All language subtitles for Air.Disasters.S05E08.Imperfect.Pitch.1080p.PMTP.WEB-DL.AAC2.0.H.264-maldini_track3_[eng]

Pilot: Better buckle up.

Narrator: An expert crew...

Pilot: No worries.

Man: The team
was very experienced.

Narrator: Pushes a commercial
airliner to the limit.

Pilot: We need to overspeed.

Man: It's a very
challenging environment.

Pilot: Hands off now.

Narrator:
Did they go too far...

Controller:
They wanted to do some 360s.

Pilot: It's pitching up
all the time.

Man: Does that seem right
to you guys?

Narrator: ...and put their plane
on a deadly flight path?

Pilot: Damn it!

Narrator: Investigators
face a terrifying mystery.

Man: Why didn't
the stall protection kick in?

Narrator: Why did one of the
world's most advanced aircraft

fall from the sky?

And how can they stop it
from happening again?

Flight Attendant:
Ladies and gentlemen,
we are starting our approach.

Pilot: We lost both engines!

Flight Attendant:
Put the mask over your nose.

Emergency descent.

Pilot: Mayday, mayday.

Flight Attendant:
Brace for impact!

Controller: I think I lost one.

Man: Investigation starting...

Man: He's gonna crash!

Narrator: Perinea Airport
in southern France.

Air New Zealand engineers

are getting ready
for an unusual flight.

Pilot: Gentlemen,
good afternoon.

Find any problems
under the hood?

Narrator: They've spent
the last three weeks

giving the A320
a complete maintenance check.

Man: Everything looks good.
You won't have any problems.

Narrator:
Now Captain Norbert Kaeppel

is going to put
its automated systems

to the test in the air.

Norbert Kaeppel:
Looks like it's my turn.

Narrator: XL Airways Germany

has been leasing the A320
from Air New Zealand,

but a fresh coat of paint now
displays its owner's colors.

There's just one more step

before XL can
give the plane back.

Kaeppel: Better buckle up.

The cabin is clear.

Narrator: Before XL Airways

returns the plane
to Air New Zealand,

it must demonstrate
that the plane

is in perfect working order.

John cox: It's very similar
to returning a car off lease

where the dealership
will take the car,

they'll let maintenance
look at it,

make sure that it hasn't
been in an accident,

that it hasn't been
abused in some way,

and that the systems
actually work as designed.

Controller: Triple 8 tango,
how many minutes do you need?

Narrator: Captain Kaeppel
from XL Airways Germany

will be flying the plane.

Kaeppel: Two minutes.

Narrator: His colleague,
First Officer Theodore Ketzer,

will help monitor
the instruments.

Theodore Ketzer:
Two minutes we'll be ready.

Narrator: Also on board,

Captain Brian Horrell
of Air New Zealand.

He'll be guiding
the German pilots

through a series
of 35 in-flight tests

that make up what's known
as an acceptance flight.

Cox: An acceptance flight

is a flight where a crew,
a specially trained crew,

will take the airplane out
and exercise all the systems,

including the alternate systems.

Controller: Ok, triple 8 tango,
departure is three-November.

Kaeppel: Three-November.
Do you have that?

Cox: The test director
and the pilots

go through the test plan

and agree, step by step,
what they're going to do.

It is a very intense
period of time

because you have a lot to do
in a short period of time.

Controller: Triple 8 tango,

cleared for takeoff,
runway 3-3.

Narrator: There are
no regular passengers

on this kind of flight,

but three engineers

and an aviation official
from New Zealand

are along for the ride.

When the test is complete,

they'll stay on board for
the flight home to New Zealand.

Cox: They are about to inherit

the maintenance responsibility
for this aircraft.

So having engineers
very close to the airplane

for an extended period of time

is good business,
it's good safety.

It's the way it should be done.

Narrator: For Air New Zealand,
a successful acceptance flight

is the key to getting this A320
back into commercial service

as soon as possible.

Ketzer: V-1.

Rotate.

Narrator: The Airbus A320

is one of the most automated
passenger planes in the world.

