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  • 5/31/2025

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00:01An Airbus A320 en route to Singapore disappears while flying over the Java Sea.
00:08It crossed my mind what could have caused it.
00:10Is it an act of terrorism, sabotage, something extreme happening to the aircraft?
00:15For days, a massive search and rescue effort turns up nothing.
00:20A crash at sea is challenging. It's difficult to lock it
00:23because you usually don't have the full flight path down to the surface of the ocean.
00:29What they find paints a confounding picture of the final minutes of flight.
00:34The plane started to bank.
00:37We were very surprised by this action.
00:40What are they doing?
00:42The investigation uncovers a single tragic misunderstanding that claimed the lives of 162 people.
00:59AirAsia Flight 8501 cruises high above the Java Sea, north of Indonesia.
01:09AirAsia Flight 8501 cruises high above the Java Sea, north of Indonesia.
01:14It's a few days after Christmas, and many of the 156 passengers aboard the Airbus A320 are on holiday.
01:33The pilot in command is 53-year-old Captain Irianto.
01:40He's highly experienced with more than 20,000 hours in the air.
01:45His first officer is French national Rémy Emmanuel Plaiselle.
01:50He is 46 with about 2,000 flight hours, much of it on the Airbus.
01:57On this particular leg, it was the first officer that was manipulating the controls.
02:02The captain was in command of the flight, but was performing the duties of the pilot monitoring or the non-flying pilot.
02:11Today's flight originated in the Indonesian city of Surabaya.
02:15It's heading across the Java Sea to Singapore.
02:19Total flight time is expected to be two hours.
02:27Looks like weather ahead.
02:29No, I don't like the looks of that.
02:3122 minutes into the flight, the pilots notice bad weather ahead on their radar.
02:36Anti-ice?
02:38Anti-ice?
02:40On.
02:43The crew would definitely be taking care to avoid penetrating these thunderstorms
02:46because it contains possibly extreme turbulence, hail, lightning,
02:51everything that the aircrew don't want to expose themselves and the passengers to.
02:58The captain instructs the flight attendant to prepare the cabin for turbulence.
03:03Ladies and gentlemen, please return to your seats and fasten seatbelts.
03:07The captain's seatbelt.
03:08The captain's seatbelt is one of four flight attendants helping to look after the passengers as they cruise at 32,000 feet.
03:22As an additional precaution, the captain decides to increase altitude to go above the storm clouds in their path.
03:38I'm going to radio for a higher cruise, get around that weather.
03:42Good idea.
03:44But before the captain can contact air traffic control, he gets a fault warning from the flight computer.
03:50Ecamm actions.
03:52The plane's sophisticated computers give the pilots step-by-step instructions on how to fix the issue.
03:58Back one off and on.
04:01Back two off and on.
04:06And on.
04:12Warning cleared.
04:16Computers control most of the Airbus A320's systems.
04:21There are basically seven computers that fly the aircraft,
04:25and they add a lot of helpful features that take workload away from the pilot.
04:29Pilots are trained to follow the instructions given by the aircraft's computers.
04:36A few minutes later, the warning sounds again.
04:40Same.
04:42Back one off and on.
04:45After addressing the fault warning, the captain radios air traffic control to request the higher flight level.
04:52Okay, so, Jakarta air traffic control, AirAsia 8501, request climb to 38,000.
05:03The Jakarta air traffic controller has had an uneventful night.
05:08He soon clears the pilots to climb.
05:11But to a slightly lower altitude than the 38,000 feet requested.
05:17AirAsia 8501, you are cleared to 340.
05:21After permitting them to climb, the controller waits for confirmation.
05:30But the pilots are distracted by a third alarm.
05:33Here we go again.
05:35E-cam actions.
05:37Back one off and on.
05:42The controller hasn't heard back, so he repeats his message.
05:46AirAsia 8501, you are cleared to 340.
05:50Zero.
05:51Very annoying and very time consuming to deal with this recurring problem.
05:55Enough of this.
05:57E-cam actions.
05:58E-cam actions.
06:10The controller still hasn't heard confirmation from the pilots.
06:13AirAsia 8501, do you read me?
