All language subtitles for Air.Disasters.S04E11.Subtle.Incapacitation.1080p.PMTP.WEB-DL.AAC2.0.H.264-maldini_track3_[eng]

NARRATOR: All that's left
of Ethiopian Airlines

flight 409 lies at the bottom
of the Mediterranean Sea.

This accident was very
unusual, very unlikely.

Everybody was shocked that we
had a major crash in Lebanon.

Turn right now, heading 270.

NARRATOR: The 737
fell from the sky

just minutes after
leaving Beirut.

Oh God!

NARRATOR: Now rumors
of a terrorist attack

are spreading to the streets.

They speculate
that the airplane

could be hit by a bomb.

NARRATOR: And investigators
are struggling

to understand the plane's
bizarre flight path.

Often, the best approach is
the Sherlock Holmes approach.

We need to check
those trim tabs.

Eliminate everything
you didn't happen.

What time did he check in?

What's left--

That's it.

--is probably
what did happen.

What is it?

NARRATOR: The evidence leads
to a finding so controversial.

This flight was in
jeopardy from the outset.

NARRATOR: Some still
refuse to believe it.

ANNOUNCER: Ladies
and gentlemen,

we are starting our approach.

We lost both engines.

Keep the mask up your nose.

Emergency descend.
- Mayday!

Mayday!

Brace for impact!

He's the last one.

Investigation
started in 2004.

He's going to crash.

NARRATOR: January 25, 2010.

It's just past
midnight at Beirut's

International Airport.

Fuel is good.

Load is calculated.

In a typical departure,
the flight crew

reviews its load,
reviews the fuel,

reviews the route then runs
through the company checklists

to get the airplane underway.

NARRATOR: Captain
Habtamu Negasa

has been flying with Ethiopian
Airlines for over 20 years

and has more than 10,000
hours in the cockpit.

Exterior checks complete?

Check complete.

No problems.

NARRATOR: The first officer
is far less experienced.

Aluna Beyene is
a recent graduate

of the Ethiopian
Airlines Flight Academy.

Tonight, there
are 82 passengers

aboard the Boeing 737.

They are preparing for
an overnight flight

to Addis Ababa, Ethiopia.

Many passengers are Lebanese.

Some are Ethiopians returning
home after working abroad.

There's also an undercover
security officer

on board tonight's flight.

Flight security
officer's there post-9/11

to intercept anybody who
attempts to interfere

with the flight crew.

NARRATOR: Beirut airport has
seen its share of trouble.

It was the site of the
1983 marine barracks

bombing that killed 241
American servicemen.

In 2006, all three runways were
destroyed by Israeli missiles

during the Lebanon war.

Today, the rebuilt
airport serves

flights from around the world.

Beirut airport is a very
busy, very well-put-together

civil airport.

Its only difficulty is
presented by the mountains

directly to the East.

NARRATOR: The Lebanon mountains
rise sharply from the coast,

forcing all flights to take off
toward the Mediterranean Sea.

Flight 409's flight plan calls
for it to head southwest then

make a U-turn towards a
navigational checkpoint

called Chekka.

Ethiopian 409,
wind's nearly calm.

Cleared for takeoff 2-1.

NARRATOR: The air
traffic controller

gives flight 409 its final
takeoff instructions.

Immediate right
turn to Chekka.

Roger.

Cleared for takeoff runway 2-1.

Immediate right turn to Chekka.

Ethiopian 409.

Left side is clear.

Right side is clear.

NARRATOR: The captain sets his
radar to display the weather.

Weather's on my side.

Roger.

Terrain on my side.

NARRATOR: While the first
officer monitors the terrain.

The weather that night
had mixed clouds with bases

from 2,000 feet overcast
up to 20,000 feet,

and there were scattered
thunderstorms in the area.

Take off thrust set.

NARRATOR: The 737
accelerates down the runway.

Speed increasing, check.

Do you see that?

Rotate.

NARRATOR: Ethiopian
Airlines 409 lifts off just

after 2:30 in the morning.

Their takeoff procedure
and the initial part

of the takeoff seemed
entirely routine and ordinary,

and well-executed.

Gear up.

Heading select.

Heading select, check.

NARRATOR: The captain begins
banking the plane to the right

as he climbs.

Ethiopian 409
control 19-3 Ma Salama.

NARRATOR: The tower controller
bids the crew goodbye

and hands the flight
off to a colleague.

Ethiopian 409, good morning.