Its advanced computer systems
handle most of the flying,

reducing the possibility
of pilot error.

Cox: It is different than a lot
of conventional airplanes

in that you fly it
through a computer.

But the handling characteristics
of the airplane

are very, very good.

Narrator: The first test...

Ketzer: Gear up.

Narrator: Checks the system
that stows the landing gear.

Horrell: Time.

Narrator: They need to make sure
the gear locks into place

within a specific
length of time.

Horrell: 14 seconds is good.

Controller:
Triple 8 tango, bonjour.

Climb level 1-8-0.

Narrator: A new controller
in Bordeaux takes over

as flight 888 leaves
Perpignan airspace.

Ketzer:
Climbing flight level 1-8-0.

Narrator: The flight plan
calls for a 2 1/2-hour trip

that reaches
the west coast of France

before looping back
to Perpignan.

The route should
provide an opportunity

to test nearly every system.

Kaeppel: Do you need anything
from us while we climb?

Horrell: It just says to climb
to flight level 3-1-0.

And bank angle to 33.

Check that it holds
the bank angle.

And beyond 33
that it rolls back.

Narrator:
Horrell asks the pilots

to bank the plane
into a steep turn.

Kaeppel: Ok.

Narrator:
The captain needs permission to
turn so dramatically off course.

Kaeppel: I'll talk to them.

Triple 8 tango, just be advised,
could we do one or two 360s?

We're an acceptance flight

so it would be nice if you
could give us some airspace

to do a few procedures.

Narrator: The controller
doesn't think it's safe.

Controller: We cannot allow test
flights in general air traffic.

We are not doing
this kind of flight, sir.

Kaeppel: Ok. Um...

So, the flight was actually
requested like that.

Cox: European airspace
has got a lot of airplanes

moving in a variety
of directions.

If there is conflicting
traffic around them,

then the air traffic controller

has no choice
but to deny the request.

Narrator:
Captain Kaeppel doesn't argue.

Kaeppel: So, no worries.

We'll just go back to Perpignan.

Cox: There is probably
a very minor annoyance level,

but professional airmen
are adaptive people by nature,

and so we'll adapt to it
and we'll pick this up later.

Controller: Triple 8 tango,

descend flight level 3-1-0
and turn right.

Kaeppel: Turning right inbound,
triple 8 tango.

Narrator: The Airbus will now
loop back east of Bordeaux

and return to Perpignan.

Twenty minutes later,

Perpignan air traffic control
has flight 888 back on radar.

But as the plane descends...

The captain begins
to lose control.

Kaeppel:
It's pitching up all the time.

It's pitching up.

Narrator:
The plane tips up steeply.

Man: Does that seem right
to you guys?

Horrell: Stick forward.

Narrator:
The captain throttles up

and pushes his stick forward
to bring the nose down.

But it doesn't work.

Cox: The captain's
side stick goes forward.

It's clearly an effort
to try to lower the nose.

And I believe
he does not understand

why the airplane doesn't respond

as he's applying
pretty well full power.

Kaeppel:
Flaps up. Flaps up!

Narrator: Pulling in the flaps
reduces drag

and should help them
regain control.

But it's no use.

The plane is diving
towards the sea.

Man: Oh, god!

Oh, god!

Computer: Pull up.

Kaeppel: Damn it!

Computer: Pull up.

Controller: Triple 8 tango,
contact tower.

Triple 8 tango, contact tower.

I've got an emergency.

Narrator:
Search and rescue teams

race to flight 888's
last known location,

but there's no sign
of any survivors.

Man: This is clearly difficult
and devastating news

for the families
of all concerned worldwide.

Narrator: The search
goes on into the night.

Investigators question
witnesses along the coast

about the last moments
of the flight.

Man, translated: I saw
the plane flying over me.

All of a sudden,
it went into a dive.

Man: This is the map
we're working with.

Narrator: French Air crash
investigators from the BEA

are responsible for figuring out
what went wrong.

Man: It went down
right...here.

Narrator: Sebastien David
leads the investigation.

Sebastien David: The first phase
of the sea search operation

was finding precisely where
the wreckage was.

