All language subtitles for When.Big.Things.Go.Wrong.S01E05.Man.vs.Machine.1080p.AMZN.WEB-DL.DDP5.1.H.264-BurCyg_track3_[eng]

ANNOUNCER: This program is
rated PG, and contains

ANNOUNCER: This program is
rated PG, and contains

mature subject matter.

Viewer discretion is advised.

(SIREN WAILING)

(MAN SPEAKING)

NARRATOR: It's one of the most
shocking plane accidents
in US history.

The plane literally
spirals down the runway.

It is a complete disaster.

NARRATOR:
But why did it crash?

Is it a mechanical problem,
or is this
a human factors problem?

How could this accident
have happened?

NARRATOR: Now, engineers unlock
the clues to the world's
biggest disasters...

(PEOPLE SCREAMING)

...to find out what happens
when Big Things Go Wrong.

MAN: Watch it! Watch it!

These are the ultimate fears

that keep structural engineers
awake at night.

(THUDDING)

MAN: Oh, my God.

(AEROPLANE WHOOSHING)

NARRATOR: Incheon International.

One of Asia's
busiest airports.

Check-in is underway
for the 291 passengers
on Asiana Flight 214.

A 10-and-a-half-hour trip
across the Pacific,
to San Francisco.

Among the travelers,
the Jang family.

They're returning home
from a month-long vacation.

Both my parents are from Korea,
they were born there,

but they both moved
to The States
at a pretty young age.

My parents planned it
so that we could see a bit
of like where they grew up

and our culture,
and stuff like that.

I think we were there,
for about a month

and we did
a lot of sight-seeing,

but I was really looking forward
to going back home.

NARRATOR: They'll be flying
on a Boeing 777.

One of the most high-tech
passenger jets in the world.

(AEROPLANE WHIRRING)

The 777 was innovative
from the start.

The way it was manufactured,
designed, and built,
was completely new.

NARRATOR:
It's also among the safest.

A key selling point
is its advanced
autopilot system.

It draws information
from multiple sensors
all over the plane.

Then crunches the data
and sends out commands.

It's a complex,
state of the art airplane.

And with safety
the number one priority
in its design,

every flight should be routine.

(TICKING)

ESTHER: It was like
any other typical flight.

They told us
to bring our seats up,

put our trays up,

and just get ready
for a landing.

(MAN SPEAKING KOREAN)

(AIR TRAFFIC CONTROLLER
SPEAKING)

(PILOT SPEAKING)

NARRATOR: There's no
obvious sign of anything wrong,
but that's all about to change.

I don't know what it was,
but I had like this
weird gut feeling

that, like, something
was a little off.

I remember thinking,
"Oh, I see the seawall,
is that normal?"

(TICKING)

NARRATOR: At the last moment,
the pilots power up
the engines.

The issue is
it's too little, too late.

Instead of clearing the seawall,
he clips it, and disaster.

(LOUD EXPLOSION)

It was a rollercoaster
off its tracks,
it was extremely rough.

I remember just bouncing
up and down.

After all the movement stopped,
I just remember
being in total shock

(SIREN WAILING)

(MAN SPEAKING)

I remember
looking over to my parents,

and that's when
I really started to freak out.

(SIREN BLARING)

SARAH:
They were on the ground,
their seats half-fallen,

and they were super pale,
with like,
blood dripping down their faces.

NARRATOR:
It's a horrific crash
that shocks America.

MATT: What's going on here?

Is it a mechanical problem,
or is this
a human factors problem,

or a combination of both?

NARRATOR:
With multiple safety systems
built into the plane,

a disaster like this
should never happen.

So what's really behind
the Asiana tragedy?

NARRATOR: The answers begin
at the airport itself.

San Francisco Airport
is one of the busiest airports
in the world.

However it's not
one of the biggest,

and it does come with its
own set of challenges.

The primary approach
is over water. There's not much
margin for error.

NARRATOR: Featureless terrain
like water makes it harder
for pilots to judge height.

