All language subtitles for M.2003-S23E06-Cockpit.Catastrophe.Sichuan.Airlines.Flight.8633.WEBDL-1080pEAC3.5.1h264-PiTBULL_track4_[eng]

(tense music)

NARRATOR:
High above the Himalayas…

(cracks)

The windshield of Sichuan
Airlines Flight 8633 cracks.

It’s on the inside.
That’s not good.

NARRATOR: And then gives way completely.
(explosion)

(shattering)

NANCE: It’s almost like having a
bomb explode right beside you.

NARRATOR: The decompression forces the
first officer halfway out of the plane.

LIU (yells):
Xu!

NARRATOR: In freezing temperatures
and rapidly running out of oxygen,

the captain needs to find a
way to get his plane to safety.

Useful consciousness
is probably about 40 seconds.

NARRATOR: The lives of everyone onboard
now rest in the hands of one man.

I’m just so, so cold.

PILOT (over radio):
Mayday! Mayday!

(alarm blaring)
GPWS: Pull up! Pull up!

(indistinct radio chatter)

(engine roaring)

NARRATOR:
High above central China,

Sichuan Airlines Flight 8633
reaches cruising altitude.

Level at 321.

Roger.

NARRATOR:
45-year-old Captain Liu Chuanjian

is a highly experienced former
military pilot and a flight instructor.

We’re approaching an area of turbulence.

It shouldn’t be too rough.

NARRATOR:
First Officer Xu Ruichen is 27-years-old

and has five years of flying experience,
four of them with Sichuan Airlines.

The crew is flying an Airbus A319.

NANCE: The A319 is part
of the Airbus A320 series.

It's a little bit shorter,
a little bit lighter,

but with still two very powerful engines,

very well suited for taking a heavy
load out of a high-altitude airport

where your weight and
balance is extremely critical.

NARRATOR:
There are 119 passengers on board.

Many catch up on lost sleep after
an early morning departure.

It should be a smooth
ride from here to Lhasa.

NARRATOR: The plane took
off from Chongqing Airport.

It’s a two hour and 40-minute flight to
Lhasa, tucked in the Himalayan Mountains.

They’re flying into Lhasa, which is one of
the most demanding airports in the world.

It’s not a dangerous airport,

if you follow the rules and you
watch the weather carefully.

NARRATOR: Captain Liang Peng
is the second in command.

- I’ll be back well before landing.
- See you then.

NARRATOR:
He’s been a pilot for ten years.

Today, he’ll assist with the
high-altitude landing in Lhasa,

which involves more
challenging procedures.

PETCHENIK:
This particular flight had three pilots;

a captain, a first officer,
and a secondary captain,

because the aircraft was landing at
a higher elevation airport

and those require specific procedures.

When you’re flying into
a high-altitude airport,

you’re worried about performance issues

and you’re also concerned about the
approach path through the mountains.

All three of the pilots involved here were
very experienced with high altitude,

captain especially.

NARRATOR: There are five
flight attendants on board.

Among them, Bi Nan, who’s been
with Sichuan Airlines for 11 years.

Six minutes after
reaching cruising altitude,

Flight 8633 crosses
into the Tibetan Plateau,

the largest and highest plateau on Earth.

The altitudes are way above 20,000 feet,

not just for the peaks,
but the plateau itself.

Chengdu Control, Sichuan 8633, reporting
crossing Mikos Bravo 213.

Chengdu Control, roger. Sichuan
8633 at Mikos Bravo 213.

Not a cloud in the sky.

NARRATOR:
40 minutes into the flight…

(cracks)

(tense music)

XU:
The windshield is cracked.

(beeps)

LIU:
You got the checklist?

NARRATOR: Just as First Officer Xu finds
the checklist, the situation deteriorates.

(cracks)

One of the procedures is
to run your finger lightly over it,

and see if you can feel any bumps,

and try to figure out is this
external or an internal crack.

It’s on the inside. That’s not good.

NARRATOR: A crack on the inner pane makes
the windshield vulnerable to shattering.

Sir, it says here
descend to a lower altitude.