Narrator: David and his team
are under enormous pressure.

David: I want you to mobilize
all the resources.

Narrator: The A320

is one of the industry's
most popular passenger planes.

David: A large number
of this kind of aircraft

is being flown
all over the world.

Narrator: It's also
the first airliner

to use advanced
computerized controls.

Cox: With the A320,

automation flies the airplane
the majority of the time.

Narrator: If there's a problem

with the plane's
high-tech flight computers,

many more lives
could be at risk.

Investigators need to find
the cause of the crash quickly,

before it happens again.

No one has survived the crash
of XL Airways flight 888.

Grieving families
arrive in France

to recover the bodies
of their loved ones.

Woman: I didn't expect
to be on my own at 34,

um, like this.

Narrator:
Air New Zealand executives

are also on the scene.

Man: My commitment
to the families was

I want to stay here until
we can bring our boys home,

or we're in a position
to determine

that that's not possible.

David: What on earth
is an acceptance flight?

Narrator: The unusual
nature of the flight

presents an extra challenge
for investigators.

David: We did not have
any reference

for that kind of flight.

There was no defined framework.

Narrator: No one may ever know
what the crew was doing

unless they can find
the plane's flight recorders.

Man: We have to send
the divers into the sea

to find the plane.

Narrator: But the bad weather
is making it nearly impossible

for divers
to locate the wreckage.

Man: With the worsening
forecast,

the search and rescue teams have
re-emphasized personally to me

that there is real urgency
behind their efforts

to locate
the two flight recorders.

Narrator: Yann Torres
leads the recovery effort.

Yann Torres, translated:
Most of the time

there was severe wind and swells
on the surface,

which made visibility
on the bottom deplorable--

that is,
only 50 centimeters to a meter.

Narrator:
Searchers turn to sonar

to hunt for debris from
the plane on the sea floor.

Torres: This was possible,

thanks to a minesweeper
from the navy.

By using sonar,

we were able to identify
the larger pieces of wreckage.

Narrator:
But finding the wreckage

is only half the battle.

Bringing it to the surface
will take more time.

David: It was climbing
like this when you saw it?

Narrator:
Investigators ask witnesses

to describe
the motion of the plane.

David: Some of them related
an unusual flight path.

Witnesses say
it was climbing here.

And they were descending here.

Right here it looks like they
lost control of the plane.

Those testimonies
were very important

for the beginning
of the investigation.

Narrator: Investigators wonder
if the pilots lost control

attempting a risky flight test.

They ask controllers
what they know.

Controller: They wanted
to do some 360s.

Kaeppel:
We're an acceptance flight,

so it would be nice if you
could give us some airspace

to do a few procedures.

Controller:
I told them, "No way."

Narrator: They learn
the pilots asked permission

to perform some tests,

but that the controller
turned them down.

Controller: We are not doing
this kind of flight, sir.

Kaeppel: So, no worries.

We'll just head back
to Perpignan.

Narrator: If the flight test
was called off,

there must be
another explanation

for the plane's
unusual flight path.

Three days after the crash,
a major breakthrough.

The recovery team
finds the black boxes.

The flight data recorder
and cockpit voice recorder

may hold the clues
investigators need.

Man: Nice and easy.

Narrator: Johan Condette
is a BEA Investigator.

Johan Condette, translated:
The recorders were recovered

very quickly,

which made us think
that we would be able

to recover the data on
the recorders just as quickly.

Narrator: The boxes
are drenched in seawater.

The memory cards
need to be dried out

before the data
can be recovered.

Condette: We open it.

We remove the various
layers of protection

that the memory card
is wrapped in.

And once the card
has been extracted, we dry it,

and then we read it out.

Narrator: But this time,
it doesn't work.

Condette: Damn it!

There must still be
some moisture in there.

We weren't able
to recover the data.

And we have a laboratory
designed just for that job,

so it was very frustrating.

Narrator: Investigators suspect
moisture could be trapped

deep in the electronics.

Desperate to know what the
pilots of flight 888 were doing,

they take the boxes
to their U.S. Manufacturer.

