WHY didn’t this Airplane just TURN BACK?! | Air Accident Investigation

a boeing 737-800 from air india express is lining up for takeoff runway 2-7 in trichy india for a flight over towards dubai in united arab emirates as the aircraft is accelerating for takeoff suddenly the backrest of the captain's chair collapses backwards what happens after this is one of the strangest accidents that i have read about recently stated a huge thank you to skillshare for sponsoring this video the story actually starts on the 11th of october 2018 and it starts in dubai where the crew consisting of two pilots and four cabin crew started their flight they're supposed to fly two sectors over to trichy in india and then back again to dubai the captain of the flight is a 32 year old male he has got 4295 hours of total experience and 4045 hours on the 737. his command experience was only about 542 hours which makes him a fairly new captain the first officer was a 51 year old male with 4 202 hours of total time and 3 84 of those hours being on the 737. the first flight of the day was completely uneventful the first officer was pilot flying for that flight they flew over from dubai to trichy taxid in and at time 2337 they pulled up on stand they did the pre-flight walk around for the following flight and during the walk around which was made by an engineer in trichy he recognized that one of the tires on the right-hand main landing gear was worn to limit so they they replaced that tire and they refueled the aircraft and prepared for the return flight towards dubai the weather in treachery was really good only a few clouds around the temperature of about 27 degrees celsius and corn wins which meant that the crew had a choice of which runway they were going to use the captain was going to be pilot flying for the return flight and he decided that because runway 2-7 had a shorter departure route they would go for runway 2-7 the crew did all of the pre-flight setup according to company procedures and when they did the performance they did the performance for a flap five takeoff we normally take flaps five rather than flaps one if we can because it gives us a better tail margin for rotation the speed for departure was 143 for v1 144 for the rotation speed and 151 for v2 and these are pretty normal speeds for a fairly heavily loaded 737-800 at around 40 minutes past midnight local time the crew was ready to depart and they started taxiing out backtracking to line up runway to seven up until this point everything was completely normal and at times citizen of 409 the crew received their takeoff clearance and they started their takeoff procedure and the way that this is done in the 737 800 is that the pilot flying advances the trust levels up to initially 40 percent the reason you do this is because you need the engines to start accelerating up to that value more or less in order to make sure that during the latest state of the engine acceleration they will accelerate at the same pace pilot monitoring in this case which is the first officer called stabilized and then the captain pressed the toga button and said set take off trust now in this case the auto throttle then engaged and started setting the trust to the predetermined value which in this case was about 98 now the way that the outer throttle works during the takeoff roll is really important to understand initially and up to about 84 knots the other throttle will be set in n1 mode so that means that it drives the trust levels up to the predetermined value but at 84 knots which is pretty much where the speeds change from the low speed regime to the high speed regime of the takeoff it goes into something called throttle hold okay this means that the trust is set where the trust levels are at that speed and it can be manually changed by the pilot now you might ask yourself why would the other trouble do that and the quick answer that is because if there is a rejected takeoff after that point you don't want the trust levels to inadvertently start moving up again so it's kind of a protection mode another thing that's really important to understand about the way that we do the takeoffs is that the captain is the one who always takes the decision about the rejected takeoff and because of that the captain remains with one hand on the trust levels until we pass the v1 speed after which there is no decision to reject anymore so the captain who was pilot flying in this case would have sat with one hand on his yoke and another hand firmly on the trust levels the takeoff run initially was completely normal they passed 80 knots checked they then continued to accelerate and at 117 knots now this is very high speed the backrest on the captain's share suddenly collapsed backwards and what do you do if you suddenly fall backwards well you grab for something to hold on to don't you and this is exactly what happened in this case as well when we look at the flight data recorder readings it shows that there was a momentarily pitch up command from the captain's side but also crucially for this story the trust that was set at 98 percent with throttle hold on the outer trust was moved back to 77 now as the captain collapsed backward he handed over the controls to the first officers so he said your controls and the first officer who was now dealing with something that he definitely didn't expect did not verify the uh the position of the trust levers and this is actually even though it's a lot to ask in a situation like this it is mandatory in case of an incapacitation which is actually what we're talking about here the first thing that you have to do is verify the position of all switches and levers in this case that should have led to the first officer