Original subtitles

NARRATOR: In 1979, chaos when the FAA grounds

every DC-10 in America.

You can imagine if one of your real workhorse airplanes

is grounded, it's a terrible situation.

NARRATOR: The reason.

Look at this.

NARRATOR: American Airlines Flight 191.

- I'm losing it. - Go right.

Go right. Come on.

Come on.

It only got about 300 feet above the ground.

What do you got?

NARRATOR: As investigators search for evidence.

It's one of the bushing bolts.

NARRATOR: In the worst air disaster in US history.

Split right in two.

There's the bolt. This is a fracture point.

NARRATOR: They face intense media pressure

to identify the cause.

Some very crucial photographs showed the aircraft

on its final, fatal plunge.

NARRATOR: The shocking images may finally explain.

We need to see those slabs.

NARRATOR: Why 271 people died seconds

after leaving the ground.

WOMAN 1: and gentlemen, we are starting our approach.

MAN 1: We lost both engines.

Emergency descent. MAN 2: Mayday.

Mayday.

WOMAN 2: Brace for impact.

MAN 3: He's gonna crash.

Any updates on the weather?

Surface wind 20 degrees at 22 knots.

Nothing but blue skies.

NARRATOR: On a Friday afternoon,

the seasoned crew of American Airlines Flight 191.

Rudder set.

NARRATOR: Makes final preparations for takeoff.

Spoilers.

Armed.

NARRATOR: From Chicago's O'Hare Airport.

Captain Walter Lux was scheduled

to have the weekend off, but is covering for a friend.

This crew was a very experienced crew.

The captain had approximately 22,000 hours

of flying time, of which about 3,000 hours were in the DC-10.

So he was a very, very experienced

pilot in the aircraft.

NARRATOR: The DC-10's three-engine layout

makes it one of the most recognizable

passenger jets on the runway.

They're being flown by almost every major airline.

The DC-10 was a very popular airplane.

It was one of the first jumbo jets.

So the airlines were able to put twice as many people

on board the airplane and only feed

three engines instead of four.

So it was much more economical for them

because they could eliminate a lot of flights

and still carry the same number of passengers.

American 191, good afternoon.

Taxiing to position on runway 32.

Right and hold.

American 191, thank you.

Taxi and hold, runway 32 right.

Flaps and slats to 10.

Takeoff and landing are the most

crucial and most difficult and busiest times in the cockpit.

NARRATOR: It's the Friday before Memorial Day.

There are 258 passengers on board

for the flight to Los Angeles.

On this flight, a live feed from a video camera mounted

in the cockpit allows passengers to watch

the takeoff from the cabin.

It's a new feature for American Airlines.

It was simply showing the runway and what

the pilots were seeing as you took off

or as you came in for a landing.

So it was just like a movie for the passengers.

American 191, you are cleared for takeoff.

American 191, underway.

You have control.

I have control.

Runway clear?

Clear.

OK.

Setting takeoff thrust.

Here we go.

Replied takeoff power.

You've got three engines pushing you down the runway.

NARRATOR: Sharing the pilot's view from the cockpit

is a thrill for many on board.

At 3:04 PM, the plane is seconds away from lifting off.

V1.

You accelerate to V1, which is

the speed beyond which you can no longer abort the takeoff.

So you have to keep going.

You have to take off no matter what happens.

Rotate.

A few seconds later, you reach rotation speed.

This is when the pilot would lift the nose.

The front wheel would come off the runway.

Damn.

There's the turbulence.

Not too rough.

Did you see that?

I've lost power to my sight.

NARRATOR: The captain's instruments suddenly go dead.

It looks like we've lost number one.

NARRATOR: And he's lost power from the left engine,

but the plane is already airborne.

You have to keep going.

You have to climb out.

And if there's something wrong with the airplane,

even if the problems are critical,

your best hope is to keep going,

to climb, contact ATC, and come around

and land somehow, somewhere.

Look at this.

Look at this.

Equipment.

I need equipment.