Climb flight level 290.

NARRATOR: The area
controller instructs flight

409 to climb to 29,000 feet.

Flight level
290, Ethiopian 409.

NARRATOR: But the weather
ahead is becoming fierce.

There's lightning in the air.

You see the flashes.

You're beginning
to feel turbulence.

Sir, I suggest that,
due to the weather,

you follow heading 270
to be in the clear.

2-1, say again.

Confirm heading 210.

NARRATOR: Just a few minutes
into the flight, something

is going wrong.

An alarm warns the
crew that their turn

is becoming dangerously steep.

The airplane is
being banked beyond

its normal operational limits.

NARRATOR: Captain
Negasa is struggling

to correct the problem.

He veers back to the left
towards the thunderstorm the

controller wants him to avoid.

As you enter
heavy precipitation,

the cockpit can become very
noisy with a tremendous worst.

It gets your attention.

NARRATOR: The controller sees
that flight 409 is starting

to veer back towards Beirut.

He warns the pilots again
that they need to turn.

Ethiopian 409,
follow heading 270.

Turn right, heading 270.

At this moment,
the controller

was probably most
concerned with the fact

that the crew had
overshot its heading,

would be conflicting
with inbound traffic

and had to be moved away
from a possible conflict

with terrain.

Correct heading 270.

Roger.

OK, what heading did he say?

270.

Set.

NARRATOR: The cockpit fills
with a disturbing sound.

What is it?

NARRATOR: The control
columns vibrate,

warning them that the
plane is about to stall.

Speak.

What is it?

Go around.

Go around.

Roger.

Go around.

NARRATOR: The captain pushes
the throttle all the way up

to go around the problem.

Ethiopian 409, follow
heading 270, sir.

Follow heading 270.

Turn right, heading 270 now.

Whenever a controller tells
the pilot to do something now,

the controller is telling
the flight that they're

in immediate danger.

Speed is going down.

Ethiopian 409, you are
going into the mountain.

Turn right now, heading 270.

He was worried
that the crew was

going to fly the
airplane into the hills

behind Beirut airport.

NARRATOR: But their
situation is even more dire.

The chaotic motion of the plane
is torture for passengers.

It's horrible.

You're feeling a 3G load.

It's pushed you
down in your seat.

You're getting squashed.

Your fellow passengers, some
of them are silent some of them

were screaming.

God.

Oh, God.

Oh, God.

Ethiopian 409, Beirut?

Ethiopian 409, Beirut?

We've lost an aircraft.

Ethiopian.

We don't know what's
happened, and we

don't know his position.

NARRATOR: Ethiopian
409 has plunged

into the Mediterranean Sea just
five minutes after takeoff.

Within minutes of the
crash, the Lebanese military

issued a distress call to all
available ships in the area.

Local boats, as well as foreign
warships, join the search.

My first reaction
was this accident

was very unusual,
very unlikely,

that really required a very
good investigation to see

what we could learn from it.

NARRATOR: It's the first major
commercial aircraft accident

in Lebanon in nearly 35 years.

Within hours, the
Lebanese Civil

Aviation Authority dispatches
Hamdi Chaouk to take charge.

As soon as I
reached the airport,

I had to try to manage the
environment of the accident.

All right.

The hardest part is how
to deal with all the search

and rescue of major
parties, from defense

to the interior ministry to
all the concerned parties who

have never done this before.

NARRATOR: A former
pilot, he's one

of the few experienced
investigators in the country.

So we've got to make
this our search area

right here on this grid, OK?

We have ships here,
here, and here.

OK.

NARRATOR: Mohamed Aziz
is his second in command.

First of all, we
wanted, if by any miracle,

anybody had escaped,
we wanted to be

able to pick any
survivor, especially

that the first hours they
discovered two or three

bodies, most probably
they were thrown out

of the plane when it crashed.

Have you any
sign of wreckage?

Negative, nothing.

NARRATOR: Chaouk is
under intense pressure

to locate the wreckage fast.

So you want to
answer very important

questions to the family.

Why my relative died?

It goes to your head as
an investigator always.

I want to know the truth.

Nothing here?

No.

No?

NARRATOR: But the storm
flight 409 was trying

to avoid is still raging.

A major deterrent to the
search and rescue operation

was whether.

Bad weather was high waves
and the sea and so on.

So this makes the search and
rescue operation difficult.

OK, let's see what kind
of weather they were flying.

