All language subtitles for M.2003-S23E01-Pressure.Point.Japan.Airlines.Flight.123.WEBDL-1080pEAC3.5.1h264-PiTBULL_track4_[eng]

(crashing noises)

NARRATOR: Japan Airlines Flight 123
crashes into a mountain,

killing 520 people.

It's the deadliest
single aircraft accident in history.

SCHLEEDE: We were working in this terrible
carnage. I get chills thinking about it.

NARRATOR: Investigators
immediately suspect an act of terror.

Right now it's a bomb. That's
what the crime guys are telling us.

NARRATOR:
But the wreckage tells a different story.

INVESTIGATOR 1: There's no fire
damage. No shrapnel damage?

NARRATOR:
What they soon discover…

It was the only thing
holding the two sides together.

NARRATOR: …threatens to ground

one of the most popular commercial
jets on the planet, the 747.

SCHLEEDE: We were concerned that we
had a structural flaw in the airplane,

and others were worried, too.

(tense music)

(theme music plays)

MAN (over radio):
Mayday! Mayday!

(alarm blaring)

GPWS:
Pull up.

(indistinct radio chatter)

NARRATOR:
It's 6:10 p.m. at Tokyo's Haneda Airport.

Japan Airlines Flight 123
is ready for departure.

SASAKI:
Number one engine start.

NARRATOR: In the left-hand seat is
39-year-old First Officer Yutaka Sasaki,

training to become a 747 Captain.

(engines powering on)
I'll handle the radios while you fly.

NARRATOR: The Captain is
Masami Takahama, a former military pilot,

who joined Japan Airlines 20 years ago.

The flight plan calls for
a right turn out.

Haneda ground, Japan Air 1-2-3.
Request taxi. Charlie 7.

Thank you, sir.

NARRATOR: Today's flight is full,
with 509 passengers on board.

It is the start of the Obon holiday.

(speaking Japanese)

(translation) Obon is a Buddhist
event about the ancestors' spirits.

It happens in summer.

People in the city go back to their
hometown with families to celebrate.

(continues speaking Japanese)

NARRATOR: Twenty-six-year-old Yumi
Ochiai is an off-duty flight attendant.

Hi. So glad to have
a break for the holiday.

(speaking Japanese)

(translation) Yumi Ochiai was
like many young Japanese,

she wanted to see the world.

Working for the airlines
allowed her to do that.

(continues speaking Japanese)

(engines powering up)

V-1.

Rotate.

NARRATOR: Thirty minutes
before sunset, Flight 123 lifts off.

- Positive rate.
- Gear up.

Very nice.

NARRATOR: Flight 123 is one of dozens of
747s carrying passengers throughout Japan.

(inaudible dialogue)

To this day, the 747 is the
most iconic jetliner ever built.

When it debuted in the '70s,

it was by far the biggest commercial
plane that had ever flown.

And every pilot wanted to fly this plane.

NARRATOR: To meet growing demand
for cheap travel within Japan,

Boeing designed the 747 SR,
a special version of the jumbo jet.

SMITH: The 747-SR, or Short Range,
was an unusual variant,

in that it was designed
for high-density, short-haul operations.

The Minister of Transportation
was on the last leg.

I hope you gave him a smooth flight.

NARRATOR: Assisting on tonight's trip
is Flight Engineer Hiroshi Fukuda.

He's flown on 747s since they were
introduced to Japan Airlines in the 1970s.

SMITH: These earlier 747s
required three pilots,

the third pilot being a flight engineer

who sat behind the
captain and first officer,

controlling all of the airplane's
systems and subsystems

that were later consolidated

into the more computerized,
two-pilot airplanes that we have today.

Through 10,000.
Flight level 2-4-0 selected.

NARRATOR: It's an hour-long
flight from Tokyo to Osaka,

one of Japan's busiest domestic routes.

Eleven minutes into the flight,

Japan Airlines 123
approaches its cruising altitude.