He blew an engine.

NARRATOR: The DC-10 should be able to climb

with only two engines.

These multi-engine planes are specifically designed to take

off with one engine out.

They're designed to climb out at a brisk rate of speed

and to climb to a safe altitude with one

of the engines missing.

NARRATOR: Pilots are trained to cope

with this kind of emergency.

First, they need to get as far from the ground as they can.

Altitude is critical.

There's a saying that pilots have.

The three things you need are altitude,

airspeed, and an idea.

NARRATOR: They put their plane into a steeper climb.

Forward speed drops.

If you have room to play with,

if you have the altitude, now you

can look around and try to figure out what went wrong

and try to institute some corrective measures.

American 191, heavy.

You want to come back?

And to what runway?

- We're banking. - Go right.

Go right.

NARRATOR: The plane is banking sharply to the left.

It's only 325 feet from the ground.

They were applying full right aileron because the left wing

was going down.

And by applying full right aileron, what you're doing

is trying to lift that wing back up that has gone down.

You might try to turn the ailerons the other way harder.

And if that still doesn't work, something's clearly wrong.

I can't hold it.

American 191, heavy.

Do you copy?

He's not talking to me.

NARRATOR: Losing power from one engine

should not be causing the plane to bank.

Passengers have a frightening view of the ground below.

What's going on?

NARRATOR: The pilots can't get the altitude they need,

and they're banking further and further to the left.

- I'm losing it. - Go right.

Go right.

Come on.

Come on.

300 feet.

We're losing altitude.

NARRATOR: The cockpit camera gives passengers

a glimpse of their fate.

But they are not the only ones whose lives are in danger.

A trailer park just north of the airport

is home to thousands of people.

Oh, God.

NARRATOR: And the plane is heading straight for it.

Witnesses on the ground can clearly see

Flight 191 flying on its side.

We're still turning.

Level, baby.

Level.

Brace, brace, brace.

Brace, brace, brace.

Well, certainly it would be a very, very scary thing.

And you would certainly know that you were about to die.

We're losing it. Go right.

Go right.

Go right.

There he goes.

The DC-10 crashes into an airport hangar

at the edge of the airport.

The full load of fuel instantly ignites.

DC-10 with 271 souls on board has gone down

northwest of runway 32 right.

It only got about 300 feet above the ground.

And it traveled maybe 4,600 feet or so

beyond the end of the runway before it

crashed into a field.

As soon as we pulled out of the station,

we could see the column of smoke.

And of course, as we got closer and closer, it was heavier.

And you could see how big the site was.

NARRATOR: Less than a minute after takeoff,

there was almost nothing left of Flight 191.

Everything was smoldering.

And I remember seeing pieces of the aircraft

that were very recognizable, such as the landing gear.

And I remember seeing one of the engines also.

NARRATOR: Rescuers find a horrifying scene.

We saw-- what was recognizable is torsos,

body parts.

It just brought back the human element.

And you realized and thought about the people

who were on board.

NARRATOR: As they begin assessing the full scope

of the disaster, they have very little

hope that anyone survived.

American Airlines Flight 191 has crashed

just short of the trailer park beside Chicago's

O'Hare Airport.

The DC-10 has also obliterated a hangar beyond the runway.

There were some distinct odors.

Jet fuel.

Certainly, that was the overpowering odor.

And then the eerie quiet I remember.

NARRATOR: Once the fire is under control,

the search for survivors can begin.

But as you walk the scene, it was

pretty obvious pretty quickly that there were no survivors.

It was very, very frustrating to realize that no matter

what your training was, there was nobody there

that you could help.

NARRATOR: All 271 people on board are dead.

Two workers inside the hangar have also been killed.

It's the worst aviation disaster in US history.

A lot of people saw this happen.

Let's see what they can tell us.

NARRATOR: The National Transportation

Safety Board must now figure out

what went wrong on Flight 191.

REPORTER: This is a Breaking News Special Report.

Good evening.

