Original subtitles

NARRATOR: In 1972, the Hawker Siddeley Trident is

the pride of British aviation.

Rotate.

DAVID LEARMOUNT: The Trident was a completely

British-built airplane.

And the carriage up.

COLIN WRIGHT: It was the equivalent

of having a sports car.

NARRATOR: When BEA Flight 548--

Look at the speed.

Look at the speed.

NARRATOR: --falls from the sky moments after takeoff.

The carnage shocks the nation.

FRANCES CASTLEDINE: It was so tragic that there

wasn't anyone who survived.

DAVID LEARMOUNT: It was the worst

airline accident that Britain had ever experienced.

Ladies and gentlemen, we are starting our approach.

We lost both engines.

- Put the mask over your nose. - Emergency descent.

Mayday, Mayday.

Brace for impact!

I think I lost one.

Investigation started on the tragedy.

He's going to crash!

NARRATOR: London's Heathrow Airport,

Beeline 548 requesting start.

NARRATOR: The crew of British European Airways Flight 548

is completing final preparations for an afternoon

flight to Brussels.

Looks like the weather is going

to give us a bumpy ride today.

Beeline 548 cleared for start.

NARRATOR: Captain Stanley Key was

supposed to have today off, but was

called in at the last minute.

Key is a former Royal Air Force pilot and one of the airline's

most qualified captains.

Starter master.

On.

Captain Key had been on the aircraft for a long time.

So he's very experienced.

And if you expected to fly with him,

you expected to fly to the book and to do

it accurately with no arguing.

NARRATOR: Many of the 112 passengers

are business travelers taking advantage of BEA's

rapid service to Brussels.

The jet-powered Trident can make

the trip in just 45 minutes.

COLIN WRIGHT: The Trident was really

competition for the propeller and the turboprop aircraft,

which were much slower.

So you now had an aircraft which was fast,

it flew above the weather, and it was halving the time

to European destinations, which is

an enormous economic advantage to the airline.

NARRATOR: It takes three pilots to fly the plane.

Droops down.

NARRATOR: Jeremy Keighley is the co-pilot.

Flaps 20.

Simon Ticehurst will help monitor the instruments.

Engine one start.

Engine one start.

COLIN WRIGHT: It was an immensely popular

airplane because it was the equivalent

of having a sports car.

It had terrific performance.

It had very powerful controls, which were all hydraulic.

It was a delight to fly once you got used to it.

NARRATOR: Today's flight is getting off to a slow start.

The airline has told the crew to wait for

some last minute passengers.

Another flight crew needs a ride to Brussels.

Have a seat, captain.

COLIN WRIGHT: It was over 30 years

difference between Captain Key and the two

other members of his crew.

And this produces the natural differences

you have between a generation.

One regards the other as old and stuffy, and then

one who regard the youngsters as being

young and irresponsible.

This produced a generational gap.

Beeline 548 ready for takeoff.

TRAFFIC CONTROLLER: Beeline 548 clear for takeoff.

548.

NARRATOR: The captain calls for takeoff power.

Maximum thrust.

NARRATOR: The Trident gets its name

from its three rear-mounted Rolls-Royce engines.

Second officer Ticehurst monitors the plane's speed.

100 knots.

NARRATOR: They can't lift off until they reach

rotation speed, 139 knots.

Stopwatch on.

NARRATOR: Meanwhile, Keighley keeps a close eye on the time.

It's part of a special procedure

designed to minimize aircraft noise over populated areas.

It's a very noisy engine with a particularly

nasty crackle to it.

So noise abatement would be an issue wherever it flew.

Rotate.

NARRATOR: Once they've gained enough altitude,

they'll have to throttle back slightly to reduce

the noise of the engines.

They've got to adjust the power, i.e.

reduce it just when it would be really rather nice to keep

the full power on, but they've got to reduce it

for noise abatement reasons.

NARRATOR: Officials at the airport measure the noise

level after 90 seconds.

If the pilots get it wrong, it'll go on their record.

The pressure on you is to do it quickly

and to do it accurately.

Undercarriage up.

60 seconds.

NARRATOR: As the plane climbs, passengers

are rocked by turbulence.

It was a gusty day.

