All language subtitles for Mayday.S09E07.The.Final.Blow.1080p.AMZN.WEB-DL.DD+2.10.H.264-playWEB_track3_[eng]

Just minutes
from Strasbourg Airport...
- Merde!

...an Airbus A320 slams
into a mountaintop.

Delta Alpha, your position?

There are survivors.

And I panicked
because I'm going to burn.

But they are still
in grave danger.

It's bitterly cold,

and what they don't realize
is that no one knows
where they are.

They could be anywhere
in there.

We can expect this
in the jungle or the rainforest,

but not in a...

highly populated area.

Before investigators
can begin searching

for what caused the crash
of Air Inter Flight 148...

...they must first
find the plane.

Mayday, mayday.

January the 20th, 1992.

Air Inter Flight 148
has departed from Lyon, France.

124.95, thank you.

Captain Christian Hecquet...

and First Officer Joel Cherubin
are experienced pilots

with over 12,000 hours
of flying time between them.

The flight is a short hop
between Lyon, in central France,

and the city of Strasbourg,
in the mountainous
Alsace region.

The French airline Air Inter
caters mostly
to business travellers

and prides itself
on being timely.

Crews are motivated
to avoid delays,

as former Air Inter pilot
Gerard Arnoux explains.

We were famous
for our very short turnaround.

And the faster we flew,

the better wages we got.

Have we been flying
for 35 minutes yet?

Forty-one minutes.

The crew is flying
an Airbus A320,

one of the most technologically
advanced commercial airplanes
in the world.

Even before takeoff,

the pilots programmed
the autopilot to land

on a specific runway
in Strasbourg.

The cockpit of the A320
is also very different
from other planes.

Instead of analog gauges,

the pilots look mostly
at digital displays.

Strasbourg,
good evening.

Runway in use: 05.

Transition level: 50.

040, at 18 knots,

visibility: 10 kilometres.

A recording
from Strasbourg Airport

informs the crew
of a change in plan.

Due to high winds
and poor winter weather,

they'll have to land
on an alternate runway...

05 in service.

...not the one programmed
into the autopilot.

05? What sort of wind
are they giving us?

Eighteen knots.

Eighteen knots.

Captain Hecquet
doesn't like the idea
of changing runways.

No chance.

He was hoping
to use Runway 23,

an approach that provides
the autopilot with a precise
navigational fix.

The new runway, Runway 05,

is surrounded
by mountainous terrain

that can interrupt radio signals
sent to the autopilot.

You know, if we go
with the Runway 05 procedure,
we...

Well, no. Ahem.

Captain Hecquet
suggests a compromise.

I'm putting back Runway 23.

Otherwise, I couldn't make
the ILS interception.

He'll program the autopilot
to fly towards Runway 23.

But near the airport,

the captain will take over
the controls

and make a visual landing
on Runway 05.

You're taking 23, then?

Yes!

Agreed.

Ladies and gentlemen,
we are commencing our descent.

We ask you to please...

Nicolas Skourias is a university
graduate student.

It was a... quiet day.

I was, uh...

expecting to go to see
my girlfriend in Strasbourg.

So I was very happy.

Roger 854, proceed to GTQ.
Air level: 140. Contact Reims.

Delta Alpha, Strasbourg.

Uh, yes, we intend to proceed
to do an ILS on Runway 23,

uh, then an indirect
for Runway 05 after that.

The Strasbourg controller
considers the captain's plan.

Delta Alpha.

He warns
that there will likely be
a delay due to heavy traffic.

Given that we're going
to have three takeoffs on 05,

you risk waiting
in a stack at 5,000 feet.

We're not going
to mess about like that,
descending at full speed.

If they had warned us
in advance! Cripes!

Delta Alpha, Strasbourg.

I hear you.
Aware of the captain's frustration,

the controller offers
assistance.

If you want,
I can take you with the radar
to lead you to ANDLO at 5,000.

ANDLO is a navigational point
on the approach to Runway 05.

It helps pilots align the plane
for landing.

Yeah, that's good.

Oh, yeah.

Okay, then, turn left
to heading 230 degrees.

148, turn left to heading...

