Original subtitles

[dramatic music]

Mayday, mayday, engine flameout.

NARRATOR: A dash cam video captures the last moments

of a horrific plane crash.

A minor flight issue--

[alarm beeping]

Right engine oil pressure.

NARRATOR: --turns into a crisis.

PAUL STASSEN: Gerrit, Gerrit.

TODD CURTIS: There was several places where the airplane

could have been saved.

Fire.

NARRATOR: A revolutionary new aircraft breaks

up during a critical flight.

Three tragedies caused by fateful decisions

made in the heat of the moment.

JOHN NANCE: The tendency is always, let's solve

the problem right this minute.

And we've lost a lot of airplanes that way.

FLIGHT ATTENDANT: Ladies and gentlemen,

we are starting our approach.

LIU TZE-CHUNG: We lost both engines.

WOMAN 1: The last--

emergency descend.

WOMAN 2: Brace for impact.

MAN: It's going to crush.

[explosion booming]

[calm music]

NARRATOR: Taipei, capital city of Taiwan.

Near its center lies Songshan Airport.

The next plane scheduled for departure this morning

is TransAsia Flight 235.

The first officer is Liu Tze-chung.

He has almost 7,000 hours of flying time.

Oil pressure.

Check.

NARRATOR: The captain, Liao Chien-tsung,

is a former military pilot.

A third pilot is observing today's flight.

TransAsia 235 is a one hour commuter flight from Taipei

to the Taiwanese island of Kinmen,

just off the coast of mainland China.

TransAsia 235, runway 10, wind 100 degree, nine are not,

cleared for takeoff.

LIAO CHIEN-TSUNG: OK, cleared for takeoff.

[engine accelerating]

NARRATOR: Immediately after takeoff, the captain

engages the autopilot.

Gear up.

LIU TZE-CHUNG: Gear up.

NARRATOR: Flight 235 climbs over metropolitan Taipei,

home to more than seven million people.

Seconds later, the Master Warning sounds.

The Master Warning is indicative of an emergency

situation requiring an immediate response.

NARRATOR: TransAsia 235 has lost an engine.

The captain disengages the autopilot.

I have control.

You have control.

Heading mode?

NARRATOR: He needs a heading back to the airport.

Below 2,500 feet.

Turn to heading, it's--

Come on!

Zero, zero niner five.

Check.

PETER RENSHAW: When you lose an engine in a twin engine

aircraft, you need to be able to maintain

your client performance.

LIU TZE-CHUNG: OK, engine flameout check.

Check.

NARRATOR: The speed and climb rate are dropping fast.

Watch the speed.

STALL WARNING: Stall, stall, stall.

NARRATOR: The Stall Warning indicates the plane is flying

too slowly to maintain lift.

PETER RENSHAW: The Stall Warning at low altitudes,

a critical situation that no pilot ever wants to end up in.

Terrain ahead.

LIU TZE-CHUNG: Tower, TransAsia 235.

Mayday, mayday, engine flameout.

[suspenseful music]

Engine flameout, both sides.

HUNG PING-CHUNG: How is this possible?

PETER RENSHAW: The crew was surrounded by high density

housing, high rise apartment blocks,

a heavily populated area.

Impact, brace for impact!

Oh, no!

LIU TZE-CHUNG: Oh.

Oh no!

STALL WARNING: Pull up.

[plane crashing]

[mournful music]

NARRATOR: TransAsia flight 235 has

gone down in the Keelung River.

Suspend all takeoff and landing operations.

Begin emergency procedures.

NARRATOR: Rescuers rushed to the scene.

[helicopter blades whirring]

Of the 58 people on board, only 15 make it out alive.

All three pilots are dead.

[investigative music]

Investigators from Taiwan's Aviation Safety Council

need to start collecting evidence at the scene.

But even before they leave headquarters--

INVESTIGATOR 1: Take a look at this.

NARRATOR: --a stunning piece of evidence from a dashboard

camera surfaces.

What?

What was happening on that plane?

INVESTIGATOR 1: What do you think?

Left engine?

When we watched the video clip,

we know there's something wrong about the engine.

The prop seems very slow.

Is this the left engine?

Uh, yes.

