Impact! A Horizon Guide to Plane Crashes

Air travel has transformed our lives.

Fast, direct,

and above all safe.

And it keeps getting safer.

In 2012, the global accident rate for Western-built jets

was the lowest in aviation history.

But the carefree flying that we enjoy today

has been bought at a deadly cost...

Because improvements in aviation safety

have been driven by the stuff of nightmares...

Air crashes.

Every crash has its causes,

and this information is used by scientists

to prevent the same failures from happening again.

For more than 60 years, Horizon and the BBC have reported

on the accidents that have revolutionised aviation safety.

In this programme, we'll chart the most significant improvements

through the stories of the most deadly disasters.

Tenerife Airport,

March 27th, 1977.

Debris is strewn far and wide.

Thick plumes of smoke fill the sky.

This is the wreckage from the deadliest air crash in history,

a crash that happened not in the sky

but on the runway.

The control tower just 700 metres away

didn't even see it happen.

Just ten minutes earlier,

the airport had been busy but running smoothly.

Two Boeing 747s,

one KLM, the other Pan Am,

were a mile apart at opposite ends of the runway.

They'd been instructed to position themselves ready for take-off.

The KLM was to wait at one end of the runway

while Pan Am was to turn off it

and allow KLM to depart first.

As they were manoeuvring,

a thick fog came over the mountains

and enveloped the airport.

With the runway now shrouded in fog

neither plane could see each other.

Crucially, neither could the air traffic controller in the tower.

The Pan Am pilots taxiing down the runaway missed the turning.

At six minutes past five

the KLM pilot, believing the Pan Am was now off the runway,

began his take-off with Pan Am still ahead of him.

First time in my life I've ever had a situation occur

that I couldn't believe was happening.

I just could not believe this airplane was coming

down the runaway at us.

My comment was, "Get off!" to the captain,

which he tried everything he possibly could.

As we were turning,

I looked back out of my right window

and the KLM airplane had lifted off the runway.

Basically, what I did was just close my eyes and duck.

During lift-off, the KLM plane collided with Pan Am.

Although briefly airborne, it lost control,

crashed and burst into a ball of flames...

..while the Pan Am plane broke into several pieces and exploded.

Almost 600 people died that day.

The accident shocked the world.

Everyone wanted to know what could have caused this devastating crash.

Initially it seemed the obvious cause of the disaster was fog.

562, turn tight, heading 070...

But the crash investigation

revealed that fog was only one factor.

123 out of air...

123, 29 miles over.

Bad communication and poor crew dynamics

also played a major role.

Wind squall at 5524.

5524.

The Tenerife disaster showed

that the causes of plane crashes are rarely straightforward.

And that's not surprising

given that aviation is an incredibly complex business

and there are so many things that can go wrong.

If you stop and think about it for a second,

travelling by plane is a pretty odd thing to do.

Hundreds of us strapped into this narrow tube,

hurtling through the air at upwards of 500 miles an hour,

and separated from the freezing, oxygen-starved atmosphere

by just a few centimetres of metal and plastic.

Today we pretty much take it for granted

that the aeroplane is up to the job.

It's not going to fall apart around us.

But in the early days of commercial aviation,

even the structural integrity of the plane couldn't be guaranteed.

Scientists realised the hard way

that there were some significant gaps in their knowledge.

There is arguably no single plane that's been more important

in the story of aircraft engineering than the ill-fated Comet.

-REPORTER:

-When the 36-seater, jet-propelled De Havilland Comet

opened the latest act in the drama of man's conquest of the heavens,

the eyes of many nations were focused upon it.

Built in Britain and launched in 1952,

it was the first passenger jet to go into service.

Cruising at 490 miles an hour,

the Comet offered all the attractions

of smooth, high-altitude travel.

The Comet had grace and beauty.

But unfortunately that's not what it's remembered for.

Between May '52 and April '54,

three of the nine Comets in service broke up in mid air.

The Comet 1 never flew again.

After the third disaster,

bits of the aircraft were recovered

from the bottom of the Mediterranean.

In all, 67 people died in the crashes.

It was a disaster for the British aircraft industry,

particularly because no-one knew why the planes

had apparently just fallen out of the sky.

So all the Comets were grounded,

and scientists set to work on one of the greatest

aircraft detective stories in aviation history.

As in any investigation,

scientists started by painstakingly sieving through the crash wreckage.

Their first clue came in the form of a curious anomaly

found in fragments of the fuselage.

There were unexplained rips through the aluminium shell.

The scientists next had to work out

what could have caused these tears,

and the only way to do that

was to try to recreate the damage.