An American Airlines DC-10 crashed just after takeoff

this afternoon from Chicago's O'Hare International Airport.

This is the kind of accident which unfortunately really

grabs the imagination of the public

and can do so much to cast a stain

on the reputation of an airline, of an aircraft,

on air travel in general.

NARRATOR: Thousands of people fly aboard DC-10s every day.

If there's a flaw in the plane, investigators need to find it

before more people are killed.

The stakes were very high for the NTSB

to get this investigation right.

The airlines wanted the public to understand that this was

fundamentally a safe aircraft.

NARRATOR: They are eager to hear

from the many people who saw the crash, especially

those with the best view.

Controllers in the tower.

Look at this.

Look at this.

NARRATOR: The controllers revealed

that Flight 191's left engine didn't simply fail.

The engine fell off the plane just after they lifted off.

I saw it fall.

If you were sitting on the left hand

side of the airplane, what you would have seen

was the number one engine on the left side

rotated up, and flipped back, and disappeared behind you.

Did you see that?

That's the last thing an airline

passenger wants to see.

These engines are actually designed

to go back up over the wing in case of failure,

so that they will miss the tail as they go by

and not cause damage to the tail section.

They will go over the tail.

NARRATOR: The engine has landed nearly 2,500 feet from the end

of runway 32 right.

The team scours the tarmac for any pieces

that came from the plane.

How does a DC-10 lose an engine?

NARRATOR: The smallest piece of evidence

can be of vital importance.

I've never seen anything like this.

That is not supposed to happen.

The engineering is supposed to be so robust

that that will not occur.

So when that happens, you'll have the undivided attention

of everybody involved in the investigation

because that's a big deal.

NARRATOR: In the entire history of commercial aviation,

there have only been a handful of similar incidents.

But concerns over the safety of the DC-10 are not new.

This is the third major accident for the plane

in the last five years.

There were a series of fatal accidents

that were very high profile in the news.

And the name DC-10 kept appearing time

and again in headlines led the public to wonder what was

going on with this airplane.

NARRATOR: In 1972, American Airlines Flight 96

lost its rear cargo door shortly

after takeoff from Detroit.

The DC-10 was at almost 12,000 feet

when the door blew out, causing an explosive decompression

that severed essential control cables.

The pilots were able to make a successful emergency

landing, saving all on board.

Two years later, the 346 people aboard Turkish Airlines

Flight 981 were not so lucky.

They all died when their DC-10 crashed

into a forest in France after suffering

a similar cargo door failure.

Public confidence in the airplane

was fairly low at this point.

And a lot of people would not fly on that airplane.

They would book another trip or book another airline to stay

away from the airplane.

They say if it's a DC-10, put me on another flight.

I don't particularly like flying DC-10s,

but you know, it's the only flight we can take,

so we take it.

NARRATOR: Investigators desperately

need to know how an engine fell off

a plane carrying 271 people.

They searched the charred debris for the plane's

flight recorders.

You've got a plane that is destroyed on impact

as this plane was, the data from the recorders

can be essential because that really is your only source

of information.

NARRATOR: The team is able to recover both black boxes.

But the recorders are heavily damaged,

it will take time to analyze the data.

What you got?

NARRATOR: The investigative team

soon makes another discovery.

It's one of the bushing bolts.

Split right in two.

NARRATOR: It could prove to be crucial.

They found a bolt that had broken.

And the question that was raised

was did this bolt break before the accident and cause it,

or did it break as a result of the accident?

NARRATOR: The left and right engines of a DC-10

are mounted to the wings through a rigging

system known as the pylon.

The bolt found on the runway is one of the few

holding it in place.

The badly damaged bolt was found

closer to the start of the runway,

suggesting that it may have been the first thing

to come off the plane.

So what do you think?

NARRATOR: The investigative team believes

they have found the culprit.

This would explain it.

NARRATOR: The NTSB is under immense pressure

to explain how an engine could simply fall off

a widely used passenger jet.

Two days after the crash, they hold

a news conference to announce that they found the cause.