CURTIS: The windshield of an aircraft
actually has several layers of glass,

and this was the inner
pane that was cracked.

The safe thing to do is
divert to a safe landing zone.

It’s what we call a precautionary
emergency, but it’s still very important.

I have control. I have the radios.

Chengdu, Chengdu, Sichuan 8633.
We have a malfunction.

LIU:
Requesting descent to a lower altitude.

Sichuan 8633, descend to flight level 280.

28,000 feet. I’m turning back.
We have a cracked right windshield.

Sichuan 8633. Got it. Confirm…
You have a broken windshield?

Affirmative.

Sichuan 8633, confirm will
you divert to Chongqing?

Negative. We must divert to Chengdu.
The window crack is severe.

Confirm, you will divert to Chengdu.

NARRATOR:
As the pilots begin their descent…

Affirmative. We…

(explosion)

NARRATOR:
…the cracked windscreen explodes,

sucking the first officer
partially out of the window.

(beeping)

NANCE: The sound and fury of
losing a windshield is something

like almost having a bomb
explode right beside you

without it doing you any physical damage.
It is soul shaking, to say the least.

(beeping)

All of the high pressure wants
to go to the low pressure air.

So anything that isn't attached is going
to want to escape through that hole,

including a human being.

(beeping)

(screaming)

(gusting wind)

Sichuan 8633, roger. Descend
and maintain flight level 280.

NARRATOR: As the aircraft
dives toward the mountains,

the first officer hangs on
at 32,000 feet above the Earth.

When the first officer was pulled forward,

he impacted the sidestick, and that pushed
the aircraft down and to the right.

This flight is over high terrain,

so it has a much higher probability
of impacting terrain more quickly.

NARRATOR: On the ground, the controller
notices a sudden shift in altitude.

ATC:
Sichuan 8633?

NARRATOR: With no time to review all the
warnings, the captain returns to basics.

He begins to fly the plane manually.

There were a number of different warnings
happening at the exact same time.

But the most important
thing is to fly the airplane,

focus on maintaining a safe altitude.

(beeping)

NARRATOR: Captain Liu regains
some control and levels the plane.

But he’s facing oxygen deprivation
from the rapid decompression.

PETCHENIK: In the case of an explosive
decompression at cruise altitude,

hypoxia will set in fairly quickly.

NARRATOR: As it’s stowed in a compartment
to the left and behind the pilot’s seat,

Captain Liu can’t reach his
mask with his right hand.

His left hand must
remain on the sidestick.

(dramatic music)

At about 31,000 feet, the
time of useful consciousness

is probably about 40 seconds
for a healthy individual.

This is something that you can't play
around with, because it is lethal.

NARRATOR: The captain can’t
get his first officer back in.

He’s on his own.

The former fighter pilot knows if he
can’t make a rapid descent,

there’s no hope of saving his passengers,

and his helpless first officer.

(dramatic music)

Immediately after Flight 8633’s
cockpit windshield shatters,

Captain Liu tries
to return to Chengdu Airport.

PETCHENIK:
This is an incredibly stressful situation.

The first officer has been partially
sucked out of the aircraft.

The captain needs to get down to breathe.

But the mountains are higher
than that breathable oxygen.

NARRATOR: To get out
of the mountains quickly,

the captain puts the Airbus
into a sharp, descending left turn.

In a emergency situation, the pilots
going to maneuver the aircraft outside

what would normally
be an acceptable envelope.

(gusting wind)

(yells) Xu! Can you get back on your own?
I can’t let go of the control stick!

After the first officer is
sucked out of the windscreen,

he’s trying to get back into the aircraft.

NARRATOR:
61 seconds after the windshield explodes,

the pressure between the internal
and external air equalizes.

Once the pressure equalizes
between the flight deck

and the exterior of the aircraft,

the first officer is able to bring
himself back into the aircraft.

Xu! Xu! Are you okay?

Get your harness!

NARRATOR:
With the pressure equalized,

the airstream reverses, and an
ice-cold wind comes rushing in.

Your mask too!