Condette: Honeywell
has special equipment

for reading the cards
individually.

It seemed to us the quickest way
to recover the data.

Narrator: While they wait
for word on the data,

investigators
turn to the wreckage

recovered from the sea floor.

They focus on pieces
from the engines.

Horrell: Stick forward.

Narrator: If the engines failed,

it could explain why the plane
fell into a fatal dive.

Bent blades
from the engine turbines

provide an important clue.

Torres: We could see
significant damage

inside the turbines.

And this suggests the engines

were at significant speed
of rotation at impact.

Narrator: The type of damage
tells investigators

that the engines
were working properly

when the plane hit the water.

David: No sign
of any problems here.

The engineers worked on these
for three weeks.

Narrator: Investigators study
the A320's maintenance records.

David: See if we can
find something, ok?

Narrator: They know that
engineers spent three weeks

preparing the plane

for its return
to the Air New Zealand fleet.

Cox: It's a good thing
for both parties to recognize

exactly the state
of the airplane

when the operational control
of the airplane

reverts from one party
to another.

Narrator: If the aircraft
had a mechanical problem

or defect,

there should be
a record of it in the file.

But there's nothing
that even hints

at a problem with the plane.

David: Anyone? Anything?

Nothing?

Cox: They were comfortable

that the airplane
was not only safe to fly,

but in condition that matched
the contractual obligations.

Narrator:
Investigators still have no idea
what brought down flight 888,

so getting the black box data
is more important than ever.

David: It was a big frustration.

We were sure that
the flight recorder's data

would help us to understand
what happened.

Narrator:
Six weeks after the crash
of XL Airways flight 888,

the water-soaked
flight recorders are repaired,

and investigators can finally
listen to the conversations

captured in the cockpit.

David: Let's hear this.

Kaeppel:
We're an acceptance flight,

so it would be nice if you
could give us some airspace

to do a few procedures.

Narrator: What they hear
confirms that the controller

didn't give the crew permission
to fly any tests.

Controller: We cannot
allow test flights

in general air traffic.

We cannot do
this kind of flight, sir.

Narrator: Then they hear
something disturbing.

Horrell: We haven't done
a VHF-3 yet, have we?

We've got to do a call on that.

Narrator: Despite
the controller's refusal,

the crew continues
testing the plane.

Kaeppel:
Ok, we can do the VHF-3.

David: Stop.

Play that back.

Narrator: Investigators listen

and take note of the tests
the crew performed.

Kaeppel:
Ok, we can do the VHF-3.

David: Navigation systems, 2.

The fact that the ATC controller

did not allow the crew
to perform the 360

led to a situation where
the crew had to improvise

to be able to follow
the flight program.

Controller: Triple 8 tango,

descend flight level 3-1-0
and turn right.

Kaeppel: Turning right
inbound, triple 8 tango.

Narrator: The crew finds a way
to fit some tests in

while they fly back
to Perpignan.

Horrell: Ok, that's good.

During the turn,
let's roll to 33, then to 45.

Narrator: A right turn

gives the captain a chance
to test the system

that prevents the plane
from banking too steeply.

Horrell: Hands off now.

Narrator: Then he waits
for the flight computer

to level the plane.

Horrell: Yup, yes, voila.
It's all good.

David: Bank angle test, 7.

The tests are out of order.

They're improvising now.

Cox: They recognized
at that moment

they were not going to finish
the entire test plan.

So, what can we do to maximize
the time we have left?

Horrell: We need to overspeed.

David: They followed
the flight program,

taking into account

opportunities that were
presented to them.

Kaeppel: You just want to hear
the overspeed warning?

Narrator: Many of the tests

activate the plane's
safety systems

and set off alarms
in the cockpit.

Horrell: There it is.

You can cancel the warning
if you like.

David: Overspeed, 8.

Narrator: The crew manages
to complete twelve tests

in just half an hour.

David: That's a busy crew.

Cox: An acceptance flight

is very enjoyable
from a pilot's standpoint.

But it is a very
challenging environment

because you're doing a lot
of things with the airplane.

