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00:00Sudden impact and scorching flames.
00:05I thought, am I going to die?
00:07A fiery crash nearly kills a racing legend.
00:11Thank God I made it through.
00:13But for driver-turned-airline owner Nicky Lauda,
00:16a more devastating accident is still to come.
00:19I had a phone call from the news.
00:21They said one of the airplanes crashed.
00:27We just couldn't find the smoking gun.
00:29Austria's famous champion defies conventional wisdom.
00:33If they had lost only 10%, they would still be here.
00:36Fights to uncover the truth.
00:38It's my name, my airplane, my crash.
00:41And discovers a new and widespread threat to modern aviation.
00:59Captain Thomas Welch and First Officer Josef Thörner are flying a new aircraft.
01:15You need a little bit of a rudder trim to the left, huh?
01:18What's that?
01:19You need a little bit of a rudder trim to the left.
01:23Okay.
01:25Captain Thomas Welch and First Officer Josef Thörner
01:28are flying a Boeing 767 from Bangkok, Thailand to Vienna, Austria.
01:37The flight is operated by Lauda Air,
01:39the brainchild of famed Austrian Formula One driver Nicky Lauda.
01:45For me it was a logical step after retiring from racing
01:49to start in this kind of business.
01:51And that's what I did with Lauda Air.
01:54Throughout the 70s, Lauda dominated Formula One racing.
02:02Nicky was the best driver in his days.
02:06Nicky Lauda's Ferrari still in the lead.
02:09I think Nicky is the best-known Austrian since Mozart.
02:13And that's how they finish. Nicky Lauda takes the flag.
02:17He won the World Championship three times,
02:20then used his fame to launch a new career and a new airline.
02:26One of the main reasons was to give the passengers
02:29a different way of flying.
02:31Better service, better food.
02:33The airplane had to look in a certain way.
02:36The Lauda Air 767 is less than 15 minutes
02:39into its 11-hour flight to Vienna.
02:44It's a route Nicky Lauda knows firsthand
02:46because he's not just the owner of the airline.
02:50He's also one of its pilots.
02:52When you run a company and you fly, it's very simple.
02:57Because when you are with your passengers,
02:59then you know what is going on.
03:02You can look yourself what the problems are.
03:05And I corrected things quicker in that way.
03:15In the cockpit, Captain Welch and First Officer Furner
03:19monitor their instruments,
03:21while the autopilot controls the climb.
03:32Suddenly, the plane begins dropping from the sky.
03:38Christ!
03:46Wait a minute!
03:50Oh, damn it!
03:54The pilots have lost control.
04:02Lauda Flight 4 is plummeting to earth.
04:15The plane slams into a remote jungle
04:17110 miles northwest of Bangkok.
04:21I was at home and I had a phone call
04:23from the news station here in Vienna
04:26and they said one of the airplanes crashed.
04:30When rescuers arrive, it's immediately obvious
04:33that there's no one to be rescued.
04:38All 213 passengers and 10 crew members are dead.
04:43The airplane took off at 16.01 UTC.
04:47There was no fault or whatever reported from the pilots.
04:50The airplane flew about 20 to 25 minutes
04:53and then suddenly disappeared off the radar screen.
04:56So we have no indication whatsoever
04:59happened to the airplane.
05:03It's the first time a Boeing 767 has ever crashed.
05:07The loss of a US-made aircraft prompts quick action
05:10from the National Transportation Safety Board.
05:14The NTSB immediately sends
05:16veteran investigator Bob McIntosh to Thailand.
05:20The first crash of an aircraft
05:23that was in service intercontinentally
05:26for almost a decade with a perfect service record.
05:31It was extremely important for us to learn what had happened.
05:36223 people are dead
05:38and one of the world's most popular planes
05:41lies in pieces in a remote Thai jungle.
05:45Most of the territory was mountainous,
05:48very tropical-type territory.
05:51We recognized that we were going to have a major challenge
05:54trying to identify all the components.
05:58The difficult terrain isn't the only problem
06:01the investigators face.
06:03There were numerous local folks around
06:06and unfortunately they were not controlled by the local police.
06:11There was looting and treasure hunting
06:14going on around the crash site.
06:16First thing we've got to do is put a stop to that.