And gusty days give you a bumpy ride.

Left, heading 145.

Heading 145.

NARRATOR: The plane's flight plan

calls for a left turn just after takeoff, taking

it east of the town of Staines before it

flies on to Brussels.

Beeline 548 climbing as cleared.

TRAFFIC CONTROLLER: 548 airborne at 09.

Good day.

Roger.

NARRATOR: Keighley prepares to throttle back the engines.

If he does it too soon, the plane won't

have enough power to climb.

JEREMY KEIGHLEY: 75 seconds.

NARRATOR: He'll have just 5 seconds to get it right.

There is a lag in the time that the engines

take to respond to that.

And on occasions, you can actually reduce the power

by more than you intended.

And it would take a while to actually

get the engines to settle.

85 seconds.

90 seconds.

NARRATOR: Keighley reduces power just in time.

Passing 1,500 feet.

NARRATOR: The procedure goes well.

TRAFFIC CONTROLLER: 548 climbed to flight level 60.

Squawk 6615.

NARRATOR: The tower clears them to a higher altitude.

Up to 60.

NARRATOR: Then--

What was that?

NARRATOR: --the plane begins to lose altitude.

Look at the speed!

Look at the speed!

COLIN WRIGHT: The air speed dropped quite rapidly.

It was in a very high rate of descent.

They were just passengers in their own aircraft.

NARRATOR: The plane has crashed in an empty field just yards

from the town of Staines.

I was at home with my baby of 12 weeks,

and I heard a very loud thump.

NARRATOR: Local resident Frances Castledine

leaves her infant son with a neighbor

and rushes to the crash site.

If it had gone another 50 yards,

it would have hit the center of Staines with the shops

and the houses there.

NARRATOR: Frances is a nurse.

She immediately begins searching

the wreckage for survivors.

I was very much afraid there was

going to be a fire because the vapor

was very heavy in the air.

And I had to decide, basically, whether I was going to go back

home to my baby or whether I was

going to go forward and help.

But I had had a lot of intensive training

in the accident and emergency department,

and I really felt that I needed to be there.

NARRATOR: Nearly everyone is dead,

but Frances is able to help one survivor.

Can you hear me?

FRANCES CASTLEDINE: I did my best.

I did what I could.

Can you hear me?

I manipulated his legs and put them into some wreckage

splints with some bandages.

You are going to be OK.

Hey!

Hey!

Help is on the way.

NARRATOR: The man's injuries are too severe.

Despite her quick response, he dies.

FRANCES CASTLEDINE: It just was so tragic that there

wasn't anyone who survived.

NARRATOR: All 118 people aboard BEA Flight 548 are killed

DAVID LEARMOUNT: This accident was pretty horrifying

because it was the worst airline accident that Britain

had ever experienced and BEA was reckoned in those days

to be the kind of airline that just didn't have crashes.

And this time, they did.

REPORTER: Flight BE 548 en route to Belgium crashes

in a field not far from Heathrow

and only a few feet from houses in the main road.

NARRATOR: News that a plane crashed and narrowly

missed the town of Staines is soon the top story

across the country.

Within an hour, the news reaches Chris Pollard,

a new investigator with Britain's Accidents

Investigation Branch.

CHRIS POLLARD: At the time that I arrived on the site,

the rescue attempt had started big time

and the site was very, very active with people.

NARRATOR: Investigators are struck by something unusual.

In most accidents, momentum carries the wreckage forward

after it hits the ground.

The crash at Staines is different.

CHRIS POLLARD: The tail had not moved

very far from where it had initially struck the ground.

And the rest of the aircraft probably hadn't moved forward

more than about 50 yards, which for such a heavy aeroplane

is very, very little distance.

NARRATOR: Nearby, power lines tell part of the story.

CHRIS POLLARD: The older investigators, they

were pointing out the power lines, which

it had passed over very, very shortly

before the first impact point.

PETER COOMBS: If you walked around the back of the remains

of the tail unit, you could look backwards and upwards,

and there were overhead high tension cables.

This told you really that the aircraft must have been coming

down at a very steep angle in order

not to interfere with the cables.