David: We had the impression

that everything went
very fast for the crew.

Narrator: As the plane
descends below the clouds,

the crew sees an opportunity
to do another test.

Kaeppel: So, you want what?

Horrell: Yeah, we need
to go slow with recovery.

Cox: This test requires

that the airplane be slowed
well below normal speed

to let the automated
protections activate

and then record what they do.

Narrator: When the Airbus
slows down too much,

the flight control computer
should automatically boost speed

to prevent the plane
from losing lift.

Kaeppel: Down below the clouds.

Cox: You would not want to do
slow flight conditions

at very low altitudes.

Those would be items that you'd
want to do at 10,000 feet,

because if something
does go wrong,

you want to have room
to maneuver and sort it out.

Horrell:
Get your power at idle.

Adjust pitch.

Flaps full.

Narrator:
The captain reduces speed

and waits for the automatic
protections to kick in.

But this time,
nothing happens.

Suddenly, this test
is going horribly wrong.

Kaeppel:
It's pitching up all the time.

David: Why didn't
the stall protection kick in?

Cox: Why isn't
the airplane responding?

What do we need to do?

Is there something else wrong?

It's a diagnostic process

that you don't have
a lot of time with.

So, the big question
that keeps coming back up is,

why isn't
the airplane responding

as it has always done
for me before?

Narrator: Airbus'
automated protection system

has proved invaluable
on other flights.

In 2009, just after
takeoff from New York...

A flock of geese
disables both engines

on a U.S. Airways A320.

As Pilot Sully Sullenberger

prepares to ditch the plane
in the Hudson River,

the computer automatically
adjusts the plane's angle

into the wind,

the angle of attack.

It keeps him from stalling,

saving the lives
of everyone onboard.

Investigators wonder
if the crash of flight 888

has revealed a hidden flaw

in one of aviation's most famous
electronic safety nets--

a flaw that is putting thousands
of passengers at risk every day.

David: We had to understand
the conditions

which could have led
to this situation.

Narrator: As the investigation

into the crash
of flight 888 continues,

the BEA learns
of another aviation tragedy.

An Air France Airbus A330 has
crashed off the coast of brazil,

killing all 228 people on board.

Sebastien David is losing
some of his best investigators

as they are reassigned to deal
with the Air France crash.

David: The team we had at the
beginning of the investigation

had to split
into both investigations.

So that makes it more difficult
to conduct the investigation.

Narrator:
David and his smaller team

now face even more pressure to
solve the mystery of flight 888.

Condette: Monsieur David,

I have the angle of attack
sensor data.

Narrator: Investigators hope

the flight data recorder
from XL Airways flight 888

will finally explain
what went wrong

in the skies
over Perpignan, France.

Information from a key set
of sensors stands out.

David: That's odd.

Narrator:
Partway through the flight,

two critical sensors failed
at exactly the same time.

David: We know they were
descending here,

but the sensors
still show a climb.

Narrator:
Angle of attack sensors

act like small weather vanes
on the outside of the plane.

During flight, they pivot.

Their movement
helps the flight computer

monitor the position
of the plane

so it can automatically
adjust the flight systems

to maintain lift.

Cox: It is something

that airplanes
calculate continuously,

and it is most critical

as far as advising the pilots
of an impending stall.

Narrator: If the sensors
got stuck in one position

when they malfunctioned,

it would explain why
the computer didn't detect

the dangerous angle
of the plane.

David: We need to get a look
at those sensors.

Narrator: But the sensors
are still missing

at the bottom of the sea.

Torres:
The entire gendarmerie

was mobilized for the search.

We made it understood

that it was absolutely critical
for our investigation.

Narrator:
The wreckage is so deep

that divers must work in shifts

to avoid
decompression sickness,

or the bends.

Torres: Diving at 40 meters
starts to become

what we call a deep dive.

And so a diver can only be
exposed for a short time

because we're dealing
with compressed air.

Narrator: Investigators
catch a lucky break.

After two days of searching,

divers manage
to recover both sensors.