I've flown into
San Francisco Airport myself
a number of times

and if you look out the window,
all you see is water.

And you continue to see water
essentially until you're
on the runway.

And so you're just waiting
to see the sea-wall
flash underneath you,

and then hit the ground.

NARRATOR: But that's not
the only challenge for pilots
coming into San Francisco.

The airport has intersecting
parallel runways
unusually close together.

Planes can arrive simultaneously
just 750 feet apart.

And six weeks before the crash,
landing here gets even trickier.

Construction work forces
the three-month shutdown

of a vital piece
of safety equipment.

The airport's landing guidance
system called a glide slope.

It transmits this radio signal
out to aircraft,

and it tells them,
"Hey, this is the angle
you need to fly,

"in order to reach the runway."

If you go above it,
you're probably going
to overshoot the runway.

If you go below it
you're in danger
of colliding with terrain.

NARRATOR: It's an
invaluable tool for pilots.

(SIGNAL BEEPING)

In 777 the autopilot
detects this signal and follows
the glide slope automatically.

And then from that point,
it's just monitoring
to make sure

you're on glide slope
following that angle safely
all the way down to touchdown.

NARRATOR: But with this
failsafe system turned off,

the angle of approach
is all down to the air crew.

It's not just planes
that rely on safety systems.

Trains need them, too,
as one driver finds out
in Taiwan in 2018.

A high speed train races south
from the capital, Taipei,
carrying 370 passengers.

But as it approaches a bend
at a local station,

its speed is twice
what it should be.

It jumps the rails,
and slams into
the station pillars.

Four of its
eight carriages overturn.

Eighteen die, and
two hundred and ninety-one
are injured.

So what causes the crash?

When the Puyuma express sets out
from Taipei at 2:50 p.m.,

its driver immediately realizes
he has a problem.

It keeps wanting to stop,
and he can't figure out why.

So he turns off the automatic
train protection system.

Now, this automatic
train protection system
is designed to keep

the train from going too fast,
particularly when it's going
into a curve.

NARRATOR: The driver must now
carefully monitor his speed.

That's okay,
because along the way
there are signs,

there are visual cues
that the driver can see,

alerting him
that he has to slow down.

NARRATOR: But half a mile
from Xinma Station, he misses
a vital trackside sign.

And instead of going around
a curve that had a maximum speed
of 45 miles per hour,

he was actually going
93 miles per hour.

(LOUD CRASH)

LUKE: Humans can make errors,
humans can get distracted,

humans can miss visual cues.

And and whilst we don't know
why this driver necessarily went
into this corner too quickly,

it's clear that if
the automated system
had been there to warn him,

it's very unlikely that
that could have happened.

NARRATOR: In San Francisco,
turning off the safety system

also adds pressure
to human operators.

Yet for six weeks
before the crash,

around three and a half thousand
flights land without a problem.

So what else went wrong
on Asiana Flight 214?

NARRATOR: Coming up...

More evidence uncovered.

If the wing
isn't generating lift,

the airplane is basically just
falling out of the sky.

NARRATOR: And could
a Taiwan air crash
hold a vital clue?

(PILOT SPEAKING)

(EXPLOSION)

(EXPLOSION)

NARRATOR: When
Big Things Go Wrong...

engineers must find out why.

(GLASS SHATTERING)

In the terrifying crash
at San Francisco,

the first issue,
no landing guidance system.

But this didn't cause problems
for any other planes
landing here.

So what else goes wrong
on flight 214?

A second clue lies
in the plane's speed
on final approach.

Crash investigators
salvage the black box
from the wreckage

and reveal a big surprise.

In the seconds
before the disaster,

the aircraft's travelling
15% slower than it should be.

The reason why
airspeed is so critical
in airplanes

is because there requires
a certain amount of flow
over the wings to generate lift.

If the wing
isn't generating lift,

the aeroplane is basically
just falling out of the sky.

NARRATOR: Why is flight 214
going so slow
at such a critical moment?

The black box data
only adds to the mystery.

For just over a minute
before impact, its engines
are set to zero power.