verifying where the trust was reset the trust but this wasn't done probably just because of how quickly this happened so the first officer continued to maintain the aircraft down the center line now the thrust is set to 77 instead of 98 which is a considerable reduction the captain takes about five seconds to kind of compose himself back into the seat put the seat back up to the correct position again and once he is sitting correctly he looks out and he realizes that it's only about two thousand feet left of the runway that's about 600 meters he looks down and he also sees that they haven't reached the speed they're supposed to have they're nowhere near the v1 and rotate speed so he continues to accelerate and he says my controls so now the rules are reversed the second time and he is now pilot flying when there's about 1000 feet left of the runway and they're approaching the v1 rotate speed the captain initiates the rotation he recognizes that there's more control forces needed than what he's used to but he continues to rotate more and more and more and eventually at about 14 degrees nose up the aircraft gets airborne when the aircraft gets airborne both the first officer and the captain recognized as a vibration in the aircraft something that they liken to wake turbulence anyway they don't think much more of that the first officer calls out positive rate and he takes the gear up and about here the captain increases the thrust back up to 98 percent again the crew now proceeds to climb away normally they're retracting the flaps and proceeding on their way towards dubai but at the same time in the back of the aircraft the cabin crew who's sitting in the rear galley have also noticed during the take-off role that the aircraft was suddenly decelerating and then as the aircraft rotated they felt a bump a bump that they said in later investigations they thought maybe was due to the cargo shifting below them they communicated this to the senior cabin crew as soon as the foster seatbelt sign was turned off meanwhile in the trichy air traffic control tower the controller looks down onto their dashboard and realizes that the localizer part of the ils for runway 2 7 suddenly has stopped working they find this really strange because they know that airing the express 611 has just departed so they sent out an investigation crew to have a look at the localizer antenna the localizer antenna is a setup that is comprised of several individual antennas that's situated on the far end of each runway you will probably see them if you look out as you're taxing alpha takeoff they're normally colored red in a different part of the airport close to the localized antenna for runway two seven a security guard was also working at this time and he heard a very strange noise as air in the express 611 took off and he also saw some smoke and dust being thrown up in that general area as soon as the maintenance crew reaches the threshold from the cedar line that's the opposite end of runway two seven the first thing they see is that one of the threshold lights is missing and as they continue further away from the threshold they see that several of the individual antennas that forms part of the localizer were either broken or missing completely and beyond that there is a perimeter wall and to their horror they realize that there are two gaping holes in this brick wall as well now all of this information is immediately relayed back to trichy tower and treaty tower starts to reach out to air in the express 611 at time zero zero five four so this is five minutes after the departure um air traffic control sends the following message to air india express 611. while departing your aircraft passed the end of the runway at a really low altitude the crew responds that they have checked all their engine instrumentation and their pressurization and that all indications are okay two minutes later air traffic control comes back again and tells the crew that they have received report from a firefighting crew that the perimeter wall is broken at the end of runway 2-7 the crew responds that all operations are normal but they are clearly shaken by this message because only a few minutes later they called tricia tower back up again and asked can you have you figured out uh what has happened tricia tower are very quick to respond that yes while you took off you hit the localizer antenna and the perimeter wall the localizer is now not working and to that the pilot responded okay sir copied thank you after this the flight crew elects to continue to climb initially to flight level 210 at 21 000 feet and they are doing several um confidence checks during this climb where they are checking the hydraulic system for leaks for example they are checking the engine parameters which all look normal and they're also looking at their pressurization system to make sure that they're pressurizing normally and to all of these checks they come up with the same thing that yes it looks like the aircraft is performing normally and they're using that information to take the decision to continue to fly towards dubai when they reach flight of a 2-1-0 they contact the next air traffic controller and they ask to maintain flight for 2-1-0 for a while so that they can slow the aircraft down and to check if the landing gear system is working correctly so they do this they reduce the speed back to a speed where you're allowed to both extend and retract the landing gear they do so the landing gear functions normally and based on that they have to continue to climb up to flight of a 350 which is their final cruising level right here we have to take a little bit of a step back to look at the situation so what we have here is clearly an you know