Torres: One was still attached
to a part of the fuselage.

A second was sitting
by itself on the bottom.

Narrator: Investigators
test the mechanism

that allows the sensors to move.

David: Anything?

Narrator:
It's working perfectly.

David: It was
very difficult to imagine

a common technical problem

that led to the blockage
of two angle of attack sensors

at the same time,
at the same values.

Narrator: There seems to be
no way to explain

why the sensors failed.

David:
Well, something jammed them.

I want to see
the FDR data again.

Narrator: David returns
to the flight data

and searches for anything
that might explain

why both sensors failed
at exactly the same time.

Cox: I have never heard of

angle of attack
simultaneous failures.

Narrator: David graphs altitudes

and corresponding
air temperatures

throughout the flight.

David:
Minus 50 at 32,000 feet.

Narrator: At high altitudes,

the air outside the plane
is extremely cold.

This gives him an idea.

David: Can the sensors freeze?

Narrator: If there was ice
in the sensor mechanism,

it might have
frozen them in place.

The theory would explain

why they both jammed
at the same time...

Kaeppel:
It's pitching up all the time.

Narrator: Sending the plane's
computer faulty data

about the angle of attack
for the rest of the flight.

Kaeppel: It's pitching up.

Cox: With the two
angle of attack vanes frozen,

the flight control computers
were not going to get the input

that said you are reaching
critical angle of attack.

Narrator: Investigators wonder
if rainwater from a severe storm

flooded the sensors
and then froze.

David: We investigated
meteorological conditions

during the cruise

in order to find
if those conditions

could have led to the jamming
of the angle of attack sensors.

Narrator: It's a dead end.

David: The weather
was nice that day.

Narrator: The plane didn't
encounter any bad weather.

If water got inside the sensors,

it happened on the ground,
not in the air.

But the advanced sensor is
designed to keep rainwater out.

David: So, water would have to
get all the way in here.

Narrator:
To get inside and freeze,

the water would
first have to travel

through a long, winding channel.

It seems like water had nothing
to do with the failure.

The edge of one of the sensors

provides another
intriguing lead.

It's coated with
several layers of paint.

David: This should all
be sanded off.

What else did those painters do?

We wanted to focus on all
the maintenance operations

that could have had
an influence on the sensors.

Narrator: Investigators
visit the hangar

where the plane spent
three weeks being serviced.

They learn the work included
painting the plane,

replacing XL Airways' colors

with those
of the Air New Zealand fleet.

David: This led to investigate
the painting operations

because
the angle of attack sensors

need some specific protections.

Narrator:
The procedure directs painters

to cover the sensors first,

so they don't
get clogged with paint.

Cox: When airplanes are painted,
it's the same with your car--

very special protections have
to be made for certain items.

With your car,
you cover the headlights

because you don't want paint
over the headlights.

That's a very simple analogy.

But to a much more complex way,

the same thing
is true with airplanes.

Narrator: Investigators
consider the possibility

that the sensors malfunctioned

because of
a sloppy coat of paint.

Torres: At this point,

the investigation
focused on finding out

if there was any possibility

that paint
might have adhered there

and created a blockage

that prevented
the rotation of the vane.

Narrator: They re-examine
the angle of attack sensor data

from the flight recorder.

If paint was
jamming the sensors,

it would have caused problems
throughout the entire flight.

Ketzer:
Climbing flight level 1-8-0.

Narrator: But the data clearly
shows the sensors didn't fail

until 22 minutes after takeoff.

Kaeppel: Do you need anything
from us while we climb?

Torres: The recorders showed

that the sensor was working
at the beginning of the flight.

David: We need to get
a look at those sensors.

Narrator: Investigators conclude
paint wasn't the problem.

There must be another
explanation for the failure.

They notice something else
in the maintenance records.

The plane needed extra cleaning
after the paint job was done.

David: Some dust was covering
the top of the aircraft.

The maintenance people
had to remove this dust.

Tell me exactly how
you cleaned this plane.

Narrator: Normally, maintenance
workers use a clean cloth

to remove any dust.

But this time, they rinse
the plane with a hose.