Miraculously, the pilot
survives the crash

and investigators
are eager to interview him.

He admits that on final approach
he wasn't monitoring
his air-speed.

The reason,
he believes his speed

is guaranteed
by a 777 safety feature.

Low Speed Protection.

Every airplane
has a minimum speed

at which it wants to land at.
And for the 777,

if the plane starts to go
too slow, it will boost
the power of the plane.

And so it's
one of those safety nets

that you just
don't have to worry about
going too slow.

They were anticipating
that the system was,

the auto throttles
were going to hold
that airspeed for them.

NARRATOR: But for Asiania 214,
that doesn't happen.

This massive plane
has become a glider.

NARRATOR: And if an airplane
loses power, it's game over.

As one pilot discovers
in Taiwan, in 2015.

In the capital Taipei,
TransAsia 235 prepares
for take-off.

It's carrying 58 passengers
and crew on a routine flight
to China.

Then something goes wrong.

On take-off, the connection
between the engine

and the sensor
monitoring it breaks.

As a result,
the computer no longer thinks
that the engine's getting power.

NARRATOR: And human error makes
a bad situation much worse.

The pilots inadvertently
shut off the power in the actual
functioning engine.

This causes the plane
to stall and begin to crash.

(PILOT SPEAKING)

NARRATOR: Both engines
are now completely unpowered,

and the airplane plummets
towards a busy highway.

(THUDS)

Just three minutes
after take-off, it crashes
into Taipei's Keelung River.

As it's crashing down,
it clips a taxi

that happens to be
on the roadway
right in front of it.

(THUDS)

NARRATOR: Miraculously,
driver and passenger
both survive.

But the airplane passengers
aren't so lucky.

The plane strikes the water
upside down, and tears apart.

It takes 35 minutes
for rescue boats
to reach the site.

Fifteen are seriously injured.

Forty-three die,
including the pilots.

DAN:
You have a small component

that malfunctions,
but the consequence
of that malfunction means

you lose all power
to the aircraft. Well then,
that's almost a knock-out blow.

NARRATOR: Coming up...

The 777 pilots rely on
automation to keep them safe.

But does it let them down?

Automation is there to help you,
but it can bite you.

And when it does bite you,
it bites hard.

NARRATOR: And more
Big Things Go Wrong...

(PEOPLE SCREAMING)

(ALL SCREAMING)

(OBJECTS CLATTERING)

NARRATOR: In San Francisco,
investigators race

to explain the crash
of a Boeing 777.

Immediately after the crash,
there were some

burning questions
that needed to be answered.

I mean,
this was a clear sky day.
Perfect flying day.

There was no warning
from the pilot

that there was anything wrong
with the plane.

How could this accident
have happened?

NARRATOR: The survivors
are also dazed.

The wind got knocked out of me.
My ears were ringing.

There was a lot of yelling,
a lot of moaning.

SARAH: I remember
it just being chaos.

Everyone was screaming, crying,
and just in complete shock.

NARRATOR:
The pilot made a mistake
with his approach angle,

and the jet's low speed
also appears to be a factor.

But why doesn't
its advanced safety system
prevent disaster?

1995.

At press launches
around the world, Boeing parades
a brand new plane.

A high-tech passenger jet
named the Triple Seven.

This airplane is in fact
what we all know it to be.

It's more than safe
and it's more than reliable.

The Boeing 777
is an amazing plane,
because it's enormous.

It can hold upto
400 passengers.
It can fly up to 10,000 miles.

It weighs 380 tons
and it's a workhorse
in the aviation field.

NARRATOR: The 777
is one of the most sophisticated
passenger planes ever built.

And the first large
commercial jet designed entirely
by computer.

One key feature,
its advanced autopilot.

Much more complex
than previous generations.

It prevents the aircrew
from getting the aircraft
into a bad situation.

It automatically
will prevent stalls.

It will prevent the aircrew
from over stressing,
over banking the aircraft.

NARRATOR: That's not the end
of the 777's
electronic revolution.