NARRATOR: High winds hamper
the first officer’s efforts.

If you’re flying at 30,000 feet,
it could be 40 degrees below zero.

So you have not only the extreme cold,

you also have the extreme pressure
of the wind coming in at you.

(gusting wind)

NARRATOR: With the first
officer safely back inside,

the captain accelerates his descent
to the airport, 71 miles away.

Can you reach the transponder?

NARRATOR: Liu wants to notify air
traffic control of their emergency.

(tense music)

(beeping)

When an aircraft squawks
7700 on the transponder,

it identifies the air
traffic controllers in the area

something is wrong and
that aircraft needs priority.

Sichuan 8633, what is
the nature of your emergency?

Sichuan 8633?

Tibet 9832, Chengdu.

NARRATOR: The controller
contacts other pilots for help.

PILOT:
Tibet 9832. Go ahead.

Could you call Sichuan 8633 on the
frequency? They’ve got an emergency.

Let’s see if you can get through.

PILOT:
All right.

Sichuan 8633, this is Tibet 9832.
Chengdu control is calling you.

NARRATOR: In the cabin, Captain Liang
retrieves his electronic flight bag.

HAUETER: The electronic flight
bag on the aircraft provided

the crew with the escape
routes they could fly

to get to lower altitudes
in the mountains.

(gusting wind)

- Give me a hand with the navigation!
- LIANG (yells): Copy.

Your mask.

I’m good for now.
I can’t let go of the controls.

LIANG:
Altitude is 23,700.

NARRATOR:
As the plane nears the lowest altitude

it can fly over mountainous
terrain, the captain levels off.

- LIU: Speed?
- LIANG: 297 knots.

The cabin has oxygen masks.
Bi Nan is in charge.

- Xu? Can you hear me? Are you hurt?
- I’ll perform the FO duties.

NARRATOR: With First Officer
Xu too injured to assist,

Relief Captain Liang
takes over his duties.

- Got the escape chart?
- LIANG: On it.

NARRATOR:
Captain Liang checks the charts

for the safest exit route
over the mountains.

LIANG: Chengdu is 63 miles away.
Continue descent at 500 feet per minute,

then level at 22,000
until we clear the mountains.

(stutters) Copy.

LIANG:
I’ll call the altitudes.

The second in command can see
that the captain is handling this.

But there are things that have to be done,

and one of them is making
sure that they don't go too low.

NARRATOR: The Airbus reaches 23,400
feet and is nearly out of the mountains.

LIANG:
You can do it.

I’m just so, so cold.

NARRATOR: Captain Liu is fearless. But
at this altitude, he risks hypothermia,

and the airport is still 60 miles away.

(dramatic music)

NARRATOR: 12 minutes
after a rapid decompression,

Flight 8633 clears the
towering Tibetan Plateau.

LIANG: 34 miles to the airport!
Getting there, Captain.

NARRATOR: Captain Liu turns
the plane towards the airport.

LIANG:
Altitude is 20,900.

(stutters) Copy.

CURTIS: They were able to get beyond
the mountains. Then other concerns.

Do we communicate with air traffic
control? Do we set up for the landing?

LIANG: Chengdu, Sichuan 8633.
Mayday. Mayday. Mayday.

Message received. Mayday declared.

Sichuan 8633 cleared to
descend to flight level 190.

Siberia 581, climb to flight
level 250, off-set three miles.

NARRATOR: The controller clears the
airspace around the damaged airplane.

West China 6271, maintain flight
level 160 and off-set three miles.

(tense music)
(rattling)

NARRATOR: In the cabin,
Bi Nan tries to contact the crew.

PETCHENIK: The flight
attendants are doing their best

to ensure that the cabin is calm,
everyone has their supplemental oxygen.

But one of the complicating events here

is they never get into communication
with the flight deck,

to understand the full
scope of the situation.

NARRATOR: Flight 8633 is
now 28 miles from Chengdu.

Approaching 19,000 feet.

NARRATOR: The captain
can breathe a little better now.

Roger. Roger.

Hang in there Xu.

Sichuan 8633.