A broken bolt.

There is the bolt. There is a nut

still attached to part of the bolt.

This is the fracture point.

Well, I arrived at the scene of the investigation.

And it was a press conference going

on at that time, in which the vice-chairman of the Safety

Board was speaking.

And he had just concluded.

NARRATOR: Michael Marks is a metallurgist with the NTSB.

What did you guys say about the bolt?

We said this is it.

This is why the engine came off.

NARRATOR: He's an expert in fractures and failures

of airplane parts.

It was related to me that he had indicated that a bolt that

was found on the runway was involved

in the engine separation.

Tell me you have more evidence than that.

When I visually looked at it, I could see nothing

on the bolt that would indicate anything out

of the ordinary, which all I could do is say,

this bolt didn't have any preexisting cracking on it

or have anything that would indicate that it had

a weakness in the structure.

This thing broke when it hit the runway, not before.

So not exactly our smoking gun.

We need more information.

And to announce that you basically

have some kind of cause for that engine separation

without really looking at it, it

was not a good idea to come out with this

at that particular time.

And so more caution was needed.

OK, look.

We've got to forget about the media

and focus on the evidence.

It turned out that it didn't cause the accident.

But going in, you don't know what

is going to turn out to be important

and what's just a red herring.

NARRATOR: The confusion at the press conference

only increases the pressure.

There is no room for any more mistakes.

For now, the team can only study the wreckage for clues.

They hope there is enough left to the plane

to help them make sense of what happened.

Hold on, let me see that.

OK.

Good.

Anything from the main crash site goes over here.

Anything from the runway, any engine or wing parts,

goes to that side.

Well, my first priorities would

be to look at the actual parts, the actual separation.

Where is it that this thing broke?

This is definitely part of the pylon.

I've never seen one break like that.

NARRATOR: The pylons are mounted under the wings.

Each one is strong enough to suspend

an 11,600-pound engine.

The pylon is designed very well, I mean, strength-wise.

So it basically could take a lot of load.

Much more load than you would normally see in the course

of the airplane life.

NARRATOR: The pylon gets its strength

from two internal bulkheads.

One forward and one aft.

These bulkheads also provide secure points of attachment,

ensuring that the engines are firmly fixed to the wings.

It's also designed to have multiple load

paths, so that it's what they call failsafe design.

NARRATOR: It seems incredible that a pylon,

one of the strongest parts of the plane, could have broken.

Conceivably, the failsafe design is flawed.

If so, it could just be a matter of time

before another pylon breaks in mid-air.

Any idea what happened to it?

I need to see the rest of the pylon.

NARRATOR: As some investigators search the wreckage

near the airport for the rest of the broken pylon,

others are finally able to listen

to the cockpit voice recorder.

It should reveal if the pilot had

any indications of a problem as they were taking off.

OK.

Go ahead.

PILOT: American 191, thank you.

Taxi and hold, runway 32 right.

Flaps and slats to 10.

NARRATOR: The taxi and takeoff rule are perfectly routine.

American 191 underway.

NARRATOR: There is no indication the pilots

were having any problems.

PILOT: OK.

Setting takeoff thrust.

Here we go.

Sounds pretty routine so far.

PILOT: V1, rotate.

Damn.

Is that it?

Well, the tricky things about this accident

for investigators was that the nature of the damage

was such that the cockpit voice recorder itself

was rendered inoperable.

So that was a big loss of clues.

NARRATOR: The voice recorder was

powered by the left engine.

Damn.

NARRATOR: Once it fell off, the recording stopped.

Thanks.

About the last thing they heard on there was just damn.

And that was the end of the recording.

And that told them absolutely nothing.

NARRATOR: They may never know what happened in the cockpit

after the engine fell off.

The flight data recorder is also nearly useless.

Because of the extreme way the plane was flying,

a lot of the data makes no sense.

This isn't going to help us.

NARRATOR: At the hangar, there has been some progress.

Investigators have recovered all the pieces of the pylon.

