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  • 5/27/2025

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00:00It's Spain's worst air disaster in 25 years.
00:07It was a tremendous tragedy.
00:09A crash that kills 154 people.
00:14Our thoughts were with our colleagues and the passengers.
00:19Investigators face intense pressure to pinpoint the cause.
00:22When you get to the accident site, you need to collect facts.
00:26When you come up with a mechanical irregularity...
00:29Do you see anything outside?
00:30It's like, ugh, what next?
00:33Right, got it.
00:35...could a minor maintenance issue...
00:37So, we're done?
00:38Yep, you're good to go.
00:40...have led to this deadly catastrophe.
00:43It's 2.14 p.m. at Madrid Barajas Airport.
01:13After being delayed for more than an hour,
01:16Spanair Flight 5022 is finally getting back underway.
01:24There are 166 passengers on board,
01:28many of them looking to escape the stifling heat of Madrid in August.
01:34Everyone was full of anticipation.
01:37Everyone wanted to be on their way.
01:40Anna Stefanidis has come to Spain from Sweden.
01:43She is on her way to the Canary Islands to meet some friends.
01:48Most of Europe has holidays, different summer holidays in August.
01:54I was going to Gran Canaria to meet my girlfriends.
01:57We were going to have one week's holiday, four ladies.
02:03Today, Captain Antonio Luna is in command.
02:07A former Spanish Air Force pilot, he's been with Spanair for nine years.
02:13How's our time?
02:17About an hour and a quarter behind schedule.
02:21First Officer Francisco Moulet is on his way.
02:26About an hour and a quarter behind schedule.
02:30First Officer Francisco Moulet joined the company just a year and a half ago.
02:36Almost all of his 1,300 flight hours are with Spanair.
02:40Maybe we can make it up in a year.
02:43Maybe.
02:45The flight began with a morning hop from Barcelona to Madrid.
02:50From Madrid, they'll fly two hours and 50 minutes south to Gran Canaria in the Canary Islands.
02:56Spanair 5022, your next in line on runway 36L.
03:02OK, here we go.
03:14Preparing for takeoff is an extremely busy time for the flight crew.
03:18They've got multiple checklists that they have to run.
03:21Ignition. Set. Spoilers. Armed.
03:25Make certain the aircraft is properly configured, the thrust is set right, the brakes, etc.
03:30Air conditioning.
03:32So there are a plethora of factors that are all running through their minds simultaneously.
03:37And final items, we have 8, 11 aligned, 11 stowed.
03:46Spanair 5022, you are cleared for takeoff, runway 36L.
03:51Cleared for takeoff, Spanair 5022.
03:54OK, your aircraft.
03:56First Officer Moulet will fly the plane from here.
03:59My aircraft.
04:03At 2.23, the MD-82 aircraft starts speeding down the runway.
04:16One hundred.
04:19The captain watches their speed.
04:21They can't lift off until they reach 157 knots, takeoff speed.
04:29It didn't feel right.
04:31I thought they were putting in all the power and force that they had, and now we will lift off.
04:36But something was just not right.
04:42It's taking so long.
04:45Does that seem right to you?
04:50And then I thought, how long is this runway? We have to lift off now.
05:00V1. Rotate.
05:12An alarm warns the pilots something is going wrong.
05:27The first officer increases power, but he's losing control of the plane.
05:33When we finally lifted, everything went suddenly to the right,
05:37and then I just heard screams and crashing.
05:45The plane is less than 40 feet from the ground.
05:53I managed to think, this is my last chance.
05:59I managed to think, this is my last trip.
06:03I've had a good life.
06:06I thought, now I die.
06:22I put my arms over my head and put my head between my legs.
06:28I protected myself as much as I could.
06:50Just seconds after takeoff, Flight 5022 slams into a riverbank beside the runway.
06:57Airport fire crews are quickly on the scene.
07:05The plane with 172 people on board is now shattered wreckage, spread over half a mile.
07:17Anna Stephanidis has landed in the water, still strapped to her seat.
07:23When I woke up, first there was this quiet.
07:27But then I realized, I'm not dead.
07:30I looked around me. Where am I? What is this?
07:38Airport workers have raced to the crash site to try to help, but they can't get to Anna.