230 degrees.

There you are.
That will save you some time.

Since Runway 05 doesn't allow
for a full autopilot approach,

the captain must calculate
the angle of descent on his own.

That makes...

3.3 degrees.

3.3 degrees
is a normal flight angle

that provides a good slope
for landing.

Ladies and gentlemen,
we are continuing our descent...

The flight from Lyon
to Strasbourg was quite short.

I think 50 or 45 minutes,

nothing special.

It was, uh, very natural
and very ordinary.

Thank you.

Turn left, steer 90.

Zero-niner degrees, Delta Alpha.

The controller talks
Flight 148 through the last turn

to align the plane
with the runway,

now 25 kilometres away.

Then First Officer Cherubin
notices the plane
is slightly off course.

You are headed inside.

You're inside there.

You should've started with 070.

Yeah.

- At least that much.
- Ahem.

The controller also notices
that the plane is off course.

Air Inter Delta Alpha.

It has missed
aligning itself with ANDLO,

the runway's
electronic guidepost.

Delta Alpha, you're passing
to the right of ANDLO.

Nevertheless,
he authorizes the landing.

Authorized for final approach,
05.

Delta Alpha.

The captain
initiates the landing sequence.

- Flaps towards 2.
- Flaps towards 2.

Flaps at 2.

Gear down.

Ladies and gentlemen,
we are going to land
in a few minutes.

Hecquet notices that the plane
is travelling too fast,

so he extends the speed brakes.

They disrupt airflow
over the wing,

which helps create more drag
to slow the plane.

We have to watch our descent.

The approach axis...
The first officer
is more concerned

with their horizontal position
in relation to the runway.

- It was 60. Check it out.
- Oui, oui.

But before the crew
can adjust their course...

Merde!

Delta Alpha, your position?

Air Inter Delta Alpha,
Strasbourg.

The crash is catastrophic.

The A320 has flown
into the side of a mountain.

Delta Alpha, your position?

Flight 148
is no longer on radar...

...nor responding
to radio contact.

An emergency is declared
at Strasbourg Airport.

This is the last hit we got.
They were flying 20 kilometres
away from the airport.

Officials need to pinpoint
the crash site.

But it's not as easy
as it might seem.

The airport's radar
is not recorded.

There has been no signal
from the plane's
emergency beacon.

And, surprisingly,

no one has reported
seeing a plane go down.

It could be anywhere in here.

The proposed search area covers
more than 20 square kilometres

of dense forest
just outside Strasbourg.

Nicolas Skourias survives
the crash
of Air Inter Flight 148

with only minor injuries.

I took off my, uh, seatbelt.
I get up.

I tried to find my, uh,
suitcase, uh...

in the lockers,

but, uh...

there wasn't any lockers.

I realized that I was alive;
it was a crash.

I saw fire in front of me
and I panicked,

because I say to myself:
I'm going to burn.

I went to the back of the plane,
what remained of the plane...

I found some other survivors.

Come on!

It's gonna blow!

I was afraid of the explosion.
I was a panic.

With the smell
of leaking jet fuel in the air,

the survivors move away
from the burning plane.

We stayed together,

waiting for the first aid.

But the wait will be longer
than anyone might expect.

The first reaction that we have
after the crash was:

Okay, in half an hour,

one hour...

most and worst,

okay, the rescue team
will be here.

And it wasn't here.

One hour after the crash,

rescuers still have no idea
where the wreckage lies.

Skourias and the others
now face a new ordeal:

Surviving sub-zero temperatures
in a dark and isolated forest.

Two-and-a-half hours
after Flight 148 disappeared
from radar

near Strasbourg Airport...

...the missing plane
has still not been located.

Amidst growing tension,

the French aviation bureau,
the BEA,

sends in its lead investigator,
Jean Paries.

I immediately called
my two main investigators,

and we organized the go team.

And we got prepared
to rush to the site

as soon as this site
was located somewhere.

The delay feels
like an eternity.

A bit surprisingly long.

We can expect this
in the jungle or the rainforest,

but not exactly in a...

highly dense populated area
like the Strasbourg area.

With no help in sight,

Skourias returns to the wreckage
to look for more survivors.