Michael Marks may now be a step closer to figuring

out why it broke apart.

Now I had an indication that maybe this is the area that we

really should be looking at.

So in doing that, you needed to get more

detailed inspections of it.

You needed to get it to the laboratory

back in Washington, DC.

NARRATOR: Investigators also examine the plane's history

for anything that might relate to this catastrophic failure.

John Goglia spent nine years as a senior maintenance expert

for the NTSB.

Instantly, if we know we had an engine falling off,

you're going to go right for the maintenance records.

You're going to go right to the history of the airplane.

They had the engine out at the end of March.

NARRATOR: Eight weeks before the accident, the left engine

was removed for servicing.

Any time that you have an airplane that's

been into maintenance just before a crash, that raises

all sorts of warning flags.

All sorts.

Let's go down to Tulsa.

See what they did.

If you have an investigation that involves maintenance,

if you don't go inside the hangar,

you don't follow that trail, you're

going to miss some issues.

NARRATOR: Why the pylon broke is not the only question

that needs to be answered.

Damn.

I've lost power to my sight.

Looks like we've lost number one.

NARRATOR: Two of the DC-10's three engines kept working.

The plane had the power it needed to keep climbing

and then get back to the airport.

In fact, you could lose a second engine shortly after

lift-off and you would still be able

to power the aircraft around.

NARRATOR: But somehow, experienced pilots

weren't able to fly this plane after losing just one engine.

With 270 people dead after an engine fell off a plane,

the FAA makes a drastic decision.

On June 6th 1979, the agency grounds every DC-10

in the United States.

138 planes in total.

Well, you can imagine if one of your real workhorse

airplanes is grounded, disrupting flights,

inconveniencing passengers, generating headlines,

it's a terrible situation.

You spend $100 million for an airplane,

you can't leave it sitting around very long.

It's costing you a lot of money every day to have

that airplane on the ground.

NARRATOR: All foreign-based DC-10s are banned

from entering us airspace.

The pressure on investigators mounts

as the effects of America's worst air disaster

spread across the globe.

Investigator Michael Marks believes the shattered pieces

from the engine pylon may explain why

Flight 191 fell from the sky.

Hey, look for yourself.

Did that had to happen before the crash?

I just don't know why.

We're looking at that bulkhead in detail.

There was one very puzzling thing.

NARRATOR: A close examination reveals

a crack in the metal that clearly

developed slowly over time.

It's a telltale sign that the pylon bulkhead was already

damaged before the crash.

You can see where it's spread, all along there.

NARRATOR: The crack that Michael

Marks finds runs along the top edge of the aft bulkhead.

The cracks were consistent with a fatigue phenomenon

or a cyclic behavior, a crack extending from repeated loads.

Each time the load occurs, you then have

an extension of the crack.

NARRATOR: The microscopic examination

gives Marks another clue.

A dent on the pylon bulkhead at exactly the point

where the crack began.

There was also a deformation that

was on one of the fractures.

At that time, I was not absolutely sure

what it all meant because it just showed a deformation.

It looks like something hit the pylon.

I'm just not sure what or when.

OK.

I'll see what I can find.

Take notes on everything.

Got it.

The information is available.

It's on the hangar floor.

It's in the minds of those people.

We just have to ferret it out.

NARRATOR: Investigators arranged

to watch as another DC-10 undergoes the same maintenance

that was performed on Flight 191

just weeks before the crash.

Can you take me up and show me how the engines mount?

We're going to talk to the people involved.

Most likely, it's going to be the maintenance personnel.

And we're going to ask them pointed questions

on what have you done?

Have you done this job before?

What kind of problems did you encounter?

Did you follow the paperwork to the letter

religiously, step one, step two, step three?

They found procedures that were not in the manual.

They found procedures that the manufacturer

didn't recommend be performed.

NARRATOR: To save time, the airline has modified

a key maintenance procedure.

OK.

Bring her up.