An entire fuselage was immersed in a high pressure tank

and subjected to cycles of increasing and decreasing pressure

to simulate an aircraft in service

constantly climbing and descending.

The fatal weakness suddenly revealed itself.

A weakness that would change aircraft design forever.

It was metal fatigue, a type of weakness that starts

as a small crack somewhere in the fuselage

and spreads catastrophically across the plane

when it undergoes pressure changes in flight.

It would have quickly and suddenly

caused the plane to completely break up.

Metal fatigue wasn't seen as a major problem

prior to the Comet crashes,

because aviation experts didn't fully understand

the destructive effects of pressurisation

and had been performing the wrong types of tests.

The challenge for engineers was to find a way

to protect the plane against the repetitive stresses of flight.

How are you going to tackle the weakness in the fuselage?

Well, it will be largely a question of a thicker skin

and much improved detail design.

Here's your skin.

When you talk of a skin, what do you really mean?

It isn't what we think of as a skin?

Is it double thickness?

Is it like a sort of insulated window, or...?

-No, no, no, it's a single skin...

-It is single?

Oh, yes, high strength, light alloy,

just single,

and made thick enough to withstand the pressures and the loads

that come on it from structural loads.

Scientists also learnt that square cabin windows were problematic.

The corners would often be where cracks in the fuselage started,

so engineers simply got rid of the corners.

The British civil aircraft industry never fully recovered

from the Comet disasters.

But what was learnt about metal fatigue

and how to properly test for it was shared with airlines

and engineers across the world.

The emphasis was now on full-scale aircraft testing,

because aviation experts realised

that testing the structural integrity of individual plane parts

can't be done in isolation.

40 years after the Comet crashes, full-scale testing had become

mandatory and a bit of a spectator sport for engineers.

It's 1995, at the Boeing factory.

Cables are pulling hard on a Triple 7 wing

to test whether it can survive

the strongest forces turbulence or bad handling could produce.

REPORTER: As the test progresses, the forces on the wings

are so strong that they cause ripples in the fuselage.

The engineers hope that the wing will withstand

150% of the strongest forces it will meet in flight.

They're predicting a wing deflection of about 24 feet before it breaks.

-ENGINEER:

-Can I have your attention?

We're now holding at 120% design limit load.

We will make a loads check.

It should be a short hold here.

As the tension in the wing increases,

the crowd of observers,

including many of the people

who have lived with the plane for four years or more, falls quiet.

At 150% loading, it's the moment of truth.

Will the wing remain intact?

To the engineers' delight, the wing survives.

151.

They've got a safe, strong wing ready for service.

156.

If you've ever worried about wobbly wings,

just see how much bending they can take.

153.

Now the engineers are going to push their creation

to its absolute limit.

154.

It finally breaks at 154%...

Way beyond the strongest forces any plane should experience.

154.

This is just one of the many tests a plane must pass

before it's let anywhere near the runway.

They're devised to weed out any weaknesses in the design

or materials.

So today it's very rare that a plane's strength

is ever called into question.

By the 1960s, the days of aircraft breaking up in mid air

for no apparent reason were largely gone.

But in terms of aircraft safety,

fixing structural integrity actually turned out to be the easy bit.

Much trickier was another major cause of crashes.

What in the aviation world is called bad operational conditions,

we would call bad weather,

and the potentially lethal effects were highlighted

by the investigation into

one of the most mysterious crashes in history.

On August 2nd, 1947,

a British Lancastrian airliner called Star Dust

took off on a routine passenger flight across South America.

Although scheduled to fly from Buenos Aires to Santiago,

the plane never reached its final destination.

Instead it completely vanished

just moments before touchdown.

Despite an extensive search of the Andes mountains,

no trace of the plane was ever found.

But in 2000, 53 years after the crash,

parts of the plane suddenly reappeared...

..on a glacier high up in the Andes.

Crash investigators examined the site in a bid to work out

what had happened to the ill-fated plane.

There was no explanation for why Star Dust had crashed

when there was apparently nothing wrong with the plane.

The plane had crashed 50 miles away from Santiago,

even though the crew thought they were close to landing.

So they focused on one key factor that could have caused the crash...

navigation error.

The investigators already knew that shortly before the crash

the crew had decided to avoid bad weather by climbing

above the clouds and flying over the top of the mountains.

Although they didn't know it, by trying to fly over

the tops of the mountains, they were sealing their fate.

They were about to encounter an invisible meteorological phenomenon

which they knew nothing about.

The jet stream.

This powerful, high altitude wind

only develops above the normal weather systems.

It blows at speeds of well over 100mph.