NARRATOR: The undamaged wires and compact crash zone

tell investigators that the plane fell to the ground

suddenly and steeply.

It's a sure sign that the plane stalled.

DAVID LEARMOUNT: An aircraft stalls

when it's flying too slowly to generate

sufficient wind over the wings to give it lift.

When that aircraft hit the ground,

it was actually slightly nose up.

It was falling through the sky like that.

All the sort of basic impact signs

were that the aircraft was stalled.

The first question is, why?

NARRATOR: An airplane can stall for many different reasons

from engine failure to pilot error.

Pollard studies the wreckage in search of the specific reason

for the stall.

Every piece of debris is a potential clue.

CHRIS POLLARD: You may come across something

which-- which is unexpected.

At which point, you have to try to explain it.

It may prove to be a red herring.

It may prove to be something crucial.

How you do the salvage actually very much

influences how easy you make things for yourself.

Hang on, will you?

You can by careless salvage make things incredibly

difficult for yourself.

NARRATOR: There's another challenge.

In 1972, planes in the United Kingdom

are not required to carry cockpit voice recorders.

GRAHAM BRAITHWAITE: The modern investigator

is helped enormously in so many accident situations

where a cockpit voice recorder is present because it really

does help you understand what was

going on in the flight deck.

I think we forget how difficult this

must have been to investigate.

NARRATOR: Investigators will only

have the information from the Trident's flight recorders.

It will take time to recover and process that data.

The rest of the debris is carefully

labeled and sent to AAIB headquarters in Farnborough.

All this has to get back to the hangar.

NARRATOR: There the plane will be put back

together like a jigsaw puzzle, a process

that could take months.

PETER COOMBS: Following an impact of this sort,

everything is comprehensively wrecked and jumbled up,

and most of the components on the aircraft,

particularly the electronic components, all

look very similar.

NARRATOR: The team has no time to lose.

If there's a problem with the Trident,

investigators need to know as soon as possible.

There is enormous pressure to find the cause of the crash.

DAVID LEARMOUNT: You have to recognize

that the Trident was a completely British-built

and British-engined aeroplane.

Therefore, for British industry,

it was very important that if there

was anything wrong with the Trident,

it should be found out and corrected.

GRAHAM BRAITHWAITE: It's usually

a very complex picture drawn painstakingly

over months, sometimes years.

And so the pressure to find the answer

can be quite significant.

NARRATOR: The weather could provide an early lead.

COLIN WRIGHT: There was a cold front about 30 miles away.

And at the airport at the time, there was low cloud

at about 1,000 feet--

And the carriage up.

COLIN WRIGHT: --and there was moderate turbulence,

which would vary rather like driving

a car over a rough road.

NARRATOR: In bad weather, storm clouds sometimes create

powerful columns of air that can

force a plane to the ground.

PETER COOMBS: Extreme wind shear or something of

that sort can lead to a stall.

NARRATOR: Planes are especially vulnerable during takeoff.

They're so close to the ground that pilots have little time

to recover from the problem.

DAVID LEARMOUNT: The aircraft had only just taken off

and it was still pretty low.

If a stall like this had happened at multiple thousands

of feet, there would have been plenty of time

to recognize what the problem was

and to do something about it.

NARRATOR: Investigators need to just how severe

the weather conditions were at Heathrow

when the Trident took off.

The AAIB receives detailed meteorological reports

from the day of the crash.

They reveal that the turbulence simply

wasn't strong enough to knock a plane out of the sky.

PETER COOMBS: There was no wind shear.

There was nothing excessive in the weather.

And certainly, it would have to be

very extreme to contribute to a stall

at that phase in the flight.

NARRATOR: Meanwhile, investigators

turn their attention to the preliminary information

captured on the Trident's black box.

PETER COOMBS: The amount of recording on the Trident

was the greatest amount of any airliner

I was aware of at that time.

It was very much state of the art.

NARRATOR: They focus on engine data, searching for any sign

that the engines flamed out or lost power.

A sudden loss of thrust could explain why the aircraft

stalled, but the data shows the engines

were working perfectly.

The Trident had climbed with enough thrust

to maintain a safe speed.

PETER COOMBS: With regard to the engines,

we were quite satisfied that there was no evidence

of a gross loss of thrust.