I think that some people
that die, uh,

could have survived
if the first aid...
had come sooner.

Nearly 1,000 people search
for the missing plane.

But three hours after the crash,
there's still no sign of it.

Frustrated,
Skourias goes looking for help.

He stumbles into a TV crew
trying to find the crash.

But with no wreckage in sight,
they react with skepticism.

They didn't expect...

...uh, survivors
from an airplane crash.

Hey!
Hey, you have to believe me!

They didn't believe
that I was one of...
the survivors,

but believe me, I was,

because my face was black, uh,

due to the smoke,

the kerosene and so on.

Come on!

The journalists follow him
back to the crash site...

...where they discover
eight other survivors.

Finally,
the first rescuers arrive.

The crash site is located
near the top of the 2,500-foot
Mont Ste. Odile...

...19 kilometres
from the runway.

They found us...

after four hours
and 30 minutes.

So it was a mess.

I was very, very disappointed

that at 20 kilometres
from Strasbourg and, uh...

they couldn't find us.

A total of 87 passengers
and crew have died,

including the pilot
and co-pilot.

The survivors begin to tell
their stories,

but no one reports anything
that might explain
why the plane crashed.

I don't know what happened.

We were landing,
I lost all consciousness.
We must've hit the trees.

Bob MacIntosh,
an American NTSB investigator,
arrives at the crash site.

The BEA of France, uh,

recognized
the international attention
would be on this accident.

Even though
it was a domestic accident,

he invited a group
of international accident
investigators, uh,

to come and participate.

Jean Paries.
Welcome to the team.

The first priority
for investigators

is to retrieve
the plane's black boxes.

We have not removed
the recorders yet.

With the boxes trapped
in the burning tail section,

any delay could prove costly.

We were very anxious about...

the state of the tape inside.

Will it be possible to use it?

Will we get the critical
information we need?

In France,

aviation accidents
are also investigated
by the justice system.

Paries and his team
are not allowed access
to the site

until judicial officials
secure the black boxes.

I had a visual picture
of the Gendarmes Aériennes,

the transport police,
standing around,

keeping us away
from the wreckage for a while.

And were very suspicious
of these international
observers...

- Maybe we should wait.
- ...even taking photographs,

which was somewhat surprising
to us.

In a previous crash,
the crash of Air France
Flight 296 in 1988,

investigators waited 10 days
before turning the black boxes
over to police.

Rumours persisted
that these boxes
had been tampered with.

This time, police are keeping
investigators at bay.

I can recall seeing
the glowing embers,

and seeing the flight recorder
sitting there and, uh...

not being able to intervene
and say,

"Get that thing cooled down
as soon as you can."

After midnight,
the boxes are retrieved from
the plane and sent for analysis.

Investigators can only hope
it's not too late.

They were extremely hot.

They looked damaged,
they looked burned.

In the light of day,

investigators get
some of their first clues
from the crash site itself.

They discover why the plane's
emergency locator beacon
didn't send a signal.

It was actually destroyed
by the impact.

The beacon
is located inside the cockpit

and is designed to start working
after a crash.

Its failure suggests
an unusually forceful impact
with the ground.

We had this first feeling...

the descent
was abnormally steep.

Investigators examine the engines

to see if they may have stalled
before impact.

If you find the blades curved
and a lot of wood, uh...

...sucked inside the engines,

then you understand
that the engines
were working properly.

And that's exactly
what they find.

The plane clearly had power,

yet it plowed steeply
into a mountainside

without ever sending out
a distress signal.

Investigators are puzzled.

They hope that the box
which recorded
the plane's flight data

will help them
solve the mystery.

Those particular recorders...

had the best survival record
of any recorders.

They were the top-of-the-line
as far as survivability
is concerned.

The black box is designed
to survive temperatures

up to 1100° Celsius
for half an hour.

The tape recorder inside
is protected by a capsule
filled with water.

When the recorder heats up,
the water turns to steam,

absorbing the energy,

and actually vents out
through a little hole
in the crash enclosure.

But when the flight-data
recorder is opened,

investigators make
a troubling discovery.

