- [Petter] A Boeing 777 is in a go-around after a very late decision by the pilots. The mighty aircraft is slowly turning its nose towards the sky but something is not right. And as the landing gear is being retracted, the aircraft starts falling down towards the runway below.
What's happening? Stay tuned. - [Radio Altimeter] 100, 50, 40, 30, 20, 10.
- This accident is one of those where armchair pilots were very quick to assign blame. And that's because, from the onset, it looked very clear what and who was to blame. But as always, when you dig a little bit deeper, it becomes much more complicated.
On the 3rd of August, 2016, at around 7:30 UTC, the pilots of Emirates Airlines Flight 521 were getting ready for a standard arrival into their home base in Dubai. They were coming towards the end of a three-and-a-half-hour long flight between Thiruvananthapuram International Airport in India and Dubai International Airport in the United Arab Emirates. Behind the two pilots in the cabin, 16 cabin crew members were taking good care of the 282 passengers that were travelling on board.
The 34-year-old captain was operating as pilot flying and he was now getting ready to brief his first officer about the approach they were expecting to fly into Dubai. Despite his young age, he was quite experienced with just under 7,500 hours of total time and with slightly over 5,000 hours of those flown on the Boeing 777, the same aircraft as they were operating on this day. His first officer who was pilot monitoring on this flight was 37 years old with just under 8,000 hours of total time, but only about 1,300 hours on the 777.
Both pilots were feeling well-rested and in a good mood. They had a nice long rest before and this flight was scheduled at a very civilised time in the morning. So jet lag and fatigue was not an issue.
The first officer was listening to the captain's briefing intently. It was the first time he was flying with this captain but he seemed really nice and the cockpit gradient was really well managed. The captain had listened to the first officer's suggestions during the flight and the CRM was flowing smoothly.
It was a good day in the office in other words. The pilots had just received the latest weather from Dubai Airport and it looked like they could expect an RNP approach into Runway 12 Left as the ILS was not being used on this day. An RNP approach is based on the aircraft internal GPS navigation systems and needs to be briefed and prepared for thoroughly.
The weather looked generally nice with clear skies but it was really warm in Dubai, almost 49 degrees Celsius, that's 120 degrees Fahrenheit and with varying gusty winds from different directions. Because of those winds, there was also a wind shear warning issued for all Dubai runways at the time when the aircraft was scheduled to arrive. A wind shear is a sudden change of wind direction and/or velocity and it can be dangerous for aircraft because it affects the indicated airspeed, meaning the amount of air that's flowing over the wings and, therefore, the performance of the aircraft.
Wind shears are normally associated with thunderstorms, but on this day in Dubai, there was another explanation for it. The wind affecting Dubai Airport would normally be caused by existing weather patterns, but sometimes it could also be affected by another meteorological phenomenon called sea breeze. Now sea breeze forms when the air over land is heated up by the sun and starts rising upwards.
This air is then replaced by cooler air coming from the sea and that causes wind to blow from the sea in over land. In this case, the sea breeze was just starting to overtake the normal prevalent wind and because of that, two different wind directions were now meeting over the airport, causing this potential wind shear. The pilots in the cockpit discussed this warning and the captain briefed his first officer about the possibility that they might have to execute a wind shear escape manoeuvre.
This manoeuvre is critical for all pilots to know because it needs to be executed immediately and accurately if a wind shear would be detected. In this manoeuvre, the pilots needs to immediately apply full thrust and press the TO/GA buttons on the thrust levers and then they need to pitch up to a predetermined attitude, normally around 15 degrees or so and not change the configuration of the aircraft until it's verified that they are out of the wind shear. This is done to keep the aircraft climbing away from terrain as quickly as possible and to protect the aircraft if it would touch down.
The Boeing 777 that they were flying was equipped with two different warning systems for wind shear, one predictive system connected to the weather radar that could sense a wind shear ahead of the aircraft and one reactive, connected to the Enhanced Ground Proximity Warning System. Both of these systems were inhibited if the aircraft was below 50 feet over the ground. Now the fact that the captain reviewed this procedure with his first officer was a sign of good airmanship and adherence to company procedures.