NARRATOR: Engine failure did not bring down Flight 548.

DAVID LEARMOUNT: The stall happened very suddenly

during a normal climb.

The speed, although it was a bit lower than it should have

been, it was not dramatically, though,

lower than it should have been.

It should not have led to a stall.

NARRATOR: At AAIB headquarters, engineers piece together

the wreckage of Flight 548.

CHRIS POLLARD: When you do a reconstruction

for investigation, the best technique

is to try to lay the wreckage out in-- in plan form

so that in essence you know automatically if you're

looking for-- for a particular bit,

you know where to go for it.

NARRATOR: By testing the reassembled systems,

investigators should be able to tell if there is

a broken part or faulty mechanism that

could have caused the stall.

PETER COOMBS: By reconstructing the aircraft,

it's possible to untangle flying control

cables and hydraulic pipes and identify

whether there are any failures that preceded the impact.

NARRATOR: They soon notice a problem.

That can't be right.

NARRATOR: A lever is set to an unexpected position.

It's used to operate crucial lift devices

on the wing known as droops.

It could be seen that the droop lever

was in the retracted position.

NARRATOR: Droops are aerodynamic surfaces

that can be extended from the front of the wing.

They increase lift during takeoff

to help the plane climb.

The front section of the wing was hydraulically powered

and would lean and droop forward

to give an extra curvature of the wing.

And at lower speed, that would give you extra lift.

NARRATOR: Droops should only be retracted

once the plane has enough speed to maintain lift without them.

If one of the pilots pulled in the droops too early,

it would have instantly put the plane into a dangerous stall.

The discovery baffles investigators.

PETER COOMBS: How on Earth did somebody

manage to retract the droop lever and nobody noticed

that that had happened?

And it didn't make a lot of sense.

NARRATOR: There's no way to tell just

by looking at the droop lever whether the crew moved it

before the crash or if it was jostled out

of place by the crash itself.

It might even have been moved during recovery operations.

Hang on, will you?

We had the whole-- the droop system laid out on tables

in front of the wing.

NARRATOR: To determine how the all-important lever was last

moved, Pollard must carefully examine

the cables connected to it.

The droop lever operated a cable system which went down

to the drive motor and selected a position, which the drive

motor would drive to.

Retracted.

DAVID LEARMOUNT: They determined by an examination

of the wreckage that the droops had been retracted at impact.

NARRATOR: There's no longer any doubt, someone in the cockpit

moved the droop lever.

It's a troubling discovery.

PETER COOMBS: As the awareness develops that there had been

incorrect operation of the droop lever,

the inevitable question arose, well, who had operated it?

NARRATOR: The deadliest aviation

accident ever to occur on British soil

was caused by pilot error.

This prompts urgent questions about the mental and physical

state of the crew.

DAVID LEARMOUNT: Autopsies are always done on flight crews

if they don't survive an accident.

A very simple thing is they want to find out

whether there was any alcohol or drugs

in the blood of the pilots.

NARRATOR: While pathologists search for a physical cause--

Put up the personnel records, will you?

NARRATOR: --investigators focus their attention

on the pilot's history.

GRAHAM BRAITHWAITE: The technical investigation

at Staines had to rule out technical causes

of the accident.

And when it had done that, it really

needed to look at the performance of the crew,

why did they do what they did or why did they not do what

they may have done on the day?

So--

NARRATOR: They study the captain's previous flights.

He has an impeccable reputation.

GRAHAM BRAITHWAITE: Captain Key was a very

experienced Trident pilot.

He had over 4,000 hours, and he was an experienced captain

as well.

NARRATOR: His takeoffs from Heathrow

are almost always flawless.

Undercarriage up.

NARRATOR: But on the day of the crash,

he does things differently.

Let me see those air speeds from the day of the crash.

Thanks.

Beeline 548 climbing is cleared.

TRAFFIC CONTROLLER: 548 airborne at 09.

Good day.

Roger.

NARRATOR: As he flew out of Heathrow,

Key was flying the Trident a bit slower than usual.

DAVID LEARMOUNT: On this occasion,

from almost immediately after takeoff

until the accident had occurred itself,

there was a noted disparity between the speed that he

should have been aiming at and the speeds that he

was actually achieving.