06:15Please acknowledge.
06:16AirAsia 8501, do you read me?
06:17Please acknowledge.
06:18But in the cockpit, the fault warnings have escalated.
06:39In the cabin, passengers have no idea their pilots are struggling to maintain control
06:47of the plane.
07:06The pilots now notice that the plane is rolling sharply left.
07:11Level.
07:13OK, level.
07:15Something is going terribly wrong with flight 8501.
07:20The first officer is struggling.
07:22Level.
07:23But soon the plane is rolling again.
07:26Level.
07:27I'm trying.
07:29The pilots can't seem to regain control.
07:32It's not responding.
07:34AirAsia 8501, please confirm you are climbing to flight level 340.
07:41The controller still hasn't heard confirmation from the pilots when the plane starts to climb
07:46towards 34,000 feet and then continues climbing steeply, even higher.
07:52No airline passenger would have ever experienced something like this under normal circumstances
08:04before.
08:05It would have been a very violent, shocking maneuver.
08:09The plane seems to have taken on a life of its own.
08:13The plane seems to have taken on a life of its own.
08:16It climbs higher and higher as the pilots fight to level off.
08:22Then, inexplicably, the plane starts to drop.
08:29That would certainly cause near panic in some people.
08:33Other people would be waiting for the pilots to, quote, fix it.
08:37Flight 8501 is plummeting from the sky, speeding toward the ocean below.
08:52The rate of descent here was very, very high.
08:57It seems the pilots can do nothing to save their plane.
09:01Pull.
09:02It's not correcting.
09:03What's going on?
09:04Max power.
09:05Slowly.
09:0643 minutes into what should have been a two-hour flight, AirAsia flight 8501 disappears from
09:24radar.
09:25Pull.
09:26I'm trying.
09:27Pull.
09:28I'm correcting.
09:29Ah!
09:39News quickly spreads of the mysterious disappearance of a commercial flight to Singapore.
09:47The loss of AirAsia 8501 was a classic case of a flight degenerating from mundane, normal
09:54cruise conditions to the loss of the aircraft in a span of just 20 minutes.
09:58Within hours, relatives of the 162 passengers and crew are demanding answers.
10:06How could an airplane just disappear?
10:09We don't want to speculate anymore.
10:10We don't want to speculate anymore.
10:11Right now, of course, the plane has been missing for 12 hours and there's an active
10:16sense of depression.
10:20We don't want to speculate.
10:21All the authorities know is that the plane vanished from radar somewhere over the Java
10:26sea.
10:29The speculation runs wild about what could have brought the airliner down.
10:36It crossed my mind.
10:37What could have caused it?
10:38Is it an active terrorism, sabotage, something extreme happening to the aircraft?
10:42But it was very difficult to come up with a clear picture on the first news reports as to what
10:47had taken place.
10:48It's been only a few months since Malaysia Airlines Flight 370 disappeared in eerily similar circumstances.
10:56Vanishing from radar without sending any mayday call.
11:03Search and rescue vessels are dispatched.
11:06But combing the vast and choppy sea between Sumatra and Borneo for Flight 8501 is a mammoth task.
11:15An international team of air safety investigators flies in to join the local experts in Jakarta.
11:23Ray Nurkayo is an air crash investigator with the Indonesian National Transportation Safety Committee.
11:29The air traffic control radar data is our main source to detect the location of the aircraft.
11:37They begin by interviewing the air traffic controller.
11:41So, can you tell me what happened?
11:43They were the ones who could tell us a little bit more about what had happened.
11:47They had seen the plane trajectory, the plane flight path.
11:51They learned that the plane was flying towards an area of bad weather.
11:54When you start out in an investigation, you look at everything.
11:59In this case, there were weather considerations.
12:05And then?
12:07Then they started losing altitude fast.
12:14And then it disappeared from radar at 24,000 feet.
12:19Thank you very much.
12:20How could this plane, being in cruising altitude, suddenly climb and fall with a very high rate of descent?
12:31Could the aircraft have lost engine power in a violent storm?
12:35The weather might be in fault of the accident.
12:39So, we tried to get more information on the weather data.