abnormal takeoff the crew has not only felt the vibrations of the tail strikes themselves they've also gotten information from air traffic control that you know that the localizer antenna and the boundary wall of the airport has been broken and they have talked to the senior cabin crew which has relayed the information from the junior cabin crew city in the back about them hearing a thud when they departed so all of this together should paint a really clear picture to the flight crew that they have suffered a tell strike in our quick reference handbook which is the emergency manual where all of the emergency checklists are held there is a tail strike checklist and it is very straightforward it basically has three points in it first of all it gives a condition a tail psych is suspected then it basically tells us that do not pressurize the aircraft because there might be structural damage to the aircraft it gives the three action items which is pressurization mode selector to manual outflow valve hold in the open position until you have depressurized the aircraft and three land at the nearest suitable airport and the reason it says this is if you have actually scraped your tail if you have had a tail strike you don't know what kind of damage you have sustained you don't know if there are weaknesses in the aircraft structure that might get you know much worse by pressurizing the aircraft so this is what we're supposed to do we train for this we make sure that before we depressurize the aircraft we're not above flight level 100 because that would then cause a rapid depressurization and a potential emergency descent and we just nice and calmly set the aircraft up and normally return to the airport that we departed from that's what we're supposed to do however in this case it seems like the pilots were made confident by their check of their systems and never even considered going into the quick reference handbook to check for the tail strike checklist so the crew continues to watch the destination we don't know exactly what the conversation was in the cockpit during the takeoff and the initial part of the flight because the cockpit voice recorder only records the last two hours of a flight and this flight ends up being over four hours long but somewhere in the middle of the flight as the crew is approaching a rna point called totox we start to get the cvr transcript and in the cpr transcript you can see that the pilots are very uneasy about this they're saying things like uh uh wall the wall is broken no wall is broken that's that's the antenna that must have hit the wall and they're also saying several times i hope it doesn't become a news i hope it doesn't become a news so they're definitely aware that something very bad has happened and about this time the company representative aware india express have visited the site in trichy and they've looked at the broken um localized antenna and the perimeter wall and the close to that they have identified pieces of aircraft skin and honeycomb material and this representative from the pieces that are left behind can actually say with quite good confidence that yes these pieces comes from our aircraft so there's now no doubt that this has happened the company now calls the pilots up via hf frequency and tell them that they want them to please divert towards mumbai the problem here is that the aircraft is now much closer to the destination dubai than mumbai and the diversion back towards mumbai will actually use more track miles so the pilots have to calculate whether or not they have enough fuel initially they think they don't but then they they look at it and they see that if they get a direct routing towards mumbai they can do it so they accept that direct routing and they start their flight towards mumbai as the aircraft is approaching mumbai the captain who's still pilot flying starts to configure the aircraft early to make sure that all of the flaps gear and all of the associated systems are working correctly he also asks air traffic control to please have the local firefighting equipment and emergency equipment on standby just as a precaution at time 0508 the aircraft touches down safely in mumbai but do you want to know what the engineers found after the aircraft had parked on stand well if you just wait until after this short message from my sponsor i'll tell you all about it a special thank you to the sponsor of this episode which is skillshare now i know that you are watching this because you are a curious person a lifelong learner someone who constantly wants to improve and understand the world around you better and in that case skillshare is definitely something that you should be checking out okay they have thousands of high quality video courses and pretty much anything that you can imagine a course that i'm using myself at the moment is five minutes creativity with jasmine cheyenne where she gives kind of hands-on tips on how to chisel out a few minutes to be creative every single day and it's something that i personally really need but there are also courses in you know storytelling creative photography or even how to use your own home simulator to improve and prepare before you start your private pilot license so if you think peter that sounds amazing well then the 1000 first of you guys who clicks on this link here below will get one month of premium skillshare absolutely for free so click the link and start exploring your curiosity today as soon as they arrived the stat it became immediately apparent that the aircraft was severely damaged turned out that the tail strike had been so severe that it actually ripped up a big hole just aft of the main wheel well the first indication of the damage that the