NARRATOR: It's an intriguing clue.

This is not the way Captain Key usually ascends after takeoff.

COLIN WRIGHT: The performance at low speed

was quite critical.

The aircraft relies on its speed to provide lift.

That means, particularly close to the ground,

it has to be flown very accurately.

Put up the photo of Key.

DAVID LEARMOUNT: Key's normal performance came up

to normal standards, but this on the day

was well below standard.

So they looked for reasons why this might be so.

Now the tray table from the wreckage.

NARRATOR: A piece of wreckage points

to a possible explanation.

In the sort of engineer's area,

there was a little table.

And on that table, there was some graffiti scribbled

which gave a few rather facetious comments,

obviously, from a pilot who'd been sitting in that position.

Bloody fools.

COLIN WRIGHT: It said, key must go,

and then a few other derogatory comments added as well.

Could you hand me the photograph?

Thank you.

NARRATOR: A note I found in the cockpit hints

that the crew wasn't getting along.

Perhaps a poisonous atmosphere inside the cockpit

made it difficult for the pilots to do their job.

Lights up.

GRAHAM BRAITHWAITE: Investigators looking

for any kind of clue that tells you

about perhaps the atmosphere within the airline

or within the crew on the day.

Could you get this over to handwriting analysis for

me, please?

GRAHAM BRAITHWAITE: Was it particularly tense?

Was it particularly aggressive?

And these are small factors that

might give a clue to that.

NARRATOR: If handwriting analysis can identify who

wrote the note, investigators may be one step closer

to understanding what really happened in the cockpit of BEA

Flight 548.

Investigators interview other BEA pilots to find out all

they can about Captain Stanley Key and his crew.

I hear you're someone we should talk to.

Yeah, I need to tell you what happened.

NARRATOR: Pilots at British European Airways

are on the verge of a strike.

Captain Key is seen by many as a company man.

COLIN WRIGHT: There was a work-to-rule going on.

Most of the co-pilots, which included me, working to rule,

and he thoroughly disapproved of this as not being

a professional way to behave.

I was leading a campaign against it.

NARRATOR: According to witnesses,

things came to a head 90 minutes

before the flight to Brussels.

I'd say it was just a couple of hours before the flight

when it all happened.

Captain Key, may the battle start and go our the way.

What did you say?

I-- I just meant that--

You know that during the war we flew in real battles?

Captain Key was very, very angry.

He felt very passionate this strike should not go ahead.

Acting like some selfish, pampered, immature crybabies

making a lot of ridiculous demands.

Look here, just because your lot flew in the war--

And as for your refusal to--

Witnesses describing captain Key's outburst

at this other pilot described it as being just exactly that.

It was a real outburst, a tirade.

You ungrateful bastard!

If you're flying that plane for money,

then you're in the wrong profession.

I think we better agree to disagree.

Bunch of fools.

NARRATOR: The argument is so severe that investigators

consider an unusual theory, that the captain's

agitation interfered with his ability to fly the plane.

Bloody fools.

TRAFFIC CONTROLLER: 548 climb to flight level 60.

Squawk 6615.

NARRATOR: Distracted and angry--

Up to 60.

NARRATOR: --he might have pulled the droop

handle without thinking.

The multiple warnings would have added to his confusion.

If you go from what is apparently a normal flight

into something which is seriously dangerous,

it will produce a shock response.

And that means your ability to think clearly

and to act decisively is very difficult.

When we've got that cued up, let me listen to it,

will you, please?

Thanks.

NARRATOR: Although the Trident is not equipped with a cockpit

voice recorder--

STANLEY KEY (ON SPEAKER): Beeline 548 ready for takeoff.

NARRATOR: --the captain's conversations with air

traffic control are recorded.

TRAFFIC CONTROLLER: Beeline 548 clear for takeoff, 28 right.

STANLEY KEY (ON SPEAKER): 548.

GRAHAM BRAITHWAITE: The human performance investigator

is trying to understand a simple thing, what

was going through the mind of the crew

at the time of the accident?

Why did what happen make sense to them at the time?