12:42Can I get the weather overlay for this map, please?
12:52Investigators examined detailed weather charts from the day of the accident.
12:57There were thunderstorms here and here.
13:02It's quite a large red color.
13:05So, I assume there has been a bad condition on the area.
13:09It was monsoon season, and so there's a lot of thunderstorms.
13:14They can do damage to the airplane.
13:16It's something that you learn early as a pilot, and it's something that you adhere to very strongly.
13:24You do not fly through thunderstorms.
13:26Then they start mapping the flight track to see if the plane could have entered the storms.
13:31They were at cruising altitude.
13:32Then here, they asked for deviation.
13:36They made it here, and then they started to drop.
13:41They almost flew into the first storm, but then just missed it.
13:45Bad weather.
13:47The first possible explanation for the disappearance of Flight 8501 proves to be a dead end.
13:52This is a spot they were last seen on radar.
13:57Based on Flight 8501's last radar coordinates, investigators have at least narrowed down the search area.
14:07Dozens of rescue vessels and aircraft from multiple countries scour the target area.
14:12A crash at sea is challenging. It's difficult to lock it because you usually don't have the full flight path down to the surface of the ocean.
14:24The Indonesian president decides to address a nation in mourning.
14:28For all of the passengers and aircrafts, now I feel a lack of loss at this event.
14:42And we all pray.
14:45Two days into the search, the first pieces of wreckage are recovered from the Karamata Strait in the Java Sea.
14:52Main wreckage was found not far from the point that we predict based on the ATC radar.
15:05Soon, searchers are finding bodies.
15:08Among the first is that of flight attendant Kairinisa Haidar Fauzi.
15:15In a moving tribute, hundreds attend her funeral.
15:19Funerals for many more follow.
15:24Of the 162 passengers and crew, there are no survivors.
15:35As the wreckage is brought in for examination, investigators can see that the task ahead of them is daunting.
15:41Why would a highly sophisticated airliner, flying at cruising altitude, suddenly fall from the sky?
15:47We had a lot of little pieces everywhere.
15:51My first reaction was, it's not going to be easy.
16:04Is it all like this?
16:06A crash at sea is challenging because usually the main interesting parts are underwater.
16:10And that's a little bit difficult to get them.
16:14With much of the plane still missing at the bottom of the sea, investigators study debris found floating on the surface.
16:22To see if the plane exploded, they look for distinctive smaller pieces with burnt edges.
16:27The debris that was recovered did not exhibit any tell-tale signs of having been subject to a bomb explosion.
16:46This plane didn't blow up.
16:50The pieces of AirAsia 8501 are large and clean.
16:55We could eliminate a possible in-flight breakup.
17:00It's a step forward.
17:01But unless they can find the black boxes, the mystery of AirAsia 8501 may never be solved.
17:15The flight recorders offer the only hope of figuring out what was happening in the cockpit.
17:19The search for them goes into high gear.
17:23The black box search team, assisted by Singapore, France, UK and China.
17:31We utilize side-scan sonar and underwater unmanned camera.
17:40All black boxes are equipped with an electronic beacon that transmits a signal underwater.
17:45Ship-based sonar systems can detect the signal and help guide searchers towards the black boxes.
17:53When we get this signal, we are in a range of about 2,000 meters from them.
17:58So this helps us narrow it down to where they are.
18:02And then the divers then have to try to find them.
18:06But weather complicates the search.
18:09The depth was about 40 meters and the sea was rough.
18:13And we couldn't go every day where we wanted to go.
18:19So we had to adapt our strategy to the weather.
18:22After a two-week search, they finally succeed.
18:27The black box were found first on 12th of January, the flight data recorder.
18:33And the following day, we found the cockpit voice recorder around the same area.
18:39We were relieved to get the boxes because this was a real major step towards the explanation of what had happened.
18:48Investigators start by listening to the cockpit voice recording.
18:58It should reveal pilot conversations and other sounds from inside the cockpit of Flight 8501.
19:04OK, let's start when they ask permission to climb. Play recording.
19:11Jakarta Air Traffic Control, Air Asia 8501. Request to climb to 38,000 to clear storm clouds.
