Turkish Airlines Flight 981

Turkish Airlines Flight 981
	The unlucky machine at London Heathrow Airport, 1973
Accident summary
Accident type	Structural failure
place	Ermenonville , France
date	March 3, 1974
Fatalities	346 (all passengers + crew)
Survivors	0
Aircraft
Aircraft type	McDonnell Douglas DC-10-10
operator	Turkish Airlines
Mark	TC-JAV
Passengers	333
crew	13
	Lists of aviation accidents

Turkish Airlines flight 981 was a scheduled flight of the Turkish airline Turkish Airlines from Istanbul to London Heathrow with a stopover at Paris-Orly Airport . The wide-body aircraft of the type McDonnell Douglas DC-10 with the aircraft registration TC-JAV and the name Ankara took off on Sunday, March 3, 1974 around noon from Paris-Orly. About 10 minutes later, the machine crashed into the forest of Ermenonville , killing all 346 people on board. The air disaster Ermenonville thus claimed almost twice as many victims as by this time most serious accident in the history of aviation , which in January 1973, the Boeing 707 JY-ADO of Alia Royal Jordanian Airlines on the Kano ran off the runway and caught fire. Ermenonville was the worst single plane accident until Japan Airlines Flight 123 crashed in August 1985.

The cause of the crash was the loss of an improperly locked cargo door in flight, which led to explosive decompression . As a result, the rear cabin floor of the machine was partially destroyed, with important cables and control cables of the machine being impaired or interrupted. After that, the machine was hardly controllable.

As it later found out, the problem with the cargo door locking was known to the manufacturer McDonnell Douglas after a similar incident in June 1972. On the recommendation of the US aviation authority NTSB , McDonnell Douglas published the "Service Bulletin 52-37" for retrofitting the cargo doors for all DC-10s in July 1972. Two machines built in the spring of 1972, which were originally intended for the Japanese airline All Nippon Airways , were delivered to Turkish Airlines in December 1972 without these modifications , after All Nippon Airways waived acceptance. One of the two DC-10s was the unlucky machine on Flight 981. After these events were announced, McDonnell Douglas' reputation was severely damaged and the DC-10, which was built until 1988, received a negative image, also due to later accidents.

accident

Memorial in the forest of Ermenonville

Flight 981 took off from Istanbul and landed in Paris-Orly shortly after 11 a.m. local time in the morning. The DC-10 had 167 passengers and 13 crew members on board. 50 passengers ended their flight in Paris. The second leg of the flight from Paris to London was not fully booked, but due to a strike at British European Airways (BEA), many BEA passengers were rebooked on flight 981. Among the passengers from a dozen countries were 17 English rugby players who had played an international match in France the day before, the track and field athlete John Cooper , several British models and 48 Japanese bank management trainees.

The plane took off from Orly at 12:30 p.m. local time from runway 08 in an easterly direction. To fly around Paris, the flight went via Coulommiers in the east and only then turned towards Montdidier (Somme) with a course 345 degrees ( north-northwest ) on London. The tower in Orly gave clearance for FL 230 (7000 meters). When the aircraft was climbing over the town of Meaux at flight level 130 (approx. 4000 meters) at about 12:40 p.m. , the tower in Orly received distorted radio messages from Flight 981: While the pilots were speaking Turkish, the words “pressurization” (“pressure system ") And" Overspeed "(" too high speed ") mentioned. The following sentence could also be heard: "the fuselage has burst" - in German: "the trunk has burst open".

The aircraft disappeared from the radar screen shortly afterwards. A short time later the completely destroyed machine was found southeast of the city of Senlis in the forest of Ermenonville. The parts of the DC-10, many of which could not be assigned, were scattered on a 700 meter long and 100 meter wide aisle. All 346 people on board were killed. Only 40 of the bodies could be visually identified, the identity of 9 passengers could no longer be determined.

The extraordinary degree of destruction led to the assumption that a bomb could have caused the accident. After two terrorist organizations reported to the authorities and wanted to confess to the attack, Turkish reporters speculated that terrorists originally wanted to blow up a BEA machine and that the strike forced them to transfer their plans to the Turkish plane.

Investigations

The two flight recorders of the DC-10 were quickly found. The evaluation of the flight data recorder (FDR) and voice recorder (cockpit voice recorder, CVR) showed that the crew lost control of the aircraft after an explosion, which was practically no longer controllable after it had flown over Meaux. The explosion was followed by a loud sound of air. At the same time the middle engine (engine no. 2) located in the center of the tail failed. During these events, one of the pilots had pressed the radio transmission button on the microphone, which transmitted what was happening in the cockpit over the radio.