NARRATOR: Investigators can see in the dash cam video

that the plane was banked steeply to the left.

A faulty left engine is the most likely suspect.

But the recovered engine shows no sign of a fault.

Left engine completely operational.

Ah, strange.

NARRATOR: When they study the right engine, what they find

is equally mystifying.

Look at the blades.

They're feathered.

NARRATOR: Feathered is a propeller's fail safe position.

When a propeller engine loses power in flight,

the blades automatically rotate parallel to the airstream

to reduce drag and allow the plane

to operate with one engine.

Why would the right engine be feathered

when the dash cam video clearly shows

the plane banking to the left?

It doesn't make any sense.

Let's have a look.

When we discover a feathered of the propeller,

we know there should be something

wrong about the engine.

NARRATOR: But their inspection shows the right engine

is also in working condition.

If both engines were operational,

why did this plane crash?

[suspenseful music]

NARRATOR: Investigators hope the plane's flight data recorder,

which records dozens of flight parameters, can tell them more.

But all data points indicate the plane was operating

normally, except for one.

Take a look at this.

The torque is all over the place.

NARRATOR: Torque is the twisting rotational

force created by the engine.

It increases and decreases during specific phases

of flight, but it's not supposed to fluctuate

in such rapid bursts.

Why is it doing that?

NARRATOR: They dig deeper, studying

how the Pratt & Whitney engine measures torque.

THOMAS WANG: So we try to find out the design

logic for the system.

What's the connection between the torque

and the feather propellers?

NARRATOR: They learned that the engine's

auto feathering system includes an electronic torque sensor.

It measures how much rotational force the engine is producing.

An extremely low torque reading indicates

that the engine has failed and triggers automatic feathering.

But investigators have already concluded

the engine was operational.

They need to find the reason incorrect torque

readings would cause the right engine to feather.

Maybe the sensor is sending a faulty reading, triggering

the auto feathering unit.

NARRATOR: Investigators find the circuit

board from the right engine.

Took a look underneath.

NARRATOR: And look for any defects

that could have caused the propeller to feather in flight.

INVESTIGATOR 1: It's a broken solder.

NARRATOR: They discover microscopic faults

in the circuit board.

With a broken circuit board, the sensor

couldn't detect torque even though the engine

was functioning perfectly.

So the system automatically feathered the propeller.

LIU TZE-CHUNG: OK.

Engine flameout check.

Check.

NARRATOR: They now understand why the right-side propeller

feathered.

Investigators now face an even bigger mystery.

Losing thrust in the right engine

should cause a right bank, but the dash cam video clearly

shows the plane banking left.

The power lever angle.

NARRATOR: When investigators check the throttle settings

on the left or number one engine,

they make a stunning discovery.

Unbelievable.

The power of the number one engine

was gradually being reduced, reduced,

and eventually being shut off.

NARRATOR: On this ATR 72, the throttles

can only be moved by hand.

It had to have been shut down by one of the pilots.

THOMAS WANG: So we start to wondering,

why the pilot was shut down the good engine.

That's crazy.

HUNG PING-CHUNG: How is this possible?

NARRATOR: Investigators turned to the cockpit voice recording

to help explain why TransAsia flight 235 crashed

in Taipei's Keelung River.

AIR TRAFFIC CONTROLLER: TransAsia 235,

contact approach a one, one, niner decimal seven, good day.

We still have number one engine produce power normally,

but for some reason the pilot decided

to shut down the good engine.

We have to find out why.

[alarm ringing]

What's that sound?

It must be the engine Default Warning.

NARRATOR: Investigators already know

a faulty torque sensor caused the right engine

to feather and lose thrust.

This is a crucial moment.

Let's hear what they're going to do next.

LIAO CHIEN-TSUNG: I have control.

NARRATOR: Investigators hear the sound

of the autopilot turning off.

He's disengaging the autopilot.

He shouldn't be doing that.

He just made a difficult situation worse.

LIU TZE-CHUNG: OK, engine flameout check.

Check.

There's a checklist procedure on the screen.

If they follow the procedure, do everything correctly,

they should be able to fly back to land without any problem.

NARRATOR: But instead of following

the emergency checklist--

Watch the speed.