It has an incredible new
flight control technology.

It was fly by wire.
This is no longer cables
and control rods

going directly from the cockpit
to the control surfaces,

or to the hydraulic actuators.
This was wires.

NARRATOR:
The pilot's instructions

from cockpit controls
are processed by computer.

Electronic signals are sent
to motors throughout the plane.

And these motors
activate the flaps,
rudder and engines.

Fly by wire has been
in widespread use
in the military for decades.

However, in the 777
this was brand new

to the civil aviation,
commercial aviation world.

NARRATOR: In this new
electronic era,

pilot, machine and autopilot
must work seamlessly together.

But automation can lead to
over-reliance on the computer

to do the right thing
in every situation.

Any time you relinquish control
to an automated system,

you have the potential
for that system to make a wrong,

or ill-advised,
or ill-informed decisions.

NARRATOR: It's essential that
777 pilots constantly monitor
what the autopilot is doing.

Because even
the most advanced technology
doesn't always cooperate.

Sometimes there is combinations
that just come together

that can lead to
unexpected outcomes.

Those unexpected outcomes
can be dangerous,
or even deadly.

NARRATOR:
That's just what happened

to a cruise ship
off the coast of Norway.

March, 2019.

The Viking Sky loses power
in a violent storm.

(PEOPLE SCREAMING)

(PEOPLE SHOUTING)

And a computer program
is the trigger.

(OBJECTS CLATTERING)

The danger of any
automated system is,

the system doesn't have
the contextual information

it needs to make
a good decision in all cases.

If it does the wrong thing
at the wrong time,

really bad stuff is possible.

NARRATOR: So what went wrong?

The Viking Sky is two days
into a cruise along the rugged
Norwegian coast.

The ship set out from Tromso,
heading over 1200 miles south
to Stavanger.

Then, the weather turns ugly.

She started heading into
extremely rough seas with

thirty feet high waves coming
at her every 12 seconds.

NARRATOR: An automatic
trip-switch is
about to put lives on the line.

Viking Sky begins to get a lot
of low level lube oil alarms.

So lube oil
is lubrication

for the diesel
generators,

and as the ship
is rolling back and forth

in these heavy sea states,

the ship is having trouble

pulling that fluid

into the diesel generator

to ensure lubrication
for those components

to properly work.

NARRATOR: Without lube oil,
the engines will overheat
and sustain damage.

CAITLIN: The automation
for this system is that

if those generators
are not getting enough lube oil,

then they will shut down
to not cause harm.

NARRATOR: Suddenly,
all the ship's generators
cut out,

plunging it into black-out.

(WIND BLOWING)

(CRACKING SOUND)

MAN: Whoa!

(METAL CLANGS)

And the Viking Sky
starts drifting towards
the rocky coastline.

All 1300 people on board
are in serious danger.

You may have saved the engine,
but you put the passengers

and the ship itself
in great peril.

(WOMAN SCREAMS)

(METAL CLANGS)

(OBJECTS CLATTERING)

(INTENSE MUSIC PLAYING)

A helicopter evacuation begins.

(HELICOPTER WHIRRING)

The crew
partially restart the engines.

But they take no chances.

Tugboats tow the troubled ship
into port.

Finally, 26 hours
after the black-out,
the ordeal is over.

The Asiana 777 has the most
advanced safety features
of its day.

But could an unexpected
computer glitch
help explain its crash?

Coming up...

A chance to warn 777 pilots
of danger is missed.

All it takes is one little thing
to go wrong
and catastrophe can happen.

(EXPLOSION)

NARRATOR: And an
oil platform explosion shows
just how deadly this can be.

NARRATOR: In San Francisco,
the mysterious crash
of a Boeing 777

demands urgent investigation.

And evidence is now emerging
to explain what went wrong.

A dangerously low speed
on approach...

The airplane is basically
just falling out of the sky.

...and an overly complex
new computerized
flight control system.

There's always the chance
that there are going to be

hidden interactions that
we don't fully understand.

NARRATOR: But by 2013,
777 pilots have clocked up
38 million flight hours.

