All language subtitles for Mayday.S05E09.Mixed.Signals.1080p.AMZN.WEB-DL.DD+2.0.H.264-playWEB_track3_[eng]

Alpha Lima Whiskey,
301 Santo Domingo,
come in.

A Boeing 757
disappears from radar

with 189 people on board.

The plane's wreckage
is soon found at sea.

There are no survivors
to say what happened.

This accident was
the first major loss
of a Boeing 757 aircraft.

Investigators find no clues
in the wreckage.

Only the plane's black box
can tell them what happened.

The tape raises
a perplexing question.

310, Santo Domingo,
come in, please.

My airspeed indicator
is not working.

What's happening?

How had the failure
of one single instrument...

Sir, pull up!

...caused the crash
of one of the world's
most sophisticated jetliners?

Mayday! Mayday!

Gregorio Luperon
International Airport in Puerto
Plata, the Dominican Republic.

February the 6th, 1996.

The small Caribbean island is
a popular winter getaway.

A group of German tourists
has been delayed.

There are mechanical problems
with the jet that was supposed
to take them back to Frankfurt.

The airline has arranged
to lease another plane
for the flight.

The replacement jet is owned
by Turkish Charter Company
Birgenair.

They have a 757 that's been
sitting on the tarmac
for almost three weeks.

But it takes several hours
to get the plane ready to go...

and to get
the Turkish crew aboard.

By 10:15 p.m.,
the plane and most of its crew
are at the gate.

More than four hours after
they were supposed to take off,

the first of the passengers
begin boarding the plane.

They have a nine hour flight
to Frankfurt ahead of them.

Puerto Plata Alpha Lima
Whiskey 301...
requesting push back.

Shortly after 11:30,
Birgenair Flight 301 is given
permission to leave the gate.

Push back granted.

Moments later,
it taxis to the threshold
of the runway.

Cabin crew, take your seats,
ready for takeoff.

Cabin announcement
is completed.

First Officer Aykut
Gergin is new to the 757,

with fewer than
75 hours
in the plane

in the last three months.

Thank you.
Ready for takeoff.

In contrast,
Captain Ahmet Erdem is one of
Birgenair most senior pilots.

He's logged thousands
of hours in this type of plane.

Alpha Lima Whiskey 301,
ready for takeoff.

301 cleared for takeoff,
runway 08.

Cleared for takeoff.
Runway 08, 301.
Thank you.

A good flight.

Good flight.

Good flight.

Muhlis Evrenesoglu
is on this flight
as a Relief Pilot.

Like First Officer Gergin,
he's been flying the 757
for less than three months.

As the plane
accelerates to takeoff speed,
a light rain begins to fall.

- Power's set.
- Okay, check.

First Officer
Aykut Gergin watches
his air speed indicator

for a routine
instrument check.

As the airplane's
accelerating to
takeoff speed,

the First Officer
calls 80 knots.

- Eighty knots.
- Check.

The captain, in theory,
should verify that

his airspeed indicator
also reads 80 knots.

My airspeed indicator's
not working.

The captain's airspeed
should read the same as
his First Officer's.

120.

But the readings
do not match.

- Is yours working?
- Yes, sir.

You tell me.

Erdem wants his
First Officer to tell him

when the plane
hits takeoff speed.

V-one.

At 150 knots,
the plane hits V-one,
the point of no return.

Rotate.

The captain must
pull back on his column and
get the plane in the air.

Positive climb, gear up.

Positive climb,
gear is up.

At 11:42,
the plane takes off.

Seconds later,
Captain Erdem's airspeed
indicator comes to life.

Is it possible to
turn off the wipers?

Okay, wipers off.

- Climb thrust.
- Climb thrust.

First Officer Gergin
reduces power

to the engines
for a gradual climb
to cruising altitude.

301 airborne 45.

Switch over
Santa Domingo 1243.

1243.
Bye bye, sir.

Climbing through
2500 feet,

First Officer Gergin
establishes contact

with the island's main tower
in Santo Domingo.

