The DEADLIEST crash of its time. Turkish Airlines flight 981

This video will include references to large historical loss of life, so if you are a sensitive viewer, please note that it is March 3, 1974. Turkish Airlines Flight 981, a McDonnell Douglas DC-10, leaves the airport of Paris Orly as the plane climbs. At about 12,000 feet a sudden explosive decompression occurs when the rear cargo door is torn off the aircraft. If you think this sounds familiar, it's because less than two years ago the crew of American Airlines Flight 96 defied all odds and managed to land. your plane

crash

ed after a very similar incident this

time

, although the result is much scarier, so what really happened this

time

has parallels with the previous accident and if so, how is it possible?

As always, we will find the answer in the final. report, so stay tuned, it's impossible to tell you the story about Turkish

airlines

like 981 without first explaining American Airlines Flight 96. Well, these incidents are very similar and I made a video about American Airlines Flight 96 last week, so I highly recommend you check it out before watching this video in summary. American Island Flight 96 was also flown by a Mcdonnell Douglas DC-10 and as the crew departed Detroit and climbed approximately 11,700 feet, the aft cargo door was torn off the aircraft, causing explosive decompression. and due to the lack of ventilation between the passenger cabin and the cargo hold, part of the aft cabin floor collapsed towards the missing door, severely damaging the control cables of the horizontal stabilizer, elevator rudder and engine. number two, now through a combination of skill of both the

flight

crew and the cabin crew, this aircraft managed, after some severe difficulties, to land safely on the ground and everyone survived, but in the case of the

flight

981 of the Turkish airline became the largest aviation accident in terms of human lives. lost at the time, so what are the differences between the two?

Well, first of all, we have to look at what happened in the almost two years that separated the two accidents of American Airlines Flight 96 that occurred in June 1972 and the safety of national transportation in February 1973. the board came with their final report in the final report they had some pretty harsh comments on the design of the mcdonald douglas dc10 it said that the aft cargo door locking mechanism needed to be reinforced specifically in the torque tube that connected the handle to the ventilation door to ensure that it cannot be bent, thus ensuring that the door handle could not be closed if the locks were not in the correct position, on top of that, some kind of verification procedure needed to be performed so that The person operating the door was able to verify that the locks had been fully set into position and it was also necessary to increase ventilation between the cargo and passenger holds due to the position of the control cables on the floor between the two compartments, the rapid Depressurization should not be allowed to damage these critical control functions.

As soon as the Federal Aviation Administration got this excellent report, they started working on something called AED law, which is an Air Verdan directive and an Air Vertex directive is the big hammer. in aviation law, okay, if a flight limitation directive is issued, then anyone flying the type of aircraft that you know is covered by the announcement should basically ground it and resolve the problems before they are allow to continue. Flying it will involve really big costs for any airline flying that type, it was covered by the announcement and will be a huge embarrassment for the aircraft manufacturer and it could be why the director of Douglas McDonnell Douglas department contacted the FAA administrator and the boatman sat down and reached what is known as a gentlemen's agreement and in the gentlemen's agreement the FAA promised not to issue an awareness directive and in exchange mcdonnell douglas would ensure that any of The issues raised in the final report would be addressed through something called service bulletins with alert status.

Now the service bulletin is a less powerful tool than an advertisement, whereas an advertisement would force anyone to fix problems immediately. a little bit of leeway a little bit of time for

airlines

to implement the necessary fixes, they are still powerful, especially if it comes with an alert status, indicating that this has saved the implication that any airline that does not comply with the Safety bulletins open themselves up to possible litigation in case something were to happen, but there is the big hammer. Very quickly after this, Mcdonnell Douglas issued three separate service bulletins for the DC10.

The first ordered the airline to put up some kind of bracket to keep the torque tube connected. to the handle and because of that support tube it would be impossible to bend the tube and therefore in theory it would be impossible to close the door handle if the locks were not in the proper position. The second was an instruction to create approximately one inch in size. viewing hole in the door so that anyone operating it could look through that viewing room and physically see that the locks had reached the correct position. The third service bulletin was to provide better electrical wiring to the electric motor that drove the locking mechanism to ensure that it did not stop prematurely when the part of the special report that mentioned increasing ventilation between the passenger cabin and compartment came. load.