NARRATOR: --the captain does something inexplicable.

Pull back number one.

NARRATOR: Both engines are capable of producing power,

but because the right engine has feathered,

it has lost thrust behaving like a car in neutral gear.

When the captain then pulls back the left engine throttle,

he leaves himself with no thrust at all.

How could he do such a thing?

NARRATOR: The captain of Flight 235

has shut down the plane's only working engine.

No, wait a second, cross-check.

PETER RENSHAW: The pilot monitoring, to his credit,

did try to stop the pilot flying from manipulating the engine

number one power lever and he announced

he wanted to cross check.

Heading mode.

NARRATOR: But the captain interrupted the first officer

to ask for a new heading.

Come on!

LIU TZE-CHUNG: Zero, zero niner five.

LIAO CHIEN-TSUNG: Check.

PETER RENSHAW: All of a sudden they've got a dual engine

failure and the pilot monitoring I think

has been caught off guard.

And he's not really sure what's going on.

Restart the engine.

I can't restart the engine!

NARRATOR: When the captain realizes his mistake--

Oh, well, I shut off the wrong engine.

NARRATOR: --there's no time to restart the engine.

HUNG PING-CHUNG: Impact, brace for impact!

Oh, no!

[plane crashing]

NARRATOR: Investigators now have an even more

puzzling question to answer.

Why didn't the captain understand what he was doing?

[speculative music]

NARRATOR: Did taking manual control of the plane

distract the pilot from verifying which engine failed?

[alarm blaring]

LIU TZE-CHUNG: Watch the speed.

He could have been suffering from change blindness.

PETER RENSHAW: Change blindness, people are focused or fixated

on another item or area of interest

and so they miss what would be considered

a very distinguishable change in the environment,

but they don't perceive it.

[alarm blaring]

I will pull back engine one throttle.

Even when all the systems were telling him it was engine two,

his perception told him he was doing the right thing.

Change blindness.

NARRATOR: Investigators finally understand what went wrong

aboard TransAsia Flight 235.

A microscopic crack in a circuit board

disabled a sensor in the right engine,

causing the system to incorrectly determine

that the engine had failed.

This was a series of mistakes on the part of the captain.

When engine two feathered, the captain

reacted before he had properly assessed the situation.

NARRATOR: The captain should have followed a checklist.

I have control.

NARRATOR: But in the heat of the moment,

he turned off the autopilot and reduced

power in the wrong engine.

I will pull back engine one throttle.

He shut down their only working engine.

By the time he realizes, it's too late.

LIAO CHIEN-TSUNG: Restart the engine!

I can't restart the engine.

Wow, I shut off the engine.

NARRATOR: The crash of Flight 235

would be the last accident for TransAsia Airways.

In November 2016, the company went out of business.

When you talk about the TransAsia situation in Taipei,

we've got a situation there where if they had just delayed

until they had enough altitude and air speed doing anything,

they would have probably lived.

[exciting music]

Runway in sight.

NARRATOR: But sometimes when a split second decision is made--

GERRIT LIEVAAR: Steer, steer!

NARRATOR: --even a minor issue can turn deadly.

PAUL STASSEN: Gerrit!

[plane exploding]

NARRATOR: It's Easter Monday, 1994,

at Amsterdam Schiphol Airport.

Set torque.

My controls.

NARRATOR: KLM Cityhopper Flight 433

is preparing to fly from Amsterdam to Cardiff, Wales.

Torque set.

NARRATOR: Flying time is an hour and 20 minutes.

PAUL STASSEN: V1, rotate.

NARRATOR: The plane is a Saab 340B, a dual turboprop designed

for short regional flights.

The captain on Flight 433 is 37-year-old Gerrit Lievaart.

The first Officer Paul Stassen is 34.

There are 21 passengers on board.

Amsterdam KLM 433.

AIR TRAFFIC CONTROLLER: Go ahead, 433.

Is flight level 200 available?

Climb to 200.

You are recleared flight level 200.

Thank you, sir.

Climbing flight level 200, KLM 433.

NARRATOR: But on the way up to 20,000 feet.

[alarm ringing]

Right engine oil pressure.

GERRIT LIEVAAR: Check.

