capacity, with 509 passengers, 12 cabin crew members, two pilots, and a flight engineer on board.

The flight was under the command of Captain Takahama, a senior training captain, who was supervising First Officer Yutaka Sasaki, who was training to become a captain and was occupying the left-hand seat. Despite its tight schedule, at 1804hrs, it was ready for pushback from Gate 18, and eight minutes later, the 747 took off from Runway 15L. By 1824hrs, the jet had reached its cruising altitude of 24,000ft.