Okay, 1,000 feet to go
and we'll level off.

Yes, sir.

NARRATOR:
As they near 24,000 feet,

the crew settles in for what's
expected to be a smooth flight.

(explosion)
(rumbles)

Whoa.
(alarm wails)

SMITH: If an airplane is suddenly
displaced by some violent force,

the autopilot can suddenly kick off.

Then the pilots now have to take control
and physically steer the airplane again.

Something exploded?

I'm squawking 7700.

SMITH:
Putting 7700 into the transponder

is a way of broadcasting
an urgent situation.

Was that a gear door?

TAKAHAMA:
Check gear. What about the engines?

All engines are good.

SMITH: When something
unusual or sudden happens,

pilots are trained to stop, analyze,

evaluate the situation
before simply reacting.

Look at this.

NARRATOR:
Sixteen seconds after the explosion,

the pilots realize the cabin
is losing pressure.

SMITH: If an airplane depressurizes
at anything over 20,000 feet or so,

now suddenly you don't
have oxygen to breathe.

WARNING SYSTEM: Put on
your oxygen mask, fasten seat belts.

We are making…
(shouts of panic)

NARRATOR: The emergency masks
provide only 15 minutes of oxygen,

just enough oxygen for an emergency
descent to below 10,000 feet.

Something exploded.

(grunts)

Right turn. (yells) Right turn!

(Sasaki grunts)
Tokyo, Japan Air 1-2-3, having trouble.

Request return back to Haneda.

- Descend and maintain 220. Over.
- Roger. Right heading zero, nine zero.

NARRATOR: The pilots of Flight 123 attempt
a sharp turn back to Haneda Airport,

now 70 miles behind them.

- Don't bank so much.
- SASAKI (grunting): Okay.

The R-5 door is broken. We're
making an emergency descent.

TAKAHAMA:
Don't bank so much!

Hydraulic pressure has dropped.

NARRATOR: While the crew tries
to determine why the cabin depressurized,

they face an even more serious problem
with the hydraulic systems.

(grunting)

(speaking Japanese)

SUZUKI:
Without the hydraulic pressure,

it's very difficult to move
the control surfaces.

(continues speaking Japanese)

(Sasaki grunting)

Don't bank so much, it's manual!

NARRATOR:
The decrease in hydraulic pressure

is making it difficult
for the first officer

to stop the dangerously steep right turn.

- Turn it back!
- It won't go back.

TAKAHAMA:
Hydraulics are all out.

SMITH: Nobody in that cockpit had
ever seen a complete hydraulics failure.

There was no checklist,
no procedure for how to deal with that.

Descend.

NARRATOR: The pilots are unsure if
their control inputs are doing anything.

What's going on?

He's not turning back to Haneda.

NARRATOR:
Air traffic controllers are puzzled

by Flight 123's erratic flight path.

Why isn't he descending?

Japan Air 123, confirm,
you were declaring an emergency?

TAKAHAMA (over radio):
Affirmative.

CONTROLLER:
Request nature of your emergency.

- TAKAHAMA: Uncontrollable.
- Uncontrollable. Roger. Understood.

Put your heart into it.
(Sasaki grunts)

SMITH: If you've lost pitch
control, elevator control,

an airplane will fall into an oscillating
series of climbs and descents, a phugoid.

The plane will pitch up
until it runs out of speed.

It will then nose down into a descent.
It will pick up speed and momentum.

As the wings begin to generate more lift,
the plane will again begin a climb.

(grunts)

NARRATOR: The pilots try using engine
power to turn the airplane towards Haneda.

(engines roar)

SMITH: By increasing power on the left
side, the plane would turn to the right.

Increasing power on the right side,
the airplane would turn to the left.

(engines increase)

NARRATOR: It works. The 747
starts a slow turn to the right.

WARNING SYSTEM:
We are making an emergency descent.

Put on your oxygen masks,
fasten seat belts…

OCHIAI: Don't worry, the
pilots have turned us back.