The plane quickly descended into a 20 degree descent angle, accelerating as Captain Nejat Berkoz and First Officer Oral Ulusman tried to regain control. With increasing speed, the nose of the aircraft tilted further and further down, Captain Berkoz shouted "Speed!" And tried to get the nose of the aircraft up again with more engine thrust . 72 seconds after decompression, the DC-10 sped into the forest at a speed of 430 knots (796 kilometers per hour). The high speed led to the complete destruction of the machine.

The degree of destruction was so high that many parts could not be correctly assigned and it was not possible to determine whether parts were missing. After the accident, the radar showed a second echo behind the plane that did not move. A call from a farmer explained this echo: The rear cargo hold hatch, parts of the cabin corridor and six passenger seats with their dead occupants had fallen into a beet field near the municipality of Saint-Pathus , about 15 kilometers south of the main crash site.

French accident investigators found that the lock on the rear cargo hold hatch had failed, which opened the hatch and was then torn off the aircraft. This initially led to an explosive decompression in the cargo hold - not in the passenger cabin . However, the cabin floor could not withstand the high pressure difference. In the rear area of the cabin, the intermediate floor was torn out together with two rows of seats and thrown out through the open hatch of the cargo space. The control cables and lines laid in the false floor were destroyed, as a result of which control of the elevator and rudder was lost, so that the aircraft could no longer be steered. In addition, the (middle) engine number two failed.

Causes of the accident

Picking up the rear of the machine. Part of the cargo door, the loss of which led to the crash, can be seen at the bottom of the picture, between the passenger door and the wing

Due to its size, the loading door of the DC-10 could not be swung into the interior of the hold without having to sacrifice a considerable area of the hold. Instead, the hatch was opened to the outside, but there was a risk that if it was not locked correctly, the hatch could be pushed out due to the pressure inside the hold. The fact that the construction used was not designed to be sufficiently operationally reliable became apparent almost two years before the crash of the Turkish plane, when an incident occurred for this reason: On American Airlines Flight 96 with 67 people on board, the DC- 10-10 (N103AA) on June 12, 1972, the rear cargo hold door during flight, which led to a sudden loss of pressure and the collapse of the cabin aisle in the rear area of the machine. The crew managed to land the machine safely at Detroit Airport. In aviation history, the incident was also known as the "Windsor Incident", after the Canadian town of Windsor, Ontario , over which the accident occurred.

As a result of this incident, on July 3, 1972, a technical bulletin (Service Bulletin) was issued by McDonnell Douglas and the United States Aviation Administration (FAA ), which provided for a repair of the locking system of the cargo door. Lists were issued listing the machines that were to be converted. On it were all DC-10s previously delivered by the operators American Airlines , United Airlines , National Airlines and Continental Airlines , but two aircraft that were completed in February / March 1972 and originally ordered by the Japanese leasing company Mitsui for All Nippon Airways were missing . However, All Nippon no longer showed any interest in the machines and decided on a different type of aircraft. The two DC-10s with the construction numbers 46704/29 and 46705/33 were finally handed over to Turkish Airlines in December 1972 without the improved locking system and as Ankara with the registration number TC-JAV (46704/29) and Istanbul TC-JAU (46705 / 33) used for international flights to Europe and Asia. In February 1973 Turkish Airlines received a third DC-10 ( Izmir TC-JAY with the build number: 46907/78).

The changes to the DC-10's cargo hatch were recommended by the NTSB and FAA. The NTSB had proposed an electrical system that should be made mandatory by law. However, the FAA had advocated that an upgrade "should" be made to the hatch, but not legally stipulated, as this process would be associated with additional costs. In the end, both organizations and the manufacturer agreed that the change “did not have to be made”.

The two planes “Ankara” and “Istanbul” were delivered to Turkish Airlines six months after the “Windsor Incident”. The change to the hatch could have been made, but would have been associated with delays, which in turn would have meant costs for the manufacturer. The cargo hold locking on the two Turkish Airlines planes was therefore not changed.

Mohammed Mahmoudi, the baggage handler who closed the hatch on Flight 981, had noticed that it didn't take a lot of force to close the latch handle. The accident investigators concluded that the system was no longer intact beforehand.

A first change that was made after the "Windsor Incident" was the installation of a small control window through which one could check the complete locking of the hatch. However, Mahmoudi was not aware of the purpose of this window. He had been told that if the locking handle were operated correctly and the pressure relief valve flap completely closed, the hatch would also be securely closed. The work instructions for checking the secure locking were written in Turkish and English next to the control window on the machine, but the Algerian Mahmoudi did not speak either language.

The task of ensuring that all doors and hatches are closed, was either that of the flight engineer of the machine or the Chief Ground engineer of Turkish Airlines. However, the company did not have a chief ground engineer in Paris-Orly, and the aircraft's flight engineer did not conduct the inspection. Some media called for Mahmoudi to be arrested. However, experts found it unrealistic that an uneducated, poorly paid baggage handler who could not read the warning labels should be responsible for the safety of the aircraft.