Take action.

Copy, taking action.

NARRATOR: First Officer Stassen consults the Engine

Oil Pressure Warning checklist.

There are several reasons where oil pressure

could drop in an engine.

Primarily due to leaks or some sort of damaging event

in the engine system.

Emergency checklist for engine and propeller oil pressure low.

NARRATOR: The checklist tells him

to monitor the Warning Light and the oil pressure gauges.

If the Warning Light is on or the gauge is below 30,

then you can continue.

But if you have both, then shut down the engine.

That's not the case.

NARRATOR: The crew decides it's safe to keep flying.

But then.

GERRIT LIEVAART: OK, we're not climbing anymore.

NARRATOR: Approaching 17,000 feet

captain Lievaart notices the plane is not climbing

as quickly as it should be.

No.

We need to return to Amsterdam, make a pan call,

request to maintain flight level 160.

Tell them we have a technical issue.

TODD CURTIS: A pan call means there is an unusual situation.

Please pay attention to us, we need extra help.

Amsterdam KLM 433, pan-pan, pan-pan, pan-pan.

We have an engine problem and we'd like to maintain

160 for return to Schiphol.

That's copy sir.

You may turn right heading to Schiphol.

KLM 433, 3 can you give me any details?

GERRIT LIEVAART: KLM 433, situation's under control.

We have an engine oil pressure problem in engine number two.

Yes, OK, we can bring you in 406, you're our number one.

NARRATOR: Five minutes later, the plane

lines up with a runway.

PAUL STASSEN: Runway in sight.

Flaps 20.

Flaps 20, out of marker.

Check.

NARRATOR: KLM 433 is just 500 feet above the ground.

Watch your speed.

NARRATOR: The plane has slowed to the point

that it could stall.

I'm on it.

NARRATOR: Suddenly the plane banks to the right.

Going around.

Set torque, flaps seven, gear up.

NARRATOR: Captain Lievaart attempts to go around.

But the plane keeps banking right.

GERRIT LIEVAART: Steer, steer, steer.

PAUL STASSEN: Gerrit, Gerrit, Gerrit!

[plane exploding]

Crash, crash, crash, runway 06, emergency, runway 06.

NARRATOR: KLM Flight 433 has crashed in a field next

to the runway.

Of the 24 people on board, two passengers and the captain

are dead.

Eight passengers and the first officer are seriously injured.

Investigators from the Netherlands Aviation Safety

Board recover the plane's black boxes

and send them off for processing.

[investigative music]

Meanwhile, lead investigator Ben Groenendijk is eager to speak

with air traffic control.

BEN GROENENDIJK: We go to the tower and approach

and we get the first information.

They issued a pan call, we're coming back to the airport.

Amsterdam KLM 433, pan-pan, pan-pan, pan-pan.

We have an engine problem and we'd like to maintain

160 for return to Schiphol.

Did they tell you what the problem was?

Yeah, they said it had to do with the oil pressure.

KLM 433, situation's under control.

We have an engine oil pressure problem in engine number two.

Next thing I knew they were going around.

Going around.

Set torque, flap seven, gear up.

NARRATOR: Pilots conduct a go around if their landing

becomes unstable.

TODD CURTIS: They increase the power, they gain altitude.

They circle around and they try a second time for that landing.

Right before the aircraft is about to touch down--

GERRIT LIEVAAR: Steer, steer.

TODD CURTIS: --the potential for danger

is much much higher than if the same problem

happened at altitude.

[plane exploding]

NARRATOR: In a hangar at Schiphol Airport

the investigators try to determine

the nature of the oil pressure problem

and if it contributed to the crash.

He could have the seizure of an engine or overheating

because the oil is not there.

Hm, turbines are moving.

NARRATOR: But curiously, they find no evidence

of any oil pressure issues.

Any damages from the impact, not from oil pressure.

NARRATOR: It seems the pilots reported

a problem that didn't exist.

Why would they report a problem

if they didn't have one?

What were they looking at?

NARRATOR: Investigators now wonder, did the cockpit

instruments on KLM Flight 433 somehow malfunction

and mislead the pilots?

[alarm ringing]

Right engine oil pressure.