We will be arriving in Haneda soon, okay?

WARNING SYSTEM:
Fasten seat belts.

NARRATOR:
Still at 22,000 feet,

the captain can see Haneda
in the distance, 81 miles away.

Can you hold?
(Sasaki grunts)

SMITH: The crew reflexively thought,
"Let's get this plane back to Haneda."

And why Haneda and not somewhere closer?
Because they were familiar with Haneda.

NARRATOR: Haneda is within reach, but
the plane's erratic behavior is worsening,

and the pilots are at breaking point.

(grunting)

WARNING SYSTEM: Put on your
oxygen masks, fasten seat belts…

NARRATOR: In the cabin, emergency
masks are running out of oxygen.

WARNING SYSTEM: Put on
your oxygen masks, fasten seat belts.

We are making an emergency descent.

(tense music)

SASAKI:
I don't understand what's happening!

NARRATOR: For 14 minutes,
the crew of Japan Airlines 123

has been struggling to control their 747.

They can't get the plane to descend.

SASAKI:
Gear down.

SMITH:
Lowering the landing gear,

dumping all of that machinery
down into the airstream

will slow a plane down by
vastly increasing the amount of drag,

helping it to descend.

It doesn't work. The gear won't go down.
(Sasaki groans)

Let's try the alternate.

In an emergency situation,
like a hydraulic failure,

the crew can lower
the landing gear with gravity.

However, once the gear is down,
it cannot be pulled back again.

- Lower!
- Yes! Yes!

Gear coming down.

SMITH: Really, they're just
trying desperation moves here,

trying to find the right configuration
to stabilize the plane as best they can.

- TAKAHAMA: Keep the nose down.
- Yes.

NARRATOR: With the landing gear down,
the aircraft begins to slow.

We are descending now.

NARRATOR:
Fifteen minutes after the incident began,

Japan Airlines 123
is finally losing altitude.

The gamble has paid off.

SMITH: It's not in what I
would call controlled flight,

but it's a steadier
condition than it was in,

and it's descending now
into lower altitudes

where passengers can breathe again.

Hold it here.

SASAKI (grunts):
We're over Lake Sagami.

NARRATOR: Just ahead, the pilots
see the familiar lights of Tokyo.

(grunts)

But the captain's optimism vanishes when
the plane suddenly banks hard to the left.

This may be hopeless.

Lower the nose more.

- Request radar vectors to Haneda.
- Roger, understood.

Keep heading zero, nine, zero
for runway 2-2.

Whoa. (grunts)

NARRATOR: As the plane descends
below 10,000 feet, the situation worsens.

(grunts)

TAKAHAMA: It's uncontrollable again.
Watch out for the mountain.

SMITH: So then, it suddenly begins
descending at a high rate of speed

directly towards the mountains.

NARRATOR: Japan Airlines 123 is
flying directly away from Haneda airport,

heading straight towards high
terrain north of Mount Fuji.

- Right turn or we will hit the mountains!
- (yells) Yes!

NARRATOR: Nine minutes
after lowering the landing gear,

the plane has descended 15,000 feet.

Where did he go?

NARRATOR: Flight 123 drops below
the peaks of the surrounding mountains,

out of range of Tokyo's radar.

TAKAHAMA: Max power.
(Sasaki grunts)

NARRATOR: Incredibly, the pilots
are able to arrest the dramatic dive.

SMITH: The plane begins
a very abrupt pitch up,

so much so that now they're
very worried about the airplane stalling

at the top of that climb.

NARRATOR: When the airspeed drops to
108 knots, the stick shaker activates.

FUKUDA:
Increase power.

(grunts) Not good. We're stalling.

SMITH:
The plane slows to a 108 knots,

which is beyond
the stall margin for a 747.

How they didn't just drop out of
the sky at that point, I'm not sure.

We are losing altitude. Raise the nose!

NARRATOR:
The flight crew is exhausted.

For 25 minutes,
they have fought for control

as they continue to fly away
from Haneda Airport.