NARRATOR: Could the storm
have been fierce enough

to bring down a 737?

Well, there were
thunderstorms west

of the airport.

Thunderstorms can
be very dangerous.

They can interrupt the flight
and the airplane structurally,

and they complicate the safe
operation of the airplane.

NARRATOR: In rare
cases, a lightning

strike can damage
the electronics

that control the aircraft.

While a lightning
strike on an airplane

is not uncommon
and usually doesn't

create damage to
the airplane, it

can under some circumstances.

NARRATOR: At the
same time, rumors

are spreading that
flight 409 was the target

of a terrorist bombing.

When you live in a country
like Lebanon, every now

and then, you have fighting.

You have explosions.

And the first thing that
comes to mind when you lose

an aircraft just like
that is maybe there

is an explosion on
board the flight.

NARRATOR: As day
breaks, wreckage

begins to wash up onshore.

Navy ships recover
floating debris,

and some human remains.

It's painfully obvious
there are no survivors.

The Lebanese army have
recovered seven bodies.

NARRATOR: 82 passengers
and eight crew are dead.

Most of the plane
is still missing.

Without more wreckage,
investigators

may never know what happened.

At the airport, controller's
eyewitness accounts

seem to support a
possible terrorist attack.

I saw a bright orange flash.

It looked like the
plane exploded.

The controller he saw a
ball of fire at the place.

He presumed that
the plane crashed.

So some people they say that
it could be an explosion.

NARRATOR: Hard
evidence of sabotage

requires a close
examination of the wreckage.

You have to go
back to the evidence

because the evidence speaks.

The part itself of
the plane can tell

you how the accident happened.

NARRATOR: And so far, the
inexperienced team is having

trouble locating the plane.

No luck yet.

Have you searched
this sector here?

Yeah, we looked everywhere.

We looked here, here, here.

We were able to determine
where probably the aircraft

would have been, yet when
the Navy and the Air Force

started to search for the
plane, they could not find it.

NARRATOR: A Navy ship
is searching for signals

from the plane's black boxes.

These begin
transmitting an alert

as soon as they come
in contact with water.

That is what
we call a pinger,

and that emits a signal for
about 30 days after the crash.

NARRATOR: But two days in, the
search hits a major hurdle.

Investigators learned the
Navy sonar they've been using

can't home in on the signals.

It's not precise enough.

We'll never find
them this way.

We don't have the
right equipment.

We could not sleep.

We were always thinking
that we need the recorders.

NARRATOR: Chaouk contacts
aviation authorities

in France for help.

We're hoping you
can come immediately.

Yeah, it's quite urgent.

NARRATOR: They have the
equipment and the expertise

to find the recorders.

OK, great.

All right, thanks.

Great.

They're on their way.

It was a learning curve
for everybody, the leaders

or divers or the Navy people.

NARRATOR: With the right gear--

Thank you for coming.

NARRATOR: --the team should be
able to search more quickly.

But valuable time has
already been lost,

and other people
could be at risk.

These type of airplanes are
flying all over the world.

And if there is a
problem, we need

to take whatever corrective
action that's needed.

NARRATOR: The United
States also sends help.

Because the 737
is American-made,

the National Transportation
Safety Board's

Dennis Jones joins the team.

Welcome to Beirut.

Thanks.

We still don't have
a crash site, per se,

the flight recorder,
which is always

a big concern of interest,
was still yet to be found.

We got the flight track.

NARRATOR: With no
wreckage to study,

Jones and Chaouk
turned to a record

of the plane's flight path.

We got the radar
track from the airport.

This should show us
exactly what they did.

When we first got there,
some of the information

we had that was
helpful was the radar

data and air traffic control
information in general.

So we were able to
start evaluating

that pretty quickly.

NARRATOR: The radar
paints a baffling picture.

It's like no one's flying.

Exactly.

NARRATOR: Almost from
takeoff, the plane follows

an unusual and erratic path.

Once you see what
happened to the plane,

you would wonder really
what's happening.

As if there were no
crew in the cockpit.

It is almost similar--

270.

--of a situation where nobody
is in control of the plane.

NARRATOR: Now that they've
seen the strange flight path.

OK, so here's the track.

So they could be
anywhere along here.

NARRATOR:
Investigators are more

anxious than ever to
get at the wreckage

and search for answers.

Let's take a look
at that monitor.