19:19Up to that point, the flight was normal, was uneventful.
19:22Continue recording.
19:23Almost immediately, investigators make a discovery.
19:29E-cam actions.
19:32Back one off and on. Back two off and on.
19:38Warning cleared.
19:39They were dealing with some kind of warning.
19:45Play recording.
19:49E-cam actions.
19:51Same.
19:53OK, the warning came back.
19:55They were getting continual fault warnings through the, what's called an E-cam system, electronic central aircraft monitoring system.
20:04Play recording.
20:06Here we go again.
20:08E-cam actions.
20:10Back one off and on.
20:13Back two off and on.
20:18It's cleared.
20:20At this point, the crew's behavior was standard, was normal.
20:23They were quiet.
20:25They were communicating on what checklist to apply.
20:29Air Asia 8501, you are cleared to 340.
20:33OK, stop.
20:34We know from the controller that he never heard back from them again.
20:39Play.
20:42There it is again.
20:43E-cam actions.
20:46Then the recording reveals something surprising.
20:50No, I've got a better idea.
20:52The captain appears to have done something different.
20:55And then there's a new warning.
20:57Cold recording.
20:59Now the autopilot has disengaged.
21:03An unexpected disengagement of the autothrottle and autothrust system results in a pretty loud warning.
21:11This is a very serious concern to the investigators.
21:14What was that?
21:16OK, let's see what we have.
21:18Master, caution.
21:20Why?
21:22Checking.
21:26Level.
21:28Level.
21:30Investigators now hear yet another cockpit warning.
21:32Stall warning.
21:33Stall warning.
21:35The airplane would have warnings to tell the pilot that they were getting close to an aerodynamic stall.
21:44Pull.
21:45Slowly.
21:47What's going on?
21:48Stall.
21:49An aerodynamic stall occurs when the angle between the wings and the oncoming air gets too steep.
21:56The amount of air flowing over the wings is reduced.
22:00The aircraft loses lift and can no longer stay aloft.
22:03It's a highly uncommon event to have an airbus stall, particularly in cruise because it's protected from stalling.
22:14Normally, the computer won't allow the aircraft to stall.
22:17It won't allow the wings to go at too high an angle to the airflow and stall the aircraft.
22:22What caused this technically advanced plane to stall?
22:25The autopilot disconnects, the aircraft stalls, they struggle to recover.
22:31It makes no sense.
22:34Only the FDR data can reveal what was happening with the aircraft the moment the crisis hit.
22:40Until that data is ready for analysis, the deadly mid-air stall remains a mystery.
22:56What were you guys struggling with?
22:59One of the questions that the investigators would have faced is,
23:03why and how did an aircraft that is supposed to be stall proof end up stalling?
23:07The flight data recorder should provide answers, but it needs to be flushed of salt water before it can be read.
23:26In the meantime, investigators pull the plane's maintenance records to look for clues.
23:33They soon make a discovery.
23:34The aircraft seems to have an issue with its RTLU.
23:39RTLU is the rudder travel limit unit.
23:42The plane had had a history of RTLU failures.
23:46The rudder travel limit unit is a computerized component that prevents the rudder on the tail from deflecting too far in either direction,
23:55when the plane is traveling at high speed.
23:57If the flight computer detects any problems with its rudder limiter, it sends a warning to the cockpit.
24:07Records show the aircraft's rudder travel limit unit had been malfunctioning for almost a year.
24:1323 reports of the exact same failure.
24:18The RTLU failures on this particular airframe have become increasingly frequent.
24:23There were 11 in the last couple of months and 23 in the preceding period, which is highly unusual.
24:30That seems like a lot of failures with the RTLU.
24:32Could these be connected to the mystery warnings the pilots were experiencing?
24:38It could be a major breakthrough.
24:41Three days before the crash, there were two exact same failures.
24:47Why was this happening?
24:49After each failure, maintenance workers reset the RTLU.
24:55As long as the reset resulted in the computer to prompt pass, maintenance personnel doesn't have to investigate further.
25:05They just kept resetting it and then putting it back in service.
25:11But they never found a permanent fix.