(grunts)

Flaps?

SMITH: The first officer
suggests deploying the flaps,

which may help them
stabilize the airplane,

allow them to fly at a
slower speed without stalling.

- Extend the flaps.
- Flaps coming out.

SMITH: Because the normal hydraulic
deployment is obviously unavailable,

when flaps are deployed electrically,
they come out very, very slowly.

NARRATOR: For more than a minute,
Flight 123 flies almost normally.

(yells) Left turn!

NARRATOR: As the crew attempts
a left turn back to Haneda,

the plane banks hard to the right.

(engines whirring)

Japan Air 1-2-3, request position.

CONTROLLER: Your position is
45 miles northwest of Haneda.

NARRATOR:
Unknown to the pilots,

the flaps on each wing are
extending at different speeds.

SMITH: What's happened
is the flaps on the left side

have come down faster
than the flaps on the right side.

This has caused the left wing
to produce a lot more lift,

which is turning the plane
hard to the right.

TAKAHAMA (yells):
The nose!

NARRATOR:
The uneven flaps make the situation worse.

The nose!

NARRATOR:
Four thousand feet from the ground,

Japan Airlines 123 is dropping fast,
losing 15,000 feet a minute.

TAKAHAMA: Raise the nose. Raise the nose!
(Sasaki grunts)

WARNING SYSTEM: Quite soon, we
will be making an emergency landing.

(whimpers)

NARRATOR: The pilots use
all their strength to regain control.

I can't hold it much longer!

- NARRATOR: But nothing works.
- Flaps up! Flaps up!

TAKAHAMA:
Flaps up!

GPWS:
Sink rate.

- TAKAHAMA: Raise the nose!
- GPWS: Pull up.

- TAKAHAMA: Power!
- GPWS: Terrain. Pull up.

(grunts)
GPWS: No sink.

(somber music)

NARRATOR: Japan Airlines Flight 123
has crashed into a mountain

in a remote area northwest of Tokyo.

When rescuers reach the crash site the
next morning, they find devastation.

Only the left wing and rear section
of the aircraft are recognizable.

As rescuers examine the tail section,
they make an astonishing discovery.

There are four survivors.

SMITH: To have made it out and to have
survived the next 15 or so hours

under the wreckage in the wilderness,
I don't know how it happened, but it did.

NARRATOR:
Five hundred and twenty people have died.

The deadliest single
plane crash in history.

Japan's Air Accident Investigation
Commission, or AAIC,

is soon joined by experts
from the NTSB and Boeing.

We were working down
there in this terrible carnage,

and family members had already
been brought up to the mountain

and they built little altars.

And that's… I get
chills thinking about it.

NARRATOR: One of the survivors is Yumi
Ochiai, the off-duty flight attendant.

INVESTIGATOR 1:
She's able to talk?

NARRATOR: Though injured,
Yumi is able to speak to investigators.

Yumi, can you tell me what you remember?

We were ascending when
something exploded behind me.

NARRATOR: Investigators discover
that 12 minutes into the flight,

over Sagami Bay, there was an explosion.

The survivor's account
gives investigators their first big clue.

(wind gusting)

(speaking Japanese)

After the sound of the explosion,
Mrs. Ochiai saw a white fog,

and this white fog is a result of a
sudden decompression.

(continues speaking Japanese)

NARRATOR:
Immediately after decompression,

the flight attendant describes
seeing a hole in the fuselage.

INVESTIGATOR 1:
Thank you.

NARRATOR: Based on the survivor's account,
investigators are immediately suspicious.

Right now it's a bomb. That's what
the crimes guys are telling us.

NARRATOR:
Japan is already on high alert.

Two months before the crash,
a bomb detonated at Narita Airport

on the same day that an Air India 747 fell
from the sky off the coast of Ireland.

SCHLEEDE: There was all kinds of
concern, internationally, and in Japan

that we had a terrorist group
trying to blow airplanes out of the sky.