Now, what we're seeing is
basically an external view

with the radar data and
air traffic control,

but we didn't get an idea
of what was actually going

on board the aircraft itself.

So we became even more
eager to get the recorder.

That's it.

That's it.

That's exactly what
we're looking for.

NARRATOR: Finally, eight
days after the crash,

the French equipment
detects the vital signals.

It was found 45 meters
deep and 5 kilometers

southwest of Beirut airport.

NARRATOR: Cameras
mounted on unmanned subs

captured the first images of
what remains of flight 409.

We heard the
Odyssey submarine

that had been used
for taking photos

and survey for the wreckage
located on the seabed.

NARRATOR: It's too expensive
to bring all the wreckage

to the surface,
so investigators

focus on the tail
section where the two

black boxes are stored.

They retrieved the tail,
the horizontal stabilizer,

with the tail comb as well.

They were still
attached together.

And they found the FDR
located underneath.

We were quite
delighted about that,

and the Lebanese
government immediately

started making plans so
having that transported

to a facility to be evaluated.

NARRATOR: But they only find
the Flight Data Recorder.

What of the CVR?

NARRATOR: The Cockpit Voice
Recorder is still missing.

So it's got to
be in this sector.

That's what we think.

NARRATOR: As divers continue
to search for the CVR,

investigators study underwater
video of the wreckage.

OK, let's start
mapping this out.

NARRATOR: When a plane
explodes in midair,

the debris falls in
a circular pattern.

But if a plane hits
the water intact,

the debris will fall
in a linear pattern.

The underwater video
allows investigators

to map the position of
every piece of wreckage.

Another one here
lining up nice and neat.

In this case, we
found all the pieces

laying in the bed of
the water in almost

300 meter straight line.

NARRATOR: They also search
for any sign of fire damage.

You would look for
a certain signature

to show us perhaps there
might have been some heat

damage or fire damage.

Go back.

I want to see that piece again.

NARRATOR: But there's no
sign that the metal was

ripped open by a blast
and no burn marks

on any of the wreckage.

We looked at the footage.

We couldn't identify any
black spot, black soot

or anything of the sort.

We saw none at all.

There's no sign
of any explosion.

Ethiopian 409 Beirut.

NARRATOR: They
conclude that the tower

controller may have been
fooled by a trick of the light.

It was a stormy night,
so throughout the night,

you were hearing
thunderstorms, lightning,

and they do sound
exactly like explosion,

and they give you a
bright light even stronger

than any big explosion.

NARRATOR: Next,
investigators focus

on the flight data recorder
or FDR found in the wreckage.

Nothing so far.

NARRATOR: There are more than
1,000 parameters to analyze.

The flight data recorder
records essentially

the instrument and other
parameters from the aircraft,

basically what the
aircraft is doing.

And that retains, in this
case, 25 hours of information.

NARRATOR: Almost all
the data is normal,

but one number stands out.

Take a look at that
stabilizer setting.

It's a bit low, but
still in the green.

NARRATOR: The stabilizer
is part of the tail.

Pilots adjust its
angle depending

on the weight of the plane.

Move it up, and the
plane pitches up.

Move it down, and it
forces the nose down.

OK.

Fuel is good.

Load is calculated.

Check complete.

No problems.

NARRATOR: The FDR
reveals that flight

409 stabilizer was set further
down the normal for takeoff.

Such a small variation probably
wouldn't cause the pilots

to lose control of their plane,
but investigators won't know

its effect until they can
test the configuration

in a flight simulator.

At that point, obviously,
everything was on the table.

We knew we had a lot more
factual finding to do.

We got it.

Oh, here it is.

NARRATOR: In the
Mediterranean Sea,

the arduous search for
the CVR finally pays off.

Oh, yeah, that's it.

Hey, Aziz.

We got it.

Oh, you found it?

Yeah.

I have to praise the
Lebanese Navy diver

because, with the
equipment they had,

had to do a real hand search
45 meters underwater, which

is quite difficult,
but they were

able to recover it at the end.

NARRATOR:
Investigators can only

hope that the pilot said
something that will reveal

why their plane went down.

PILOT (ON RECORDER):
Fuel's good.

Load is calculated.

NARRATOR: Investigators sync
up the conversation on the CVR.

PILOT (ON RECORDER):
Exterior check's complete.

NARRATOR: With the
plane's known flight path.

FIRST OFFICER (ON
RECORDER): Roger.

Check complete.
No problems.

NARRATOR: They listen
for any sign of trouble.