A wing mounted engine on a DC-10 as a 24-hour adventure,

which is extremely long.

So there's a lot of pressure on getting

whatever is broken repaired and getting

the airplane back in the sky.

NARRATOR: The normal procedure for servicing

an engine involves removing it from the pylon

and leaving the pylon attached to the wing.

There are hundreds of connections to be undone.

Procedures from the manufacturer would deem to be

too time-consuming, and they could do it faster,

better, cheaper.

So they were deviating from the procedures.

NARRATOR: The quicker way involves

taking out just three bolts.

The engine is removed from the wing while still

attached to the pylon.

It saves about 200 man hours of labor.

It was easier.

The attach points from the pylon to the wing

were accessible.

The attach points from the engine to the pylon

were much more difficult to take

apart and put back together.

Removing is not the issue.

It's the attempt to reinstall-- - Whoa.

Stop

Is where the problem comes from.

Left a bit.

Now up.

NARRATOR: Maneuvering the pylon into position

with an engine attached to it is a tricky procedure.

Trying to put the engine in the pylon back together,

some 13,000 pounds for the engine

and 2,000 pounds for the pylon, it's not easy.

They were using the forklift.

And this forklift is not very manageable.

It cannot be finely controlled as far

as the altitude is concerned.

The minimum movement on the forklift

was something on the order of a quarter of an inch.

And we're talking about trying to fit something

together that might be in the order

of thousandths of an inch.

Whoa, stop.

Stop.

So you get just slightly the wrong angle,

and you get too much pressure on it,

and you're going to crack those fittings.

I'm sure they didn't realize how quickly

they could get in trouble doing it the way they were doing it.

I think I know what happened.

NARRATOR: A possible explanation surfaces--

Take her down.

NARRATOR: For the mysterious dent found

on the pylon from Flight 191.

The team in Tulsa calls Marks.

What you got?

NARRATOR: They describe how the maintenance crew struggled

to fit the pylon attachment into the mounting bracket

or clevis.

And then it all came together,

just like a bolt of lightning.

The clevis itself had produced this deformation

that was on the fracture.

NARRATOR: Marks concludes that on the accident plane,

the clevis must have slammed into the top

of the pylon bulkhead as the engine was being reattached.

The impact could have started the crack

that led to the pylon's failure and to the crash itself.

The maintenance people that did this operation which

cracked the pylon probably didn't

hear anything, a bang or crack or anything like that.

OK.

Bring her up.

We call it working around.

So they worked around the manual

to get the job done quicker.

But the process never gets the proper vetting, if you will.

Review from engineering and from the manufacturer.

And sometimes, those alternate methods

have unintended consequences.

NARRATOR: Over the next eight weeks,

each time the plane took off, the stress

that the massive engine put on the pylon

made the crash grow larger.

The engine is not only imparting a thrust load,

but it's also imparting a sideways load.

So each time you have this load,

it breaks a little bit more, and more, and more.

NARRATOR: It was only a matter of time

before the pylon snapped, and the engine fell off.

So the process was flawed, and the people

made adjustments to a flawed process

to try to make it work.

And collectively, that is a recipe for disaster.

How long have you been putting

the engines on this way?

Not sure, but every airline does it.

NARRATOR: Even more worrying, the mechanics

at American Airlines are not the only ones cutting corners.

The airlines shared processes.

And since this engine change was

so time-consuming and costly, they were all looking

for a better way of doing it.

Faster, better, cheaper way to do it.

And so when one would discover it,

a process to use that maybe made

the engine change go quicker, the others

were very quick to adopt it.

And that's exactly what we see here.

We need to get the entire fleet inspected for this.

NARRATOR: It is now clear why the engine fell

from the plane, but what happened

after that is still a mystery.

Flight 191 could have landed safely

with one missing engine.

Instead, 273 people died in a horrific crash.

The plane was completely flyable.

It was in bad shape.

It had lost an engine.

It had lost several critical systems.

But it was still airworthy.

And it was still able to fly.

What happened in that cockpit?