Let's keep an open mind
and look for something else.

Well, even if you think it might
be a bomb, that's speculation.

The 747 was one of the more popular
airplanes in service at this time

and we were worried
that if it was something else,

it might ground the airplanes.

INVESTIGATOR 1:
Make sure we catalog everything.

NARRATOR: With the black
boxes sent off for analysis,

investigators examine the
wreckage in an aircraft hangar.

Let's test for explosive
residue near the back.

I had this package of glass bottles
and cotton swabs and tweezers

and alcohol and water, and
diligently swabbed the aft lav walls

and sent the samples
back to the company in Seattle.

NARRATOR: To reconstruct
the final 30 minutes of the flight,

they turn to the radar track.

- Almost 24,000 feet over Sagami Bay.
- INVESTIGATOR 1: Yeah.

NARRATOR: As investigators zero in
on how and where the incident began,

- they get a break.
- Hey. That's our plane.

NARRATOR: A witness on the ground took
a photo of the plane during the incident.

INVESTIGATOR 2:
A piece of the tail missing.

INVESTIGATOR 1: The vertical
stabilizer is pretty much gone.

NARRATOR: Losing a vertical fin has never
happened to an airliner this big before.

SMITH: The airplane
had lost most of its tail.

And it makes sense
that investigators were focused

on the possibility
of an in-flight explosion, a bomb.

INVESTIGATOR 2: A missing tail, and Yumi
Ochiai said there was a hole behind her.

It all adds up. But we
need the tail to prove it.

NARRATOR: The day after the crash
of Japan Airlines Flight 123,

part of the missing tail is found floating
in Sagami Bay south of Tokyo.

So what do you think?

NARRATOR:
Investigators examine the tail,

looking for any clues
that point to a bombing.

There's no fire damage.

- No shrapnel damage?
- NARRATOR: But that's not what they find.

PURVIS: Nothing really
looks like bomb damage.

There's a lot of telltale signs.
I saw none of that.

NARRATOR: Until they get the
swab results back from the lab,

they can't rule out a bomb entirely.

So you were the controller
that handled Japan Air 123, right?

Correct.

NARRATOR:
Investigators speak to the controller

who was in contact
with the crew for 32 minutes.

Did the pilots say anything
about what happened to the plane?

Right from the start,
they said it was uncontrollable.

- Hmm. Did they say why?
- No.

But they did mention to dispatch
something about damage to a door.

The R-5 door is broken.
We're making an emergency descent.

Thank you, it's very helpful.

PURVIS: The pilot reported
that the door may have come off

and there was a concern
that if the door came off,

it may have damaged the airplane.

The right rear door is here.
Behind our survivor.

INVESTIGATOR 2: Maybe that's
the opening our survivor described?

That would explain the depressurization.

SMITH:
There's a precedent there.

In 1974, the cargo door of a Turkish
Airlines DC-10 had blown off,

causing instant decompression of the cabin
and failure of the cabin floor,

resulting in the loss of flight controls.

A door is big, so it could
definitely do damage to the tail.

Enough damage to knock
it right off the plane?

NARRATOR: Several days after the
crash, the right rear door is found.

It looks like the door was locked, and it
was found with the rest of the wreckage.

So it didn't fall off in flight.

- It was a good theory.
- INVESTIGATOR 1: I know.

We're missing something.

(fax machine whirring)

We are back to square one.

No trace of explosives
found on the wreckage.

NARRATOR:
Flight 123 was not brought down by a bomb.

Well, one thing's for sure. Something
happened in the back of that plane.

PURVIS: Was there a structural issue?
Was there a design issue, even,

which might affect
more 747s than just this one?

We really needed to get an answer to that.

We need to reassemble the tail.

NARRATOR: While investigators
focus on the rear of the plane,

the Japanese government orders
inspections of all 747 tail assemblies.

Around the world, the safety
of the 747 is questioned.

There was moves by the Europeans
and the Brits to ground the 747,

and that would have had terrible
economic impact on the United States.