06:21Looters are swarming the wreckage.
06:24Vital evidence is in danger of disappearing.
06:27It was of great concern to us
06:29that critical parts might have been taken away from the site
06:33simply by folks who didn't understand
06:36the criticality of that evidence.
06:40The badly burned wreckage is strewn
06:43over a square mile of rough terrain.
06:47We were confronted with what appeared to be
06:50evidence of an in-flight breakup
06:53in that the major components of the wreckage
06:56the cockpit, the tail, the main body
06:59they were scattered far enough apart
07:02that certainly they had not come down together.
07:06The large field of debris leaves McIntosh with little doubt.
07:11The 767 broke up in mid-air, not when it hit the ground.
07:16What could have caused that?
07:19So it sounded like an explosion.
07:22Witnesses say the plane blew up
07:25and came down engulfed in flames.
07:29The evidence is pointing to a troubling possibility.
07:33Lauda Air Flight 4 was brought down
07:36by a deliberate act of sabotage.
07:42There was a lot of speculation about the possibility
07:45of a terrorist act affecting the aircraft.
07:49Glad to have you on board.
07:51Let me show you where we're at so far.
07:53This is Fred.
07:55Boeing sends its own investigator to Thailand.
07:58Kevin Darcy has an intimate knowledge of the 767.
08:01He helped design the plane.
08:04He too suspects this could be a case of foul play.
08:07We're glad to have you with us.
08:09It is pretty unusual for an accident to occur
08:12on a plane that is so close to the ground.
08:15It's pretty unusual for an accident to occur
08:18on the early climb-out portion of the flight.
08:22My initial thought was that it was some sort of sabotage
08:26or a missile or something like that.
08:31It's been just 3 months since Western powers
08:34pushed Saddam Hussein out of Kuwait in the Persian Gulf War.
08:39The timing sparks rumours of a revenge plot,
08:42a terrorist attack against a soft target, Lauda Air.
08:47They pop into your mind ideas like that
08:50and you have to work kind of hard to get those out of your mind
08:53so you can just see where the facts take you.
08:56The passenger list suggests a possible lead.
09:03One of the people travelling on Flight 4
09:06was an advisor to the United Nations Drug Control Programme.
09:10Donald McIntosh was helping the Thais fight a war on heroin.
09:16Perhaps the powerful drug barons who rule Thailand's Golden Triangle
09:20have somehow engineered the disaster.
09:23Investigators begin the painstaking task
09:26of testing the wreckage for explosive residue.
09:32Airline owner Niki Lauda is reluctant to believe
09:35terrorism brought down one of his planes.
09:38He arrives in Thailand to see for himself.
09:41My first decision was to go there myself
09:44and try to find out what happened.
09:48And this is what I did.
09:51Where was the tail found?
09:53I've never seen an airplane crash in all my life.
09:59The scene for me, this was the most horrific picture I've ever seen.
10:05Surrounded by the scattered remains of an airliner that carried his name,
10:09Lauda is overwhelmed by the magnitude of the disaster.
10:14When you have 223 people killed,
10:17the families all want to know why.
10:22And I think this is the worst for people if they do not know
10:25why they lost their husband, children or whatsoever.
10:30Lauda is determined to figure out what went wrong.
10:34If it's the fault of Lauda, technicians or pilots,
10:38I am responsible for everybody, I will certainly resign.
10:43His conviction may be rooted in his own traumatic past.
10:49At the German Grand Prix in 1976,
10:53his Ferrari slammed into a wall and erupted in flames.
11:04Lauda suffered third-degree burns to his head and body.
11:09He barely survived.
11:13And I said, I'm not going to die.
11:16And thank God I made it through.
11:19But it was very touching, not because of my burns,
11:22it was my lung damage which was the problem.
11:26His lungs were badly scarred from inhaling toxic burning fumes.
11:31But in spite of his injuries, Lauda only missed two races.
11:35Just 40 days after doctors had given up hope
11:38and a priest had knelt at his bedside,
11:41the Austrian ace climbed back into the cockpit of his glaring red Ferrari.
11:46He was back on the track six weeks later.
11:52But the cause of his near-fatal crash was never uncovered.
11:56This time, he wants things to be different.