Alpha Lima Whiskey 301,
climb and maintain 280.

Center autopilot on, please.

- Center autopilot has command.
- Thank you.

One minute and
thirty seconds into the flight,
the autopilot takes over.

Onboard computers
now make
all the calculations

and adjustments necessary
to keep the plane flying safely.

Almost immediately,
the computer reports a problem.

Rudder ratio.
Mach airspeed trim.

Two different alerts
warn the pilots that the plane
is traveling far too fast.

Yes... trim...

But the First Officer's
airspeed indicator

Shows the plane climbing
at a normal speed,
220 knots.

Something's wrong here.

Unaware that there
are any problems,

the controller directs
Birgenair Flight 301
to continue climbing.

Alpha Lima Whiskey 301,
report Pokeg.

Okay, 280,
I'll call you over Pokeg.
301.

Okay,
there's something crazy.
Do you see it?

In the cockpit, the situation
gets more confusing.

The First Officer's
airspeed indicator

shows that the plane
is flying much too slowly.

Mine shows only 200 now,
and decreasing, sir.

But the captain's gauge shows
the plane flying far too fast.

Three hundred and
twenty-five knots.

Both of them are wrong.

What can we do?

Let's check
the circuit breakers.

Yes, sir.

As the first warning
is eliminated,

- a more persistent warning
replaces it.
-

The over-speed warning
tells the crew

that they are approaching
350 knots.

The maximum speed at which
the plane was designed to fly
at this altitude.

Okay, it's no matter.

Let's pull the air speed,
let's see.

Resetting the circuit breakers
turns off the alarm,

but it doesn't
fix the problem.

Captain Erdem's air speed
indicator still shows
he's flying much too fast.

Now it's 350, yes?

Confused by
the conflicting information,

Captain Erdem decides to do
what the plane wants...

He slows down.

Let's take
that like this...

...with terrifying results.

Oh, God!

The 757
is sending out warnings that
are confusing the crew.

Bewildered,
the crew struggle to
solve the problem.

The lives of 189 people
depend on them
getting the answer right.

Shortly after taking off from
the Dominican Republic,

Birgenair Flight 301
is in trouble.

God! God! God!

The cockpit is filled
with an ominous sound...

The stick shaker alert.

Stick shaker warning is
a warning of imminent stall.

It means that the airplane is
about to attain a speed so low,
that it cannot sustain flight.

The alert is so
serious that it actually shakes
the pilots' control columns.

Combined with a loud rattling,
it's impossible to ignore.

To add to the crew's confusion,
the plane begins to
vibrate and dip wildly.

I'm sure every passenger on
the airplane knew something was
unusual, because the aircraft

started to, uh,
started to shake in
a very violent maneuver.

It's not the only
problem the crew is facing.

A.D.I.

The Attitude
Deviation Indicator
is basically a round gauge,

that on this airplane
is a screen

that is blue on the top
and brown on the bottom.

And it shows
not only the pitch of
the airplane, but also roll.

On the gauge,
blue represents sky.

The more blue,
the steeper the climb.

Right now it's showing that
the plane's nose is pointing
dangerously high.

Then,
more than 7,000 feet
above the ocean,

the plane rolls hard
to the right,

and begins to plummet
from the sky.

From the time that
the stick shaker activates,

it is now going to require
proper action from
the flight crew

to sort this out,
or they will end up
losing control of it.

The window of decisions
is closing on them.

For if they
let it stall completely,

maintaining control of
the airplane will prove
to be very difficult.

Captain Erdem
struggles desperately to
get his plane to climb.

Nose down!

He has just a few
thousand feet

to pull a 100 ton airliner
out of a deadly stall.

The less experienced pilots
utter prayers and
offer suggestions.

- Thrust.
- A.D.I.!

301...

Squawk 377.

Standby!

Air Traffic Control
is still unaware that Flight 301
is in grave danger.

Not climbing?
What am I to do?

You can level off.
Our altitude's okay.