But in 1947, the phenomenon itself was still largely unknown.

The crew of Star Dust would have had no idea

what they were flying into,

and now that the plane was flying above the clouds

the crew could no longer see the ground.

As Star Dust climbed, it began to enter the jet stream

and slow down dramatically.

But the crew had no knowledge of this.

They believed that they were making much faster progress.

At 24,000 feet, Star Dust was flying

almost directly into the jet stream, which was blowing at around 100mph.

The Jet Stream's effect was devastating.

At 5.33, the crew was convinced they were crossing

the mountains into Chile.

But they weren't.

They radioed their time of arrival as 5.45.

In fact, the plane was still on the wrong side of the mountains.

The plane descended towards what the crew thought would be

Santiago Airport.

But in fact they were flying

straight into the cloud-covered glacier of Mount Tupangato.

All 11 lives were lost in the crash,

and the plane was buried within seconds, vanishing from sight.

The Star Dust tragedy was the direct result

of the unknown effects of the jet stream.

Today, thankfully, high-altitude weather is no longer a mystery

and sophisticated weather forecasting makes sure

crews are prepared whatever the conditions.

One of the paradoxes of aircraft safety is that every major leap

in aircraft capability creates its own new set of problems,

and many of those are connected with the weather.

So, for Star Dust, it was its ability to climb high.

In the 1960s, the industry was grappling with the problems

of flying fast,

as jet engines like this one were taking over from piston engines.

Now, that extra speed may have been good news for passengers

but it meant that common forms of weather suddenly became

very real safety concerns.

Fighter pilots were the first to find out

about the danger of rain damage at near supersonic speeds.

After only ten minutes in a rain storm, a Hunter jet fighter

landed with its radar cone damaged like this.

The nose cone is made of bonded layers of toughened glass fibre

and rubber.

This was one of the first recorded cases of rain drop damage

so massive that the aircraft had been in critical danger.

The outer cover had been torn off.

The inner rubber shell was deeply pitted.

To understand what was happening,

scientists at the Royal Aircraft Establishment, Farnborough,

constructed this gas-powered gun

to try to recreate the hazard of dangerous rain.

A magnesium bullet tipped with Perspex

is loaded into the firing chamber.

When the bullet is fired at over 1,000 feet a second,

it will collide with a raindrop suspended directly in its path.

Surface tension holds the raindrop in place on a web

of artificial fibres specially created for each test.

A carefully measured drop of soft rain water is about to be

given the destructive power of an explosive blast.

The web is shattered before you have time to hear the explosion.

The impact of the raindrop has been recorded

on the Perspex head of the bullet.

The Perspex,

the kind that's used in aircraft windows, is studied for damage.

The moment of impact, seen from a different angle.

With camera shutter speed at a millionth of a second,

the disintegration of each drop of water can be analysed in detail.

Damage is caused when the pressure built up

in the raindrop on impact is released when it shatters.

Three clear areas show where pressure built up

before the raindrops carved out their circles of damage.

The effect of a torrential downpour on a high-speed aircraft

would be many times more serious.

Even raised rivets on the fuselage could be forced out

by the impact of this kind of rain.

To test the effects of a prolonged rainfall,

they constructed this whirling arm.

The blade tip revolves at 500 miles an hour,

as water is spun off the disc mounted in front of it

to form a fine rain cloud.

Prototypes of metal, glass, paint and rubber can be fixed

to the whirling arm to see how they stand up to rain storms.

ALARM

Within seconds the arm accelerates to 500 miles an hour.

As rain drops strike the test surfaces one after another,

materials simply disintegrate...

Perspex after only 20 minutes.

Aluminium is reduced to this after 15 hours.

Metals and alloys used in the next generation of aircraft

will have to stand up to longer flying hours at higher speeds.

They prove themselves or fail dramatically on this test rig.

Even paintwork has to be strengthened

when only two minutes in rain does this.

This research has shown that streamlining of aircraft is vital

because it lessens the head-on impact of dangerous rain.

Aircraft designers quickly applied these findings to modern jets.

Raised rivets were lost,

paint became protective,

and the shape of aircrafts became increasingly tapered

as their speeds increased.

Rain at high speeds no longer caused any serious damage to the plane.

Of all the problems caused by bad weather,

one of the most potentially dangerous is losing visibility.

It can seriously disorientate a pilot

and make any manoeuvre that requires particular accuracy

or precise judgment that much more difficult.

So it makes sense that, out of all the conditions,

the one that pilots have feared the most is fog.

Fog is particularly dangerous when a pilot is attempting to land.