12:01After the crash near Bangkok,
12:04the only way for him to survive as an intact person
12:10was to find out what really had happened.
12:16Finding answers won't be easy.
12:19Early evidence from the crash site
12:21is already raising doubts about the bomb theory.
12:25One of the most important signatures in looking at terrorism
12:29is to look at the baggage containers in an aircraft
12:32and see if they're damaged in any way
12:35and what that damage is, if there are signatures of explosions.
12:40I don't know.
12:42There's no charring.
12:44There's no outward pedaling.
12:46It doesn't say bomb to me.
12:49We didn't see any evidence of terrorism.
12:54The black boxes may have captured important clues
12:57about the cause of the in-flight break-up.
13:00But they're badly burned.
13:03To have any hope of retrieving the data,
13:05Thai investigators need to send the boxes to a sophisticated lab.
13:10Bob McIntosh makes the case for the NTSB to get the job.
13:14They should go to Washington.
13:17There was an obvious reason,
13:19and it was because the aircraft was certified by the United States FAA
13:25and the manufacturer is located in the United States.
13:31Days after the crash, crucial pieces of the plane are still missing,
13:35including the engines.
13:39Tracking down the wreckage at the Lauda crash site
13:42was certainly a major challenge.
13:45It was mountainous.
13:47It was totally overgrown.
13:50We climbed a mountain, went back down in the valley
13:53and found the left engine.
13:57Well, would you look at that!
14:00Then investigators see something that sends a chill
14:04through the aviation world.
14:15Investigators in Thailand have made a surprising find.
14:20The thrust reverser on Flight 4's left engine is fully deployed.
14:28Once we actually saw that the thrust reverser had deployed,
14:33for me it was shocking.
14:35It was not anything I really expected would happen.
14:39Thrust reversers help jetliners come to a stop on landing.
14:43They work by redirecting engine thrust forward to slow the plane down.
14:49Left side deployed in mid-air.
14:53No doubt.
14:55Planes have built-in safeguards
14:57to prevent reversers from deploying during flight.
15:00But even if it does happen, it shouldn't cause a crash.
15:04The widespread feeling of what would happen
15:09if a reverser deployed in flight
15:12was that the airplane would be controllable,
15:16that you could make a safe landing after that happened.
15:20In fact, flight testing has already shown exactly that.
15:25Before the 767 first went into service,
15:28Boeing had to prove that pilots could keep flying safely
15:32after a mid-air deployment.
15:34I was actually on one of the flight tests
15:37when we tested the thrust reverser deployed.
15:47There was a lot of vibration, a lot of noise,
15:52but the airplane was controllable.
15:55The pilots only experienced a small loss of lift.
16:00As a result, Boeing certified the 767
16:03as capable of continued safe flight and landing
16:06under any possible position of the thrust reverser.
16:11But the discovery of an engine with a deployed reverser is so unusual,
16:16investigators must conclude that it's somehow related to the crash.
16:20How does a thrust reverser bring down a 767?
16:25We're missing something.
16:27If it turns out that a faulty thrust reverser can bring down a plane,
16:31it has ominous implications for the entire airline industry.
16:35The lives of hundreds of thousands of passengers around the world
16:38could be in jeopardy.
16:40We recognized that we had something that was very unusual
16:44and would require a lot of analysis.
16:48The deployed thrust reverser is the strongest lead investigators have.
16:54But no one can figure out how it could have caused the crash.
16:59What would have caused the loss of control of the aircraft
17:03because it had been demonstrated
17:06that this very condition could occur in the air
17:11and you could continue to land.
17:18Investigators will have to solve the mystery
17:21without their most valuable tool.
17:25The flight data recorder is so badly burned
17:28that technicians at the NTSB can't recover any data.
17:33The disappointment was the flight data recorder was completely destroyed,
17:37which was very unlucky.
17:40But there's better news about the cockpit voice recorder.
17:43It has survived the fire.
17:45Ready to go?
17:49Investigators on both sides of the world
17:51can finally listen to the last moments of Laudaair flight 4.
17:5680 knots. Check.
17:59For me it was very important to listen to the voice recorder
18:03to understand things in a better way
18:05because you need answers.
18:08V1. Rotate.
18:11We recognized that the first officer
18:14had been in the pilot monitoring position.