Doing this improves the shared situational awareness and preparation for this perceived threat. And it's something that we always try to do if something unusual can be anticipated. After the captain had finished his review of the wind shear escape manoeuvre, he continued his normal briefing of how he was going to fly the approach.
This briefing included how he was going to fly the missed approach procedure, which included retracting the flaps to 20 and climbing straight ahead to 3,000 feet. Now, one thing that is important to discuss here is how Emirates Airlines train their pilots to execute a go-around. It was company policy to fly all approaches with the auto-throttle activated.
The autothrottle governs the thrust of the engines and makes sure that the thrust is appropriately set for each flight phase either by trying to achieve a specific speed or climb and descent rate. The use of autothrottle would reduce the workload for the pilot flying and help setting the correct go-around thrust during the go-around. All simulator training that the pilots had received in normal configurations had been done with the autothrottle available and ready to activate.
And anytime the TO/GA buttons were pushed, the autothrottle normally would work flawlessly. The TO/GA buttons, by the way, are two buttons located on the thrust levers. They stand for takeoff and go around.
And, if pressed, they will tell the autothrottle, flight directors and, sometimes, the autopilot to activate certain settings for either takeoff, go-around or in case of a wind shear. The captain had also done some special handling training in the simulator as part of Emirates recurrent training programme. This include go-arounds after touchdown, but that training had been done with the autothrottle completely disconnected, meaning that go-around thrust would have to be set manually.
In those exercises, the use of manual go-around thrust was briefed beforehand as part of the exercise and the pilots were very ready for it. Now the go-around manoeuvre itself in the airline manual had some text in it, instructing both pilots to verify that go-around thrust was set after the go-around was initiated. But there were no call-outs connected, verifying that the thrust actually had been set.
On top of that, the flight mode annunciator changes which were normally always called out was not to be called out below 200 feet since that was thought to be distracting. Now, there was a small note in the Pilot Flight Crew Training Manual and the FCOM manuals explaining that the autothrottle would not be available after touchdown and as long as the aircraft was on the ground, but that fact was not greatly highlighted during the initial or in the recurrent training. After the briefing was finished, the pilots asked for descent and ATC gave them clearance to start descending down towards the airport.
During the descent, the pilots briefly discussed their previous experiences of wind shear and the captain mentioned that he had had one in Dubai just a couple of months earlier, and that it had just felt like a sudden increase in speed and it had led them to fly a normal go-around. As they were descending, the captain also was thinking to himself about another phenomenon he'd recently experienced during landing in such hot conditions, a phenomenon called thermals. Thermals are basically pockets of warm air that releases from warm surfaces and start rising upwards like balloons.
You probably will have seen these on summer days. They tend to create dust devils and sudden gusts of winds and it's also these thermals that birds and gliders use to gain altitude. Thermals have a tendency to form over the runway surfaces and they can cause similar effects to positive wind shears during landing.
But since both thermals and light wind shears were pretty common occurrences in Dubai, the captain didn't think that they would affect them much. He had had ample experience of both. The approach performance was calculated with the use of flaps 30 and normal approach wind speed additive of five knots making the final approach speed 152 knots and the touchdown reference speed 147 knots.
Runway 12 Left in Dubai is 3,600 metres long, so the pilots calculated that landing performance was not going to be a problem, even if the wind would turn into a 10-knot tailwind, which could often happen. At time 08:17, Emirates Flight 521 descended through 16,000 feet and the first officer got into contact with the Dubai Approach Controller. The controller informed the crew that they could expect vectors for the RNP approach into Runway 12 Left, just like they had planned.
The aircraft continued to descend according to the controller's instructions, but what the pilots didn't know was that two aircraft ahead of them had just gone around from Runway 12 Left due to the wind conditions that they encountered. That information was not heard by the crew as they started receiving final vectors towards the final because the crew was still talking to the approach controller and the go-arounds were both reported on the tower frequency. If the pilots would have heard this, it's likely that they would have been a little bit more vigilant when it came time for their own approach and landing later on.