Mcdonnell Douglas had not yet found a suitable solution for that, so there was no service bulletin. issued on that matter at that time the plane that would later become Turkish Airlines Ship 29 Flight 981 was handed over to Turkish Airlines with documentation indicating that these three service bulletins had now been successfully implemented in subsequent investigations. that would come it came to light that only one of them had been completed, but we will talk about that within a while Turkish Airlines Flight 981 was scheduled as a two-leg flight starting in Istanbul and then an approximately four-hour flight to Paris Orly airport and then a very short last leg to London Heathrow on the first leg there were 167 passengers and 11 crew the captain of the flight is called neyat berkus he is 44 years old he has 7,000 hours in total of which 438 hours were in type On the day of the accident along with him was the first oral officer Ulusman 38 years 5589 hours and 628 hours in type the flight engineer's name was Erhan Archer 37 years 2113 hours and 775 hours in type there were eight flight attendants from both the United Kingdom, France As from Turkey on board the first flight was uneventful, leaving Istanbul at 7:57 local time and landing about four hours later at 11:02 local Paris time.

When it arrived in Paris, 50 of the passengers disembarked from the plane and boarded another 216 passengers, this was quite unusual because normally this second leg had a little less reserve, but due to a strike that was taking place, the Air France passengers and British Airways had been rebooked on this Turkish Airlines flight to take them to London, the return time was initially supposed to be just one hour. but because of all these additional passengers that were boarding the plane, they delayed the flight another 30 minutes and while they were making the change, the cargo room was completely emptied of cargo and there was no new cargo entering that compartment, so it was closed there three people working to empty the aft cargo compartment and the person who closed the door later reported that he had no problem closing the door, that no additional force was needed to put the handle in place and also said that there was no I checked the small verification window that had been installed, the reason for this was that no one had instructed you on why you should do this.

He didn't know what to look for. He had only seen other people do it now by the verification window. door handle after American Airlines Flight 96, some notes had been installed instructing people to close the door and how important it was to verify that this appearance was actually in place, unfortunately, although that note was written in Turkish and in English, the person who was closing the door only spoke French, so he never saw or understood the meaning of this note at time 12, 24 local time, Turkish Airlines Flight 981 received its pushback clearance and boarded clearance to the holding position of runway 08 at Orly during taxiing, everything appears to be normal, the cockpit voice recorder does not indicate anything out of the ordinary and at time 1229 the plane began its takeoff roll initially the clearance was to climb to 4000 feet and then contact the departure controller the weather in the area was perfectly fine light winds of 0.60 degrees and only a few cumulus clouds around the departure was completely normal, the aircraft climbed to 4000 feet, He switched to the departure controller and the new controller instructed the aircraft to continue the clamp to flight level 230, which is 23,000 feet, and turn left. to a vor navigation aid called montidiere mike tango delta, the plane completes its turn toward montiria, deploys on a five-cylinder three-greave heading, which is more or less a pitch heading, and continues its climb as instructed, but As the plane climbs about eleven,500 feet as a sudden decompression can be heard on the cockpit voice recorder and also indicated on the flight data recorder, the first officer is heard yelling that the plane has exploded and then complete pandemonium, well, the flight data recorder indicates that the airplane is pushed in one yaw to the left when the rudder is deflected to the left the elevator pitches three degrees down, this puts the nose of the airplane in position of a dive and at the same time engine number two begins to fail, very similar to what happened on American airlines.

Flight 96 at the air traffic control center in Paris, air controllers can hear a transmission believed to be coming from Turkish airline flight 981. The reason they are not sure is because of the person holding down the transmit button on the plane. is not actually communicating with our traffic control, you can hear voices in Turkish talking about the seriousness of the problem they are facing. You can also hear the cockpit altitude alarm in the background as well as the overspeed alarm as this transmission continues for several seconds. Two more transitions will also follow in the next 70 seconds remaining of this flight at the same time as the controllers look. both its primary and secondary radar the secondary radar is the one that receives information from the aircraft's transponder and approximately when the first transmission comes from the aircraft, the aircraft code disappears from the secondary radar, but on the primary radar controllers can still see what now appear to be two different radar echoes, so the first one is representative of the aircraft. which continues north turning slightly to the left, but the secondary echo remains in approximately the same location and remains for about a minute or two before disappearing from the screen.