That's because the plane needs to be perfectly aligned

to hit the runway at the right spot at the right time.

But in foggy conditions, pilots might not have any visual cues

to help them.

Without good visibility,

the plane could clip something on the way down

or even overshoot the runway.

So, in the 1960s, some scientists thought

the answer to the problem might be to find a way

to simply get rid of fog at airports.

In America, they attacked the problem

with a rather unique approach.

This equipment is the latest on the anti-fog scene.

It's been developed by an American horticultural company

from a standard crop spraying machine, and if it works

it could do away with the need

for special aircraft for spraying chemicals.

Instead, with this machine, detergents or dry ice

could be sprayed through an inflatable plastic tube

from a height of 200 feet.

A fan at the base of the machine inflates the tube.

It also powers the spray which can pivot vertically

or horizontally while being towed along a fog-covered runway.

By the time these development tests are over, the researchers hope

they'll have an effective fog killer that could be in operation

by the end of next year.

Perhaps not surprisingly, this particular fog killer

wasn't very effective, and it was soon abandoned.

A quarter of a mile from touchdown.

You're on the glide path.

On track, on the glide path.

Once scientists realised completely eliminating fog at airports

is no easy task,

they concentrated on improving tools

that pilots could use to work around it.

It's called ILS, or Instrument Landing System.

Instead of relying on a ground controller,

a pilot watches two cross wires on an instrument in his cockpit.

When they're centred, he knows he's on the glide path,

flying down a fixed radio beam

coming from a transmitter on the end of the runway itself.

As ILS became more advanced,

it, together with radar and radio technology,

equipped pilots with the means to fly and land in fog

with much more safety.

Reducing the threats of bad weather

and improving the structural integrity of planes

meant that, during the 1960s and '70s,

aircraft safety began to improve.

By the 1980s, aircraft safety seemed to have become

a good news story.

Planes were far less likely to fall out of the sky

and the rates of crashes had fallen.

But there was one statistic that was worrying safety experts.

Although the rate of crashes had fallen,

the chances of actually surviving one had stayed the same.

Engineers had been concentrating on preventing accidents

rather than saving us if the worst was to happen.

Fire is the greatest single threat to survival in any plane crash.

That's because, as a passenger,

you're sitting on top of up to 300,000 litres of fuel,

and if it comes into contact with even the smallest of sparks,

it's likely to explode into a deadly inferno.

It seemed logical to scientists working in the early 1940s

that the way to tackle the threat of fire

was to prevent it happening in the first place.

ARCHIVE REPORTER: The United States Air Force

provided a group of service-weary aircraft

with which to conduct their research.

A landing or a take-off accident was chosen for study

because the chance for passenger survival of crash impact

is highest in this kind of crash.

The US Air Force discovered that what was particularly dangerous

about jet fuel was the way it dispersed on impact.

Here, you can see test planes being deliberately crashed.

The fuel has been coloured red.

When the plane impacts, the fuel at first trails behind.

Then, as the aircraft slows,

it moves ahead in a fine mist.

It's this mist that's particularly volatile.

It was a major discovery.

The task for the next 40 years would be to develop a fuel

that didn't mist.

And in the 1980s, it was us Brits

that looked like we may have figured it out.

The answer, then, is to make the fuel thicker so it doesn't mist,

and the thickening ingredient that the scientists have come up with

is an additive called FM-9.

Now, the molecular structure of FM-9 is like a long chain.

It's called a polymer, which,

if you dissolve it in kerosene, floats freely.

But if you shake the kerosene around,

as would happen in a violent accident,

the chains of the polymer will tangle together

and make the kerosene behave like a jelly.

Well, here's the real stuff.

Aviation fuel with FM-9 on this side

and fuel that doesn't have it, here.

Now, side by side they look exactly the same,

but if you shake them both,

you can see that the fuel with the additive over here

goes like jelly, and jelly can't mist.

But hold on. It can't ignite either,

so it's not going to be much use in an engine.

So any engine using this stuff would have to be modified

to break down the polymer chains to make the fuel behave normally.

The Federal Aviation Authority in America

was so taken by the research that they organised a test crash

using a plane carrying the new anti-misting fuel

and the scientists were optimistic

that the test was going to be a success.

I've got a great deal of confidence that we're not going to see a fire.

The crash date was set for December 1st 1984.

All hopes for a new, safe jet fuel

were pinned onto this 9 million experiment.

The aircraft will fly into cutters that will rip open the wings

and the fuel tanks inside them.

The world's press and television have been invited

to observe from a safe distance.

There's no pilot on board.

He too is watching from a distance by television.