NARRATOR: The crash of Flight 191

has a devastating effect on the entire airline industry.

It was a huge economic problem for the airlines

because their major airplane was now on the ground,

and they couldn't fly it.

And of course, I think it had a big impact on the public

as well.

Have you seen this?

NARRATOR: So why weren't the pilots

able to save their plane after losing one engine?

A chance photograph taken just before the crash

may provide some answers.

There was certainly one very famous photograph that was

published in many newspapers of the aircraft

in semi-inverted position, almost

ready to strike the ground.

Everyone saw this picture.

I want you to track down all the pictures you can

and get them blown up.

I want to see those wings.

You got it.

These photographs that can do so much to horrify the public

can have a real use for the accident investigators.

NARRATOR: By examining photographs taken just prior

to the crash, they might be able to tell

whether the pilots made some mistake when they configured

their plane for takeoff.

Flaps and ailerons look fine.

By blowing up and zooming in on the leading

edge of the wing, the aircraft investigators

were able to determine what was going on.

Is that hydraulic fluid?

NARRATOR: If the fluid leaked from the plane's

hydraulic system, it might explain why the plane

was so hard to control.

Sometimes, the crucial element in air crash

investigation can be some very small,

subtle detail from which everything else can devolve.

NARRATOR: Several of the DC-10's hydraulic lines

run along the leading edge of the wing.

Take a look at this.

NARRATOR: It's the area that was damaged the most

when the engine broke free.

We need to see those slats.

American 191, thank you.

Taxi and hold runway 32 right.

Flaps and slats to 10.

NARRATOR: The plane's slats are extended before takeoff.

They're essential for providing the lift needed

to get the plane airborne.

The slats are on the leading edge of the wing.

And when you deploy the slats, they move out forward.

So the air has a longer distance to go

and therefore, is moving faster.

And it creates more of a lift a vacuum above the wing.

NARRATOR: If the hydraulic system controlling the slats

failed, it could explain the plane's loss of control.

Investigators discover that while all the slats

in the right wing were extended for takeoff,

some on the left wing were not.

It's a configuration that's normally impossible.

You have one wing that is flying

and the other wing that isn't.

And when you have a wing that's flying

and one that isn't, the one that isn't flying dips,

and the one that is flying continues to fly,

which means the airplane goes into a roll.

NARRATOR: They conclude that the engine

hit the wing with enough force to rupture

the hydraulic lines.

The fluid keeping the slats extended on the left wing

would have drained quickly.

I can't hold it.

NARRATOR: Without fluid, some slats on the left wing

retracted, causing that wing to lose lift.

The plane began to roll.

The actual stalling speed was 124

knots for the airplane at this weight and configuration.

I'm losing it.

The fact that the slat had retracted

raised the stalling speed to 159 knots from 124 knots.

So it was a huge difference.

NARRATOR: Without the slats, they

needed to be flying much faster than normal to avoid stalling.

One final question remains.

Why couldn't the pilots recover from the stalled wing?

Investigators recreate the takeoff in a flight simulator

to find out.

OK, you all set?

We're ready.

Let's try one.

V1.

This crew had almost 5,000 hours in this aircraft.

You couldn't ask for a more experienced

crew in this airplane.

And if anybody was going to be able to fly

that airplane in that condition,

it would have been this crew.

NARRATOR: Immediately after the slats retract,

there are dramatic warnings in the cockpit.

There is a stall warning system

that will advise the pilots when the airplane is

about to stall.

It's called a stick shaker.

And when you're nearing the stall speed,

your stick will actually start to shake to warn you of this.

NARRATOR: The stick shaker does exactly as the name suggests.

It vibrates the control column to get the pilot's attention.

If you get a stall warning, you obviously lower the nose,

and you apply for power, and you fly it out of the stall.

If they had lowered the nose, let the airspeed increase,

they actually would have been fine.

The plane was recoverable.

It was landable.

NARRATOR: The simulator tests show

that once the pilots are alerted to the problem,

it is possible to recover.