STANLEY KEY (ON SPEAKER): Beeline 548

climbing as cleared.

TRAFFIC CONTROLLER: 548 airborne at 09.

Good day.

STANLEY KEY (ON SPEAKER): Roger.

NARRATOR: They immediately notice something unusual.

Captain seems awfully quiet.

TRAFFIC CONTROLLER: 548 climb to flight level 60.

Squawk 6615.

STANLEY KEY (ON SPEAKER): Up to 60.

NARRATOR: The captain's infrequent

radio calls are so short they don't

even meet aviation standards.

COLIN WRIGHT: For a proper response, if you are given

a clearance, you have to repeat it back with a course

on of the aircraft.

That was all missing.

NARRATOR: Inadequate responses are out of character

for this strict captain.

DAVID LEARMOUNT: With hindsight, you and I

might make a judgment about the way Captain Key was feeling

at the time, that he felt he was under stress or very busy

or having to concentrate very hard or maybe all of those.

NARRATOR: The conversation with the controller

provides no hint about why the captain is stressed.

Investigators are left with yet another question.

What was going on in that cockpit?

GRAHAM BRAITHWAITE: Stress takes many forms.

It can be physical stress, or it

can be anxiety perhaps caused by, well,

in this case, an argument.

All of those things will add workload to our brains

and reduce our ability to deal with things.

NARRATOR: Results from the handwriting analysis are in.

These are similar C's on the BRAC and on the license.

NARRATOR: Discovering who wrote the note in the cockpit

could be the break investigators need.

Experts find that the handwriting

sample is similar to the co-pilot's, but it's

not a match.

DAVID LEARMOUNT: They never positively identify

the handwriting and the graffiti

as definitely being one of the pilots who was in that crew.

NARRATOR: It's another dead end.

Investigators are no closer to understanding why BEA

Flight 548 ended in tragedy.

All right, could you show me some of the switches

on the Trident here?

NARRATOR: Desperate for leads, they travel to BEA's flight

simulator outside London.

The team hears about a nagging problem for pilots

of the Trident plane.

The handle used to retract the droops

is nearly the same shape as the one used to adjust the flaps.

I can see why you confuse them.

COLIN WRIGHT: One has to bear in mind that it's being moved

by the palm of the hand and it's not easy to identify one

from another.

Beeline 548 climbing as cleared.

NARRATOR: It's the co-pilot who's supposed to raise

the flaps after takeoff.

TRAFFIC CONTROLLER: 548 airborne at 09.

Good day.

Roger.

NARRATOR: But the third pilot sometimes helps out.

85 seconds.

NARRATOR: The noise abatement procedure

added to the pressure.

If the flaps were already up, it

would be all too easy to pull in the droops instead.

DAVID LEARMOUNT: There were circumstances under which it

would be possible, quite easily,

to retract the droops early, and that

could be catastrophic.

NARRATOR: If their theory is right,

investigators should be able to find other cases where

pilots made the same mistake.

The team reviews the flight records from nearly

100 other Trident flights.

It's not just this crew.

NARRATOR: They find two near accidents where pilots pulled

in the droops by mistake.

It's suddenly beginning to look like the captain's argument

in the crew room had nothing to do with the accident.

Poor design may be the real cause.

Then comes news that puts investigators

on an entirely new path.

DAVID LEARMOUNT: In Captain Key's

routine medical examinations before this,

nothing was reckoned to be wrong with his health.

It was only after the accident when an autopsy was carried

out that it was found that he actually had

some severe coronary problems.

PETER COOMBS: There was medical evidence

showing that the captain suffered of a heart condition.

It seemed to be the missing link.

NARRATOR: Although the captain's heart problem did

not show up in his regular medical exams,

he had a deadly heart condition.

Now, as you can see--

DAVID LEARMOUNT: Key had, without even knowing it,

a clogging of the coronary arteries.

This in turn caused the heart attack.

What did you say?

Do you realize that during the war we flew in real battles?

Acting like some pampered, crybaby--

NARRATOR: Pathologists believe that Captain Key suffered

heart failure sometime within a 2-hour window

before the crash.

Totally unprofessional.

NARRATOR: It may have been caused by a sudden rise

in blood pressure.