Further investigation will show that when the rear cargo door opened once again in flight and was torn from the plane, this time the floor of the passenger cabin at the rear of the plane collapsed in a much more catastrophic manner and two rows of passengers were pushed through the open cargo compartment and it is likely that that echo from the secondary radar that the air traffic controller saw was actually what was happening, the plane is in a dive of almost 20 degrees nose down and that is a horrible attitude. Well, while this is happening, the speed of the plane is increasing to 360 400 and subsequently at 430 knots, the speed is increasing.

The way airplanes are built is that if they do not have any type of control, the stability of the airplane will return the nose to a nearly level position and this is what appears to happen on this flight and if the nose subsequently increases from a minus 20 degrees pitch to about -4 degrees pitch, the speed stabilizes around 430 knots, but although the pilot appears to have control of his ailerons, in this case there is no control or pitch, so the plane will actually continue flying for another 15 kilometers or so. Before impacting the Ermenoville forest, which is about 37 kilometers northeast of Paris, the plane initially makes contact with the treetops at a downward angle of about four degrees and a slight turn to the left and subsequently

crash

es into the ground with almost 800 kilometers per hour due to that speed and the force of the impact, the plane shatters into thousands of small fragments and cannot beNo fire occurs from the force of impact alone, obviously this is an unsurvivable event and all 346 people on board are killed instantly, making this the

deadliest

aviation disaster at the time.

Now the investigation begins and among the debris field they managed to find both the cockpit voice recorder and the flight data recorder, which greatly helps the investigation also in a field approximately 15 kilometers before, just below where it occurred. The initial incident, they find the bodies of six passengers still strapped to their seats and what remains of the aft cargo door and when they begin to look through the cargo door they immediately recognize the similarities to accident two. years before American Airlines flight nine and six because when looking at the locking mechanism they see once again that the four main locks are not properly activated, they have been partially activated but have not reached the center position which makes the entire locking mechanism irreversible but how is it possible?

There were three separate service bulletins in effect to prevent precisely this from happening. As investigators continued to look out the door, they realized that even though the aircraft had been certified to all three of these safety bulletins. In fact, the bracket that is supposed to hold the upper torque tube and support it to make sure it can't bend has not been installed. It hasn't been installed at all. There is some indication that work has been started on the door, but it has never been completed and when they continue to look down at the locking mechanism, they look at the locking pins.

The way locking pins are supposed to work is that as long as the locks are not fully in position, the locking pins are hidden behind them. a pair of metal zip ties, so if you try to close the door handle with the locking pins behind them, the zip ties will basically prevent the mechanism from moving and make it impossible to close the door, but on the crashed plane it seems that These pins have been manually adjusted and are now about eight millimeters shorter than they should be and what that means is that when the door handle is closed the locking pin comes into contact with the back of the flange metal, but there is very little margin and that margin can be overcome by bending the entire mechanism and because the support bracket has not been installed, the torque tube is allowed to bend again, making it easier to close the door, It would only take about 50 pounds to close the door. and this came up with the ground handling agent who said that he did not feel that he needed to use any excessive force more than what he was accustomed to to close the door handle.

Another adjustment that was found is that the lock indication mechanism is supposed to send the signal to the cabin indicating when the doors are properly closed. It has also been adjusted so that in the position it is in, the closed door light would have gone off before the lock reached its properly closed position, now the ground handling agent would do this. He would have been able to stop this sequence of events if he had been properly trained to verify that the locking mechanism had been activated correctly, but he had not been trained and, in fact, on a regular basis it would be the Turkish airlines ground engineer who would have to walk and verify that these locks were in place, but he was not on duty that day, so you can see the guys, as is the case with many of these accidents, if any of these factors had not been in place.

It would have stopped the sequence of events that led to the disaster if the ground service agent had checked the observation room and verified that the locks were in place, would have seen that they were not and would have stopped it if someone from the service bulletins that were implemented to prevent this from happening had they been implemented correctly, it would not have happened either, but since that was not the case, the aircraft proceeded to take off with the locks not correctly activated and as the differential pressure within the cargo hold began to increase. , as well as the pressure in the loading door.