25:13They were returning the airplane to service after reset and from a legal standpoint, it did clear the problem.
25:21But obviously, whatever the fault was, they hadn't found it because the problem continued to reoccur.
25:28The aircraft seemed to operate perfectly despite the warnings.
25:34Even the day before the crash, the plane had successfully flown from Surabaya to Kuala Lumpur.
25:40Have we got the unit?
25:41The plane's RTLU is among the wreckage that's been recovered from the Java Sea.
26:02Let's send it back to the manufacturer and see if they can find something.
26:06The unit is sent to France for analysis.
26:08Finally, investigators get to examine a key piece of evidence, the flight data recorder.
26:21If they can download all the flight data, it should provide a detailed picture of exactly what was happening with the electrical and mechanical control systems on the aircraft.
26:33After the black box recovered, they transferred to our laboratory.
26:34After the black box recovered, they transferred to our laboratory.
26:43We worked to the Indonesian investigation authority in extracting the data, which requires a lot of precautions since the flight recorders had been immersed.
26:53Move it down to a little bit.
26:54On examination, they discover the data board has been damaged by the impact of the crash.
27:14It's uncertain whether the information they desperately need will be retrievable.
27:23The download begins.
27:24The download begins.
27:37Even though the condition of the black box was damaged, we managed to recover all of the data.
27:46Success.
27:47Okay.
27:48So, let's start with those chime warnings.
27:49Okay.
27:50So, here's the first warning.
27:51It clearly was the RTLU.
27:52Okay.
27:53They do the fix, simply resetting the entire system.
27:54The procedure to reset the system was much like your PC rebooting the PC.
28:08They only had to turn the system off and turn it back on again.
28:12Back two.
28:13Off and on.
28:15Two more times, the RTLU warning goes off.
28:21And each time, they did the right thing.
28:24Then it went off on a fourth time.
28:27Then suddenly, there was a glitch.
28:31What did they do different?
28:35After the fourth time, the warnings change.
28:40There is now a fault with the aircraft's two main computers, known as the flight augmentation
28:45computers.
28:48Put the new data up on that screen.
28:57Something caused both computers to fail at the same time.
29:02But nothing in the data shows what the crew did differently after the last warning.
29:07What does come to light is that when the autopilot disengaged, the rudder moved slightly.
29:14Now, let's see.
29:17The plane started to bank to the left.
29:21The electrical interruption on the flight control computers created a rudder movement of about two degrees to the left.
29:32Two degrees does not sound like a lot, but at the speed they were flying, it's exactly what caused them to roll left 54 degrees.
29:39That's almost twice the normal bank that you would feel in an airliner.
29:46Now, look at this.
29:50It took them nine seconds to do anything about the bank.
29:54Despite the steep bank angle, it seems the crew was slow to react and level the plane.
30:00During the first nine seconds, there was no crew inputs on the controls following this roll that reached 54 degrees.
30:09Then the first officer suddenly reacts, pulling hard to the right, then left again.
30:15And just as suddenly, he starts to pull up.
30:18All they had to do was steady the plane.
30:21What were they doing?
30:25The FDR data shows that the plane climbed steeper and steeper until they reach a remarkable 45 degree pitch up.
30:34Then it stalled.
30:36Investigators know that the captain did something different.
30:39Something that led to a computer glitch causing the autopilot to disconnect and the plane to bank sharply.
30:46But they don't know what he did.
30:49The single event of autopilot, autothrottle disengagement sends the investigators in two different directions.
30:55One, what caused it?
30:57Two, how did the crew handle it?
30:59As investigators struggle to answer puzzling questions about Flight 8501 and its crew.
31:10Hello, NTSC.
31:11They get an important new lead.
31:13Wait, wait, slow down.
31:15What happened?
31:20A mysterious action by the captain to solve a routine error appears to have set off a deadly sequence of events.
31:28Investigators are still trying to understand what happened when they receive some new information.
31:34Start from the beginning.
31:36Where was he?
31:37Three days before the accident on the 25th December, this same captain was about to fly from Indonesia to Kuala Lumpur when he had an RTLU malfunction.
31:49He asked for an engineer to come to the cockpit and try to fix that.