The pilots now received cabin secure from the purser and started their final preparation for landing. But before we get into the accident sequence of this video, I just wanna share this short message from my sponsor. Consider supporting me by supporting them.
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The pilots of Emirates Flight 521 were now getting closer to the airport. They started extending flaps and had completed the approach checklist by the time air traffic control gave them the final vector and cleared them for the RNP approach into Runway 12 Left. At time 08:34, the captain asked for gear down and the flaps set to 30.
This was done, and the first officer started completing the last part of the landing checklist. The captain armed the speed brake. And from this point, the aircraft was completely stabilised and ready for landing.
They were well above the 1,000 feet landing gate as stipulated by the company and everything looked completely normal. The approach controller switched them over to Dubai tower and on that frequency, two Boeing 777s who were just ahead of the aircraft, had recently landed without reporting any problems. It was likely because of this that the tower controller didn't mention the earlier go-arounds.
Flight 521 checked in on the frequency and at time series 08:36, the tower controller cleared them to land Runway 12 Left with a surface wind of 340 degrees, 11 knots. This meant that they were now facing a tailwind of 10 knots but like we discussed before, this was well within the landing performance of the aircraft. Now one thing that the tower controllers were seeing on their instruments but didn't inform the crew about was that the wind indicators on the opposite runway also indicated around the same amount of tailwind, meaning that the wind was now blowing from both directions in towards the centre of the runway.
This was not mandatory information to pass on, but it was certainly an indication that the wind conditions over the runway could become quite tricky. At times 08:36:10, as the aircraft descended through 930 feet, the captain disconnected the autopilot in order to hand-fly the rest of the approach, but he left the autothrottle engaged as per company procedures. At this point, the autothrottle was engaged in speed mode, which enables the captain to move it around as much as he needs, but it would stay armed for a go-around if the TO/GA buttons were pushed.
As the aircraft descended through 750 feet, the wind started shifting from a headwind into a tailwind. The aircraft kept descending with a descent rate of around 700 feet per minute and when they passed 450 feet, where the automatic. .
. - Minimums. - [Petter] Call was made, the captain responded, "Land," to which the first officer responded, "Check.
" The airspeed was now 156 knots reducing towards the target speed of 152, still well within the stabilised approach criteria. When the aircraft descended through 190 feet, the first officer called out, "16 knots tailwind," which the captain acknowledged. Now that's quite a lot of tailwind.
But what determines if we can land or not is the tower reported wind. Tailwind can disappear quite quickly as we descend down and it's only really the surface wind that will affect our landing performance. At 115 feet, the first officer called out, "Reducing to 13 knots, with reference to the tailwind and the captain responded, "Check.
" This was then followed by the GPWS call-out. . .
- 100. - A few seconds later, the aircraft passed the threshold at 54 feet, more or less exactly on profile. But since the tail wind was now reducing, the indicated speed started increasing and as a result, the autothrottle started retarding the thrust to idle in order to try to keep the commanded speed of 152 knots.
During the next four seconds, the GPWS calls out, - [Radio Altimeter] 50, 40, 30, 20, 10. - Now we, pilots, use these radio altitude callouts in order to judge when we should start the flare. And in the Boeing 777, just like in the Boeing 737, the flare should normally be initiated at around 30 feet, but here the captain instead initiated his flare a little bit earlier around 40 feet.
Now, it's worth talking a little bit about the correct landing procedure we, pilots, use and where we're supposed to look when we're landing. During the initial part of the approach, the pilot flying will be looking mainly inside on the instruments, but as we get visual contact with the runway and certainly below the minimums, we'll be looking increasingly outside but still scanning the instruments to check that everything is alright. But when we pass over the threshold, we should be looking outside and towards the far end of the runway.