The plane
is falling fast.

Okay, 5,000 feet.

Captain Erdem
is trying to fly a plane that's
become virtually uncontrollable.

Thrust levers! Thrust!

Gergin pushes
the throttles to full power...

but it doesn't help.

The plane spirals
towards the sea.

Sir, pull up!

Oh! What's happening?

Alpha Lima Whiskey 301,
Santo Domingo.
Come in, please.

Alpha Lima Whiskey 301,
Santo Domingo.

Come in, please.

Less than
five minutes after takeoff,
Birgenair Flight 301

- vanishes from radar.
Alpha Lima Whiskey 301.

Come in, please.

The Dominican Navy
begins searching

for the missing plane
and it's passengers.

Enroute,
I was always thinking
of what I would find.

I thought I would find people
screaming, people yelling
and asking for help.

They discover
something very different.

The strong smell of
jet fuel hangs over
the water.

Pieces of wreckage
float on the waves.

I thought to myself there
is no one alive here.

We didn't see any survivors
and we didn't see bodies.

I really thought the plane
disintegrated on impact.

Within hours,
more than just wreckage
begins floating to the surface.

Around 5:20
in the morning, when
the bodies started to come up,

I did feel a great sorrow
in my heart.

I felt like I wasn't sure
if I would have the strength

to continue the work
at that moment.

The search continues by
the light of the next morning.

American and Dominican
rescue ships

scour a 1300
square kilometer area
for survivors.

None are found.

Now it's up to the Dominican
Republic's Aircraft Accident
Investigation Bureau

to find out
what caused this accident.

We established
a base camp at a hotel
on the Cabarete Beach,

which was directly
south of the accident site.

Over the next couple of days,
investigators, reporters,

and some of
the victims' families
arrive at the hotel.

Nearby, evidence of the disaster
reaches the Dominican shores.

Wreckage and passenger's
possessions are washing up
on the beach.

Even the smallest piece could be
a valuable clue as to
what caused the crash.

The USA's National
Transportation Safety Board,

Agrees to assist
the Dominicans with
their investigation.

They send an investigator to
Puerto Plata.

We could see that
this was going to take some
international co-operation,

to get to the bottom
of the event.

Robert MacIntosh
will also provide support from
the NTSB's Washington Offices.

Any signal from the recorders?

This particular accident
was the first major loss

of a Boeing 757
in the water.

There was added urgency,
because the aircraft
was going into the livery

of many American
operated airlines,

and on the market
for the worldwide
passenger service.

In order to understand
what had happened here,

we only had one key.

That key was
the black boxes.

Like all
commercial airliners,

the Boeing 757 carries
a Cockpit Voice Recorder

that records all the sounds
in the cockpit.

And a Flight Data Recorder,

that records a wealth of
information about the plane's
operation during flight.

We've got underwater locator
beacons on these recorders.

They work for 30 days
upon immersion.

But the ocean where
the plane crashed is over
7,200 feet deep.

We needed to locate them
before the signals faded.

And we also needed to remove
them before the data was
damaged by salt water.

So we were in a race
against time.

The NTSB enlists the
help of the US Navy, who hire
a submersible called the CURV.

CURV stands for Cabled
Underwater Recovery Vehicle.

It's a tethered vehicle.

It has an umbilical and
it's controlled by an umbilical.
It's not autonomous.

The CURV is essentially
a remote controlled submarine,

which can work
at depths no manned submarine
could handle.

While the CURV travels
from the United States,

Major Souffront starts to
examine the evidence he has.

Radar on the ground tracked
the plane as it climbed
into the night sky.

I have the radar.
The history of the flight
is recorded here.

Investigators study
the radar records,

along with the conversation
between the ground controllers
and the crew.

I have the recording
from the control tower.

Santo Domingo, good evening.

Alpha Lima Whiskey 301,
climbing with you.

Alpha Lima Whiskey 301,

c limb and maintain 280.

Okay, 280.