31:53RTLU problem again?
31:55Yeah, it just keeps coming back.
31:56The maintenance engineer rebooted the system.
32:02But the problem came back.
32:08I've got an idea.
32:12He then pulled the circuit breakers for the main computer.
32:21Maintenance on the ground has a very specific list of circuit breakers that says you can utilize pulling these circuit breakers to reset computers within the airplane.
32:33As the captain watched, the problem was fixed.
32:38Problem solved.
32:39And can I do the same thing if it happens again?
32:41Yeah, just do what the E-Cab tells you to do.
32:46Don't tell me he tried to do that in the air.
32:51Investigators think that they now know what the captain did that led to the crisis in the cockpit.
32:57Begin simulation.
32:59To see if they're right, they decide to simulate the cockpit warnings heard in flight.
33:05Okay, so let's start with the RTLU warnings.
33:08Okay.
33:11FAC 1, off.
33:13FAC 2, off.
33:16FAC 2, off.
33:21Enough of this.
33:22After the fourth RTLU warning, he takes a new approach.
33:25E-Cab actions.
33:26No.
33:27I've got a better idea.
33:29Investigators believe the captain pulled two critical circuit breakers.
33:37Captain pulls circuit breaker one.
33:39The result is immediate.
33:51And there goes the autopilot disconnect warning.
33:54Investigators can now be certain of one thing.
33:58This had to be what he did.
33:59He was perhaps copying what he'd seen the ground engineer do.
34:03But of course the consequences in flight to disabling critical systems are quite different.
34:08The captain wrongly assumed that if it worked on the ground it'll work in flight.
34:13The circuit breaker, which is part of the flight augmentation computer, is something that should never be pulled out in the air.
34:24Pulling the circuit breakers has devastating consequences the captain didn't anticipate.
34:29Unfortunately, he was not pulling circuit breakers that affected only the rudder limiter system, but ones that also disabled the flight augmentation computer, which tripped the autopilot, the autothrottle, and all the normal mode protections that the aircraft had.
34:45The plane begins to roll.
34:48Over the next nine seconds it rolls 54 degrees.
34:52Yet no one does anything to stop it.
34:55What took them so long to react?
34:58The first officer would have been looking here and here when the autopilot warning was disconnected.
35:05And the captain was still standing behind the first officer's seat.
35:10What was that?
35:11It's likely that neither pilot was looking at the attitude indicator that showed the plane was banking.
35:18That's why it took them nine seconds to notice what this gauge here was telling them.
35:27As the plane started to roll, the first officer was focused on the fault warnings.
35:33He didn't notice that the plane was banking until the captain sat back down again.
35:41Despite losing control of these systems, the high-tech plane did have the capacity to get back on course.
35:53After the initial roll, why didn't the first officer just steady the plane and re-engage the autopilot?
36:00Investigators have to try to understand what was going on inside the pilots' heads.
36:07The co-pilot's movement of the stick to its extreme right-most position resulted in a very violent roll to the right.
36:15Two to three times what would be programmed as the maximum for an Airbus normally.
36:19In an attempt to understand the first officer's actions, investigators study how the human brain behaves in flight.
36:30A sense of balance is maintained by liquid levels in the ear canals.
36:35When that shifts violently, the brain can get mixed signals that affect balance.
36:39The FDR data shows how dramatic the plane's movements were.
36:47So the plane rolled 54 degrees left, and he pulled back almost level in just two seconds.
36:57That would scramble anybody's gyros. Maybe that was the confusion.
37:00As soon as the first officer had levelled the aircraft, the fluid in his ear canals keeps spinning to the right.
37:09The aircraft is level, but there's a very strong illusion from the ears that you're turning to the right.
37:13He pushes the plane all the way to the left. But why?
37:19Level! I am! I am!
37:22The natural response would be to roll the aircraft back to where it came from, into the 54 degree of bang, which was what they thought the level was.
37:30And then he pulls it as hard as he can, and the plane starts climbing.
37:37This is a massive input. The airplane would pitch up very quickly.
37:44What's going on?
37:47He was completely baffled.