If we do this, we will be able to use our peripheral vision to judge how quickly the aircraft is descending and adjust the aircraft attitude accordingly to make sure that we land correctly. This means that at this point, the pilot flying will not be monitoring the instrument at all, at least, for the last few seconds before touchdown, but the pilot monitoring will be and he or she should call out any anomalies that they encounter. We always aim to land in the middle of the touchdown zone, which is marked with two wide white markers, normally situated abeam the PAPIs about 300 metres from the runway threshold.
Before and after these markings, there are other less wide markings, indicating where the touchdown zone starts and ends. And if we see that, for whatever reason, we cannot get the aircraft to land inside the touchdown zone, we must go around since we, otherwise, run the risk of not being able to stop the aircraft. Now the Boeing 777 was also equipped with a warning system that calculated where they were over the runway.
And if that system sensed that they had overflown 33% or more of the runway without touching down, it will issue a long landing warning, which would also mean a mandatory go-around for the pilots. Since the captain initiated the flare a little bit early and his speed was a bit high, the aircraft also started to flare a bit early, meaning that they were now using up a bit more runway than they normally would. As part of the flare, he gently increased the pitch angle from about zero degrees to 2.
6 degrees, and the sink rate decreased from 700 feet per minute to about 350 feet per minute in order to prepare for the touchdown. About four seconds after passing the threshold, the aircraft passed the 300-metre marker at an altitude of 25 feet and a speed of 158 knots. The autothrottle now changed mode from speed to idle as it was designed to do at that altitude, meaning it would now keep the thrust in idle during the landing.
Two seconds later, the aircraft was still at 13 feet and the speed had decreased to 153 knots, but now the wind suddenly changed from a tailwind to a headwind. And when that happened, the indicated airspeed started increasing. This was likely the wind shear that we discussed before, but it was a very subtle one, less than what was required to activate the warning systems on board.
But these warning systems were inhibited anyway since they were below 50 feet. The captain reacted to this sudden wind change by inputting a bit of right aileron to counteract a slight wind-induced roll and he muttered, "Thermals," and the first officer responded, "Check. " The aircraft was now hovering at around two feet over the runway with a speed of 165 knots due to the sudden increase in headwind, but it wasn't descending.
When this happens, we, pilots, say that the aircraft is floating. And given the high speed that the aircraft was still travelling with, they were now using up a lot of runway quickly. The captain, of course, realised this and tried to fix it by gently pushing the nose forward a few times to try to get the aircraft down but it didn't seem to work.
What did happen though, was when the captain counteracted the wind with the right aileron, the right main gear momentarily touched down. This was sensed by the Weight on Wheels switches and the untilt sensor on that gear. As this happened, the speed brake partially extended for a fraction of a second until the gear got airborne and tilted again, to which the speed brake went back into armed.
During the following six seconds, both main gears indicated touchdowns and the speed brake partially activated twice. But none of that was noticed by the pilots who were both focused outside, judging the landing which was now becoming longer and longer. The fact that they hadn't noticed the touchdowns also meant that both pilots were convinced that the aircraft was still fully airborne, and that's very important for what's about to happen.
They had now overflown more than 1,000 metres of the runway and the captain judged that he wouldn't be able to safely land inside of the touchdown zone anymore. He therefore correctly decided to go around and push the TO/GA buttons. At the same time he called, "Go-around," and then started gently pitching the aircraft up to start climbing.
He knew he was close to the ground, and he was very careful to avoid a possible tail strike. This likely took up most of his attention and the workload probably rose quite quickly here. The problem was that when he pushed the TO/GA buttons, it had not activated the autothrottle.
The autothrottle was inhibited because the aircraft sensed that it was either below two feet for more than three seconds, or on the ground, exactly as it was designed to do. This meant that the thrust was now still in idle and that was shown on the flight mode annunciators ahead of both pilots. The captain kept his right hand on the thrust lever but, curiously, he didn't notice that the thrust was not increasing.