Cabin depressurization. Flying direct to
Chengdu, then descending to… 10,500 feet.

Flying direct to Chengdu,
then descending to 10,500 feet.

PETCHENIK:
The crew's transmitting in the blind

because they’re trying to tell
air traffic control their intentions,

but they can't hear anything
that air traffic control is saying

because of all of the noise coming
in from that missing window.

Look over the warnings.

NARRATOR: As the flight makes
its way towards the airport,

the pilots assess the
state of their aircraft.

The captain knows the windscreen is gone.
He knows that the control panel is gone,

but he doesn't know exactly what else
has been damaged on the aircraft.

LIANG: Auto-brakes are gone.
Anti-skids, spoilers, APU.

They’ve all got warnings.

NARRATOR: With so many
instruments potentially inoperative,

the landing must be performed manually.

This was a highly automated aircraft.

When you have damage
like in this incident,

that automation is taken offline.

And they have to figure
out how to land the airplane.

LIU:
Okay. Okay.

LIANG:
Do you want to try the autopilot?

Too risky.

NARRATOR: Re-engaging
disabled instruments

is a gamble Captain
Liu isn’t willing to take.

He could lose what little
control he has over the plane.

NANCE: That is great airmanship to
just take what he has and work with it.

Because in an emergency, you don't
know exactly what you’re gonna get.

Sichuan 8633, orbit to the
right and descend 8,800 feet

on QNH 1004 at present position.
You’re cleared to land on runway zero two.

NARRATOR: Flight 8633 makes a
360 degree turn to lose altitude

while preparing for landing.

- LIANG: 11,200 feet.
- LIU: Copy.

We’re still above our
maximum landing weight.

LIANG:
We’re heavy by half a ton.

NARRATOR: The pilots must factor in
the extra weight of their unused fuel

as they prepare to
configure the plane for landing.

An overweight landing on an Airbus
A319 where you can't dump fuel

means that you’ve
got to be much more careful

in terms of actually touching down.

You may have more difficulty
stopping the airplane.

Flaps one!

NARRATOR: They don’t know yet if
deploying the flaps will slow the plane.

LIANG:
Flaps one set.

Yes!

- The flaps are working so far!
- Good. Speed?

LIANG:
212 knots.

LIU:
Reducing to 203.

NARRATOR:
The pilots slow the engines further.

(tense music)

Bi Nan can sense that the plane
is approaching the airport.

Attention everyone.
Please remove your masks.

NARRATOR: She prepares the
cabin for an emergency landing.

Tuck your head in your
lap and brace for impact.

Landing gear!

LIANG:
Roger. Landing gear.

NARRATOR:
So far, the plane is slowing.

The pilots still don’t know if
the landing gear will engage.

Yes! Landing gear is down.

Cleared to land on runway zero two, right.
Wind 250 at two meters per second,

R-V-R greater than 6,500 feet.

We need the whole runway.

Sichuan 8633. Runway zero two right.
We need the entire runway.

PETCHENIK:
The captain selected that runway

to account for the fact
that the aircraft is heavier,

and therefore is requiring
more stopping distance.

NARRATOR: Ten miles from the airport,
the aircraft is lined up with the runway.

160 knots.

After everything that’s happened,
can they keep it on the runway?

(tense music)

50 feet! 40 feet!

NARRATOR: The 63-ton
plane prepares to touch down.

(tires screech)

Engaging thrust reversers.

NARRATOR: The thrust reversers, which help
the plane slow down, aren’t functioning.

The risk is that you’re
gonna run off the end of the runway

- if you don’t have your thrust reversers.
- Brakes! Brakes!

NARRATOR: Captain Liu gives the
foot brakes everything he’s got.

They’re his last hope of stopping the
plane from overshooting the runway.

(sighs)

We made it.

(applause)

(gasping)

Sichuan 8633, we have injuries on
board and cannot taxi to the gate.

NARRATOR:
Against tremendous odds,

everyone on board Sichuan 8633
is safely back on the ground

thanks to the pilots’ exceptional skills.

CURTIS: Once everyone was
able to exit the aircraft safely,

the real work of the investigation began.