And with
a zero crash fatality rate,

it's one of the safest planes
in the sky.

So what else is behind
the San Francisco tragedy?

NARRATOR: The next piece
to the puzzle
lies somewhere unexpected.

In 2010,
a new Boeing model

rolls off the assembly line
in Everett, Washington State.

It's the 787, follow-up
to the successful 777.

Both planes have the same
advanced autopilot.

Before the 787
can carry passengers,
it must undergo testing.

MATT: Test pilots
have quite the job.

They evaluate
every aspect of this aircraft.

Not just how it maneuvers,
how it performs,

but how they are able to
interact with the systems

and how the systems
interact with them.

NARRATOR: But during one flight,
a test-pilot
uncovers something alarming.

A test pilot
is taking the plane in

for a descent
with the autopilot engaged.

All of a sudden
the collision alarm goes off.

(ALARM BEEPING)

NARRATOR: It's a warning
there may be another aircraft
below him.

So the test pilot
turns off the autopilot,

adjusts the throttles
so that the plane can level out.

NARRATOR: It's soon clear
it was a false alarm.

But then the airplane
does something
totally unexpected.

SIAN: He realizes that

the plane has dropped
below the minimum
speed threshold.

NARRATOR:
The pilot figures out
his unusual actions

deactivate the low speed
protection system.

And that's really
the "aha" moment
that this unique situation

and the unique combination
led to the auto throttle
not engaging.

NARRATOR: Speed protection
should increase power
to the engines when needed.

But if it's
turned off unnoticed,

the plane could sink
like a stone.

(ALARM BEEPING)

NARRATOR: Luckily,
the test-pilot was high enough
to react, this time.

But it revealed
a dangerous flaw
in the autopilot design.

One that could prove fatal
for other pilots.

SIAN: This test pilot
experiences this

in the 787,
but realizes that the 777
has the same autopilot system.

So when he writes up his report,
he flags it for both airplanes.

NARRATOR: Incredibly,
these warnings
don't reach 777 crews.

The FAA informed everybody that,

"Hey, if you're flying a 787
this has the potential
to really bite you."

The sad part about this is that
it never really got transferred

over to the 777 community
and sent up from there.

NARRATOR: When dealing
with complex engineering,
things can go wrong.

But when warnings
aren't shared, catastrophe
becomes inevitable...

as workers on an oil-rig
discover in 1988.

(THUNDER RUMBLING)

The Piper Alpha oil platform,
120 miles off Scotland.

On July 6th 1988,

failure to pass on
crucial information
triggers disaster.

(EXPLOSION)

MAN: There she goes...

NARRATOR: So what's behind
this devastating blast?

SIAN: On this particular day,
one of the pipes
that is handling the gas,

the valve on it
needs to be replaced.

So the worker
takes the valve off and caps it.

NARRATOR: It's not enough
to completely seal the pipe,

but before a new valve
can be installed,
the shift comes to an end.

There is a system
on Piper Alpha to flag

and communicate works
that are underway,
but not yet finished.

But on this particular change
of shift, that communication
wasn't picked up.

NARRATOR: If any gas
is fed down the pipeline,

it will escape
from the temporary cap.

One spark and it could blow.

That evening, a pump fails
in the other pipeline
taking gas to the mainland.

(ALARMS BLARING)

Engineers can't
get it restarted,

so switch the flow
to the second pipeline.

They don't realize
it's still under repair.

ROB: When the pump
was switched on,

survivors report this
loud screeching noise

that was coming
from the temporary cap

that had been fitted
instead of the safety valve.

Apparently, this lasted
for about 30 seconds,

which would have released around
30 kilograms
of highly explosive gas.

(EXPLOSION)

NARRATOR: Despite fire-fighters'
best efforts, of 226 people
on board, just 61 survive.

The lesson for the 777?
Warnings not passed
on can lead to disaster.

And with 1,100 Triple Sevens
in the air, chances are,

a pilot will eventually fall
into the autopilot trap.