Like we discussed before, all of his training had made him rely on the fact that the autothrottle would set the go-around thrust for him during these kind of circumstances. And due to the workload and his focus on avoiding a tail strike, the fact that the thrust levers were not moving, didn't register. Immediately after the go-around was initiated, the.
. . - Long landing.
- Call was heard in the cockpit, confirming to the pilots that they were doing the right thing by going around, the captain pitched up through an attitude of about seven and a half degrees and called for flaps 20. The first officer immediately reacted and selected the flaps to position 20 and this was done within two and a half seconds from the captain's call. The aircraft now started climbing away from the runway and at an altitude of 47 feet, the first officer called out, "Positive rate," to prompt the captain to retract the gear according to their normal procedures.
The speed was now 153 knots reducing and the captain responded, "Gear up. " All of these procedural steps happened very fast indicating a well-trained manoeuvre. But, crucially, the important step of verifying go-around thrust had been missed by both pilots, likely because of over-reliance on the auto-throttle system and the lack of FMA and system monitoring.
The aircraft continued to climb past 77 feet with the speed now at 135 knots well below the safe approach speed. And with the absence of any engine thrust, it was still decelerating quickly. At this point, the tower controller saw the aircraft pitching up and decided to call them and issue a change in the go-around altitude from 3,000 feet to 4,000 feet.
This instruction was read back by the first officer and he also reached out and changed the MCP altitude, likely further distracting him and the captain from the critical situation that they were now in. Two seconds later, the aircraft reached its maximum altitude of 85 feet. At this point, the speed was insufficient to keep the aircraft climbing, especially with the added drag from the now open landing gear doors who had been opened to facilitate the gear retraction.
The speed was now 131 knots and when the captain looked down and noticed the low speed, he assumed that they had entered a wind shear. He called out, "Wind shear! TO/GA!
" And at the same time, the first GPWS - Don't Sink! - Warning was heard in the cockpit. The captain now finally pushed the thrust levers fully forward as he also pushed the TO/GA buttons a second time, and this was likely the first time that he realised that the thrust levers were still in idle.
The aircraft reacted as designed and the engine started to spool up but it takes up to six seconds to get the two huge Rolls Royce Trent 800 engines to accelerate from idle to full power. And that's time they no longer had. The aircraft now started descending with around 800 feet per minute as the first officer called out, "Check speed!
" Followed by an aural. . .
- Airspeed low! - And. .
. - Don't Sink! - Warning from the aircraft.
The speed was now 128 knots and the captain increased the pitch attitude to 9. 2 degrees in order to try to regain some height and avoid the now unavoidable crash. At time 08:37:38, 18 seconds after the initiation of the go-around and three seconds after the engines were pushed into full thrust, the aircraft crashed down on Runway 12 Left in Dubai.
The aft part of the body touched down first followed by the partly-retracted main landing gear and the right engine. This caused the engine to separate from the aircraft and a fire broke out in the right engine pylon as well as under the left engine and in the wheel well bay. The aircraft skidded down the runway, turning slowly clockwise to the right, until it came to a rest about 70 metres right of the centerline of the runway, facing about 250 degrees.
But this story is far from over. At time 09:39:04, the captain transmitted a mayday call to the tower advising them that they were evacuating the aircraft. About one minute later the pilots had managed to locate the evacuation checklist which had been thrown out into the cockpit floor during the impact and they started going through the items.
In the back, complete pandemonium had understandably already erupted. Thick smoke had started moving into the cabin from the wheel well and it effectively created a barrier between the forward and the aft part of the aircraft. Passengers had started moving out of their seats immediately when the aircraft came to stop, and, unfortunately, most of them had now also started removing their hand luggage to bring it with them.
This caused significant delay to the evacuation process. The cabin crew was doing a heroic job in trying to communicate with each other and telling passengers to please leave their stuff behind and managing the evacuation. They now started opening emergency exits, but due to the gusty winds outside, several of their slides blew up along the side of the aircraft, which made them unusable.
