Turkish Airlines Flight 981
Encyclopedia : T : TU : TUR : Turkish Airlines Flight 981
Turkish Airlines Flight 981 was a flight that flew on an Ankara–Orly International Airport (near Paris)–London Heathrow Airport (London) route. The aircraft, a DC-10 was leased from American Airlines in 1973.
On March 3 1974 the flight (registration number TC-JAV, named "Ankara") was involved in the Ermenonville air disaster — a high speed crash into the forest at Ermenonville, France, only a few minutes after take-off on the Paris-London leg. A defective latch on the cargo door caused it to open in flight, resulting in an explosive decompression. The decompression caused the cabin floor near the door to fail, blowing six passengers out of the plane and severing the control cables leading to the tail surfaces. With elevator control lost, the plane lost horizontal stability and dived into the ground at 430 knots.
Although there was no radio contact made with the ground, ATC heard the pilot Nejat Berkoz speaking with cabin crew in Turkish. On the tape from the recovered cockpit voice recorder, an explosion was heard, followed by a rush of air out of the plane. At this point Berkoz asked "What has happened", and was told, "The fuselage has burst!" During the 77 seconds after the decompression, the crew tried desperately to control the plane, but the plane did not respond to any of the attempts. At one point the crew did manage to raise the nose, but it was too late, as the plane was just a few hundred feet above the ground.
The plane left a trail over a kilometer long through the forest, and few pieces larger than a meter were left. All 346 people aboard were killed in the accident. A large number of these were English rugby fans who had transferred to the plane after their own flight had been canceled due to a strike in London. It was the worst air disaster of all time until the Tenerife Disaster of 1977, and the worst single-airplane disaster before the crash of Japan Airlines Flight 123 in 1985.
The latch of the DC-10 is an interesting study in human factors, interface design and engineering responsibility. The control cables for the rear control surfaces of the DC-10 are routed around the hatch, so a failure of the hatch could lead to the disruption of the controls. To make matters worse, Douglas chose a new latch design to close it. If the hatch were to fail for any reason, there was a very high probability the plane would be lost. This possibility was first discovered in 1969, and actually occurred in 1970 in a ground test. Nevertheless nothing was done to change the design, presumably because the cost for any such changes would have been borne out-of-pocket by the fuselage's main contractor, Convair. Dan Applegate was Director of Product Engineering at Convair at the time. His serious reservations on the integrity of the DC-10's cargo latching mechanism have long since been a classic case in Engineering ethics.
The first latch related accident, on American Airlines Flight 96, occurred in June 1972 on a commuter flight from Detroit to Buffalo, New York, when the hatch was closed improperly by ground crew unfamiliar with the new latch design. The hatch blew off at 12,000 feet, destroying the rudder control completely and damaging the elevator controls. Quick thinking on the part of the pilot and the help of a general aviation pilot in the cabin allowed the plane to land with no injuries. The NTSB made several recommendations in the wake of this first accident, but the FAA didn't order any of them made; instead, Convair offered to carry them out voluntarily.
However, these modifications were never actually carried out. The aircraft that crashed at Ermenonville had been certified by three inspectors at Convair's Long Beach plant as having been modified, but nothing had actually been done; indeed, a manufacturing error meant that the door latch was even flimsier than on other unmodified DC-10s. All of this came out in the post-crash investigation, leading to a number of changes in the FAA's reporting chain.
Similar accidents
Outward opening cargo doors are inherently not fail safe. While an inward opening door (a plug door) which is unlatched will not open due to the pressure differential, an outward opening, non-plug type door needs to be locked shut to prevent unwanted opening. This makes it particularly important that the locking mechanisms be secured. Aircraft types other than the DC-10 have also experienced catastrophic failures of a door: The Boeing 747 has experienced a number of such incidents, the most noteworthy of which occurred aboard United Airlines Flight 811 in February 1989, when the cargo door failed, and caused a section of the fuselage to fail, causing the deaths of 9 passengers who were expelled from the aircraft.
See also
Further reading
- Final report. In French[link].
- Paul Eddy et al, Destination Disaster. Quadrangle, The NYT Book Company.
- Moira Johnston, The Last Nine Minutes, The Story of Flight 981. Avon Publishers.
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.