Check, take action.

Copy, taking action.

NARRATOR: When investigators test the oil pressure system

one thing jumps out.

Ah, OK, there's a short circuit in the switch.

NARRATOR: Now they understand what the pilots were seeing,

a false warning.

[alarm ringing]

Right engine oil pressure.

NARRATOR: But a false warning alone

is not enough to cause a crash.

Investigators turned to the cockpit voice recorder.

OK, let's hear it.

NARRATOR: They hope it will tell them how a false warning, which

required no action, still led the pilots to turn

back to Schiphol Airport.

[alarm ringing]

There's the warning.

PAUL STASSEN: Right engine oil pressure.

Let's see how they handle it.

Check, take action.

Copy, taking action.

NARRATOR: The pilots consult an emergency checklist that should

help them solve the problem.

PAUL STASSEN: If the Warning Light is on

or the gauge is below 30, then you can continue.

TODD CURTIS: On Saab 340, the Warning

System and the Oil Measuring System

are two separate systems.

And if there is a confusion between the two,

the guidance on the emergency checklist

is to continue normal operations.

So the light is on, but we're above 30 PSI.

So--

Continue normal operation.

NARRATOR: The recording reveals that the pilots knew it was

safe to continue their flight.

Why the heck did they decide to turn back?

GERRIT LIEVAART: OK, we're not climbing anymore.

Ah.

GERRIT LIEVAART: No.

That must be why they turned back.

Engines are fine.

Why are they not climbing?

NARRATOR: Investigators now turn to the flight data recorder.

What's going on here?

Right-side engine thrust, it's dropping.

NARRATOR: It's a major discovery.

It suggests pilot error may have caused the deadly disaster.

Right here, right after the alarm goes off,

he actually pulls the power back.

All the way to idle.

NARRATOR: The captain may have been trying not

to further damage what he thought was a crippled engine

when he powered back.

And look, he keeps sitting idle for the remainder

of the flight.

Well, no wonder they couldn't climb.

Did having an idle engine cause this accident?

Let's see the data from the final approach.

NARRATOR: The data shows how the right engine being

at idle affected the landing.

At this point, they are too slow.

[suspenseful music]

Watch your speed.

I'm on it.

NARRATOR: The captain advances power to the left engine,

pushing the aircraft to the right

because the right engine isn't producing thrust.

Now at this point there's no way they're

going to make the landing.

So they have no choice but to attempt to go around.

Going around.

Set torque, flap seven, gear up.

NARRATOR: To climb, the captain pushes the left engine

to maximum power, but that only sends the plane into an even

steeper right bank.

Oh, steer, steer.

Gerrit, Gerrit, Gerrit.

[plane exploding]

INVESTIGATOR 2: What a blunder.

NARRATOR: Investigators finally understand

the sequence of events that brought

down KLM Cityhopper Flight 433.

[alarm ringing]

Right engine oil pressure.

GERRIT LIEVAAR: Check, take action.

Taking action.

NARRATOR: In the heat of the moment,

the captain reduces right engine power

before his first officer has a chance to read the checklist.

This fools them both into thinking they have an engine

problem when they don't.

KAS BEUMKES: The right power lever remained in the position

of flight idle, and I didn't discuss

the consequences of that.

Going around.

Set torque, flaps seven, gear up.

NARRATOR: Attempting a go around using just one engine

is the final mistake.

Steer, steer, steer.

Gerrit, Gerrit, Gerrit!

[plane exploding]

NARRATOR: The Netherlands Aviation Safety Board

determines that the cause of those errors

goes beyond the cockpit.

The final report recommends KLM review pilot testing

techniques, establish cockpit management training,

and improve guidance on flying with an idle engine.

There's an old adage in aviation about the level

of forgiveness of an airplane, but one of the things it's not

going to forgive is failing to do the things that are

in the checklist appropriately.

Checklists are there for a reason.

NARRATOR: It's an adage that holds for even the best pilots

in the most advanced planes.

[alarm blaring]

[calm music]

At the Mojave Air & Space Port in Southern California,

a revolutionary new aircraft is about to undertake

a test flight.

It's called SpaceshipTwo.

System booting.