The exchange
between the controller and
Flight 301 is normal.

The investigators
detect no signs of trouble.

The last communication
between them was only
disrupted with a "stand by".

301 squawk 377.

Stand by.

As you heard,
there is no reason why
this plane went down.

What had caused
something to go wrong,

to interrupt the flight path
of the aircraft
so rapidly?

Certainly it was a good...
It was a good question for us.

Any debris that's
found is taken to a Dominican
military base to be examined.

Investigators comb through
the wreckage
they've recovered.

Pieces of the cabin,

life vests,
even part of the landing gear
have all been found.

Every piece of debris
is studied for signs of
an explosion, or fire.

Investigators also check
if any of the life vests
are inflated.

That would suggest passengers
had some warning before
the plane plowed into the sea.

Cords on some of the life vest
are hanging loose,

But investigators conclude
that could be the result of
the plane's violent impact.

The crash was so powerful
it has compressed coffee cans
into flat pieces of tin.

The wreckage
tells investigators,

That the crash of
Birgenair Flight 301
was sudden and violent.

But they find no evidence that
there was an explosion on board.

Major Souffront looks into
the possibility
that the plane,

which was called into
service at the last minute,

may not have been ready
for the flight.

Enmanuel Souffront.
- Ah. Hi.

I'd like to see some records
of the Birgenair plane.

All right.
They're right here.

This is it.

It had been
on the ground for some time
in Puerto Plata,

and that became
interesting to us.

Why would an operating company
have an aircraft sitting there?

Investigators discover
that the plane wasn't on
the ground for repairs.

Based on maintenance records,
the plane appears to
have been mechanically sound.

Birgenair simply didn't have
enough passengers to justify
the flight financially.

So they kept the plane
and the crew
in the Dominican Republic

for almost three weeks.

The plane's maintenance records
turn out to be one more in
a series of empty leads.

The CURV arrives in
Puerto Plata harbor.

On February 28th,

more than three weeks
after the crash,
it slips below the waves,

looking for the remains of
the Birgenair jet.

It takes the robotic submarine
two hours

just to descend
the 7,200 feet
to the ocean floor.

From there,
it sends back images
of the wreck of Flight 301.

The cockpit
pretty much
was sitting upright,

and it was pretty much
the nose of the plane,
you know.

And you could see
the front part of it,
it was obviously banged up,

and cracked,
and fragmented.

The clues
investigators need to solve
the mystery of this plane crash,

lies somewhere amongst
the plane's twisted wreckage.

The flight's black boxes
are the top priority.

The CURV quickly picks up
the signal from a Pinger
on one of the units.

Operators must now maneuver
the sub towards the sound.

They have to be able to see
the boxes to pick them up
with the robotic arm.

It takes just 90 minutes
to find the first black box.

The first one
was sitting out in the open,

Okay.
It was where they
could see it.

And they picked
the first box up.

They grabbed ahold of it
and they just kind of
tucked the arm up in place.

You know,
so that they
wouldn't lose it.

The second black box
is also heard.

But after almost two hours,
the CURV's cameras
still can't see it.

You know,
they knew it was right there,

and they were
searching around
a debris pile,

and they could not
physically see it,
you know,

with the cameras
of the vehicle.

So as they went around
a couple of times they started,
you know,

lifting metal up
and moving pieces
out of the way.

And then they did find
the second box
under some debris.

Flight 301's
Flight Data Recorder,

and Cockpit Voice Recorder
are brought to the surface,

and loaded onto
a waiting jet.

Within hours, the black boxes
are at the NTSB labs
in Washington DC.

Technicians prepare
to extract the precious data
from the boxes.

Investigators hope it will tell
them what happened aboard
Birgenair Flight 301.

They'll soon uncover a stunning
miscommunication between
a seasoned pilot and his plane.

To unravel the mystery of
Birgenair Flight 301,

investigators are counting
on the plane's black boxes.

That flight data recorder
was our key.