Federal Aviation Agency engineers join NASA in Mission Control

to monitor every detail as the Boeing 720 skims in over the Mojave Desert.

Dozens of cameras follow the action.

But it's falling short of the target.

It spins to the left as it heads toward the cutters.

This is not in the plan.

The pictures that were flashed around the world that day

made it look like a total disaster.

The fire took more than an hour to extinguish.

It was a PR disaster.

Funding was withdrawn

and the idea of preventing a fire was all but abandoned.

And a disaster the following year led scientists

to focus on simply surviving one instead.

On August 22nd 1985, Flight 28M was taxiing down the runway

at Manchester Airport heading for Corfu.

But just minutes after leaving the gate,

as the plane was attempting take-off, something went wrong.

There was a loud bang on the left-hand side of the aircraft

like the report from a shotgun

and someone shouted, "A tyre has burst."

And then, within about 1.5 seconds,

the nose of the aircraft came down, bang,

hit the floor, and all the bottles,

the duty free, rattled in the bins at the top.

The captain abandoned take-off within one second of hearing that bang,

but he thought it's a tyre blow-out, so go easy on the brakes.

Even when the fire bell rang he had no idea how bad this was,

so he continued down the runway.

People watching from the terminal building

could see more clearly than the crew how burning fuel trailed behind

until the aircraft turned off the runway and across the wind

so fire and smoke enveloped the back of the plane.

The flames came through the windows and up onto the ceiling

and all the ceiling started to burn and then it rapidly spread.

It was the heat of the cabin.

It was so hot that you could feel your flesh creep,

creeping like that.

And I think myself that it was the seats,

the foam had reached the flash point and they just went up

and the thick, thick black smoke came down

and that's all there was to breathe.

People were on fire and people were burning, and some people,

because of the visibility, were running the wrong way.

I saw one, one lady who had her... just had her hair done

and she, it must have been very heavily lacquered,

because all of a sudden...

And her hair went, the lot went,

it had reached its flash point and she, in a panic, ran the wrong way.

Roy Metcalf made it off the plane, but many didn't.

55 people lost their lives.

The pilot had thought the loud thump was a burst tyre,

but the noise was in fact his left engine breaking apart

and sparking a fire.

It wasn't just the cause that was the concern in the Manchester crash.

What troubled scientists was that it should have been survivable.

After all, the plane didn't fall out of the sky,

it didn't collide with anything,

the pilot never lost control of the aircraft -

so why did so many people die?

Well, investigators began to focus

on what had happened inside the cabin

in the minutes after the engine failure.

The seats at Manchester contained a plastic foam cushion

that's commonly been used throughout the airline industry

because it's very light.

At Manchester the fire burned through the outer skin of the aircraft

in perhaps half a minute,

then up through ventilation ducts below the seats.

This urethane plastic foam not only feeds the fire,

it also gives off poison gas.

Within minutes all that's left is cinders.

But of the 55 that died, only nine of them

were killed directly by the fire.

46 were choked and poisoned by the smoke.

The seats they were sitting on killed them.

Prior to the Manchester crash, there were relatively few regulations

about what the cabin must be made from.

At the moment we have this number of specifications,

all of which are used on buildings or ships

or things used in buildings or ships.

So all these are rules for fire testing and specifications?

-All those are rules for fire testing.

-Boxes and boxes of it.

There's the building regulations of the governing document,

and all these are specifications which are used at various times

for things that go into buildings, ships or possibly cars.

Whereas at the same time,

we have one document which runs to about 11 pages,

which covers the contents of aircraft cabins.

-That's all there is?

-That's all there is.

After the Manchester disaster, the Civil Aviation Authority

hurried through a requirement

that airlines fit a new type of seat onto all aircraft.

Between the cover and the foam there's now an extra layer.

This would make the seats more fire resistant.

Although the fumes could still be deadly, the new seats would at least

give passengers more time to get out before being affected by the poison.

The toxicity of cabin materials was not the only issue

highlighted by the Manchester crash. Investigators were also concerned

at how slow the passengers were to escape.

They believed if the evacuation had been faster,

there might have been more survivors.

When the fire came in through the back of the cabin

and people started to see the smoke and so on,

many people rushed as rapidly as they could,

some of them going over the seats to the front of the cabin,

and when they came up against what we call the bulkheads,

which are the solid sections which are just in front of the galleys,

and there we have a quite narrow gap of actually 20 inches

between those bulkheads, the passengers weren't all able

to get through as fast as they arrived

and we tragically finished up with a situation

where some people just didn't manage to get through and fell,

and others moved on in spite of them.