NARRATOR: The spaceship is designed

by American Aerospace company Scaled

Composites for Virgin Galactic.

Showing green across the board.

Copy that.

[applause]

NARRATOR: Virgin Galactic's owner, Sir Richard Branson,

hopes this unique craft will soon carry paying customers

to the edge of space and back.

Together we can make space accessible in a way that

has only been dreamed of before now.

NARRATOR: The success of this stage of the program

rests on the shoulders of these two test pilots.

43-year-old Peter Siebold is an award-winning engineer.

He's piloted 11 different types of experimental aircraft.

His co-pilot, 39-year-old Mike Alsbury,

is also a seasoned test pilot and an aeronautical engineer.

They've spent almost nine months training for this mission.

ERIK SEEDHOUSE: These guys are test pilots,

very, very experienced pilots.

These are the best of the best of the best.

NARRATOR: The rocket powered spaceship

is suspended from a jet powered plane with a 140-foot wingspan.

The launch plane is called White Knight 2.

White Knight 2 will carry the spaceship up to 46,000 feet.

At that altitude, SpaceShipTwo will detach from the airplane,

fire its rocket motor, and climb another 100,000 feet

up into the Earth's atmosphere.

Flying four times higher than a typical commercial aircraft,

it will then glide back to Earth.

Monitoring today's flight is a flight director.

He communicates with a team of flight

engineers and the four pilots.

At 9:20 AM.

White Knight 2, you are go.

[engine accelerating]

NARRATOR: Takeoff speed is 150 knots.

Once SpaceShipTwo is released, Captain Siebold

will take the control column, while co-pilot Alsbury

monitors the instruments and configures

the craft for its descent.

You are clear to arm a time-on release.

I'll call fire.

NARRATOR: In the minutes before launch,

the pilots review the flight checklists

they've been training for months to memorize.

Can't pitch up, pitch down, trim feather unlock 1.4.

ERIK SEEDHOUSE: Things happen very, very, very quickly.

They do not have the time physically to go and pull out

the checklist and read the checklist

because these things are happening second after second

after second.

Glide trim's good, green for release.

PETER SIEBOLD: OK.

Here we go.

Stick.

Let's take us forward.

MAN 2: And 5, 4, 3, 2, 1, release.

NARRATOR: As SpaceShipTwo drops from its carry plane--

Clean release.

NARRATOR: --Mike Alsbury engages the experimental rocket motor.

MICHAEL ALSBURY: Arm.

Fire.

MICHAEL ALSBURY: Fire.

NARRATOR: 6,000 pounds of thrust propel them

towards the speed of sound.

Good light.

ERIK SEEDHOUSE: SpaceShipTwo, its top speed as close to three

Mach, so three times a speed of sound,

over 2,000 miles per hour.

Yeehaw.

ERIK SEEDHOUSE: It's a very, very rough ride.

So you think about the worst turbulence

you've been in an aircraft liner and then magnify that by 10.

It was supposed to be a 38 second burn of the engine.

NARRATOR: But just 14 seconds after ignition

something goes terribly wrong.

[alarm ringing]

SpaceShipTwo lies in pieces after breaking up

over California's Mojave desert.

Co-pilot Mike Alsbury was killed in the crash.

Amazingly, Captain Pete Siebold parachuted to safety.

He's badly injured, but alive.

Emergency responders rushed him to the hospital,

while a team from the NTSB Combs through the wreckage

spread over the Mojave Desert.

LORENDA WARD: One of the things that we were able to tell

by being on scene was that the motor was not an issue

as to why the vehicle broke up.

NARRATOR: Investigators hope the craft's external cameras

will provide vital information.

See here?

The tailbone folded in on the aircraft along the hinge

of the feather system.

It went into feather mode?

NARRATOR: Feather mode refers to the defining feature

of SpaceShipTwo's design.

The spaceship actually changes shape during flight.

After reaching maximum altitude the pilots rotate twin rudders

into the feather position to increase drag

and slow their descent.

The craft can then drop safely back into Earth's atmosphere

before gliding to a runway.

Lorenda Ward reviews the video from a cockpit camera.

So he unlocked the feather system?

Correct.

But did he actually deploy it?

No.