INVESTIGATOR 1: So from
their first emergency call to the crash,

it was almost 32 minutes.

NARRATOR: The team turns
to the cockpit voice recorder for clues.

Let's hear it.

- SASAKI (over tape): Be quick.
- FLIGHT ATTENDANT (over tape): Thank you.

(chimes)

It sounds normal.

It's just a flight attendant
asking for something on the intercom.

(explosions over tape)

(explosions)

Whoa.
(alarms wailing)

Something exploded?

We know there was definitely not
a bomb, but did you hear that?

Let's roll it back.

(explosions over tape)

Yeah, I heard that.

That was two explosions.

SCHLEEDE: We didn't know what the boom
boom was when we heard it on the CVR.

Okay, let's assume that the first
explosion was a decompression,

somewhere behind Yumi.

- What about the second one?
- Let's just keep listening.

(Sasaki grunts)

TAKAHAMA:
Don't bank so much, it's manual!

(Sasaki grunts)

- Turn it back.
- (grunts) It won't go back.

TAKAHAMA:
Hydraulics are all out.

NARRATOR:
The 747 has four hydraulic systems

that control the rudder, elevator,
ailerons, flaps, and landing gear.

Two booms and no hydraulics.

INVESTIGATOR 1:
Yeah, they had a lot to deal with.

NARRATOR:
For investigators, it's an important clue.

If you lose all your hydraulic
systems on the airplane,

you don't have any control
over the flight controls.

It's no wonder they told ATC
they were uncontrollable.

PURVIS:
So having gone away from the door,

we began focusing
on the aft end of the airplane.

INVESTIGATOR 1:
Somehow, they're all connected.

(tense music)

(indistinct)

Let's try to pinpoint
the cause of the decompression.

NARRATOR:
The team scours the reconstruction

of the tail section
of Japan Airlines Flight 123,

looking for evidence
of what caused the first explosion.

The United States needed
to determine the cause of this accident

because we manufactured the 747.

We were concerned that we had
a structural flaw in the airplane

and others were worried, too.

INVESTIGATOR 1: Okay, let's start
here, the rear pressure bulkhead.

NARRATOR: The rear pressure bulkhead
stands more than four meters high.

Shaped like an umbrella,
it acts like a cork in a champagne bottle,

keeping the cabin pressurized.

Any explosion in the rear of the aircraft
could explain the sudden depressurization.

SCHLEEDE: That's when we decided
we needed to focus on that area,

on the bulkhead
and see what happened there.

NARRATOR: The team recovers the rear
pressure bulkhead from the crash site,

and painstakingly reconstructs it
over several days.

- INVESTIGATOR 1: So this is it, huh?
- INVESTIGATOR 2: Yeah.

At 24,000 feet, that's over a quarter
million pounds of pressure.

That's a lot of force.

PURVIS: The rear pressure bulkhead has
to hold the pressure inside the airplane.

It's got to be very, very strong.
It's got to be failsafe.

And it needs to do its job reliably.

Look, this damage here is from the crash.

These rips are from the plane
slamming into the mountain, yeah?

SCHLEEDE: One of the things
that investigators are trained to do,

and eventually learn to do is to look for
anything that's out of the ordinary.

Check this out.

This isn't crash damage.
This is a rupture.

Yeah. And a clean one at that. Look, it
runs mainly along this line of rivets.

SCHLEEDE:
The straight-line fracture

certainly piqued our curiosity
as to what this was all about.

NARRATOR: Investigators discover
a rupture 41 inches long.

Because of this long,
flat area that we saw,

it made us very curious that this thing
had ruptured instantaneously

and caused this explosive decompression.

(explosions)

(wind gusting)

NARRATOR:
What could have caused the long rupture?

What do you have?

NARRATOR: The team examines a piece of
metal from where the rupture occurred.

Striations. Lots of 'em.

NARRATOR:
Under close examination,

they discover a web
of radiating contours called striations.