18:17The captain was flying the aircraft.
18:25Positive rate of climb.
18:27Gear up.
18:30The voice recorder shows a normal take-off and climb.
18:35Landing gears up.
18:38All this kind of normal communication
18:41which I knew all the people.
18:43So for me it was honestly hard.
18:46This was the hardest part of all my life.
18:50We are clear to level 310 and maintaining Laudaair 4.
18:55Flight 4 climbs to 7,000 feet without a problem.
19:00A little more than five and a half minutes into the flight,
19:04the first hint of trouble.
19:07It's chasing.
19:11It's come on.
19:12What's come on?
19:15Some kind of warning.
19:18The pilots have noticed an alert that's come on in the cockpit.
19:23Could this be the clue that unlocks the mystery of Laudaair flight 4?
19:30Investigators listen as the Lauda pilots discuss a mysterious cockpit warning.
19:36What's it saying there about that?
19:40Additional system failures may cause in-flight deployment.
19:43Expect no more reverse operation after landing.
19:47Stop it for a second.
19:48Additional system failures may cause in-flight deployment.
19:51Expect no more reverse operation after landing.
19:54Stop it for a second.
20:01Additional system failures may cause in-flight deployment.
20:05He's talking about the reverser isolation valve warning.
20:09The warning relates to a valve in the left engine's thrust reverser.
20:14The hydraulic isolation valve controls the flow of hydraulic fluid to the reversers.
20:20When it's open, the reverser can be stowed or deployed.
20:24When it's closed, the reversers won't budge.
20:29The crew doesn't sound worried about the warning.
20:34The reverse isolation warning that was presented to the crew was an abnormal but not emergency issue.
20:42And it didn't require any action by the crew other than to be advised that the thrust reverse might not be available on landing.
20:51Okay.
20:52They did the right thing. They read the checklist and the checklist said you can continue the flight.
20:57And they asked the ground staff.
20:59No, it's probably moisture or something.
21:03Because it's not just on, it's coming on and off.
21:05Yeah.
21:06It was a non-emergency issue and they simply discussed it.
21:12You know, it doesn't really, well, it's just an advisory thing.
21:16To make sure that they felt comfortable that it was not something that was going to interfere with the flight.
21:22I don't, it could be some moisture in there or something.
21:36For five minutes, nothing happens.
21:40Then...
21:46Reversers deployed!
21:47Oh, Christ!
21:56Wait a minute!
22:02Oh, damn it!
22:04The captain said, damn it, and reactions of a pilot which, he's out of control, basically.
22:11The co-pilot didn't say a word in this moment of the crash.
22:16So, for me, it was very obvious that something must have happened there so quickly.
22:21Because normal pilots, they communicate with each other if there is a problem.
22:26The CVR confirms that whatever went wrong, it happened blazingly fast.
22:33Just 22 seconds later, the sound of the plane being ripped to pieces.
22:47The whole thing was so difficult.
22:50You never forget.
22:53Niki knew that it had to be a mistake, which was not the airline's mistake,
22:59not Niki's mistake, and not the pilot's mistake.
23:04Niki Lauda is convinced the deployed thrust reverser is what caused the crash.
23:08The moment Niki was sure that there was something wrong with the system,
23:14he put a lot of pressure on Boeing.
23:18I was after Boeing day and night, so that the people understand that we're working on it,
23:24that we hopefully find the cause and make sure it will never ever happen again,
23:28because this is the answers these families needed.
23:35With pressure mounting on Boeing, Bob McIntosh returns to the crash site
23:40in search of any evidence that can help explain what went wrong.
23:44Let's get to it.
23:45He thinks there might be another way to get his hands on some of the data
23:48that he couldn't get from the badly burned FDR.
23:53We scampered out there with a couple of rudimentary tools,
23:57like pliers, a screwdriver and whatnot, and got out there as fast as we could.
24:03The engines of a 767 are equipped with an Electronic Engine Control Unit, or EEC.
24:09McIntosh hopes the unit's internal memory will preserve a record
24:13of how the plane's engines were operating just before the crash.
24:18And sure enough, there was the EEC, the Engine Electronic Control, fully available to us.
24:24We were extremely interested in getting that information out of the jungle
24:29and into a proper readout facility.