However unlikely.

if you play a game
a billion times,

a one in a billion chance
is probably going to show up.

NARRATOR: Coming up...

What goes wrong
in the final minutes
of Asiana Flight 214?

NARRATOR: As machines
get bigger, and more complex,

technology can be both
a blessing and a curse.

NARRATOR: The B2 stealth bomber.
One of the most
advanced airplanes in the world.

It's so complex it can only fly
with the help of its autopilot.

But in 2008,
at the US airbase in Guam,

heavy rain causes
vital speed sensors
to malfunction.

Fed the wrong information
on take-off,
the autopilot triggers disaster.

(EXPLOSION)

The pilots eject milliseconds
before impact.

It's the most expensive
air crash in history,

a $1.4 billion airplane
up in smoke.

An autopilot glitch brings down
a sophisticated B2 bomber.

And as Asiana flight 214
approaches San Francisco,

nobody on board
knows there's a trap
in its autopilot

waiting to be triggered.

(TICKING)

Twenty minutes out,
the 291 passengers
prepare for landing.

So far the journey
has been uneventful.

But nearly half
of all plane crashes happen
on final descent and landing.

The Jang family, returning from
a month's vacation in Korea,
sit in the back of the plane.

(TICKING)

The children
are across the aisle
from their parents.

We got really excited,
we were just so ready
to be home.

I always open the window
right before I land,
I like to see the landing.

(AIR TRAFFIC CONTROLLER
SPEAKING)

(UNCLEAR RADIO CHATTER)

The weather conditions
were almost ideal.
It was day time, low wind.

NARRATOR: But just two minutes
out from San Francisco,

the pilot finds himself
in trouble.

He normally relies
on the airport's glide slope
system to line up his approach.

But today it's turned off,
and he realizes
he's coming in too high.

four hundred and fifty feet
above the ideal line.

They needed to do something
fairly drastic to get back down

to an altitude
and a trajectory to the runway.

NARRATOR: The pilot is running
out of time
to get the angle right.

In a desperate attempt
to get lower, the pilot selects
an autopilot setting

he thinks will get him back
on the right path,

"Flight level change speed."

But it only
makes things worse.

(BEEPING)

Instead of bringing him down,
it starts climbing the plane,
making him too high.

NARRATOR: In response,
the pilot puts
his engines to idle.

He brings the throttle
right down to zero
on the engines.

So that the plane
will lose speed
and then lose height.

NARRATOR: Then he disconnects
the autopilot to try
and manually correct course.

But as he turns it off,
this final action
triggers the trap.

SIAN: The system automatically
changes the throttle mode
to "hold"

and the pilot has no idea
that this has just occurred.

NARRATOR:
The pilot doesn't realize it,

but the airplane's
"low-speed protection"
is now turned off.

The consequence is
that the engines
are not going to fire up

when the airspeed drops
below that critical number
that the pilot has set.

(TICKING)

(AIR TRAFFIC CONTROLLER
SPEAKING)

(PILOT SPEAKING)

(AIR TRAFFIC CONTROLLER
SPEAKING)

(TICKING)

NARRATOR: 30 seconds out.
The airplane finally seems to be
on the correct approach angle.

But instead of levelling out
as the crew expects,
it continues to drop.

JOSEPH: As we were
approaching the runway,

I had like this weird,
gut feeling that like,
something was a little off.

(TICKING)

NARRATOR: 20 seconds out.
The airplane is falling
at 20 feet per second.

Now its speed drops below
the minimum safe level.

But the engines fail to fire up.

Even now,
the pilot doesn't realize.

It's almost like
the pilot's waiting and waiting

and waiting for the system
to do its thing,
and it never shows up.

(TICKING)

NARRATOR: It's the co-pilot
who finally reacts.

He realizes he's too low,
and so what's going to happen

is that the plane is actually
going to land
short of the runway

and crash into the seawall.

DAN: He kicks in
a large amount of throttle,
to gain some air speed.

The airplane is too big,
too low, and too slow.