That's a weird thing.

No one touched the handle.

NARRATOR: There are two steps to feathering the spaceship.

First, the pilots unlock the feather system.

So the tail boom can pivot when commanded.

Second, the pilots must pull the feather handle to actually

deploy the tail boom.

LORENDA WARD: So we have the video of the copilot unlocking,

but we never see him actually operate the feathers.

But we know from external video that the feathers moved.

So we knew that we had a performance or a dynamic issue.

NARRATOR: Somehow the system designed to slow the craft

on descent deployed while the crew was accelerating

toward the speed of sound.

To learn more about the feather system,

investigators consult engineers at Scaled Composites, the firm

that designs SpaceShipTwo.

So when is supposed to unlock the feather system?

Between Mach 1.4 and 1.8.

You want to play that?

48, unlocking.

The co-pilot had actually unlocked

the feather system early.

Isn't it safer to unlock it at lower speeds?

No, ma'am.

It can be catastrophic.

ERIK SEEDHOUSE: In the transonic phase,

you get a huge amount of upward force on the tail boom,

on the tail of the spacecraft, and the feather

system was not designed to deal with that sort of load.

NARRATOR: It's a devastating discovery

that points to pilot error.

Unlocking.

NARRATOR: When co-pilot Mike Alsbury unlocked the feather

system 16 seconds early, aerodynamic forces

were so strong they pulled the tail

into the feathered position and tore the aircraft apart.

But why would a highly experienced test pilot

like Mike Alsbury, who had already carried out eight

previous flights on SpaceShipTwo,

unlock the tail boom at the deadliest possible moment?

The team pores over training materials.

We need to figure out what they were told about unlocking

the feather system early.

NARRATOR: Record show that co-pilot

Alsbury flew 112 simulator runs for this mission.

Never once did the co-pilot unlock the feather early.

Hold on now.

NARRATOR: But the records do reveal that on one occasion

he unlocked the feather too late.

12 degrees.

MICHAEL ALSBURY: Feather unlock.

14 degrees.

MICHAEL ALSBURY: Mission abort, mission abort.

LORENDA WARD: If they didn't unlock by 1.8,

they would have had to aborted the flight.

NARRATOR: Aborting a mission is not fatal,

but it could be a major setback for the program.

0.8.

NARRATOR: Investigators wonder, did this error in training

months ago lead Alsbury--

MICHAEL ALSBURY: Mission abort, mission abort.

I'll call fire.

NARRATOR: to act prematurely?

Investigators believe a time crunch

may be one reason Mike Alsbury decided to unlock

the feather system early.

Unlocking.

ERIK SEEDHOUSE: If they don't unlock

the feather mechanism by Mach 1.8,

then the flight is aborted.

So obviously that's going to be weighing

on the co-pilot's mind.

You want to get that out of the way.

NARRATOR: Then they make another discovery.

Can I see that simulator video again?

[suspenseful music]

NARRATOR: The training simulator did

not vibrate or mimic G-Forces.

The pilots didn't feel the actual sensation

of a powered flight.

Yeehaw.

ERIK SEEDHOUSE: Even if you're a very, very good test pilot,

that has to be a little bit unnerving to get all

this vibration, and G loads, and the speed, and everything else.

NARRATOR: Investigators finally know what happened.

He had a lot to do, made a decision to unlock early,

perhaps not realizing the deadly implications.

NARRATOR: The NTSB faults Scaled Composites

for not ensuring pilots understood the consequences

of unlocking the feather system early

and for failing to take steps to prevent that from happening.

Catch up!

LORENDA WARD: Even just having a sensor that physically prevents

them from unlocking until it passes

the appropriate threshold would have prevented this accident.

NARRATOR: In its final report, the NTSB

states the probable cause of the disaster

was a failure to protect against the possibility

that a single human error could trigger a catastrophe.

The common thread in all of these tragedies

is that people took action without really

examining what action was needed and they moved too fast.

MICHAEL ALSBURY: 0.8, unlocking.

JOHN NANCE: We do know how to prevent them,

and that is by sitting on your hands in most cases

until you are sure you need to take action.

You don't take action because if you take the wrong action,

it can lead you into a major problem or a disaster.