24:32You got a bag there?
24:34The critical question now, can the engine data reveal
24:38why the Lauda pilots suddenly lost control of their plane?
24:47Investigators may be a step closer to understanding what brought down Lauda Flight 4.
24:54They have critical data from the plane's Electronic Engine Control Unit.
24:58We now had airspeed and we had altitude information.
25:02And although we didn't have exact timings on those pieces of information,
25:06it led us to the understanding of the loss of control.
25:11Wow. That'll sure get your full attention.
25:15The data gives McIntosh a clearer picture of why the plane broke up in flight.
25:20Operating at nearly 4,000 feet above sea level,
25:24operating at nearly full power,
25:27the left engine suddenly goes into reverse.
25:35Reverse is deployed. Oh, Christ!
25:38Following the exclamation from the co-pilot,
25:41Ah, thrust reverse, there was a lot of action going on in the cockpit.
25:45Captain Welch immediately tries to correct the problem.
25:49Here, wait a minute.
25:52The engines had been drawn to idle.
25:59And even the fuel on the left engine had been shut down.
26:05Yet just seconds later, the Boeing 767 is plunging to earth at almost the speed of sound.
26:13No mystery why that plane broke apart.
26:15The sheer force of the blazing descent tears the aircraft to pieces.
26:20If you are in a prolonged dive,
26:23and that speed increases beyond what the airplane was designed for,
26:27the aerodynamic loads can be more than the airplane can take.
26:33The revelation explains the witness reports.
26:36The explosion they heard was the plane breaking apart.
26:40The fire was caused by the fuel leaking from ruptured tanks and igniting.
26:51Niki Lauda travels to Boeing headquarters in Seattle.
26:57He's determined to figure out why a failure that's not supposed to be dangerous
27:02killed 223 people flying on his airline.
27:06I know what it says, but that's not what happened in Thailand.
27:10And I said to Boeing, listen guys, it's my name, my airplane, my crash,
27:15and Boeing understood my problem, or their problem,
27:18and we kept on working together.
27:21Lauda's determination echoes the tenacity he showed in Formula One,
27:26always pushing his mechanics to gain a slight advantage.
27:31Basically I understood that the more you work with your car,
27:34your engineers and your mechanics,
27:36to make the car on the day adjusted in the right way that it can go quicker,
27:41this was the secret.
27:43Okay, let's try it in a simulator.
27:46It was important to push Boeing because they were the only key of the whole matter.
27:54Lauda recreates the flight in the Boeing simulator.
27:58Okay, let's begin.
28:01He wants to know why his pilots couldn't do what the plane was certified to do,
28:06recover from a deployed reverser.
28:09Approaching 24,000 feet.
28:12Speed 320 knots.
28:15Another 100 feet.
28:22It was incredible.
28:25Because the airplane just turned around and you couldn't do anything.
28:30Looking at every sequence slowly and doing it again and again,
28:35you realize nothing they could have done.
28:39Lauda's tests at Boeing show that the pilots of Flight 4
28:42didn't have enough time to execute the commands needed to save the plane.
28:47Hard right.
28:49Autothrottle off.
28:51Thrust lever to idle.
28:53Left engine shut down.
28:55There would be a four to six second warning.
28:57There would be a four to six second window where a flight crew member
29:01would have to initiate contrary flight controls to this condition
29:05in order to recover in a safe manner.
29:07And before you do any of that, figure out what the hell's happening to your plane.
29:12All in six seconds?
29:14Good luck.
29:16It was just too late.
29:17The aircraft was going to assume a very nose low, high speed attitude.
29:24Reversers deployed.
29:26It's clear the accidental deployment of a thrust reverser
29:30is much more than a harmless malfunction.
29:33It can be fatal.
29:35It was evident to the Boeing company and to the FAA certification authorities
29:41and to the operators of Boeing 767s around the world
29:45that this was going to be a major, major issue.
29:49The finding has staggering implications.
29:51Investigators must figure out why the reverser deployed in the first place.
29:56According to the aircraft's designers, it just shouldn't happen.
30:01It was pretty obvious after a while to understand that the thrust reverser
30:05made the airplane crash.
30:07So this was clear.
30:08But you still need to know the exact cause.
30:11And then, especially for the future, what are you going to do to make airplanes safer?