The CAA commissioned Helen Muir to investigate

why more people didn't escape.

She knew that standard evacuation trials were too orderly,

so she created a more realistic experience by offering her subjects

a financial incentive to be first off the plane.

The first half out of whichever exits are used

will receive a £5 bonus payment immediately,

and we have found that this does encourage people

to make their way fairly rapidly,

and very interestingly we've had survivors from accidents

come and see videos of behaviour in these experiments and said,

"Oh, yes, you know, that is how it was."

'Undo your seat belt and get out.'

In 1987 she used a real airliner with standard exits and bulkheads.

She studied how different cabin layouts affected

the flow of passengers to exits.

FRENETIC SHOUTING

This research video shows how bulkheads could cause blockages.

The researchers recommended that the opening be increased to 30 inches.

They also experimented with different seat layouts

and suggested widening the access to over-wing exits.

After the Manchester crash, the Civil Aviation Authority enforced

the introduction of new seat layouts on planes.

Airlines had to make access to mid-exit doors easier

by either removing a seat or moving the entire row back.

And they were forced to move all the emergency exit lighting

to floor level so it wouldn't be obstructed by smoke.

The Manchester disaster was a pivotal moment in improving

the chance of surviving a plane crash.

Buying passengers a little bit more time

and speeding up evacuation has saved countless lives in fires since.

The Manchester incident didn't mark the end of the study of survivability

because in a crash, fire isn't the only serious threat to your life.

In 1989, in another accident also in Britain, safety experts were

forced to investigate the other major killer in air crashes - impact.

On 8th January 1989 British Midland Flight 92

took off from Heathrow bound for Belfast.

Just minutes after take-off the left engine caught fire

and the crew were re-directed to East Midlands Airport,

but they never made it.

The British Midland plane hit the motorway embankment at about 100mph.

It came to a standstill in just over a second.

The force of the impact was staggering, yet 79 people survived,

though most were seriously injured.

Had there been a fire, only 14 would have been able to escape.

Scientists were shocked by the severity of the injuries

suffered by the survivors and so focused much of their efforts

on uncovering what happened to them at the moment of impact.

A research team quickly embarked on the most detailed study yet

of air crash survivors.

Every survivor was photographed and interviewed.

Every injury, including minor cuts and bruises, was logged.

Their seat number and the position they adopted

when the plane crashed was also recorded.

The seats were examined, numbered and photographed

from the front and rear.

The information stored on computer accurately identified survivors,

their injuries and other important details relevant to their survival.

Although the forces in the accident were very high

they alone couldn't account for the types of injuries suffered.

Even those passengers who had got into the brace position

which was supposed to protect against impact had suffered badly.

The scientists were mystified, but they felt sure the injuries had

something to do with how passengers prepared for the accident.

For the first time ever they used computer simulations

to investigate further.

Precise details of the Kegworth crash were analysed by the computer program.

The height and weight of one passenger

from the centre of the plane and the position he was sitting in

were added to recreate his exact movements

during the split-second crash.

First they looked at what happened to those passengers

who didn't prepare for the crash.

The computer program reproduced an accurate picture of why

passengers who sat bolt upright during the crash

incurred such devastating injuries.

These passengers suffered broken arms, legs

and serious head injuries. Some died.

The researchers then looked at what happened to a passenger

who did manage to get into the brace position.

He rested his head on the seat in front in between his arms.

His legs were slightly forward. As the plane plunged over the M1,

his face and arms are forced into the seat back. His legs move forward.

On impact with the motorway his face powered into the seat back,

his arms flailed and his legs flailed under the seat in front.

Most limb fractures resulted from this flailing.

When the plane stopped he impacted again.

Shocked that the recommended brace position could also cause

so many injuries, the scientists started to work on developing

a new, safer position that would do a better job of protecting the body.

Instead of the feet simply resting on the floor in front,

the scientists tucked the legs under the seat

and rather than the head being between the arms,

they positioned the arms over the head

and rested this directly onto the seat in front.

The dummy in the front seat is there

to simulate someone occupying that seat.

At 20G, roughly the force of the Kegworth crash,

the legs on the rear dummy move forward on impact,

but only slightly, and they don't flail under the seat in front.

The head impact is greatly reduced,

suggesting that cuts and bruises would be less serious,

and the flailing of the arms which caused so many fractures in Kegworth

is much less.

There is, of course, no proof, but the research team is convinced

that had passengers on the Kegworth plane adopted their brace position,

the injury toll would have been greatly reduced.

The Kegworth investigation

led to the introduction of a new brace position

which would be adopted by airlines around the world.