DFDR was totally damaged,

impossible to read
anything from it.

It was subjected to heat
beyond the 30 minutes.

The recorder
was just never designed

to withstand that kind
of sustained heat.

And so we were very, uh, disappointed.

There's now only one hope

for recovering
the plane's flight data,

a device called
a Quick Access Recorder, or QAR.

Maintenance workers use the QAR
to access the plane's computers,

but it also records
some flight data.

Unlike the black boxes,
the QAR is stored
near the cockpit.

The Quick Access Recorders
are not protected at all.

They're up in the front end
of the aircraft,

typically
in the electronics bay.

They're generally destroyed
just from the impact damage.

Investigators are encouraged
to discover that in this case,

the QAR has survived.

But on closer examination,

their optimism
turns to frustration.

The last 20 centimetres
of the tape were burned and,
uh...

stretched,

and were damaged to the point
that we could not use them
into a machine.

We couldn't read it.

Investigators are desperate
to retrieve the data,

so they take a chance
on an experimental technique.

Known as the "garnet technique,"

a light is shone
through a mineral lens
made of garnet.

You use a garnet stone
to visualize the magnetic pulses

that are actually recorded
on the tape.

The special lens
helps the technicians

differentiate between
the positive and negative
magnetic pulses,

which translate
as binary digits, or bits.

There's 768 bits per second,

so that's a lot of ones
and zeros.

You have to be very precise
in moving the tape

under the lens or the garnet

to make sure
you don't miss a bit

or read the same bit twice,
you know?

So it's difficult.

Analyzing the data
is even more painstaking.

It took about a day
to read a second of...

recording.

Any additional second recovered
could reveal something
that would make a difference.

The effort
to retrieve all the QAR data
could take a month or more.

In the meantime,

the focus of the investigation
shifts to the cockpit
voice recorder.

It was positioned
just above the other black box.

The cockpit voice recorder,
which was just inches away,
but outside of the ashes,

had air passing over it...
and survived.

...Runway 23. Otherwise...

The recording
reveals the captain's anxiety
early on in the flight.

- You're taking 23, then?
- Yes!

Investigators know
that landing on Runway 05

requires what's called
a non-precision approach.

That means pilots receive
electronic guidance

only on their horizontal
position:

left and right.

They get no guidance
when it comes to altitude.

The non-precision approach
is significantly less accurate.

It's not really difficult,
but they are less comfortable.

05?

What sort of wind
are they giving us?

The non-precision
approach increases the demands
on the pilots.

Investigators can also hear
that the captain had concerns

about landing on Runway 05.

Forty-eight, Delta Alpha,
you are number one for VOR/DME,
Runway 05.

Runway 05, 05.

Ten nautical. That won't work.

That's a lot of distress
over a non-precision approach.

Wondering what can cause
such distress,

investigators research
pilot training at Air Inter.

They find that most pilots
did not have
extensive training

making non-precision landings
in the new A320.

I think we should've
had double the training

compared to an older plane.

Investigators ask
the airline for detailed records

on the pilot's history
of runway approaches.

They're intrigued
by what they discover.

Captain Hecquet had landed
at Strasbourg countless times,

but he had never landed
an A320 there

using a non-precision approach.

We're not going
to mess around like that
descending at full speed.

Clearly the captain was uneasy

about having to execute
a landing
he had never made before.

I think the captain
was worried about making it in,

in a minimum amount of time,
in the minimum amount of delay.

Have we been flying
for 35 minutes yet?

And the co-pilot was worried
about not getting in trouble
by offending the captain.

At least that much.

More research
into the pilot's work history
offers yet another revelation.

While the two pilots had flown
more than 12,000 hours
between them,

they were both
still relatively new
to the highly advanced A320.

It's 05 in service.

The aviation community
misunderstood...

the magnitude of changes
brought by the new Airbus A320.

The captain had only 162 hours
in the A320.

And the co-pilot, even less.

Just 61 hours.

Behind this accident scenario,

there is an issue
of confidence...

...of the crew in themselves,

in the aircraft.

Eighteen knots.

No chance.

They were not prepared,
really, to fly in, uh,
this kind of condition.