30:16The reverser deployed and those guys couldn't recover.
30:19And those guys couldn't recover.
30:25Let's figure out why that happened.
30:28For the reverser to deploy, it requires you have two separate and independent valves open.
30:36The first valve is the isolation valve that controls the flow of hydraulic fluid.
30:41But the reverser won't deploy until a second valve,
30:44the directional control valve, moves from stow to deploy.
30:49Investigators wonder if that crucial second valve somehow ended up in the wrong position.
30:55To the investigation team, the directional control valve
30:58was a very critical portion of the evidence that we needed for analysis.
31:04But the crucial component is nowhere to be found.
31:08It's likely that looters at the crash site have got hold of it.
31:12The directional control valve was gold-colored.
31:16We speculate that someone thought it had some value just for being scrapped or sold.
31:25We need to find the directional control valve.
31:28That's not our top priority. That's our only priority.
31:33They offer a cash reward to get it back.
31:37We really wanted to know what had driven those thrust reversers open.
31:41And that was the piece of electronic-slash-hydraulic equipment that would give us that clue.
31:52Nine months after the accident, the reward pays off.
31:56Investigators finally get their hands on the piece they need most.
32:01The directional control valve.
32:04Someone showed up to claim a reward.
32:07They presented the piece of evidence
32:09and it made its way relatively quickly to the engineering assessment lab out in Seattle, Washington.
32:20Investigators are eager to know what position the valve was in at the time of the accident.
32:28In one position, it tells the thrust reverser to stow and remain stowed.
32:33And in another position, it tells the thrust reverser to deploy.
32:46Several screws are loose and some parts are misplaced.
32:52As soon as you see that, you know that you may not have all the evidence you really need.
32:58They find soil inside the component.
33:01A clear sign that it's been taken apart and then carelessly reassembled.
33:08It's a big blow to the investigation.
33:12It was disappointing that when we received the valve,
33:18that we knew that it had been tampered with.
33:21Engineers will need to find another way to uncover what went wrong on Lauda Flight 4.
33:33Nicky Lauda continues his quest to understand why the pilots of Lauda Flight 4 couldn't save their plane.
33:41He reviews Boeing test data that shows a 767 should lose its thrust reverser.
33:47He reviews Boeing test data that shows a 767 should lose only 10% of its lift if a thrust reverser deploys accidentally.
33:57Trust me, if they had lost only 10% of their lift, they would still be here.
34:03Lauda compares the flight conditions used during the Boeing test to the conditions his pilots faced at the time of the accident.
34:11He makes a stunning discovery.
34:14The Boeing test flights were at a relatively low altitude, just 10,000 feet.
34:21Nobody tested it high up. It is a hell of a difference if you fly at 10,000 feet or at 28,000 feet.
34:27And this is exactly what that certification misinterpreted.
34:33The Lauda 767 was flying twice as fast and at more than twice the altitude of the Boeing test plane.
34:39A height where the thin air makes it much more difficult to maintain lift.
34:45We started to home in on the issue of a possible loss of lift from the affected wing.
35:00Boeing engineers can imagine only one scenario that might make a reverser deploy unexpectedly in mid-air.
35:07The theory calls for the accidental activation of two key valves at the same time.
35:13You have to have both the isolation valve open and the directional control valve at the engine open to the deployed position.
35:24The problem is, they can't figure out how to make that happen.
35:28And until they do, it will be impossible to prevent it from happening again.
35:32There's a number of combinations of things that you needed to look at.
35:39Like a bad relay and a cut o-ring.
35:47Or a shorted wire, say, and debris in a valve that would combined cause the unwanted deployment.
36:03The engineers can find ways to activate one valve or the other.
36:09But it seems impossible to trigger both at the same time.
36:17It's always frustrating when you spend a tremendous amount of time and effort and you want to find out what happened.
36:26And you just can't find the smoking gun.
36:29A catastrophic accident can destroy small airlines.
36:33Niki Lauda is determined not to let that happen.
36:37The plane he lost represents a quarter of his fleet.
36:41He needs another plane in the air to keep his business.
36:44One of his major assets was his competition spirit.
36:49And he wouldn't accept a no and that's not possible.
36:54He finds a jetliner in France that no one is using.