They are telltale signs of growing cracks.

SCHLEEDE: Every time a little fatigue
progresses, it leaves a mark.

- What they call striations.
- It's long-term metal fatigue.

Yeah. Every flight, every time
they pressurized the cabin,

those fatigue cracks would have grown.

NARRATOR: If microscopic cracks form
under rivets on the pressure bulkhead,

they would continue to grow
with the forces of the plane

being repeatedly pressurized.

PURVIS: So once the airplane's in service
these cracks start developing.

But they start under the rivet heads
where you can't see them

and even once they progress outside,

they're very difficult to see because
they're only a few millimeters long.

INVESTIGATOR 2: Why did
the cracks form in the first place?

Yeah. The pressure bulkhead
is one of the strongest parts of a 747.

SCHLEEDE: The design philosophy
for the pressure bulkhead

included a failsafe design.

If this rear pressure bulkhead
had a fatigue crack begin,

it would stop 'cause there was
a piece called a crack stopper.

NARRATOR: The rear pressure
bulkhead consists of five bays.

Each bay is separated by a strap or crack
stopper designed to contain a small crack,

preventing it from
spreading to other bays.

So why did this rupture
spread beyond the crack stopper?

NARRATOR: Investigators dig into the
maintenance history of the aircraft.

Maybe this will help.

This plane had a previous accident.

NARRATOR: Seven years earlier, the plane
had an incident landing in Osaka.

It suffered a hard tail strike.

"Severe damage
to the rear pressure bulkhead."

Keep going.

INVESTIGATOR 1: The bottom of the
bulkhead was crushed. Sent for repairs.

PURVIS:
In this Osaka incident,

the airplane's tail
did hit the runway pretty hard

and it wore through the skin
and actually damaged some structure,

including the rear bulkhead.

NARRATOR:
Instead of replacing the entire bulkhead,

Boeing engineers decided to replace
only the damaged lower half.

Once the repair is made,
it should be as strong

or stronger than when the
airplane was originally made.

INVESTIGATOR 1: Well, this is the original
bulkhead. This is the new bulkhead.

Maybe the repair is the issue.

PURVIS: This kind of cracking
in the same area that the repair was,

was really more of a coincidence
than we could have imagined.

So how did you fit the new
bottom to the top of the bulkhead?

NARRATOR: Investigators
look into the 1978 repair more closely.

That was a really big job.

(drill whirring)

NARRATOR: Technicians worked around
the clock for eight days inside the plane

to mount and secure a new lower
bulkhead to the upper section.

Did you notice
anything out of the ordinary?

There was only one small thing.

(grunts) Now just a little higher.

NARRATOR: During the repair,
technicians had difficulty

- connecting the upper to the lower pieces.
- There's not enough overlap.

What do you mean?

We had trouble fitting the overlap
at the nine o'clock position.

NARRATOR: The difficulties with the repair
match exactly where the bulkhead failed.

Okay, thanks for your help.

NARRATOR: Investigators are now
confident that the repair seven years ago

is connected to the crash.

(sighs) Now we're getting somewhere.

INVESTIGATOR 2:
Okay, normally, the top and bottom

are held together
with two rows of rivets, yeah?

NARRATOR:
Investigators scrutinize the repair job

to Flight 123's pressure bulkhead.

Right, and they did that everywhere,
except for right here.

SCHLEEDE: One area of the bulkhead,
the skin did not overlap enough.

Boeing had to design a patch,
a repair. It was called a splice.

NARRATOR: Without enough space
for two rows of rivets in the overlap,

a separate splice plate
is attached over the area.

But only one row of rivets
showed signs of metal fatigue.

It's hard to tell how the repair was done.

We knew that there was
supposed to be a splice plate there.

But it was evident to me that there was
just one row of rivets taking up the load.

It didn't look right.

They used two different splice plates.

And by using two different splice
plates, it compromised the repair.

NARRATOR:
Investigators discover the repair team

cut the splice plate in two,
perhaps for easier installation.