David: The painting operations
had taken a little bit of delay.

To rinse the aircraft was faster

than to use a clean cloth
to remove the dust.

Narrator:
Spraying uncovered sensors

with a high-pressure hose

might explain how water
got so deep inside.

But the investigators
need proof.

They mount a sensor
in a test rig

and recreate
the cleaning procedure.

Torres: Ok, hit it.

We knew the plane
had been rinsed

with a fire hose
plugged into the water main.

So we got hold of the details

regarding
water pressure and flow.

Ok! Cut it.

Ok.
Let's get it to the lab.

Narrator: Next, they place
the sensor in a freezer...

And duplicate
the cold air temperatures

found at 32,000 feet.

Torres: It was a massive
ingestion of water

that solidified into ice.

I think we definitely
got some ice in there.

It won't budge.

Narrator: The lab results
seem to confirm

the investigators' hunch.

Ice inside the sensors could
have frozen them in place.

But there's one final test
they need to do

to be absolutely sure.

David:
We performed a test flight

to check what could be
the temperature

inside
the angle of attack sensors.

That was the first time
such a test was conducted

because nobody knew
what could be the temperature

inside
an angle of attack sensor.

Narrator: They flood the sensors
of an A320 with water,

and recreate flight 888.

At low altitudes,
the sensors work perfectly.

David: So far, so good.

Narrator: When the plane
reaches 32,000 feet,

the temperature inside
the sensor drops below freezing.

David: Here they go.

The sensors aren't moving.

Narrator:
The water inside freezes,

and the sensors stop working.

David: The temperature
was below zero degrees Celsius

when the aircraft
reached a cruise altitude.

So this fact was coherent

with the freezing of some
water inside the housing.

Ok, you can bring them home.

Narrator: The result explains
why the flight computer

didn't prevent
the plane from stalling

during the low speed test.

Horrell:
Get your power at idle.

Adjust pitch.

Flaps full.

Narrator:
With the sensors frozen,

the computer can't calculate the
plane's true angle of attack.

Cox: The flight control
computers

can only respond to data
and inputs that they get.

In this case,
the two angle of attack inputs

were simultaneously bad.

And the flight control computer
has no way to know that.

Kaeppel:
It's pitching up all the time.

It's pitching up.

Cox: Because the angle of attack
vanes couldn't move,

they could not then activate
the low speed protections

that the crew was expecting.

Narrator: The plane's
automated safety systems

are effectively crippled.

But there's another mystery.

Horrell: Stick forward.

Narrator:
Before the crash, the captain
tries to fly out of trouble.

He increases power while
pushing his side stick forward

to bring the nose down.

It's a textbook maneuver
to prevent stalling.

But it doesn't work.

The plane continues to pitch up

until it loses lift
and falls from the sky.

David: They tried to apply
the nose-down input

on the side stick,

but their efforts
were not sufficient.

Kaeppel: Damn it!

Narrator:
Investigators need to know why.

A computer simulation

helps investigators analyze
flight 888's final flight check,

the low speed test.

Horrell: Ok,
get your power at idle.

Adjust pitch.

Flaps full.

Kaeppel: Ok. Here we go.

Narrator: Captain Kaeppel

deliberately slows
his plane down for the test.

But the computer
lets the speed drop too far--

below the minimum needed
to keep the plane in flight.

David: They let their airspeed
drop to 100 knots.

Condette: We noticed
just how dramatically

their airspeed was falling.

Narrator:
Investigators notice a warning

on the cockpit flight display

moments before the crash.

David: There. What is that?

Narrator:
They learn that the warning

is supposed to alert the pilots

the flight computer is no longer
helping to fly the plane.

It has switched
to full manual mode.

Condette:
You get a message in red

that appears in the middle
of your primary flight display

telling you to use
the manual elevator trim.

The message in English
is "Use man pitch trim."

Narrator: The warning comes on

when the plane's computer
gets conflicting information.

The frozen sensors
are telling the computer

the plane is flying level,

while other onboard sensors

are relaying
its extreme nose-up attitude.