07:44The emergency personnel were calling to me.
07:47Come on! Come on! Hurry! Now!
07:54She's in the middle of the stream, tangled in debris and sinking fast.
07:59I have no idea how I managed to get free.
08:04Somehow Anna makes it to the water's edge where rescuers help her to sink.
08:10Somehow Anna makes it to the water's edge where rescuers help her to safety.
08:15She's in shock and suffering from a serious leg injury.
08:19But she's alive.
08:27It was chaos. It was so horrible.
08:33But I got out.
08:36In spite of the massive rescue effort, only 18 people survive.
08:44147 passengers are dead. So are both pilots.
08:49It was a tremendous tragedy. All the country was affected by that.
08:56This is Spain's worst aviation disaster in 25 years.
09:06Our thoughts were with our colleagues and the passengers.
09:11It was a Spanish company, so many of our colleagues were flying that type of plane.
09:18It was a very difficult time.
09:23Spain quickly recruits an international team of experts to investigate the crash.
09:28They have a massive puzzle to piece together.
09:32How could a sophisticated jet, manned by an experienced crew...
09:37Rotate.
09:39...crash on take-off on a sunny afternoon?
09:43OK, people. It looks like we have our work cut out for us.
09:48Juan Carlos Lothano is an investigator with the Spanish Pilots' Union.
09:53The accident site at the beginning is considered like a crime scene.
09:57It's very important to find out how the pieces are located.
10:02Because that will give you a lot of information.
10:06It's demanding work.
10:08Searching acres of rough terrain for shattered pieces of scorched debris.
10:13All under the blazing Madrid sun.
10:16It was difficult. The heat, because it was a very hot summer.
10:20So the heat was probably one of the worst things.
10:24Understanding what happened to Flight 5022...
10:28...is going to be one of the most difficult tasks these air crash investigators have ever faced.
10:40Investigators into the crash of Spanair Flight 5022...
10:44...immediately focus their efforts on recovering the plane's two black boxes, or flight recorders.
10:50For an investigator, the FDR is one of the most vital records that we can get.
10:55Because everything that is working, or it is not working, or it's causing an issue...
11:00...will be recorded there.
11:03Once they download the data, it could provide vital clues about what went wrong.
11:11Let's get this to the lab. ASAP. OK?
11:21Meanwhile, the nation mourns.
11:27The Prime Minister visits the crash site.
11:30The King and Queen and the Mayor of Madrid gather to console the grieving families.
11:36The pressure to announce a cause is intense.
11:41The press was putting a lot of pressure on the investigators to give answers...
11:45...even before they had any idea what could have happened.
11:51I don't have any information. I just don't.
11:57At the crash site, marks on the ground paint a vivid picture.
12:02Here's our first impact.
12:03Revealing just how quickly Flight 5022 turned to disaster.
12:08The first impact marks are just 200 feet from the runway.
12:12The plane then passed over a road and slid another 1,800 feet...
12:17...before crashing on the far side of a river.
12:22This airplane left a trail coming from the runway to the edge of the airport boundary.
12:28So it was quite clear for the investigation that the airplane had a big problem just on liftoff.
12:37The timing immediately suggests a theory that might explain the crash.
12:42Let's take a look at this engine.
12:44When an aircraft gets only 30 feet off the ground and falls uncontrollably back to the ground...
12:51...you have to wonder were the engines operating correctly.
12:55Engine power is especially crucial during the first few moments of flight.
13:00If the plane doesn't have enough power, it won't achieve the speed it needs to overcome drag and get airborne.
13:09Investigators study the engines, searching for any sign of malfunction.
13:13Both are filled with debris, mud and grass ingested during the crash.
13:19If we find mud, soil or grass throughout the engine...
13:23...we can determine that the engine was fully operational at the time of the accident.
13:28In this case, we found traces all around the engine.
13:32The finding means the engines were spinning at high speed when they hit the ground.
13:37It wasn't engine failure that doomed the plane.
13:44Right.
13:47The engines were fine.
13:49But something stopped that plane from climbing.
13:54Investigators need a new theory to explain why the MD-82 couldn't climb.
14:00What was it?
14:02I want maintenance records, weather reports, pilot records, the works.