If they had warned us
in advance. Cripes!

Investigators conclude that the crew's
training was insufficient.

But that alone
does not explain the crash.

Merde!

Investigators search
for other factors
in the crash of Flight 148.

They review the conversations
between the crew
and air-traffic controllers.

If you want,
I can give you radar headings
and take you to ANDLO at 5,000.

Yeah.

Yeah, that's good.

The radar vector
makes flying easier.

The captain was happy
because it was reducing
his workload.

Turn left, steer 90.

With the controller's
assistance,

this landing
should've been very simple.

But when investigators
reconstruct the plane's
trajectory

using radar information
from various stations
around the airport,

they discover a shocking error.

The 090 heading started here.

Zero-niner-zero degrees,
Delta Alpha.

But it won't take them
to ANDLO.

The last radar vector
the controller gave
was incorrect.

It sent them...
- Thank you.

...closer to the mountain.

They were off course...

because of following
the heading they got
from the radar vectoring.

They found themselves
in this under-shoot situation.

- You're inside there.
You should've started with 070.
- Yeah.

Investigators are also troubled by
the controller's choice of words

when he warned the pilots,
incorrectly,

that they were headed
to the right.

Delta Alpha, you're passing
to the right of ANDLO.

From the pilots' perspective,

the plane was on the left side
of the runway, not the right.

It could only add
to their confusion.

It was very poor guidance,

because he didn't employ
the usual terminology.

Investigators recommend that controllers use
only compass points

when giving directions,

never the words "right"
and "left."

The controller's mistakes
clearly brought the plane closer
to the mountain.

Turn left, steer 90.

Zero-niner...
But once again,

investigators feel
they don't have the whole story.

It's not something
totally abnormal to start
a descent from this situation.

Flaps towards 2.

Flaps towards 2.

It's not what you're expected
to do every day,

but it's not outside
the tolerance of...

the concept of this approach.

Gear down.

When investigators
study the plane's
reconstructed flight path,

they discover something
more alarming than the plane's
horizontal misdirection.

As it circled the mountain,

the plane inexplicably entered
a dangerously steep
and rapid descent.

Perhaps 2.5 times, uh,
the normal rate of descent.

That's lethal
at that altitude.

Without the steep descent,

they would've cleared
the mountain.

If the vertical, uh...

trajectory had been correct,

they would have no problem
at all.

Finding the cause
of that sudden descent

is now key to understanding
why 87 people died

in one of the most advanced
passenger planes on Earth.

Authorized for final approach,
05.

The descent was initiated
at 18:19:38.

That...

Delta Alpha.

...is the point of no return.

By studying
Flight 148's trajectory,

investigators determine
that the rapid descent began
60 seconds before the crash.

There is no indication on tape
that the descent was deliberate.

How it happened
and why the crew didn't notice
is a mystery.

It should be a no-brainer,
keeping track of the altitude.

The cockpit altimeter
gives pilots

a constant readout
of their altitude.

The altimeter
is a very precise instrument;

they've become very reliable,
they're accurate
to within five or 10 feet.

Ignoring it
would be a major error
in flying protocol.

Flaps towards 2.

The recording
reveals just one single remark
from the crew

about their descent.

We have to watch our descent.

It occurred
16 seconds before the crash.

The captain had just extended
the speed brakes.

The aircraft was accelerating
abnormally.

The captain started to realize
there was something wrong
with the descent rate.

But the first officer
changed the subject.

The approach axis.
We're hitting the axis
a half-point off.

There.

It was 60. Check it out.

He refocused...

the captain's attention
on the lateral situation...

...rather than the vertical
situation,

which was the main problem,
of course.

And they both failed
to recognize the situation.

I think they were planning...

they were gonna break out
of the clouds so they'd be able
to see the runway,

and they wouldn't need to do
the full instrument approach.

It was 60. Check it...

But the plane
never left the clouds.

There's an old adage
in aviation:

Rocks have been known
to hide out in those clouds.

Merde!

It now seems clear
that the crew was not monitoring
their altitude closely enough.

But a bigger mystery remains.

We can only guess why...
What caused
that deadly descent?