36:57Within weeks it's been added to Lauda's fleet.
37:00I picked up a 767 in Paris, flew it to Vienna to replace our crashed airplane to keep on flying our schedules.
37:12To run an airline as a business is harder than to win three world championships in Formula One, I can tell you that.
37:18Because the business challenges in an airline are enormous.
37:23The tests at Boeing finally pay off and the engineers make a major breakthrough.
37:29They're now able to trigger the double failure needed to accidentally deploy a reverser.
37:39We could get that system to activate by introducing a short, a direct short in a system.
37:47The wires for both valves were bundled in the same harness.
37:51A fault across several wires in that harness could have triggered the simultaneous short circuits.
37:58But because the wires were so badly burned in the crash, there's no way to determine what caused the short in the bundle.
38:08Scheisse.
38:10That keeps saying that.
38:12The theory accounts for the intermittent warning in the cockpit.
38:16Shall I ask the ground staff?
38:18No, it's probably moisture or something.
38:21It also explains the deployment of the thrust reverser.
38:43Two shorts in two valves at exactly the same time?
38:50What are the odds?
39:03I was upset that the airplane did something where a human being couldn't react anymore.
39:12What we had learned was that the in-flight deployment was something that could happen when we never expected it would.
39:21To the aviation industry, it was a bit of a come to Jesus moment.
39:27We couldn't allow airplanes to be out there flying where that could happen.
39:33One of the most shocking lessons learned from the Lauda accident is how serious a reverser deployment can be at high speed and high altitude.
39:45There were other airlines that joined in the questioning of how could this possibly affect the flight path to the point where you lose control.
39:55The answer to that question came from the pilots themselves.
39:59The answer to that question goes back to the 1970s.
40:03To increase fuel efficiency, designers moved towards sleeker aerodynamic designs.
40:08They began mounting engines closer to the crucial leading edge of the wing.
40:13In the case of the 767, they're up way closer to the wing and their relative size to the wing is much bigger.
40:20So the effect of reverse thrust on the 767 would be way greater than it would be on a 747.
40:30The design of the thrust reversers also changes.
40:34Earlier models used buckets at the rear of the engine that redirected air near the back of the wing.
40:40Newer designs redirect air closer to the front of the wing.
40:44To find out how the changes might affect aerodynamic lift, NASA runs a series of special test flights.
40:54Flying a DC-8, NASA pilots match the Lauda flight's high speed and altitude.
41:04Then they deploy a reverser.
41:14The results are dramatic.
41:19There was about a 25% loss of lift over the affected wing.
41:24That loss of lift would result in a roll rate that would be extremely difficult for a flight crew to combat.
41:33Deploying one reverser while keeping three engines operating normally sends the DC-8 into a terrifying dive,
41:41falling at almost 9,000 feet per minute.
41:45The experiment reveals why Flight 4 lost so much lift.
41:53Unlike previous designs, modern reversers disrupt the smooth flow of air over the wing, which decreases lift.
42:02The stunning results change commercial aviation worldwide.
42:07In-flight deployment of a thrust reverser is no longer considered controllable.
42:13And a series of mechanical locks now ensure that even if both valves get energized in flight, the reversers can't deploy.
42:22There were some major efforts made worldwide to make sure that the improvements of a sink lock system
42:30were installed in every operational airplane and every airplane that was manufactured thereafter.
42:36For Niki Lauda, it is total vindication.
42:41I was affected myself. I was affected as a pilot, so this drove me all the way to the extreme to find out as quick as possible what happened.
42:51The sports hero has gone from winning championships to protecting the lives of passengers.
42:58Niki wanted, for his own sake, to have the matter cleared.
43:03And, of course, for the sake of any passenger who stepped into a 767.
43:09Lauda Air continued to operate for nine more years after the accident.
43:14In 2000, it was folded into Austrian Airlines.
43:18For me, the worst thing in life is grey areas.
43:22I hate grey areas, and a lot of airplane crashes have been in the past
43:27where you really do not know exactly what happened.
43:33And in this crash here, thank God, it was clear what was the cause.
43:40And it was fixed for all airplanes worldwide.
43:45So I think this is the only good thing out of this terrible crash.
43:48For more UN videos visit www.un.org
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