On 12 August 1985, Japan Air Lines Flight 123, a Boeing 747SR-100 registered JA8119, crashed into a mountain ridge in Gunma Prefecture about 100 kilometres northwest of Tokyo, killing 520 of the 524 people aboard. Four passengers survived. It is the deadliest single-aircraft accident in aviation history and the deadliest accident involving any single airliner. The aircraft had departed Tokyo’s Haneda Airport at 18:12 local time on a short domestic flight to Osaka’s Itami Airport. About twelve minutes after takeoff, climbing through roughly 24,000 feet over Sagami Bay, the aft pressure bulkhead at the rear of the cabin ruptured.
The rupture was catastrophic in a specific, cascading way. The sudden release of pressurised cabin air into the unpressurised tail blew off a large part of the vertical stabiliser and severed all four of the aircraft’s hydraulic systems, which ran together through the tail. With no hydraulics, the crew lost the use of every conventional flight control — ailerons, elevators, rudder, and the ability to extend flaps or slats. Captain Masami Takahama and his crew were left to fly a 250-tonne aircraft using engine thrust alone, fighting a violent up-and-down oscillation called a phugoid. For about 32 minutes they kept the aircraft airborne, turning it by varying power between the wings, before it descended into the forested ridges of the Osutaka area and struck terrain at 18:56.
Japan’s Aircraft Accident Investigation Commission (AAIC) investigated, with participation by the United States National Transportation Safety Board and the manufacturer, Boeing. Its report, released on 19 June 1987, traced the disaster to a faulty repair Boeing had performed seven years earlier. In 1978 the same airframe, then operating as JAL Flight 115, had suffered a tailstrike on landing at Osaka that cracked the aft pressure bulkhead. The Boeing-approved repair called for a single continuous splice plate joining the bulkhead’s two halves with three rows of rivets. The repair crew instead fitted two separate splice plates, an arrangement that left part of the joint effectively carrying load through a single row of rivets and cut its fatigue resistance to roughly 70 percent of a correct repair. Fatigue cracks grew silently from the rivet holes over thousands of pressurisation cycles until, after about 12,300 flights, the joint failed.
No criminal conviction followed in Japan, though prosecutors investigated for years; the responsibility lay overwhelmingly with a foreign manufacturer’s repair performed years before the crash. The accident reshaped the inspection of pressure-vessel repairs, the philosophy of hydraulic-system redundancy and routing, and aircraft survivability standards, and it remains a landmark study of how a single hidden maintenance defect can sever the redundancy that a four-system aircraft was designed around.
On 19 July 1989, United Airlines Flight 232, a McDonnell Douglas DC-10-10 registered N1819U, crash-landed at Sioux Gateway Airport in Sioux City, Iowa, after the catastrophic failure of its tail-mounted number two engine destroyed all three of the aircraft’s hydraulic systems. Of the 296 people aboard, 112 were killed and 184 survived. Unlike most entries in this file, the outcome is remembered less for the deaths than for the survivals: an aircraft left with no conventional flight controls was kept airborne for some 44 minutes and brought to a runway by a crew improvising with engine thrust alone, a feat the investigators and the wider profession regarded as extraordinary.
The aircraft had departed Denver’s Stapleton International for Chicago O’Hare, with onward service to Philadelphia. About an hour into cruise at 37,000 feet, the stage-one fan disk of the rear General Electric CF6-6 engine fractured and burst apart. The engine failed in an uncontained manner: high-energy fragments were thrown clear of the engine casing and through the tail. Those fragments cut the lines of all three independent hydraulic systems where they passed close together near the tail. Hydraulic fluid drained away, and with it went the aircraft’s ability to move its elevators, ailerons, rudder, flaps, and slats. The DC-10 was, in the conventional sense, uncontrollable.
What followed was a controlled descent flown on differential thrust. Captain Alfred Haynes and his crew, joined by an off-duty United DC-10 training check airman, Captain Dennis Fitch, who was travelling as a passenger and came forward to help, manipulated the two remaining wing engines — adding and reducing power on each side to turn, and using power changes to coax the nose up and down — to fly the crippled aircraft toward Sioux City. On final approach the aircraft was descending too fast and drifting right; the right wingtip struck the runway, the aircraft cartwheeled, broke apart, and caught fire. That so many lived through it was attributed to the crew’s airmanship, the cabin crew’s preparation, and a well-drilled local emergency response that happened to be on a shift change with extra personnel available.
The National Transportation Safety Board, in report AAR-90/06, traced the disaster to a metallurgical defect that had been present in the fan disk since its manufacture and had grown into a fatigue crack that inspections failed to catch. The board’s probable cause did not stop at the metal; it faulted the inspection and quality-control regime that should have found the crack and did not.
On 13 January 1982, Air Florida Flight 90, a Boeing 737-200 attempting to take off from Washington National Airport in a snowstorm, climbed only a few hundred feet before stalling, struck the 14th Street Bridge over the Potomac River, and fell into the freezing, ice-choked water. Of the 79 people aboard, 74 passengers and 5 crew, all but five were killed; four people on the bridge also died in the impact. The official toll was 78 dead — 74 aboard the aircraft and 4 on the ground — with five survivors pulled from the river. It was a takeoff accident in plain sight of the United States capital, and the National Transportation Safety Board’s reconstruction made it one of the most-studied crew-performance cases in aviation.
The 737, registration N62AF, had been deiced before pushback, but a long delay between deicing and departure left it accumulating fresh snow and ice on the wings as it waited in the falling snow for takeoff clearance. Critically, the crew did not switch on the engine anti-ice system. Without it, the engine pressure probes iced over and gave falsely high thrust readings; the engines were in fact producing substantially less power than the gauges indicated. On the takeoff roll the captain pressed on despite the first officer twice voicing concern that the readings looked wrong. Contaminated by ice and under-powered, the aircraft lifted off, struggled to climb, stalled, and came down on the bridge and into the river.
The NTSB determined the probable cause to be the flight crew’s failure to use engine anti-ice during ground operation and takeoff, their decision to take off with snow and ice on the wings, and the captain’s failure to reject the takeoff when the first officer drew attention to the anomalous engine readings. Contributing factors included the prolonged ground delay after deicing, the known tendency of the 737 to pitch up when its leading edges are contaminated, and the crew’s limited experience operating jet transports in winter conditions.
The crash drove lasting changes in cold-weather operating procedures, in deicing and holdover practice, and in the training of crews for winter takeoffs. It also entered the public record for the conduct of the rescue, including a passenger who repeatedly passed a helicopter lifeline to others before slipping beneath the ice, and the bystanders and aircrews who pulled survivors from the river.