If the loading door was not closed correctly, that pressure would have been directed towards the stops it was designed to stop and nothing would happen, except that the locks were not closed correctly, all this force was now transferred to the bolts that held the mechanism instead and when the force became strong enough, it severed those balls opening the door and allowing disaster and this happened at around 12,000 feet which is almost exactly the same altitude that happened on American Airlines Flight 96 , but why did this DC-10 end up in such a big disaster when American Airlines Flight 96 managed to land the plane safely?

The answer to this probably lies in the load. of the plane because American Airlines Flight 96 only had about 56 passengers on board and in the aft part of the cabin they had a lounge and a small bar, but Turkish Airlines Flight 981 was a completely full plane, right, There were 346 people on board. which meant that when the cargo door was opened and depressurization occurred, there was still not enough ventilation, leaving the air in the passenger cabin to go anywhere to equalize the pressure difference between the cargo hold and the passenger cabin, which generated an enormous amount of pressure on the floor a pressure that the airplane was not designed for and due to the additional load of all the passengers seated on top of the floor, it is likely that the floor at the rear of that DC-10 would completely collapse cutting all the control cables to the elevator, the stabilizer, the rudder and the number two engine, if all those cables had been cut, it would have left the plane completely without any pitch control, while in the American Airlines Flight 96's floor only partially collapsed, allowing the aircrew to still have some control of their plane.

This is probably the reason for the difference in outcome between the two accidents. After this horrible disaster, several major lawsuits were filed and during the discovery of those lawsuits, documents from an employee were found. In Convair, one of McDonald Douglas's subcontractors, his name was Dan Applegate. Now Dan Applegate, in the wake of American Airlines Flight 96, he had issued a memo to his boss where he said that he was concerned about the degradation of security around the aft cargo door. and he said that American Airlines Flight 96 indicated that the design changes that had been made had compromised the safety of the entire system and were likely to lead to a total loss over the next 20 years of the normal service life of the aircraft. aircraft.

He pointed to a pressurization test that took place in 1970, where the first DC-10 airship had been pressurized during a test and the front cargo door had exploded causing the passenger floor to collapse. Now this memo is known in history as the Apple Gate memo and unfortunately it was never acted upon and the reason why it was not acted upon is still a bit of debate, but what we do know is that Convair, as a contractor subcontractor, those who were responsible for building the door, were not allowed to contact the faa themselves, instead they were required to communicate any concerns they had to mcdonald douglas who would then communicate them to the faa, but because there was some discussions between convair and mcdonnell douglas over who would take responsibility. of a complete redesign of the cargo door, this discussion seems as if it never took place after this, there were some serious disputes between mcdonnell douglas and Turkish Airlines about who was really responsible for the accident, but due to the findings and in part Because of the Dan Applegate Memo they decided to settle the lawsuits for at that time a record amount of money.

The fund's report came with several safety recommendations due to this accident, including reiterating findings that were made in the American Airlines Flight 96 funnel report, they also said. that special attention must be paid to the closing and locking of the cargo door and the behavior of the floor in the event of a sudden depressurization of the cargo compartment. They also noted that the flight controls and the cables to the flight controls needed to protect it, as well as the redundancy of those systems, but probably the most important point they made was that an airworthiness directive had not been issued and they said that in cases Later, when there was any risk that safety would be compromised, an airworthiness direction had to be used no matter what.

The financial implications of that announcement could be and this is something the industry lives by to this day after the Turkish Airlines Flight 981 disaster the locking mechanism for the DC-10 cargo doors was completely redesigned the new design ensured that the mechanism would not stop until the latches were in their perfectly closed position. Additionally, he connected the locking pins to the vent door, ensuring that the only time the vent would close and allow pressurization of the cargo compartment was if the locking pins were in position. correct position also the FAA ordered all jumbo jet operators, not only the DC10 but also the lockhead 1011 and the Boeing 747, to cut adequate vents between the passenger compartment and the cargo compartment, ensuring that rapid depressurization does not will cause a failure in the cabin. floor and would not affect any of the flight control cables in the case of the DC-10, this meant hardening and reinforcing the entire passenger compartment floor.

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