After months of work,
investigators may finally have
the answer.

All the available flight data
from the damaged
Quick Access Recorder

has been recovered.

We were very anxious
to be able to read
as much as we could.

The data confirms
that just before the crash,

the plane was speeding
toward the ground
at an extremely high rate:

3,300 feet per minute.

It also confirms
that the angle of descent
was dangerously steep.

Much greater
than the 3.3 degrees
selected by the captain.

3.3... degrees.

That's quite a difference.

Investigators now wonder:
Did the autopilot malfunction?

Did it somehow fail to obey
the captain's safe descent angle

and send the plane
into a deadly nosedive?

But what state was it in
before the accident?

Unfortunately,
the flight-control unit
which houses the autopilot

is too badly damaged to provide
any definitive answers.

We could never demonstrate
that this FCU on this aircraft,

during this flight, uh...

functioned properly or not.

But then,
when he returns to studying
the flight data,

Paries discovers something
that may finally reveal
the cause of the crash.

He notices a similarity
between two key numbers:

The plane's vertical speed,
3,300 feet per minute;

and the intended
flight-path angle, 3.3 degrees.

Coincidence?

Paries uses a flight simulator
to test a new theory.

Can you show me a descent
of 3,300 feet per minute?

He believes that the similarity
is no mere coincidence.

On the autopilot,
there are two descent modes:

Flight-path angle
and vertical speed.

But they are both displayed
on the same window.

So 3,300 is abbreviated to 33.

Now, show me a flight angle
of -3.3 degrees.

And the problem
on this aircraft...

...was the two values
were visible on the same window

and controlled by the same knob.

3.3... degrees.

- 3.3 degrees.

Paries strongly suspects

that the confusing display
tripped up Captain Hecquet.

So... it wouldn't be hard
to make that mistake, would it?

The confusion is quite easy
between the two modes,

if you don't do it carefully.

If the captain failed to push
the mode-selector knob,

then entering 33
would not have initiated

a safe 3.3-degree angle
of descent.

Instead,
it would've put the plane
into a deadly rate of descent

of 3,300 feet per minute.

Two months after the crash,

another Air Inter plane enters
a dangerously steep descent
for the same reason.

The crew only discovered
the problem when they...
broke out of the clouds.

Those pilots
also confused the plane's
flight-path angle

with its vertical speed.

They were lucky enough
to have a much higher cloud base

so they could correct
the problem.

Further research
reveals an industry-wide problem
with the A320.

Many people confused
these modes,
especially during training.

And many of them
fell in the trap
even after the training.

Eager to test his new theory,

Jean Paries programs a simulator
with all the known data
from Flight 148.

He then inputs
the same rate of descent

he believes
the Air Inter pilots selected.

If Paries is correct,

the simulation will end
with the plane hitting
the mountain.

But it doesn't.

We're missing something.

Strangely,
this didn't lead to a crash.

Every approach would overfly
this obstacle

by a significant margin.

Have we factored in the wind?

We started to work
on other, alternate hypotheses.

Let's try again...
but initiate the turn sooner.

But nothing was really, uh, credible.

No matter how hard he tries,

Paries cannot simulate
the crash.

Unable to explain why,
he turns to the plane's
manufacturer for help.

Thanks for bringing this
to my attention.
After much research,

an Airbus designer
comes to Paries
with an explanation

about a little-known element
of the autopilot's design.

In emergency situations
where the A320 needs
to change direction quickly,

the autopilot is programmed
to reverse the plane's direction
at twice the normal rate.

The reaction of the autopilot
would be much faster.

And these cases were typically
when you were descending and,
uh,

asking the autopilot to climb,

or climbing and asking
the autopilot to descend.

We immediately went back
to the data

at the very second to which...

the descent was commanded
by the crew.

Gear down.

Paries discovers
a tragic coincidence.

Sadly,
we found at this very second,

there was turbulence.

There was an ascent.

It was very slight,
but there it is.

The momentary turbulence

caused the plane
to climb slightly.

And this led to a positive...

600-feet-per-minute
vertical speed

for maybe half a second.

It was during
that same half-second

that the crew commanded
the plane to descend.