What evidence can they find that
will help them answer the question:

Why did this happen?

(cool music)

NARRATOR: Investigators from the Civil
Aviation Administration of China,

or CAAC, look into
Sichuan 8633’s near catastrophe.

- Good to see you again.
- You as well.

- Do you wanna look at the cockpit?
- That’d be good.

NARRATOR:
A French investigator from the

Bureau of Air Accident Investigation
and Analysis, or BEA, also joins the team.

Okay. I’ll speak with Captain Liu while
one of our team takes you to the plane.

Great. Thanks.

HAUETER:
The aircraft is made in France.

The BEA, as the investigative
agency for that country,

would respond to an accident worldwide.

Thank you for coming in.
Oh, please, have a seat.

NARRATOR: Did something strike
the windshield of Flight 8633,

causing it to rupture?

LIU: It was a clear day. We were
cruising along at 32,100 feet.

About ten minutes in, we heard a loud
noise and saw a big mesh crack.

And then?

A few seconds later, another loud
noise and the crack radiated further.

I touched the glass. And I could tell it
was on the inner pane, and it was bad.

NARRATOR: A cockpit windshield
is made up of three layers of glass;

two thick inner panes
and one thin outer pane.

HAUETER: The windshield's actually
a structural part of the airplane.

They’re quite thick. They’re very strong.

Obviously they’re made to withstand your
bird strikes and other objects like that.

- LIU: I called ATC to clear descent.
- You told them the windshield was cracked?

Yes, but before we finished
talking, the window exploded.

A decompression happened and
we lost a bunch of instruments.

Did you see anything hit the windshield?

No. There was no mark, no smear,
just a big mesh-like crack.

Okay. Thank you. If I have
more questions, I’ll reach out.

NARRATOR:
Investigators rule out an external strike

as the cause of the
windshield’s explosion.

Thanks for your time.

HAUETER: There’s no evidence of lightning
strike or birds or anything else.

So there was nothing to
show that that piece of the windshield

was damaged prior to the event.

- Any signs of how the crack started?
- Not really.

Almost everything was
sucked out of the windshield.

- (hums)
- Except this.

The terminal block.

NARRATOR: Located at the
bottom of the windshield,

the terminal block holds
six electrical wires

that control the temperature to
prevent freezing or fogging.

The team is dismantling it from the
frame so we can take a closer look.

Okay.

The investigators
focused on the terminal block

because it was the only part of the
windscreen assembly that they had left.

INVESTIGATOR:
Let’s download the data now.

NARRATOR: While investigators
wait for the terminal block

to be removed from the plane,

they turn to one of the flight’s
communication systems for leads.

A digital communications
system called ACARS,

or Aircraft Communication
Addressing and Reporting System,

sends electronic messages
between the aircraft

and ground stations during a flight.

ACARS messages coming from the aircraft

can lead the investigators
to certain faults that occurred

as well as what the aircraft was doing.

It’s all here.
Let’s locate the first crack.

Here it is. 7:07 am.

See that?

Anti-ice right windshield.
Huh. Interesting.

NARRATOR: Investigators discover
that after the windshield first cracked,

there was a warning message.
(beeps)

The anti-ice message
gives you an indication

that there is something wrong with the
heating element in the windscreen,

but it doesn't exactly tell you why.

CURTIS: The windshield cracking and the
warning happened almost simultaneously.

The investigators had to think
there has to be a connection.

Let’s check recent flights.

NARRATOR: Has an anti-ice windshield
warning appeared on other flights?

Investigators search the fleet’s history.

Check this out.

2009, the warning popped up on
a Sichuan Airlines flight after takeoff.

NARRATOR:
In 2009, the warning also appeared

as Jiangsu Airlines pilots detected smoke
near the bottom of their windshield.

In 2010, the warning lit up
on a China Hubei flight

when pilots noticed a burning
smell near the windscreen.

- Did they determine a cause?
- Overheating. In all three cases.

Investigators saw that
in related incidents

where this kind of warning came up,
there were certain effects,

burning smells, anything that indicated
there was an overheating happening.