We want to try to get a
better understanding if there

might have been some kind
of mechanical problem

based on what they
were perceiving.

European 409,
wind's nearly calm.

Cleared for takeoff 2-1
immediate right turn

to Chekka.

PILOT (ON RECORDER): Roger.

Cleared for takeoff runway 2-1.

Immediate right turn to
Chekka, Ethiopian 409.

Everything seemed to
be going just right.

Now, once they took off,
the first part of the takeoff

was normal.

Turn right,
initially heading 315.

315, roger.

NARRATOR: Investigators hear
the controller give the pilots

a new heading,
but the plane goes

off in a different direction.

As they approached
the heading

that they had been assigned,
they overshot the heading.

He was supposed to turn this
far, but he just kept going.

Mark?

They're way off course.

Sir, I suggest that,
due to the weather,

you follow heading 270
to be in the clear.

NARRATOR: Each time the pilots
tried to correct their course,

they turned too far
and banked too steeply.

It's a sure indication that
the airplane has lost control.

Ethiopian 409, you are
going into the mountain.

Turn right now, heading 270.

The airplane was rolling
into an ever steeper bank.

Its lift vector was
decreasing, so the nose

was dropping toward
the sea, ultimately

leading to a spiral.

Oh, God.

The plane was out of control.

NARRATOR: But there's nothing
on the recording indicating

a mechanical failure.

And we just were
not hearing anything

that showed a malfunction which
was consistent with the flight

data recorder.

It was just something
that we certainly

didn't have any answers
for in the beginning.

NARRATOR: Desperate
to know what

brought down the 737,
investigators dig

into maintenance records.

They learn that
some 737 sevens

have a small but dangerous
flaw in a vital part of a tail.

Hey, Dennis, I think we
need to check those trim tabs.

NARRATOR: Trim tabs are
small control surfaces set

into the tail of the plane.

They counteract
the powerful flow

of air pushing
against the tail,

making it easier for the
pilot to fly the plane.

To use an analogy with cars,
it's like a power steering as

compared to manual steering.

NARRATOR: If the trim
tabs were damaged,

it could explain why the
captain was struggling

to control the aircraft.

Left heading 270.

Roger.

Left heading 270.

My experiences of flying
an airplane out of trim it

can make it extremely
difficult to fly.

It can even go
beyond the forces

that the pilot could actually
use or input to counter it.

You can bring that over here.

NARRATOR: Investigators
are in luck.

The stabilizer
and trim tabs are

among the few
pieces of wreckage

recovered from the sea.

The team assembled to
evaluate this aircraft

hit the water
close to 400 knots,

so we're expecting a lot
of things to be damaged.

So we wanted to
kind of evaluate

it to see if there was
anything that was pre-existing

that might have
somehow contributed

to this sequence of events.

NARRATOR: But it's
another dead end.

A close inspection of the trim
tabs reveals no damage at all.

No sign of any malfunction.

They did not affect the pilot's
ability to steer the plane.

Jones and the team have
mechanical failure.

Now they'll focus on the final
part of the doomed aircraft,

the cockpit.

Investigators
traveled to Seattle,

Washington, to Boeing
state-of-the-art

flight simulator.

OK, we're going to
run the Ethiopian 409.

Going to set the
trim to match theirs.

NARRATOR: The flight
data has shown

that flight 409 stabilizer
was set to a shallower

than normal takeoff angle.

Investigators want to know
if that affected the pilot's

ability to handle the plane.

You kind of get a front-row
seat of perhaps what

the flight crew were
seeing at the time and how

the aircraft was handling.

OK, let's see how this
thing is going to fly.

NARRATOR: The low
angle of the nose

makes the plane difficult
to handle at first.

It's definitely not happy.

The trim was mis-set for
takeoff by a small margin

but nevertheless by enough to
create an undesirable pressure

for the pilot on the controls.

So the pilot was always
fighting the airplane

to one degree or another.

NARRATOR: But in the simulator,
the pilot has no difficulty

correcting the problem.

OK, well.

Try it with no trim at all.

Every single time we try
to recover this aircraft,

we are able to recover it.

Well, they should have
been able to recover.

NARRATOR: They conclude that
the low stabilizer setting

did not cause this crash.

Something else made the
737 spiral into the sea.

Officials from
Ethiopian Airlines

still believe
terrorism is to blame.

They insist that an onboard
bomb cannot be ruled out

until more of the
wreckage is recovered

from the Mediterranean.