Why didn't they do that?

NARRATOR: If the pilots on flight 191

had known they were stalling, they could have

been able to save their plane.

It seems possible that somehow, they didn't know.

Investigators study the cockpit warning system on the DC-10

and make a crucial discovery.

All the alarms are powered by the left engine.

When the engine fell off, it severed hydraulic systems.

It severed electrical systems.

I've lost power to my sight.

Looks like we've lost number one.

It resulted in a loss of instrumentation

and of warning devices.

NARRATOR: As soon as the left engine came off,

the warnings that could have saved the plane were disabled.

They bring in a new test pilot to fly the simulation.

OK. You're all set?

NARRATOR: What they don't tell him--

We're ready. Let's try one.

NARRATOR: Is that all the warnings

have been disconnected.

From that position in the cockpit,

you can't see that left wing.

And they didn't even know the engine was actually gone.

They thought it had just stopped.

It looks like we've lost number one.

When pilots say lose an engine, we mean we lose engine power.

This plane actually lost an engine.

NARRATOR: Without warnings, the test

pilot is in the same plight as the American Airlines crew.

He has no idea his plane has stalled.

If the stick shaker stall warning device

had been functioning, it's very easy

to imagine that the pilot flying the airplane

would have put the nose down and would

have avoided a stall.

- We're banking. - Go right.

Go right.

NARRATOR: Since they don't know about the stall,

they follow the procedure for an engine failure on takeoff.

It sealed their fate.

Pilots were taught at that point in time

that if you lost an engine, the whole idea

was to get more altitude faster and get away from the ground.

So if you lost a second engine, you would have that much

more altitude to play with.

And so you were taught to pull back on the wheel

and go back to the minimum safe flying speed

to get away from the ground.

Reduce speed 153 knots.

Reducing speed to 153 knots.

NARRATOR: Reducing speed by lifting the nose

is the exact opposite of what pilots need to do when

a plane is about to stall.

It makes the stall worse and the roll more severe.

Following the checklist for a single engine failure

made what happened next inevitable and doomed everyone

on board.

If they didn't know they were stalling,

they didn't stand a chance.

The pilots flew the plane exactly

as they'd been trained to do, exactly as procedure

demanded that they fly it.

The pilots were doing absolutely the right thing.

There was absolutely nothing that he could have done.

He was powerless.

He was along for the ride.

NARRATOR: The NTSB concludes the pilots were not at fault.

They do, however, fault American Airlines' maintenance

practices and the FAA for not enforcing proper procedures.

The FAA mandates that stick shakers be installed

on both pilots' control columns and that the warning

system be powered by more than one engine.

The plane's hydraulics are also redesigned with special plugs

to prevent slats and other control surfaces

from retracting if the lines are cut.

When the airplanes were grounded

as a result of this accident, we

found a number of other airplanes

with cracks in the fleet.

NARRATOR: Inspectors find eight more

DC-10s with damaged pylons.

It was very scary when the inspections uncovered so many

other airplanes with problems.

That was very, very scary.

Because every one of those had the potential

of being another accident.

And had we not done the grounding,

then we may have had yet another accident

before we realized the width and breadth of the problem.

This kind of action never happened again.

This engine never fell off this kind of airplane again.

In the general sense though, it teaches us

how to look at safety.

It teaches us how to look at the culture

of training and procedures in the air and procedures

on the ground. - Whoa.

Stop.

Stop.

NARRATOR: One final outcome of the Flight 191 disaster?

Airlines reconsidered the idea of sending live video

to passengers in the cabin.

The passengers were able to see the airplane going

into this dive and were able to see

their own demise in effect.

NARRATOR: The cockpit camera was abandoned.

But the shocking photo of Flight 191's last

moments remains.

An image that both the airlines and the FAA likely wish

could be erased.

They would much rather have people think of air travel

as cramped seats, bad food, luggage being lost,

than with dying.

Luggage being lost will make people grumble,

but people dying will make people not fly.