14:08Let's get to work, people.
14:10For an accident investigator, it's very, very important not to establish any presumptions.
14:17You need to collect facts.
14:22OK, let's see what the numbers tell us.
14:24Investigators know that for any take-off, the plane's weight and balance must be carefully calculated.
14:31The aircraft needs to be carefully balanced in order to get its better performance.
14:37So when you are taking off, you need to be sure that the aircraft has been properly balanced and the weight is correct.
14:47They review the passenger manifest, cargo and fuel load.
14:52They need to check the total weight as well as where the loads were carried...
14:56...to see if the plane's centre of gravity shifted dangerously forward or back.
15:02But it's soon clear this isn't the smoking gun they're looking for.
15:07Well, there's nothing wrong with their take-off weight.
15:13Controllers in the tower provide a more promising lead.
15:17They tell investigators that the Spanair crew called off an earlier take-off.
15:22They had some kind of maintenance issue right before take-off.
15:26The plane was at the threshold of the runway when the pilots noticed a temperature gauge was giving them faulty readings.
15:33Madrid, Spanair 5022, we have a slight problem.
15:37We have to exit the runway.
15:395022, taxi to apron Tango 2, stand Romeo 11.
15:46Controllers cleared the MD-82 to return to the terminal.
15:50You've spent the last 45 minutes totally focused on getting that aircraft to the runway...
15:57...and when you come up with a mechanical irregularity, it's like, what next?
16:03It's a showstopper.
16:04Ladies and gentlemen, we are experiencing a minor technical problem.
16:08We're just going to head back to the terminal to see if we can sort this out.
16:12Normally the passengers are more comfortable after a clear and direct explanation on what's going on.
16:21I guess we're not going anywhere just yet.
16:24I thought, why should I worry?
16:27I've bought my ticket. I've paid for my ticket.
16:31I want to get there. And I will.
16:34So they will have to do their job and fix this.
16:39Could the last-minute repair be the key to explaining the crash of Flight 5022?
16:45Investigators need to know.
16:49Spanair Flight 5022 was sent to a remote maintenance area in a far corner of the terminal.
16:57It took nine minutes just to taxi there.
17:01And we're back.
17:04It's shutting down the engines.
17:07By the time they reach the maintenance stand, the plane is already 42 minutes behind schedule.
17:13That delay could be an important lead.
17:16On-time performance is taken very, very seriously in the industry.
17:20And now that they're substantially behind schedule, the pressure is immense.
17:28With the engines shut down, the plane's air conditioning doesn't work.
17:33Sitting on the scorching tarmac, temperatures in the plane begin to soar.
17:40It was incredibly hot in the plane.
17:43I've never experienced that kind of heat before.
17:48Maintenance workers give investigators more details about the delay.
17:52They were trying to fix a problem with one of the plane's sensors.
17:57Oh, yeah. I took a look, but it wasn't serious.
18:03The sensor, called a ram-air temperature probe, juts out from the nose of the plane.
18:08It measures the outside air temperature and feeds the information to the engines during flight.
18:16Did you see anything outside?
18:18No, it looks fine. It's not clogged.
18:21The sensor is sending faulty readings to the engines.
18:26No, that didn't work either.
18:29Without it, the automation that adjusts engine power won't work properly.
18:33Look at that. It says 104 degrees now.
18:37The attempted repair eats up more valuable time.
18:41I've got to write all this up.
18:44Not to mention the delay, over an hour late at least.
18:47The entire economics of the present-day transport industry is built on efficiency.
18:52An airplane in the air makes money. An airplane sitting on the ground doesn't.
18:56It's all about efficiency.
18:59An airplane in the air makes money. An airplane sitting on the ground doesn't.
19:03So if you've got an aircraft that isn't where it needs to be,
19:06this has thrown a severe complication into the efficiency and the operations of the airline.
19:14Ladies and gentlemen, thank you for your patience. We hope to be on the move again very soon.
19:22Maintenance workers explained that they couldn't repair the faulty sensor.
19:29Right, got it.
19:30Instead, they disabled it by cutting the electrical power to the sensor.
19:35They simply tried to avoid the symptom,
19:40which is the high temperature in the ram head, temperature probe, by pulling the circuit breaker.