The investigators don't agree.

He told them that it's
quite a remote possibility

that there was something
put on board that plane.

When the plane explodes
with a bomb on board,

it flies its own
route, and it explodes.

It doesn't go up left and
right and up and down,

and then something
explodes on the plane.

NARRATOR: But stamping
out rumors is never easy.

Let's go over here.

NARRATOR: Investigators
are under growing pressure

to explain what happened.

If it wasn't a bomb, then what
did bring down flight 409?

An aircraft accident
investigation,

often the best approach is
the Sherlock Holmes approach.

What you do is eliminate
everything you didn't happen.

What's left is probably
what did happen.

The controllers did their job.

Turn right,
initially heading 315.

The ground-based navigational
systems were working.

The airplane was
functioning properly.

So what we have
left is the crew.

NARRATOR: Investigators
return to the CVR.

They hope the crew's
conversation can shed light

on why two qualified pilots
lost control of a mechanically

sound airplane.

Looks pretty normal.

Exterior checks complete?

Check complete.

No problems.

NARRATOR: noticed
something odd.

The mood, even the speed of
the voice or even the tone--

Feels good.

Load calculated.

--did not reflect
what is really actually

happening in the aircraft.

During the takeoff roll--

Do you see that?

--the captain saw something
because he tells first

officer did you see that?

But then, there was no reaction
from the first officer.

NARRATOR: The first officer
is uncharacteristically quiet.

OK, engage the autopilot.

NARRATOR: Even worse,
he's not following

his captain's commands.

Hold on.

Stop for a second.

That would have changed things.

The advantage of engaging
the autopilot in that situation

is that the pilot can then
let the autopilot worry

about the attitude
of the airplane

while he sits back and
takes the big picture,

maintain situational awareness.

NARRATOR: The autopilot
can adjust the throttles

to maintain a safe airspeed
and can keep the plane

on the right heading.

But investigators
learned it was

impossible for the autopilot
to engage on flight 409.

There's no way
it could come on.

PILOT (ON RECORDER): OK.

Engage the autopilot.

NARRATOR: It's designed not to
switch on if one of the pilots

is pulling other control
column as the captain was.

And for some reason,
the first officer

didn't tell the captain
the autopilot wasn't on.

Had the autopilot been
engaged when the captain

ordered the first
pilot to engage,

it would have saved
the whole flight.

The interaction
between the crew members

were not what we would expect
from a professional crew

at the time.

NARRATOR: The crew's
behavior is baffling.

It forces investigators
to consider

an unlikely explanation
for what went wrong,

something called
subtle incapacitation.

It's very difficult
to recognize

a subtle incapacitation.

If the pilot at the control
has a stroke and slumps

over the control wheel, there's
no question that you've got

a person who's incapacitated.

Confirm heading 210.

Negative, sir.

To proceed, direct Chekka.

Turn left now, heading 270.

Left heading 270.

Roger.

Left heading 270.

However, if the
pilot at the controls

starts to lose the picture
and does so silently

and starts to misapply controls
or push the wrong buttons,

it may take a while before
the other crew members

pick up on that failure.

That sequence is called
subtle incapacitation.

NARRATOR: It's a
controversial idea

that goes beyond the usual
definition of pilot error.

What is it?

Subtle
incapacitation can come

from physiological reasons,
psychological reasons,

or a combination of both.

It could be something minor.

Medications could cause it.

Stress could cause it.

Fatigue could it.

NARRATOR: Because
commercial aviation demands

such high levels
of performance,

drug and alcohol use by
pilots is closely scrutinized.

Drug testing is part of
any transportation employee,

from baggage handlers all
the way up to cockpit.

Typically, it's done
on a random basis.

It's done.

NARRATOR: But there's no
formal test for fatigue.

Other accidents with
the same kind of sequence

of events taking place.

NARRATOR: In 2009,
Colgan air flight

3407 crashed outside Buffalo.

The two overtired pilots failed
to react properly to a Warning

that the plane was
about to stall.

All 49 people on
board were killed.

PILOT (ON RECORDER): This
room doesn't make you sleepy?

NARRATOR: Investigators
continue to analyze

the cockpit recording.

What are these guys doing?

NARRATOR: They listen
to what the pilots were

saying just before takeoff.

PILOT (ON RECORDER): This
room doesn't make you sleepy?

If you hear someone in
the recorder saying sleep,

immediately our
antennas stick up.