engineers could see as it approached down was that the lower and the collision light had been completely ripped off probably by the localizer antenna on top of that the vhf2 antenna was gone there was some severe damage to the aft left horizontal stabilizer but also to the cowling of the number two engine the right hand landing gear one of the tires on the right-hand side but also on the flaps and there was also several dents just aft of the main hall in the uh aircraft structure but what was the chain of events that led up not only to the tail strike but also to the crew's decision to continue their flight towards dubai well as the aircraft investigation team came to the site in trichy they went out to the runway and safety area the reesa and they very quickly saw the trail of the main landing gear on the ground in the soft area but they also found the trail of the aircraft tail as it had impacted during the tail strike and had been dragged through the localizer antenna damaging it severely the aircraft then seemed to have taken off but not very high because about a meter up on the one and a half meter high perimeter wall they found these two holes and those two holes were at a distance from each other indicating that this was the main landing gear that had impacted the perimeter wall and knocked those pieces down further evidence for that was also the huge amount of wire mesh that they found entangled in the main landing gear when they pulled up on stand in mumbai that was proven to come from the top part of the perimeter wall to me this just speaks to the incredible resilience of the 737-800 you know that it could sustain that kind of abuse and still be able to fly when they looked into the flight data recorder as i mentioned they didn't have the cockpit voice recorder they they noticed obviously what happened at 117 knots and they started looking into the pilot chair and what they found was that a part of the recline mechanism had been tightened too much at some point which meant that instead of the mechanism actually locking for each step it was partially open so when a little bit of pressure was put on the backrest it had a tendency to just collapse backwards just like if the the actual mechanism was open so this is what caught that but what the investigation showed was that if the first officer would have initiated a rejected takeoff which he could have done at that point he would have been able to stop within the remaining runway distance and also they found that if he would have added trust he would have been able to take off normally they even proved through simulator testing that if the captain when he took back controls again if he would have at that point added the trust back up to 98 he would have been able to take off within the available runway distance however it showed that if he would have tried to reject at that point the aircraft would have overrun the runway so the investigation team now understood what had happened on the runway they kind of understood as well why the first officer hadn't said take off trust he had clearly just missed the fact that reduction was in there probably due to the commotion that happened as the seat reclined but they still didn't understand why the pilots had decided to continue to climb their severely damaged aircraft towards dubai why hadn't they just gone in done the tail strike checklist and returned back in they did several interviews with the crew and from those interviews it became apparent that because the crew had gone in and done these checks of their systems they have gained so much confidence from those checks that they basically didn't think that there was anything wrong with the aircraft they got too much confidence from checking the system and they used too little of their common sense to to kind of realize that even though the systems might indicate the aircraft is still functioning the overwhelming picture of all of the different inputs pointed at a severe tail strike which should have led them into the tailstrike checklist but this goes to show how easy it is to make faulty decisions when you're under a lot of stress no matter how much visual oral inputs you get it is still possible to take these kind of decisions and once again it points to the importance of having a set decision making model you know how i always talk about piosi you know problem information option select execute and evaluate well if that would have been taken here if the crew would have taken their time to sit down and look at what kind of information they actually had available to them what options that actually left to them this might have had a different outcome no one was hurt in this incident everyone was safe but i still wanted to share this incident with you because it highlights quite a few of the points that i've already made about decision making on the channel if you want to see another video where there's really questionable decision making well then check out this video up here have an absolutely fantastic day and remember if there's one acronym that you need to know it's the acronym class bye

Channel: Mentour Pilot

Views: 421,847

Rating: 4.9452181 out of 5

Keywords: Air India Express flight 611, Tail strike, air crash investigation, air crash, aircrash confidential, mentour pilot 737 max, mentour pilot crash, mentour pilot take off, Boeing 737, Boeing 737 800, Airbus A320, Aviation incident, aviation accidents, aviation accidents documentary, aviation accident clips crash animation, aviation accident clips air crash investigation, aviation accidents explained, aviation accidents and incidents, Fear of flying, Nervous flyer

Id: 9kA6m1U0QUA

Length: 23min 12sec (1392 seconds)

Published: Fri Aug 20 2021