You ungrateful bastard!

GRAHAM BRAITHWAITE: Captain Key may not

have had symptoms of a heart condition prior

to the accident, but following a stressful event, perhaps

after the argument, it seems to have started

to have an effect on him.

Bloody fools!

NARRATOR: The theory could help explain the captain's

unusual radio calls.

TRAFFIC CONTROLLER: Beeline 548 clear for takeoff.

STANLEY KEY (ON SPEAKER): 548.

TRAFFIC CONTROLLER: 548 climb to flight level 60.

Squawk 6615.

Up to 60.

NARRATOR: If Captain Key was in enough pain,

he would have kept his replies as short as possible.

His discomfort might even explain why the droop

lever was pulled too soon.

PETER COOMBS: His level of pain would have increased over

the period up to a point where he would have become partly

or totally incapacitated.

GRAHAM BRAITHWAITE: Anything from what

may feel like heartburn or indigestion

through to a violent pain close to death.

If you're flying that plane for the money,

then you're in the wrong profession.

NARRATOR: Finally, investigators

have a possible explanation for what happened

in the cockpit of Flight 548.

Bunch of fools.

DAVID LEARMOUNT: If his blood pressure was particularly high

because he was agitated, it might affect his reasoning,

because if you have the oxygen level in your brain reduced,

even slightly, it affects your alertness and your ability

to reason.

And the accident investigators reckoned that that may well

have been so in this case.

Right, so we have to comb through all the information.

NARRATOR: There's still a nagging question.

There were other qualified pilots

in the cockpit that day.

Why didn't one of them do something to save the plane?

The second captain seated in the back

was too far from the controls to be of any help,

but the two co-pilots could have responded to the crisis.

DAVID LEARMOUNT: Neither Captain Key

nor the other pilots realized that it was the retraction

of the droop which had caused the stall

because nobody attempted to put it back down again.

If they had done, they could have uninstalled the airplane.

Jeremy Keighley.

NARRATOR: Crew records provide a possible explanation.

22.

NARRATOR: Because of the labor dispute at the airline--

Age 22.

NARRATOR: --pilot training had been disrupted.

Both the co-pilots on Flight 548 were very inexperienced.

What was that?

GRAHAM BRAITHWAITE: In the right hand seat,

his first officer had less than 30 hours of experience

on the Trident.

COLIN WRIGHT: There's obviously some opinion

that these pilots were too young,

they needed more experience.

NARRATOR: The junior pilots may have been distracted by having

a guest in the cockpit or they may have

simply not known what to do.

Investigators believe there's yet

another piece to the puzzle.

It all comes back to that argument.

Pampered crybabies making a lot of ridiculous demands.

Look here, just because your lot flew the war--

And as for your refusal to fulfill all of your duties--

NARRATOR: Investigators learn that an hour

and a half before takeoff co-pilot Jeremy Keighley

witnessed Key's outburst.

If you're flying that plane for money,

you're in the wrong profession.

NARRATOR: They suspect it made a big impact

on the young pilot.

COLIN WRIGHT: Having witnessed an outburst like that,

one can only surmise that if you are new to the fleet,

you don't know the captain, you're

slightly unconfident yourself.

You may be nervous of your own performance.

This is not likely to enhance it.

And I would expect it would have been quite intimidating.

NARRATOR: Shaken by his captain's temper--

Bunch of fools!

NARRATOR: --Keighley may have been

more likely to make mistakes and less likely to correct

his captain's errors.

DAVID LEARMOUNT: It would certainly

reinforce the concept that the captain was authoritarian

and not somebody that you should challenge lightly,

especially on that day.

NARRATOR: There is yet another mystery.

Investigators know that the Trident

is equipped with a safety system

known as a stick shaker.

If the plane's speed drops too low,

the control column begins to shake,

giving the crew a dramatic warning that their plane

is about to stall.

PETER COOMBS: It will shake the column very distinctly

and produce an unmistakable rattling

noise at the same time.

NARRATOR: Pilots are trained to react to the stick shaker

by pushing the nose of the plane down to gain speed

and increase lift.

If that doesn't work, the system has

a failsafe, the stick pusher.

It will move the controls forward to push the nose

down even if the pilots don't.