The autopilot read this
as an emergency requiring
a blazingly fast descent.

That could be it.

Investigators now contemplate
a terrible thought:

Could a random gust of wind,
hitting at exactly
the wrong split second,

have been the difference
between life and death?

Here it comes...

And we got a crash.

Paries's theory explains
every aspect of the crash.

The crew's confusion
with the autopilot display...

3.3... degrees.

...caused the plane to descend
dangerously close
to the mountain.

Turbulence and an obscure safety feature
brought it even closer.

It was a fatal combination.

It's a fascinating lesson...

about the, uh,
random dimension of accidents.

Half a second before,
half a second later,

they wouldn't have the accident.

The discovery of a confusing
cockpit display...

...has enormous implications
for the entire industry.

The flight instrumentation
of aircraft like the DC-10,

MD11s, the 74s and so on,

all the Boeing products
and all the commuter products

that were using
that avionics suite

had this vulnerability about it.

Investigators now face
a daunting question

affecting aircraft safety
around the world.

If the design of the autopilot
interface isn't changed,

how many more people could die?

There's mounting evidence
that the design of the autopilot
interface on Airbus A320s

led the Air Inter pilots
to accidentally dial in
a dangerous rate of descent.

3.3... degrees.

We felt a need to start
the industry to work on this.

The plane's manufacturer,
Airbus, responds immediately.

The main change,
which was very quickly made,

was to change
the display window.

With the new design,

if a pilot selects
a vertical speed of 3,300,

the entire four-digit number
is displayed.

So... the confusion
between an angle

and the vertical speed
was no longer possible.

For investigators,
only one mystery remains.

All Airbus A320 jets
are designed to be equipped
with a safety device

known as a Ground Proximity
Warning System,

or GPWS.

Which is a downward-looking
single-purpose radar

that tells you how high you are
above the ground
directly beneath the airplane.

And if it gets to be too low,
it'll set off a warning.

Pull Up.

Terrain.
Pull up.

But Captain Hecquet...
- We have to watch our descent.

...never received a warning
for one very simple reason:

His A320 didn't have that alarm.

Merde!

The first question, of course,
was why...

the aircraft was not equipped.

So it's not part
of the Minimum Equipment List?

The Air Inter management
had decided...

they did not like
the false warnings

that had been produced

by GPWS equipment.

Normally,
most planes fly slower
than 250 knots

when under 10,000 feet.

But we flew at 350 knots
until the final approach.

So at those speeds,
GPWS was always giving off
false alarms.

This decision, while legal,

prevented the pilots from having
one last line of defence

before crashing
into the mountain.

It's impossible
to imagine that the pilot
wouldn't have pulled up

if he'd heard the alarm.

We should have a GPWS
on commercial flights.

In any case, yes, that's...

a... an obvious conclusion.

The report will list
these causes:
Flight Deck Ergonomics...

Investigators conclude
that there was no single cause

for the crash of Flight 148.

The tragedy involved
in an ill-fated combination

of many different weaknesses
in the airline industry.

We made...
35 or so recommendations,

including pilot training...

about the Ground Proximity
Warning System and so on.

The recommendations
lead to sweeping changes.

Pilots must now have
more A320 training

before getting
behind the controls.

One of the two pilots
now need to have

at least 300 hours on the plane.

They estimated
that 300 hours were enough.

Another change:

The design of a more
heat-resistant black box.

The FAA did a test,

did some studies
with the thermal characteristics
of post-crash fires,

where it came up
with a value of, uh,

260 degrees C for 10 hours.

Delta Alpha, your position?

Air Inter Delta Alpha,
Strasbourg.

As a result
of the Strasbourg crash,

the A320 is now a safer plane.

You can only get this...

change if there is what people
perceive to be a good reason.

And sadly,

a good reason
is still an accident.

But improved
aviation technology
is still no substitute

for well-trained,
well-prepared pilots.

There's an old axiom
in aviation,
that you're taught early on:

Never let an airplane
take you somewhere

that your brain hasn't visited
at least five minutes
ahead of time.

This is an excellent example
of a flight crew

that didn't follow
that particular axiom.

difuze