What about the windshields?
Did any of them crack or rupture?

INVESTIGATOR:
No. It doesn’t look like it.

Sichuan 8633 never reported smoke.

Nor the smell of burning.

CURTIS:
The investigators knew

there was a problem with the
right windshield heating system.

So what was different about this incident?

Let’s see what the
terminal block can tell us.

NARRATOR:
Investigators turn to physical evidence

from Sichuan Airlines 8633’s cockpit for
clues as to why the windshield shattered.

Check out these wires.

CURTIS: The windshield heating
system is electrically driven

and there are several wires
through the terminal block

that help drive this system.

One of those wires looked a lot
more damaged than the others.

Huh. It looks like the wire insulation is
charred and the copper wire is melted.

NARRATOR: The team finds
evidence of overheating.

They noticed that one of
the wires was very dark,

which is a sign of carbonization.

HAUETER: They could see evidence
of burning heat around the end of it.

INVESTIGATOR 2: Look at the
corrosion inside the terminal block.

NARRATOR: Investigators also
find evidence of moisture build up.

Water must have seeped in
past the window seals.

They discover signs of
moisture and humidity

and even unusual color you should
not see inside a terminal block.

NARRATOR:
Moisture inside the terminal block

corroded and damaged the copper wires.

When a current ran
through them, arcing occurred,

which created extremely high temperatures.

(cracks)

HAUETER: You’re reading temperatures
in excess of 400 degrees Celsius.

It's extremely hot.

CURTIS:
The investigators had to answer:

Was this enough to
make the windshield crack?

NARRATOR: Investigators dig into
the history of the aircraft,

looking for a connection between cracked
windshields and overheating.

Got one. An A340, December 1997.

I found four more.

2001, 2004, 2007 and 2011.

Here’s another one from 2009.

NARRATOR: They discover six incidents of
double pane cracks in cockpit windshields.

Every single incident
resulted from overheating.

The heat built up inside the
windshield and couldn’t dissipate.

Which is why the windows cracked.

NARRATOR: The team concludes
that an overheated electrical wire

inside the windshield cracked the inner
pane of glass on the first officer’s side.

CURTIS: The aircraft windshield
panes are very closely spaced together,

and when one side is overheated
it spreads those panes apart.

It causes stresses on those panes.

NARRATOR:
But a windshield cracking

is vastly different from completely
separating from the aircraft.

How did Sichuan 8633’s windshield explode?

HAUETER:
We know the first pane cracked.

The middle pane should have
maintained loads and kept this intact.

But it failed very quickly.
That was a mystery.

NARRATOR: To determine why Sichuan
8633’s windshield ruptured after cracking,

the team undertakes a
Windshield Failure Scenario test.

CURTIS: The mechanism of what happened
in-flight to that windshield is unknown,

because they didn't
recover the windshield.

What they could do and what they did do

was to do a laboratory test to see
if you can have a catastrophic failure.

NARRATOR: They install a cockpit
windshield with a cracked inner pane

onto a test bench,
replicating the first crack.

(grunts) Okay, the window’s ready.

The camera is now recording.

(air hissing)

Now pressurizing.

NARRATOR: The investigators
set the test chamber

to the same differential
pressure of Flight 8633.

Let’s get the shot pin ready.

NARRATOR: A small hole is
drilled in the outer pane,

through which a shot pin can
pass and strike the inner pane

in order to simulate
the second pane cracking.

All set.

(tense music)

(explosion)
(shatter)

(sighs)

NARRATOR: The test works. The
windshield is blown clear of the frame.

Well, there you have it.

INVESTIGATOR:
The pressure was just too much.

NARRATOR: At 32,000 feet,
the difference in pressure

between the outside atmosphere and inside
the cockpit was approximately two tons.

Investigators conclude that
the cracked windshield

could not withstand that pressure.

What we saw from testing is once you
break the inner pane and the middle pane,

the outer pane cannot
withstand the pressure.

It’s going to flex the window out
and it’s going to depart the aircraft.