37:49His vertigo may have led him to believe that the aircraft was pitching down, so he's actually recovering from an imaginary pitch down.
37:55He was disoriented.
37:57With all the alarms that were going off, with the rapid left-right-left rolls, and with the generally deteriorating situation, I think the crew had started to lose their spatial awareness completely.
38:11Investigators finally understand what must have been going on with the first officer's confused state of mind.
38:18But if the first officer wasn't operating the controls correctly, why didn't the captain take the one step that could have saved the lives of everyone on board?
38:30Investigators study the captain's behavior during the role.
38:38Pull down!
38:40They know from the recordings that he was trying to help right the plane.
38:43Pull down!
38:44I'm trying! It's not responding!
38:46He wants his first officer to stop climbing up and push the nose down.
38:50Pull down!
38:51His command is confusing.
38:53It's either you pull up or you push down.
38:57When one thinks that the co-pilot is holding a side stick, pull means pull it back, which means go up.
39:04And down means push it forward. So pull down is a contradictory command.
39:08In that case, the captain should have said, nose down, nose down.
39:13The first officer continues pulling back on his side stick until the very end.
39:18The input of the first officer...
39:21Pull down!
39:23...was the exact wrong thing to do.
39:26What's going on?
39:27He clearly didn't understand the command.
39:30So why didn't the captain take full control of the airplane?
39:33He tried to take over here and over here.
39:36Pull!
39:37Stop directing!
39:39There is a button on top of the side stick that can let you take full control to lock the other pilot out.
39:47Pull!
39:48So that you know what's going on.
39:50The data shows that the captain did push the take control button, but only briefly.
39:56He didn't push it long enough to take over the plane.
39:59It's not responding.
40:01But at the end, he never took control.
40:02It meant that both pilots were trying to fly at the same time.
40:09Both pilots started controlling the aircraft.
40:12When that happened, control of the aircraft become ineffective.
40:18If he'd spoken three simple words, the plane could have been saved.
40:22The training is, you say, I have control, and the other pilot stops making inputs.
40:30In this case, that wasn't happening.
40:33Investigators now know that pilot error led to a spatially disoriented first officer.
40:39The captain, who could have helped by communicating more clearly or taking over the plane, did neither.
40:48Investigators can never be certain why.
40:52The case is building to a close when they get another piece of information.
40:56The results of the RTLU analysis are in.
40:59It was a series of warnings from that unit that triggered the events that led to the crash.
41:12Ecamm actions.
41:15The failure the crew had experienced with the rudder limiter system was actually a negligible failure.
41:23It was a nuisance.
41:25And the procedures to reset it.
41:27Back one off and on.
41:30Were simple.
41:32Back two off and on.
41:34And on.
41:37Warning.
41:39All the captain had to do was keep on following the Ecamm's instructions.
41:46The plane had had a history of RTLU failures throughout the year, and this failure had never been fixed.
41:53Microscopic examination of the unit's electronic module finally reveals the cause of those repetitive failures.
42:00We found out that there was a crack in the soldering joint on the electronic module, which caused the RTLU to work from time to time only.
42:11And had the correct maintenance test been applied.
42:16Problem solved.
42:18The RTLU electronic module would have been removed.
42:22The airplane should have been sent for troubleshooting, and you could have broken the chain of events.
42:28For investigators, discovering that such a minute fault sparked events that led to the death of all 162 people on board makes this all the more tragic.
42:42As they prepare their final report, it's clear that the crash of Flight 8501 has exposed a series of serious problems.
42:51The final report calls for improved maintenance protocols to help eliminate minor recurring problems, like the RTLU fault, before they lead to a major catastrophe.
43:07When you start having four, five, six, eight, ten recurring problems, it's saying that the traditional methods are not working, and that you need to do much more heavy-duty diagnostics until they find the problem.
43:23Pull! Pull down!
43:27Pull down!
43:28And the other lesson we take from the accident was the communication between pilots to make sure the communication was well, to avoid the different interpretation of the command.
43:39This is a case that the industry learned some very hard lessons, but the thing most importantly is that the industry implements those lessons so that we don't have another one.
43:54The End
43:56The End
43:57The End
43:59The End
44:00The End