One must be wrong.

Cox: The airplane by design,

when it starts getting data

that it cannot figure out
what to do with,

reverted and said,
"Alright, something is wrong.

We don't know what.

This is up to the pilots
to sort out."

David: The plane gave the pilots
control right here.

Narrator: It seems
the crew of flight 888

either didn't see
or didn't understand

the warning being sent
by the computer.

Horrell: Stick forward.

Narrator:
The pilot uses his side stick

to try to lower the nose.

Horrell: Stick forward.

Narrator: In manual mode,
that's just not enough.

The crew also needs
to adjust the trim wheel

for a more dramatic
change of pitch.

Cox: The auto trim system
is disabled,

and the pilots were required
to do that manually.

Narrator: But they never do.

Cox: Now the pilots
find themselves

in a very, very
difficult situation.

The airplane's not accelerating,

the nose is coming up,

it's very hard
to get it to come down,

and they're at low altitude.

David: The two crew members
tried everything to recover

and to take the control
of the aircraft.

But they did not fully
understand the situation.

Narrator: Investigators check
the pilots' qualifications.

Perhaps poor training
accounts for their failure

to respond properly
to cockpit warnings.

David: The captain
who was the pilot flying

was the head of the operations
divisions in the airline.

The co-pilot was also
very experienced as a co-pilot.

And the captain that was
sitting on the observer seat

was also
a very experienced captain.

Everything looks fine.

Narrator:
Their records are spotless.

David: And so the team
was very experienced.

Narrator:
Investigators need to know

why such an experienced crew
failed to act quickly

when their plane was in danger.

They suspect one reason may be

the unusual nature
of this flight--

an acceptance flight designed
to test the plane's limits.

Horrell: Ok, that's good.

During the turn,
let's roll to 33, then to 45.

Kaeppel: Ok.

Narrator: Every time
they test the plane...

Horrell: Hands off now.

Narrator: The automation
fixes the problem.

Horrell: Yup. Yes. Voila.
It's all good.

Narrator:
Even when they hear alarms,

they don't worry.

Horrell: We need to overspeed.

Kaeppel: You just want to hear
the overspeed warning?

Narrator:
They're expecting the plane

to correct the problem.

Horrell: There it is.

You can cancel the warning
if you like.

Condette: They trusted
their plane too much.

David: The crew allowed
the speed to get so low

because they were very confident

in the good functioning
of the aircraft.

Cox: Unfortunately in this case

they allowed it to go
all the way to the point

that the airplane
actually began to stall.

Horrell: Stick forward.

Cox: Then they were
in a stall-recovery situation

without a lot of altitude
to work with.

Kaeppel:
Flaps up. Flaps up!

Narrator: With their plane
in a catastrophic stall,

the seven men aboard
flight 888 were doomed.

Man: Oh, god!

Oh, god!

Kaeppel: Damn it!

Cox: Our march toward automation

has nowhere
come close to stopping.

And it's appropriate.

In previous generation
airplanes,

you first learned
to fly the airplane,

and then you learned
to manage the automation.

In later generation airplanes,

you learn the automation
as an integral part.

But we have
to have the interface

between the pilots
and the automation

improve and mature.

Narrator:
The official accident report

highlights several
contributing factors,

including
the aircraft washing procedures

and the decision to perform
flight checks at low altitude.

Horrell: Yeah, we need
to go slow with recovery.

Narrator: The report
also calls for clearer rules

governing acceptance flights

and more training
for stall recovery.

David: This led the BEA
to recommend training

for the pilots to be able to
recover from stall conditions.

Cox: Improved training
for loss-of-control events

is something
that all pilots need.

Loss of control is
the leading cause of fatalities

in all aspects of aviation.

So it is an area that we need
to focus on as an industry

to keep our
safety record improving.

Kaeppel:
Gentlemen, good afternoon.

Cox: Acceptance test flying's
gonna be with us.

Maintenance check flights are
a necessary part of aviation.

Kaeppel: Better buckle up.

Cox: And so we need
to take these lessons

and learn them well

because we're gonna be
doing these flights again.