19:49The quick fix eliminated the faulty readings.
19:53So, we're done?
19:55Yeah, pop the breaker, so you're good to go.
19:58Okay, thanks.
20:01The maintenance workers have no idea what went wrong on take-off.
20:07Investigators wonder if the disabled temperature probe is somehow linked to the crash.
20:13I don't see how this could cause a problem.
20:16But they quickly confirm the probe is not an essential piece of equipment.
20:20The crew simply has to keep track of the air temperature and adjust engine power manually.
20:26There are alternate means to determine what the outside air temperature is.
20:31In this case, it's something as simple as just asking ground control or listening to the last official weather report.
20:37But that wasn't the only maintenance issue the crew was facing that day.
20:41It says here the right thrust reverser was disabled as well.
20:48Thrust reversers are used on landing to help the plane slow down.
20:56When engaged, bucket doors open to deflect the jet blast and redirect it forward.
21:05If a reverser malfunctions and activates during flight, the plane can lose lift and drop out of the sky.
21:13That's what happened to Lauda Air Flight 4 in 1991, killing all 223 people on board.
21:21Did a faulty reverser somehow activate on take-off?
21:27It seems unlikely, but it would explain the plane's deadly trajectory.
21:33If this thrust reverser had deployed inadvertently, because the jump movement would have taken the airplane to the right-hand side, which is actually where the airplane crashed.
21:42It's an intriguing theory, but so far there's not enough evidence to prove it.
21:51Investigators study the thrust reversers recovered from the wreckage of Spanair Flight 5022.
21:59There's no evidence that the right-side reverser deployed.
22:03But on the left engine, it's a different story.
22:07Is this the position it was in when you found it?
22:10The reverser is in the deployed position, a potentially deadly configuration.
22:16If one of the thrust reversers deployed inadvertently on take-off, given that the engines are providing full thrust,
22:23that would pose a very big threat for the controllability of the airplane.
22:30Finally, something that points to a serious mechanical problem with the plane.
22:35One that might explain the crash of Flight 5022.
22:39A lot of scrape marks.
22:42But as investigators continue to scrutinize the reverser, they realize there's a problem with the theory.
22:49I think it was deployed after impact, as the engine was dragged along the ground.
23:01Distinctive damage to the reverser tells investigators it deployed after the plane came down.
23:07Not in the air.
23:09All the damage that it had sustained was very easy to compare with the marks on the ground.
23:16So that led the investigators to rule out a thrust reverser.
23:21Something else stopped the plane from climbing out.
23:24Investigators need to shift gears.
23:28Once you have eliminated the engine failure, you have to think about lift.
23:34About the possibility of the aircraft to become airborne.
23:38What kind of wreckage have we recovered from the wings?
23:42Get me everything you have.
23:45The plane's wings are equipped with a special system of sensors.
23:49Get me everything you have.
23:52The plane's wings are equipped with control surfaces, the flaps and slats, that extend at takeoff to help generate lift.
24:00For modern airplanes, the flaps and the slats are probably the most critical parts, besides the engines and the wings itself.
24:10As it allows the airplane to take off and land in a shorter distance with lower speeds.
24:14If the flaps didn't extend properly, it would result in flight 5022 not having enough lift to climb.
24:22The investigators study the lever mechanism that pilots use to control the flaps.
24:28The flap lever was a very essential part of the investigation.
24:35If the lever was driven against the side of its track during impact, it might leave a mark showing how the flaps were set at takeoff.
24:43Well, well. What have we here?
24:47There's a deep scratch at zero, or retracted position.
24:52It's a startling finding, one that suggests the flaps on flight 5022 were not extended for takeoff.
25:00My first reaction as a pilot is that flaps and slats are absolutely necessary for takeoff.
25:06And there's just not going to be a survivable crash.
25:09And there's just not going to be a survivable crash if they've attempted takeoff and they weren't extended.
25:17It's hard to believe a professional pilot could forget to set such a vital piece of equipment.
25:23Did the flap handle shift during the accident? Or did the pilot somehow fail to set it properly before takeoff? Be one.
25:31My second innate question is, why? What happened to prevent them from being in the right position?