(MUSIC INCREASES IN TEMPO)

(TICKING)

(LOUD EXPLOSION)

The tail is ripped off
and the plane literally spirals
and tumbles down the runway.

(EXPLOSION)

NARRATOR:
It's a horrific crash.

SARAH: It all happened
so quickly.

I remember bouncing
up and down in my seat.

All of a sudden,
we just stopped.

I checked to make sure
that both my sisters were okay,

and I looked over to,
I guess look for my mum
and my dad.

(AIR TRAFFIC CONTROLLER
SPEAKING)

My initial thought was that
they died, because they...
they weren't moving.

SARAH:
They were on the ground,

their seats half-fallen,
and they were super pale,

with, like, blood dripping
down their faces.

NARRATOR: Asiana flight 214
has just crashed
in San Francisco.

LUKE: Given the nature
of the crash,

the fact that anyone survived,
frankly I think
is extraordinary.

(MAN SPEAKING)

NARRATOR:
But soon, another threat looms.

I remember
the flight attendant telling us,

"We need to get off the plane,
we need to get off the plane."

NARRATOR: At any second,
the plane's huge fuel tanks
could explode.

The wings stay intact.
And the thing about
the wings staying intact

is that that's where
the jet fuel is.

Jet fuel is extremely flammable
and if the plane catches fire,
everybody is going to be dead.

NARRATOR:
Survivors attempt to flee
the burning wreckage.

But only two of eight
inflatable slides deploy,

leaving them scrambling
for a way out.

My brother and I were able to
just jump off the side
of the plane, because

there was no slide
at this exit.

Firefighters started panicking,
and I remember one picked me up

and was running away
from the plane.

-NARRATOR: Now begins
a sickening wait.
-(SIREN WAILING)

My brother and I
were just sitting there,
worried about my parents.

The engine was still going,
the engine didn't stop,

and the fire was
massive at the time.

NARRATOR: The Jang children
are driven across the runway
to join other survivors.

Just when hope is nearly gone,
they see their parents
in the crowd.

All I remember my mom saying
was like, "Where are my kids?
Where are my kids?"

and I remember just being like,
"We're right here", like,

"We're all here together now.
It's okay."

NARRATOR: The Jang parents
are rushed to the hospital.

They're among 49
who suffer serious injuries.

Tragically,
three passengers die.

All were seated
at the rear of the plane.

We were sitting extremely close
to the the passengers

that did pass away
from the accident.

I just feel like
it was a huge blessing,

that all of us made it out
relatively unharmed.

NARRATOR: The crash came
without warning,
and left witnesses baffled.

To the general public,
one would definitely ask,

"How could something like this
happen on such a perfect day,

"with such a reliable,
safe aircraft?"

NARRATOR: But to engineers,
the answers to this puzzle
seem clear.

No airport guidance system.

ROB: Without the glide slope
system working,

the pilot ends up
coming in too high.

NARRATOR:
A vital missed warning.

In complex safety environments,
it's the thing

that you don't know about
that's often the most critical.

NARRATOR:
And one unusual factor.

An autopilot
with a deadly hidden trigger.

Automation is there
to help you...

but you need to be careful,

because it can bite you.

And when it does bite you,
it bites hard.

(EXPLOSION)

NARRATOR: In the aftermath,
suspicion falls on the pilot.

But when National Transportation
Safety Board crash investigators
start looking into it,

they soon unearth deeper causes
behind the pilot's error.

The investigation reveals
that the confusing nature
of the autopilot

was a big contributing factor
to this crash,

and they actually recommend
that all 777 pilots be trained
on this hidden trap.

NARRATOR: Most of
the latest planes have far more
advanced autopilot systems.

ROB: Huge developments
in the sophistication
of aviation systems,

along with the processing power
of the computers that run them,

mean that modern
autopilot systems

are far more capable
than they once were.

NARRATOR: And as Machines
continue to get bigger
and more complex...

Asiana Flight 214,

and other disasters
around the world,
offer a warning.

Automation can bring
greater safety,
but it also creates new risks.