So next time you're on a plane, it's worth checking out the safety card,

because getting into the right position could save your life.

In the 1980s the aviation industry had made considerable progress

on aircraft design and was working on crash survivability,

but they'd also turn their attention to another factor

that remained stubbornly immune to improvement. It was becoming clear

to safety experts that most crashes were the result of something

rather less well understood than either weather or engineering,

something notoriously unpredictable and difficult to control -

humans.

Human error had been the cause of the Kegworth disaster.

When the left engine caught fire, the crew thought the problem was

with the right one, so shut it down.

By the time they realised they'd turned off the wrong engine

it was too late to restart it,

and with no engine power, the plane and its passengers were doomed.

Human error is the most common cause of air crashes, and in the 1980s,

after a spate of accidents caused not by the plane or weather,

but by the crew,

the entire industry started looking at how best to tackle the problem.

They decided to turn to aviation psychologists for help.

Since 1975, a highly confidential reporting system

has collected over 50,000 reports from worried pilots

about serious incidents involving breakdowns in teamwork.

It's run by NASA

and at their research centre in California

they're trying to recreate those incidents in a laboratory.

At its heart is a simulator containing a full flight crew.

We have an emergency, Sierra...

Their highly realistic flight

is complete with real air traffic controllers.

Using video cameras they can now find out how bad teamwork

leads to accidents without killing anybody.

FIRE ALARM SOUNDS

Engine fire number three.

Charlie, you do the check list.

I'll fly the aeroplane. I'll do the talking.

One of their three engines has caught fire.

It will have to be shut down fast.

-Power lever number three.

-Idle.

-Start lever number three, cut off?

-Check, number three.

-Number three.

Yeah, Tony, it looks like we've lost one of the engines.

Everything else is good,

but we are going to have to go back and land.

When NASA put over 20 airline flight crews through an exercise like this

they were amazed by the variety of performance they saw,

everything from good coordination to almost complete mayhem.

I didn't want to go to Chicago anyhow.

It's clear that effective communication in the cockpit is vital,

yet the researchers have found that those skills

are often barely adequate or even nonexistent.

The psychologists at NASA are discovering that anything

that prevents a flight crew behaving like a well-oiled team

is potentially dangerous

and one of the most disruptive influences is a pilot's personality.

Many of them simply aren't fitted for commercial cockpits at all.

Cracking the sound barrier in level flight

will be more than a spectacular feat.

It will also give the Air Force valuable knowledge

of the resources of new propulsive systems.

Captain Yeager gets aboard the XS-1.

It can't be a long flight he's going to have in the little aircraft.

At full power, the flight can't last more than 2.5 minutes,

but it's going to be a fast one.

In 1947 Chuck Yeager became a model hero for military pilots

when he became the first man to break through the sound barrier

in his experimental rocket plane the X-1.

The really big moment. Through the sound barrier!

The first time ever in level flight.

His relaxed laconic style while in great peril

became dubbed "the right stuff".

"The right stuff" is, as we see it,

in test pilots and in the early, but not the present astronauts,

is really this combination of high technical competence,

a very rugged individualism and a very high level of competitiveness.

The latter two are very destructive

when you're trying to function as an effective team.

The trouble is, whole generations of military flyers who venerated

those test pilots and tried to emulate them,

went on to fly for commercial airlines

taking "the right stuff" with them.

In many accidents the result is not that the crew makes a major mistake,

but that the captain decides in an emergency situation

that HE must fly the aircraft,

he must physically take control of the airplane

because he has "the right stuff".

What he fails to do then is to manage the situation

and to use the resources that are available

from the other crew members.

So he has turned it into a single-seat fighter

when in fact he needs all the assistance he can get.

He refuses to see it as a group problem

but as an individual problem.

I think it's a real potential problem, because the factors

that would lead you to an effective, smooth-working crew

are very different from those that make you a fighter ace.

"The right stuff" is in fact the wrong stuff.

In the early 1980s, psychologists started advising airlines

on how they could reduce human error

and improve teamwork in the cockpit.

United Airlines were the first to apply their recommendations

by changing their approach to pilot training.

Gentlemen, we've been discussing this afternoon

elements in our cockpit resource management programme,

which we call CRM.

They use a number of charts which depict a wide range of

personality types between the two extremes

of concern solely for the job

and concern solely for getting along with people.

After getting the low-down from the business manager,

pilots are then put through a highly realistic flight in a simulator.

We've got two engines. Number two is flaming out. The altimeter is OK.

It looks like loss of all generators.

Checklist, loss of all generators.

When something goes wrong,

between them, the team have to come up with a way to solve the problem.