25:36The answer to that question could explain why 154 people died in one of Spain's worst air disasters.
25:48Investigators dig into the personal and professional histories of the Spanair crew, wondering if the pilots could have made a terrible mistake.
25:58Both qualified. Both experienced.
26:01You always check on their experience, if they had any issues during the training, what kind of training they had.
26:09The pilot records turn up nothing significant. Captain Luna and First Officer Moulet are both up to date on all necessary training.
26:18It's hard to believe these guys could forget to set their flaps.
26:24The commander had an excellent reputation. He was a person who was considered to be very meticulous.
26:32He enjoyed flying and took pride in being a professional.
26:42Investigators turn to the cockpit voice recorder for answers.
26:47OK, let's hear it.
26:54Ignition. Set.
26:57When you listen to a cockpit voice recorder, you're trying to understand the pilots and put yourself in the pilot's situation.
27:05They're listening for anything that might tell them how the flaps were set for takeoff.
27:12The pilots make their final preparations.
27:14And final items, we have 8, 11 aligned, 11 stowed.
27:20Including a last minute check of the flaps that's required right before takeoff.
27:25Hold it, stop right there. Final item.
27:30That includes checking the flaps. He called out 11. That's the right setting.
27:38The recording suggests the pilots set the flaps to 11 degrees, exactly where they should be.
27:45Perhaps the flap lever did somehow shift after takeoff.
27:50Maybe they did get it right.
27:52I was really shocked that the crew definitely talked about the flap position.
27:57And it seems that the flaps were not in that position.
28:01So that creates a kind of contradictory feeling of saying, wow, these guys were really looking at the flaps or not?
28:12Contradictory evidence threatens to derail the investigation.
28:16It's going to take more digging to discover what actually happened in the cockpit of Flight 5022.
28:23Questions about the flaps on Spanair 5022 could be settled once and for all with information from the flight data recorder.
28:32OK, let's hope the data can give us some answers.
28:36It records every detail about the plane's configuration, including flap settings.
28:42Flaps.
28:46Set and checked.
28:48Set and checked.
28:51Flaps were set at 11 degrees on the first taxi, exactly where they should be.
28:56The data reveals that the flaps were working and had been set correctly when the plane taxied to the runway the first time.
29:04But they didn't stay there.
29:06When the crew returned to the terminal for repairs, they retracted the flaps.
29:11And we're back.
29:14Shredding down the engines.
29:19Flaps and slats were retracted after coming off the runway as part of standard operating procedure.
29:26OK, let's see what happens the next time around.
29:30Now's our time.
29:32Investigators need to know, did the pilots extend the flaps again after leaving the maintenance area to return to the runway?
29:40Or did they make a fatal error and omit one of the most important steps in getting a plane safely off the ground?
29:47Here we go.
29:50When you analyze a cockpit voice recorder, you look for anomalies, things that are different, things that should not be there.
29:59After start checklist.
30:01The MD-82's pre-flight checklists direct the crew to check the flaps and slats three separate times.
30:07Ignition off. Air conditioning set.
30:11Flaps and slats are essential for the operation of an aircraft, for takeoff and landing.
30:17So that's why they appear several times in the checklist.
30:23On the after start checklist, setting the flaps is the final item.
30:28Hydraulic pumps and valve set and checked.
30:34Lights on.
30:36Get permission from air traffic control to taxi, will you?
30:42Hold it, hold it, hold it.
30:44What is he doing?
30:46This is the worst possible time to interrupt him.
30:48The CVR reveals that just as the first officer is about to check the flaps and slats for the first time, the captain asks him to make a radio call.
30:57Ground, Spanair 5022 requesting taxi instructions.
31:01Spanair 5022.
31:03He never returns to finish that crucial item of the checklist.
31:08This is highly irregular in the normal tempo of a checklist.
31:14So what that tells AXA investigators is that there are some factors that were irritating this captain,
31:22making him want to rush the checklist, get things done quicker.
31:26Was it the time schedule? Was it maybe the cockpit heat?
31:29It was just unbearably hot in there and he wanted to get the engine started so they could get some air conditioning.
31:34That we don't know.
31:36OK, let's see what they do for the taxi checklist, please.
