Japan Air Lines Flight 123: How the Bulkhead Burst Took the Tail

This clip from Smithsonian Channel's Air Disasters series focuses on the engineering of the Japan Air Lines Flight 123 accident. It joins the story as the 747 climbs towards 24,000 feet.

The bulkhead

The narrator explains that the cabin is pressurised while the tail behind the rear pressure bulkhead is not, so every climb stretches the bulkhead. On JA8119 a faulty repair made that joint weak. The clip shows a test that reproduced those conditions, with cracks lengthening around the rivet holes until the bulkhead failed. On Flight 123 the burst opened a hole of about 30 square feet, brought down the ceiling around the rear toilets and sent the cabin air into the tail fin, which broke off.

Thirty minutes in the air

Without the tail, and with the hydraulic lines cut, the pilots could not use the rudder or the other flight controls. The narrator explains the phugoid motion that followed: the nose drops, the aircraft speeds up and climbs, slows, and drops again, sometimes by several hundred feet at a time. An investigator interviewed in the clip calls it a miracle that the crew kept the aircraft flying for 30 minutes or more, much of it over high mountains. Four hand-picked crews were later put in a simulator with the same failure, and none of them could land the aircraft.

A single row of rivets

The clip ends with an NTSB investigator, Ron Schleede, describing how he told a senior Boeing designer of the 747 what had been found: the repair, done by Boeing, used a single row of rivets where a double row was required. The narrator notes that no fault was found in the 747 design itself.

The Fascinating Horror documentary on this page covers the full flight, the rescue and the aftermath.