Can either one of you think of anything that we haven't done

or that we need to do?

The only thing that we haven't tried, we could start the APU...

Vern has volunteered a novel solution which is not on his checklist.

He wants to try and link

an extra device called the auxiliary power unit

into the defunct third generator.

OK. I got the APU running. You want me to try it on number three, boss?

-Try it.

-Five for six.

Four, not a five for four.

-It took.

-Good.

It took, OK, you should have everything now.

Yes, sir, sure do.

Everything's back to normal, flaps are back to normal.

That's a good thought, Vern.

Vern's creativity has paid off. Control is restored.

They can now land safely,

and by praising him, Mike has reinforced Vern's behaviour.

This is what commercial airlines call "the right stuff".

United are convinced that the self-awareness

generated by that system is leading to safer cockpits.

There's a quiet revolution taking place among the world's airlines.

This kind of training proved to be so successful

that today most airlines have made it mandatory

not just for pilots, but for all crew members.

And it's thought to have significantly reduced the kind

of teamwork issues that were responsible for so many crashes.

Relationships in the cockpit are clearly critical to get right,

but it's not just human interaction that needs to be monitored.

So does the partnership between pilot and machine,

and since the 1970s, that's often been a difficult,

complicated love/hate relationship

since computers became more sophisticated

and much more involved in the business of flying the plane.

Ground crew 080.

This demonstration in the American DC-9 Super 80

shows just how powerful that technology is.

Before take-off the computer automatically works out

what the correct engine thrust should be

and sets the speed bugs in place.

The throttles advance automatically to the correct setting for take-off.

Game on, rotate!

About 400 feet into the air, the captain engages the auto-pilot.

One last dab at the computer and it will now control the rate of climb,

air speed and engine thrust right up to the assigned cruising altitude.

The route has already been programmed in, so the plane will take itself

to its destination. All the pilot needs to do is to watch it.

And that was the mid-1980s. Today, computers are even more

powerful and sophisticated, but too much automation brings with it

another set of problems, problems that played out

with disastrous effect in the cockpit of Air France Flight 447.

On May 31st 2009, an Air France Airbus took off from Rio

headed for Paris.

But just 350 miles off the coast of Brazil,

the plane crashed into the Atlantic...

..killing all 228 people on board.

The cause of the crash remained a mystery for years

until investigators managed to pull together enough evidence

to reconstruct the last few minutes before impact.

3.5 hours after take-off, just before 2am,

Flight 447 was heading into a huge 250-mile-wide storm.

When the plane started to experience turbulence, the pilot dialled

a lower speed into the computer and prepared to ride it out.

But at just 2.10am at 35,000 feet...

..a series of alarms went off...

..and the auto-pilot disconnected.

ALARMS SOUND

In total darkness and heavy turbulence

the crew are forced to re-take manual control.

Pilots are the last line of defence, so when things go very wrong,

the last line of defence is the aviator.

After more than three hours on auto-pilot

the pilots are suddenly faced by information overload.

That crew faced an almost unheard-of series of failures,

one right behind the other,

and for them to sort through it

would have been very difficult that night.

Why is the aeroplane doing what it's doing?

What are all these failures? Why are they all coming at one time?

Bombarded by faults, the pilot must cope with the most serious problem of all -

he must maintain speed or they will go out of control.

But after the pilot took manual control,

the plane lost critical speed

and went into the catastrophic condition known as a stall.

In a stall the wings of the aircraft lose lift

and the plane becomes almost impossible to control.

The pilot should have responded

by trying to increase speed, but he didn't.

No-one could be sure why, but it could be that he wasn't aware

he was stalling or maybe because he was just so used to automation

his manual skills had been blunted. Either way, the Air France pilot

couldn't maintain control and the plane simply dropped out of the sky.

To avoid the same scenario ever playing out again

the crash investigation recommended that simulator training placed

more of an emphasis on manual high-altitude flying

and aviation authorities have encouraged all pilots

to try switching off auto-pilot once in a while.

These changes should make pilots less reliant on automation

and better prepared to take back the controls in a crisis.

It is odd to think that we have only been flying

for a fraction over 100 years

and, despite the bewildering complexity, it is incredibly safe.

Crashes are very rare and something like 90% of those are survivable,

which is an amazing statistic and should give you SOME comfort

if you worry about the idea of hurtling through the air

at close to the speed of sound 35,000 feet above the ground

in a pressurised metal tube.

For me personally, ever since I was a kid,

I found air travel to be thrilling, but the more I think about it,

the more I think it's, well, it's mind-blowing.

Subtitles by Red Bee Media Ltd