31:40Spanair 5022, your next in line.
31:44Setting the flaps is so important, crews are required to check them again during the taxi checklist.
31:50Brakes, checked.
31:52Flank controls, checked.
31:54Air conditioning, set.
31:55Set.
31:57Guys, what's the rush?
32:03The impression we had when we heard the cockpit voice recorder was that the crew was rushing through the checklist.
32:12Transponder, set.
32:15Hang on, stop.
32:18Where's the takeoff briefing?
32:21The crew skip the flaps and slats check for a second time.
32:25We know from scientific studies that rushing our time pressure increases the chances of human error by 11 fold.
32:33You put a pilot in a situation where they have to rush, something like a checklist that's a very detailed item is very prone to errors.
32:43The crew has a third and final chance to set the flaps for takeoff.
32:46Final items we have.
32:488, 11 aligned, 11 stowed.
32:53Spanair 5022, you are clear for takeoff.
32:56That was awfully quick, no?
33:00I think...
33:05Center of gravity, 8.
33:07Flap display, 11.
33:09Horizontal stabilizer, aligned.
33:11And flaps again, 11.
33:14No way he had time to check all those settings.
33:18Let's go back to the checklist.
33:20Investigators suspect that although the first officer announced the flap setting, the announcement was automatic.
33:26Final items we have.
33:288, 11 aligned, 11 stowed.
33:32He wasn't focused on his instruments.
33:35He was merely reciting the list from memory.
33:37If he had looked at the gauge, he would have seen the flaps were set at zero, not 11.
33:44Spanair 5022.
33:46The captain likely isn't checking either.
33:48He's busy steering the plane towards the runway.
33:52Humans are fallible and we know that when we're multitasking, it's very easy to forget or miss a critical item.
34:023.
34:043.
34:08Separate checklists.
34:15And they never set the flaps.
34:18Investigators now have a terrifying theory to explain the crash of Spanair 5022.
34:25V1. Rotate.
34:28The plane couldn't climb because the pilots forgot to extend the all-important flaps before take-off.
34:37To prevent another accident, investigators need to understand the crew's behaviour.
34:44What was going on inside their heads to make them feel so much pressure to hurry?
34:50They dig into the company's books and discover that Spanair has been struggling financially.
35:00It has announced plans to cut one third of its workforce.
35:06And how's our time?
35:08When your job is on the line, the last thing you want is to fall badly behind schedule.
35:13It's difficult to manage the stress that starts building when a delay is getting longer.
35:22I'll have some water, thank you.
35:25The captain is also well aware that his 166 overheated passengers are getting more and more unhappy.
35:34At the peak of the afternoon sun, the air temperature was 30 degrees Celsius or 85 degrees Fahrenheit.
35:41The tarmac radiates heat, raising the ramp temperature to over 100 degrees.
35:47It must have been scorching hot on that plane.
35:50We've got large windows, the sun is beating in.
35:54I assure you, that cockpit's going to be 120. You're wearing a shirt, a tie, it gets unbearably hot.
36:04No doubt about it.
36:07Those guys were coping with a lot of pressure.
36:10When you look at all the issues that the flight crew is facing, time, schedule,
36:15inoperative components and irregular procedure to do,
36:19it's just human nature for us to rush through the normal procedures.
36:28Psychology helps explain why the crew made the mistake in the first place.
36:32But there's another troubling question.
36:42When the crisis hit, why did the crew think there was something wrong with their engines?
36:48If they had realised the flaps had not been set, they might have been able to save their plane.
36:54Understanding why they didn't will be the final question.
36:59Understanding why they didn't will be the final twist in the tale of Spanair Flight 5022.
37:06Why did the first officer think that it was engine failure?
37:11Investigators wonder if the faulty sensor, shut down by the maintenance workers,
37:16could have played an unexpected role.
37:23So we're taking off using manual thrust, right?
37:26With the sensor disconnected, engine control is no longer automated.
37:31Yeah, manual thrust.
37:34Before take-off, the first officer mentions this five times.
37:39And if we go for manual thrust, then we'll engage the autopilot after take-off, right?
37:46Right.
37:48The disconnection of the Ram Air Temperature Probe
37:52created a lot of concern from the co-pilot's point of view,
37:57because that also affects the autothrottle, which is the automatic system for engine power.