What are they doing up there?

Was there weed in it?

Did you feel dizzy?

All right, I couldn't sleep.

Well, me too.

NARRATOR: Investigators
are shocked to hear

the pilots joking
about being tired

and the reference to weed.

That would have
changed things.

NARRATOR: Subtle
incapacitation may not be such

an unlikely cause after all.

Trying to explain the
behavior of the pilots

on that particular night was
really the most difficult

part of this investigation.

And this is why we
considered every single issue

starting from the food they
had the type of rest they had.

NARRATOR: Piecing together the
pilot's movements in the hours

leading up to the crash.

What time did he check in?

NARRATOR: Is now
the top priority.

In the case of this
accident, the pilot's bodies

weren't recovered, so
there was no way they could

do post-mortem examinations.

We immediately
called the hotel

to check the garbage
if there was any bottle

of alcohol or any drugs.

Did they see the crew out
having drinks or something?

NARRATOR: Investigators study
security footage for any signs

that the pilots were impaired.

We also looked at
the footage of the crew

coming into the airport.

They were walking normally.

Everybody we spoke
to, they said no.

No, they were normal.

NARRATOR:
Investigators traveled

to Ethiopia to
interview family members

about the crew's habits.

Thank you for taking
the time to see me.

I'm very sorry for your loss.

I just wanted to ask you a few
questions about your brother.

Did he ever drink?

No.

There's no evidence
to suggest either pilot

abused alcohol or drugs.

The captain
didn't drink at all.

So he was a sport guy
concentrating on his sports.

NARRATOR: Subtle incapacitation
is difficult to prove.

In the crash of Flight 409,
the evidence so far is mixed.

But what investigators discover
next could tip the balance.

Gear up.

NARRATOR: Employment
records detailing

the pilot's flight hours.

Heading select.

Heading select.

Check.

NARRATOR: Revealed critical
information about the captain

of flight 409.

He'd been working
almost non-stop

for nearly two months.

The 51 days he
probably flew something

like 45 days out of the 51.

Daily, daily, daily flying,
just taking the minimum rest.

It's legal, but it is
quite a lot of work.

Ethiopian 409
wind's nearly calm.

Prepare for takeoff 2-1.

Work, work, work.

NARRATOR: The crew's
last chance to rest

was a scheduled stopover
after flying into Beirut.

I could use some food that
didn't come from an airplane.

What do you say?

Yeah.

A good meal will be good.

All right, let's do it.

You have any a lot
of water today?

Yeah, she'll bring
back something.

She'll bring something.

Oh, here we go.

Prior to the flight,
they had a heavy launch,

and they were not
able to rest properly,

so they were commenting
on not being able to rest

properly prior to the flight.

Did you feel dizzy?

Oh, I couldn't sleep.

NARRATOR: Investigators
suspect that the heavy meal

kept them awake at night.

Indigestion and
fatigue they definitely

they affect the pilot behavior
throughout the flight process.

Sir, I suggest that,
due to the weather,

you follow heading 270
to be in the clear.

2-1, say again.

NARRATOR: The storm
conditions likely

added to the pilot's stress.

The weather could
be a factor in adding

pressure on the pilots.

NARRATOR: Fatigued and
under increasing stress,

they lost track of
where they worked

and what they were doing.

This flight was in
jeopardy from the outset.

What is it?

It seems that the
crew was never fully

on top of what was happening.

Go around.

Go around.

Go around.

Roger.

Go around.

NARRATOR: Investigators
conclude the accident was

caused by a crew
that was simply

too tired or too
confused to recover

from the first wrong turn.

It's a textbook example
of subtle incapacitation.

We could prove that
the symptoms that we saw

are similar to the
symptoms of somebody who

has a subtle incapacitation.

Oh, God.

NARRATOR: The accident
exposes a risk

to aviation that no amount
of engineering can overcome.

After the crash of
flight 409, investigators

suggest Ethiopian
Airlines introduce

much more rigorous rules
regarding crew rest.

It's one thing to have the
experience and the expertise

to do the work, but you
have to be in good condition

in order to perform.

As long as airplanes are
operated by humans, fatigue,

distraction, and
other human weaknesses

can only be managed,
never erased.

I'm not sure that we can
prevent subtle incapacitation.

But we should at
least try to eliminate

all the possibilities that
are related to human factor

because human factors
are still the majority

of most of the accidents.

Check complete.

No problems.