COLIN WRIGHT: The pusher will make sure

that firmly the aircraft's nose was lowered

into an altitude where the speed would increase

and you would recover.

NARRATOR: Why didn't the system prevent

Flight 548 from stalling and save the lives of everyone

on board?

Investigators study flight data from BEA Flight 548,

searching for any sign that the plane's

anti-stall system failed.

So it looks as though it came on here and here

but didn't stay on.

NARRATOR: The data shows that the stick pusher did engage,

but it didn't stay on long enough to prevent the crash.

The finding can be explained in only one of two ways,

either the stick pusher malfunctioned or the crew

disabled it.

PETER COOMBS: The stall recovery system

was capable of being inhibited if they

concluded that the thing was operating incorrectly.

NARRATOR: To figure out what actually happened,

engineer Peter Coombs has to test

every electrical connection in the system.

PETER COOMBS: Fortunately, the incident sensors had actually

survived the accident in an apparently undamaged state,

and there were a number of other components

to the system.

And they were tested and found to be operating accurately.

NARRATOR: Coombs' test results point

to a stunning conclusion.

The plane's anti-stall system was working perfectly,

but for some reason, perhaps because they didn't think

their plane was actually stalling, one of the pilots

disabled it.

DAVID LEARMOUNT: By pulling out the stick pusher, by disabling

it, they took away the natural stall recovery of the airplane

and took the aircraft back into the stall.

And after that, they were doomed

because the aircraft didn't have enough height left

to recover from the stall.

NARRATOR: It now seems the crash of BEA Flight 548

was the result of a tragic combination of factors.

First, a looming strike that led to an argument.

Bunch of crybabies making a lot of ridiculous demands.

Look here, just because your--

And as for your refusal to fulfil--

NARRATOR: A heart failure that was possibly

triggered by the fight, confusion over control levers,

and co-pilots too junior or too intimidated to step in when

things started to go wrong.

For investigators, each piece of the chain

is as important as the other.

GRAHAM BRAITHWAITE: Trying to solve something that-- that's

enormously complex, there's likely to be lots

of small factors that influence any accident,

no one simple thing.

NARRATOR: After the crash, authorities

implemented a number of changes designed

to prevent similar accidents from happening again.

Handles on the Trident and other planes

are redesigned to eliminate the possibility of confusion.

Cockpit voice recorders are now standard equipment

in almost all commercial passenger planes.

Somebody-- and we're never quite sure

who it was among the crew, somebody

retracted the droops early.

And the conclusion of the investigators in this case

is that they could more likely have determined who was doing

what in the cockpit if they had been

able to judge what the pilots were saying to each other.

NARRATOR: Cockpit voice recorders

provide a major source of information for nearly

every crash, but some experts don't think

the recorders are enough.

PETER COOMBS: Listening to a cockpit voice recorder

rather resembles watching a television program

with the picture switched off.

It's quite difficult to work out what's going on.

And on a flight deck, a lot of communication is by gesture.

DAVID LEARMOUNT: One of the recommendations for flight

decks now to help investigators is that there

should be permanent filming of what

happens on the flight deck.

It doesn't have to be widescreen filming which shows

what the pilots are doing and how they're drinking

their coffee, but literally a narrow focus lens which looks

at the controls that they handle

and all the flight instruments.

NARRATOR: So far, there are no legal requirements

for the new technology, but some aviation

authorities promote the voluntary use

of cockpit image recorders.

In the years following the crash,

Hawker Siddeley faced growing competition

from rival manufacturers.

Trident production ended in 1978.

DAVID LEARMOUNT: It was being challenged by the Boeing 727,

which had a similar layout, three engines in the tail,

and in some respects had slightly superior performance.

NARRATOR: But the legacy of the Staines disaster lives on.

PETER COOMBS: The accident drew into perspective

the whole importance of human factors on the flight deck.

Bloody fools.

DAVID LEARMOUNT: Nowadays, the way

that crews interact together is taken

very much more seriously.

COLIN WRIGHT: The modern airline is operated

very, very differently.

The way the crews handle things is improved.

It's a much better and safer world.

The regret is we've had to build

it on the death of 118 people.