38:04Look, just check the weather for the temperatures. It won't be a problem.
38:08The captain reassures him that they can set the thrust levers manually.
38:12But the first officer is uncertain.
38:14OK. Got it.
38:17Already preoccupied with the engines,
38:20the first officer mistakenly assumes they have an engine problem when things start to go wrong.
38:27Engine failure?
38:3010,000 times you've done these take-off procedures in this nice, slow, methodical, well-thought-out way,
38:37and now you're inserting a completely irregular event.
38:41But there's another crucial question.
38:45Wait a minute.
38:48Where's the warning?
38:50If the flaps were not set in the take-off position,
38:54there should be a very conspicuous sound saying that the aircraft is not ready for take-off.
39:00The take-off warning didn't go off, and it should have.
39:05I want to know why.
39:09They must now track down a silent culprit.
39:12A missing alarm that could have saved Flight 5022.
39:20These failures have to be connected somehow.
39:23Investigators suspect there could be a link between the failure of Flight 5022's take-off warning
39:30and the minor problem that sent the MD-82 back to the terminal.
39:34The failure of the temperature sensor.
39:38Look at that. It is 140 degrees now.
39:41Investigators trace the complex electronics of the sensor and make a shocking discovery.
39:48The sensor and the take-off warning both pass through the same electronic relay.
39:54When you look at the electrical scheme of the take-off warning system,
39:59you find that the relay 25 controls two things.
40:05The heater of the ram air temperature probe and the take-off warning.
40:08The ram air temperature probe and the take-off warning alert.
40:11That's it.
40:14That's the link. Yes.
40:17It was very shocking to find out that two different systems,
40:21like the take-off warning system and the ram air temperature probe heating,
40:25were controlled by the same device.
40:27Investigators suspect the R25 relay failed,
40:31disabling both the temperature sensor and the take-off warning.
40:34Technicians are not able to recreate that failure in the lab,
40:38but for Juan Carlos Lozano, the theory makes sense.
40:42In my opinion, the relay 25 was the cause of the failure of the take-off warning system.
40:48Right. Got it.
40:50By opting for the quick fix to the temperature sensor problem,
40:53the maintenance crew missed a critical opportunity to find the faulty relay.
40:58Without the cockpit alarm,
41:00the pilots did not have their final line of defense to warn them of their mistake.
41:07Sadly, they were not the first crew to suffer such a fate.
41:11In 1987, an MD-82 flying for Northwest Airlines
41:16crashed on take-off from Detroit, killing 156 people.
41:30Just like the Spanair crew, the pilots in Detroit failed to set their flaps and slats,
41:36but got no warning.
41:38A disabled electrical circuit silenced their plane's alarm.
41:43After the Detroit crash, checklists were changed to highlight the flaps and slats more often,
41:49and the warning system was made more robust,
41:52in an effort to prevent such a tragedy from ever happening again.
41:57But aviation designers and engineers could not foresee the rare failure of the R25 relay.
42:07That failure sealed the fate of Flight 5022.
42:16As an aviation professional, as an accident investigator too,
42:20this is probably the most frustrating situation in the world,
42:24because when you investigate an accident, it's to avoid this to happen again.
42:31And unfortunately in this case, we had a very similar case 20 years after the Detroit accident.
42:38In both Detroit and Madrid, it was the crew's failure to follow their checklists that led to disaster.
42:46The Spanair investigators list the inoperative take-off warning as a contributing factor
42:51that prevented the crew from recognizing the danger.
42:55But Juan Carlos Lozano, representing the pilots' union, sees it the other way round.
43:01The single biggest failure in this accident is the failure of the take-off warning system.
43:08This system was designed considering that the humans can make mistakes.
43:14And this is a clear example that the last line of defense failed.
43:21After the crash of Spanair 5022, Boeing again revised its checklists
43:27to make extending flaps and slats more prominent.
43:31And electronic checklists are now being used in some planes.
43:35Unlike paper checklists, they can display clear messages to the crew
43:39to tell them what they have and haven't checked.
43:41We cannot have this absolutely vital safety layer fail.
43:47We've got to have a 100% always works system.