(engine roars)
(explosion)

- Here you go.
- Thank you.

NARRATOR: Investigators now know how
the windshield was blown from Flight 8633.

But they still don’t understand

why the moisture build-up inside
the window was undetected.

Moisture’s insidious.
It’s gonna find ways to get in.

So now the question is when they were
inspected, how they were inspected?

The left and right window
seals were replaced a year ago

because of wind erosion.

NARRATOR: Investigators
examine the inspection history

of Flight 8633’s windshields.

That’s right. Flip the page.

The last inspection was 32
days before the incident

and there were no signs of water buildup
on the terminal block. How come?

Maintenance would have had to remove
the entire windshield to access it.

They'll look around the edge to see are
the seals intact, are the seals degraded.

You look at components to see if there’s
any evidence of water intrusion.

But you don't pull the
window out of the frame.

So without fully
disassembling the aircraft,

you can't ensure that you
don't have water vapor built up.

NARRATOR:
But that’s not all they discover.

There were no sensors to detect moisture.

HAUETER: You have sensors for
controlling the temperature of the window,

but there’s nothing in there to
tell you that corrosion’s present.

NARRATOR: Even though
investigators understand

what caused the incident
aboard Flight 8633…

You know what I don’t get?

NARRATOR:
There’s one piece of the puzzle missing.

Why did so many systems in the cockpit
fail after the windshield exploded?

(engine roars)
(explosion)

(gusting wind)

(beeping)

With the loss of the windscreen,

also came a whole list of things
that went off. It was puzzling.

They lost the auto-brakes, six of the
ten spoilers, the thrust reversers.

NARRATOR: Investigators review all the
systems the pilots of Flight 8633 lost

after the explosive decompression.

(hums)

It looks like they were
disabled, not damaged.

NARRATOR: The team discovers that all
the disabled systems on Flight 8633

are connected to 17 circuit breakers on
a panel behind the first officer’s seat.

Check out all these popped breakers.

INVESTIGATOR 2: Something
must have hit the breaker panel

during the decompression.

INVESTIGATOR:
There’s damage here.

This part of the door
lines up with the damage.

NARRATOR: The damage to the
panel is at the same height

as the dented cockpit door.

(explosion)
When the windshield ruptured,

the explosive decompression
flung open the cockpit door,

which smashed the circuit panel
and popped multiple breakers.

It’s almost impossible to think that
anybody would immediately recognize

that that was a mechanical
response to the door blowing open

and hitting the side panel.

NARRATOR: Investigators finally
have all the pieces of the puzzle.

Moisture seeped into the window
seals of the Airbus A319…

You couldn’t ask for a better view.

NARRATOR: Creating a humid environment
where electrical wires overheated…

(cracks)

…to the point of cracking the glass
panes on the cockpit windshield.

Sichuan 8633, confirm
will you divert to Chongqing?

Negative. We must divert to Chengdu.
The window crack is severe.

NARRATOR:
The tremendous pressure differential

compounded the existing thermal
stress on the cracked panes,

leading to the rupture
and explosive decompression.

With his first officer
sucked out of the window,

Captain Liu’s quick
thinking, flying skills,

and tremendous courage in
the face of oxygen deprivation

allowed him to fly
the plane out of danger.

The captain didn't suffer from hypoxia.

Investigators looked at
the surrounding factors,

and kind of came to the
conclusion that he was operating

purely on adrenaline, basically, and was
able to operate the aircraft safely

down to Chengdu.

LIANG:
You can do it.

NARRATOR: The crew
endured glacial temperatures

and battled the odds to safely
land the damaged plane

and save the lives of
all 128 people on board.

Any accident and incident investigation
is also learning opportunity.

There were changes that were
made by the manufacturer

to tighten up the quality control
to make it less likely

that you would have situations that might
allow moisture to get past the seals.

NARRATOR:
The crew’s handling of the incident

earned them accolades around the world.

There have been accidents
in the past where

whatever happened at
altitude was survivable,

but the crew got so rattled
and was so non-communicative,

they end up crashing the
airplane on the other end.

This crew did a really excellent job.