The lower plate helped secure the
overlap. The upper plate did not.

SCHLEEDE: That one row of rivets
was insufficient to sustain the loads

and eventually fatigue cracks started
and the hull section failed.

The fracture followed the gap
between the two splice plates.

SMITH: This particular 747-SR
had accumulated over 18,000 cycles

in its 12-year career with JAL.
That's just an astonishing number.

(engines powering up)
V1.

Rotate.

SMITH: Each one of those cycles,
each one of those takeoffs and landings

meant pressurization
and depressurization cycles.

PURVIS:
The rear bulkhead now had a weak spot.

It was sort of like a ticking
time bomb ready to fail.

That's it. That's gotta be it.

SCHLEEDE: It's what investigators
call the golden nugget.

We found the,
"Aha, that's the cause."

PURVIS: There is no question
that, if done correctly,

the repair would not have failed.

NARRATOR: Investigators have discovered
what caused the rapid decompression,

but they still need to understand
why the tail detached.

INVESTIGATOR 1:
The bulkhead ruptures here.

And all that pressurized cabin air
has gotta go somewhere.

Now, the shock wave flows up the tail

and it must have just popped off
like a champagne cork.

The first boom was the
failure of the bulkhead…

(explosions)

…and the second one was after the
vertical tail pressurized and it failed.

(alarms wailing)

(wind gusting)

Hey. Check this out. All four hydraulic
lines run through the tail section.

INVESTIGATOR 1:
So when the decompression happens,

not only do they lose a chunk of that
tail, they lose all those lines as well.

SCHLEEDE: In this case, all four
hydraulic lines went up the vertical fin.

So that was a poor design.

SMITH: It was just considered
so unlikely, so inconceivable

that all four systems
would in some way be disabled.

But that's exactly what happened.

NARRATOR:
It's a design flaw

that rendered the rest of the plane's
flight controls useless.

- TAKAHAMA: Don't bank so much.
- (grunts) Okay.

TAKAHAMA:
(yells) Don't bank so much.

Hydraulic pressure has dropped.

NARRATOR: Without any hydraulics
to control elevators, rudder, or ailerons,

Flight 123 flew an erratic flight
path for 32 terrifying minutes.

GPWS:
Sink rate. Pull up.

- TAKAHAMA: Raise the nose.
- GPWS: Terrain.

TAKAHAMA (yells): Raise the nose!
(Sasaki grunts)

GPWS:
Don't sink.

NARRATOR: The two pilots used
all their strength to regain control.

- I can't hold it much longer! (grunts)
- NARRATOR: But nothing worked.

- (yells) Flaps up. Flaps up!
- GPWS: Sink rate. Pull up.

FUKUDA (yells):
Flaps up!

- TAKAHAMA: Raise the nose!
- GPWS: Pull up. Terrain.

- TAKAHAMA: Power!
- GPWS: Pull up.

NARRATOR: What began as a repair
seven years earlier,

set the stage for a devastating crash…

that took the lives of 520 people,

the worst single aircraft
accident of all time.

INVESTIGATOR 1: The initiation
and propagation of the fatigue crack…

NARRATOR: A series of
recommendations takes direct aim

at the original 747 design.

Operators are ordered
to install a cover in the tail

to protect the vertical fin
against a bulkhead decompression.

INVESTIGATOR 1:
…the improper repair that was…

NARRATOR: Emergency cut off
valves are also recommended

to prevent a total loss
of hydraulic pressure.

SCHLEEDE:
One way they can do this

is to put what they call fuses
in a hydraulic system.

If you cut the line, the hydraulic fluid
would be trapped in the rest of the line,

and they were installed on the 747.

NARRATOR: Today, hydraulic fuses are used
on almost every commercial airliner.

PURVIS: This accident was
a watershed moment in aviation safety.

It pointed out a lot of areas
that not only the 747,

but other airplanes flying,
could be improved,

right then and for the future,
and for future designs.