Other slides had been damaged during the crash and had also been rendered unusable. And every time that a new exit slide was found to be unusable, the cabin crew had to block that exit and redirect the passengers away from it and towards the next one, a truly Herculean effort, given the circumstances of smoke, heat and panic. The cabin crew did a fantastic job on this day.
And their training, communication and teamwork likely saved a lot of lives. Outside the aircraft, the firefighters had arrived at the scene and started fighting the fire. The fire and rescue work was not greatly organised and several firefighters suffered heat issues from the workload and the close to 50 degrees of temperature that they had to work in.
Now as a former airport firefighter myself, I can definitely understand that, given the amount of equipment and clothes that they were wearing. Nine minutes and 40 seconds after the aircraft had come to a complete stop, the 100 kilos of fuel that still left in the aircraft centre tank exploded from the heat of the fire. This caused a large piece of aircraft skin from the upper part of the right wing to fly away and, unfortunately, kill a nearby firefighter.
This firefighter became the first and only fatality in this accident as all passengers and crew escaped the aircraft. The only people left on board when the centre tank exploded was the captain and a senior cabin crew member who had don portable breathing equipment and were searching through the aircraft to make sure no passengers were left behind. When the tank exploded, it lifted the floor of the cabin and a large fire broke out, forcing the captain and the cabin crew member to jump from a forward exit down onto a detached slide below.
21 passengers, one pilot and six cabin crew members received minor injuries and four cabin crew members were seriously injured in this accident. The investigation started immediately and both the flight data recorder and the cockpit voice recorder were recovered from the wreckage. These together with the witness statements from pilots, cabin crew, passengers and the air traffic controllers soon painted a clear picture of what had happened.
The cause of the accident was deemed to be that the go-around was flown up until three seconds before the crash with the thrust levers and, therefore, also the engines at idle thrust. The lack of thrust rendered the aircraft unable to climb so it descended back onto the runway. The pilots failed to notice that the TO/GA switches were inhibited, probably because they didn't know that the main gear of the aircraft had touched down, and that they completely relied on the autothrottle to set the go-around thrust for them in line with the training that they had received.
This is actually an excellent example of where several parts of pilot training, operational procedures and pilot personality comes together to highlight shortcomings. It is really easy to only blame the pilots as Children of the Magenta Line in an accident like this but by doing that, you miss a lot of other important contributing factors. Because the investigation also stated that the pilot reliance on automation and lack of training in flying go-arounds from close to the runway surface and with the TO/GA switches inhibited significantly affected the pilots' performance.
This was very different from how they had been trained and how the system was expected to react. The pilots failed to monitor the FMA changes during the go-around partially because the company did not require those changes to be called out below 200 feet and there were no call outs associated with FMA changes in the company manuals for this phase of flight. There were also no cockpit warnings that the TO/GA switches were inhibited when the captain pushed them.
And the operator's policy to use autothrottle for all phases of flight did not consider the actions needed by the pilots in case the autothrottle was armed but inhibited after touchdown. All of these things came together during a very high workload segment of flight that only lasted for a few seconds and led to the accident. Several recommendations were made to the airline regarding flight training procedures and CRM training to improve monitoring and to avoid rushing during critical procedures.
There were also recommendations sent to Boeing to look at the possibility to implement better configuration warning systems as well as positive windshear detection during the flare. The fact that emergency exit slides had blown out of position was also highlighted. And that's actually something that we have seen in another accident that I've covered on this channel.
ATC was recommended to evaluate when the earliest point would be for calling an aircraft during such a critical phase of flight like a go-around, and to consider not calling them or changing the published missed approach procedure unless it was absolutely necessary. Now as you can see, there is always more than one link in a chain that leads up to a serious accident like this. These accident investigations are done with only one goal in mind, increasing safety.
That means finding out the whole story and rectify whatever part of the system that needs fixing, not just assigning blame and move on. This is something I think we should all try to learn from and apply in many situations in our own lives. Now, check out this video next, which is a really interesting story or check out this playlist.
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