So the technicians got busy and
gave us plots, visual plots,

of what was going on
with engines, and air speeds,
and so on,

to allow us to try
and understand why that
aircraft slowed down,

and then simply
departed controlled flight
and entered the ocean.

That's great.
That shows us
all we need to see.

So it's all the
flight data recording.

It's on a time line.
Top is the pitch.

We've got
the air speed
and the altitude.

But check out
the timeline, 44.

Investigators immediately notice something
unusual about the flight.

Fifteen degrees pitch
nose up. Seems high.

- He's almost the maximum.
- And then it stays that way.

The plane began
climbing normally.

Center autopilot on, please.

But investigators
notice that shortly after
the autopilot was switched on,

the plane's nose
pitched upward.

They also see that
the plane's airspeed seems
much higher than it should be.

Three hundred and fifty knots.

It can't be right.

There's something definitely
wonky about the
airspeed numbers.

This brought us
to the question of

perhaps we should be looking
over on the other side

at the cockpit voice recorder
and see

what kind of information
was coming from there.

Can you cue that up
and play it?

Investigators soon
start filling in the missing
pieces of the puzzle.

Eighty knots.

My airspeed indicator
is not working.

They learn that
Captain Erdem

noticed that his airspeed
indicator wasn't working.

- Is yours working?
- Yes, sir.

You tell me.

V-one. Rotate.

But Erdem didn't think
the problem was serious enough
to abort his takeoff.

The tape reveals that
once they were airborne,

the crew quickly
became overwhelmed by
a series of warnings.

Rudder ratio.
Mach airspeed trim?

To investigators, the Captain
seems to become
increasingly bewildered

by the messages
he was getting
from his plane.

Mine shows
only 200 now,
and decreasing, sir.

Both of them are wrong.
What can we do?

Investigators don't
know why the Captain's airspeed
indicator wasn't working.

They do notice that
the Captain's gauge

came back to life as
the plane started to climb.

Okay, it's no matter.

Let's pull the airspeed.
Let's see.

It's a telling discovery,

Which leads investigators
to focus their attention
on the device

that feeds the gauges
airspeed information.

The pitot tube.

A pitot tube is
an airspeed sensor,

a pipe open at one end
that responds to air pressure.

When the plane travels forward,
an increase in air pressure
inside the pitot tube

causes the airspeed indicator's
needle to move.

My airspeed indicator
is not working.

But if a pitot tube
becomes blocked,

it can send faulty readings
to the plane's gauges.

Blocked pitot tubes
have been a factor in
previous plane crashes.

In 1982, a Boeing 737 crashed in
heavy snow in Washington, D.C.
shortly after takeoff.

The pitot tubes
were blocked with ice.

Investigators suspect that
the pitot tube which fed
the Captain's airspeed indicator

on the Birgenair jet was
somehow blocked.

But they know ice can't have
blocked the tubes of a plane

taking off from
a Caribbean island.

We don't know
why it was blocked,

but it presented a very, very
interesting situation to us.

We started carefully looking
at what could cause that
kind of thing to happen.

Senor...

Major Souffront has a theory.

He returns to question
the airplane's mechanics.

- Senor Souffront...
- We're done with these,
thank you.

I'd like to ask you some
more questions about
the Birgenair plane.

Souffront suspects that
mechanics may have taped over

the pitot tubes
during maintenance.

It's a common procedure,
but if the tape
wasn't removed,

it could have caused
the deadly accident.

Maybe a piece of tape
was left on accidentally.

No, sir.

They didn't have to be taped.
We never did anything with
the Pitots.

Did you put the pitot covers
back on them when
the maintenance was finished?

It did not have
any coverage with it.

We did not take any off
and we did not put any on.

And that's when
we discovered

that the pitots had
not been covered for
the 25 days

that the aircraft remained
parked at the international
airport in Puerto Plata.

A pitot cover slips
over the end of the tube.

Regulations state that these
covers must be installed

any time a plane will be on
the ground for an extended
period of time.

A prominent flag is meant to
remind pilots and technicians

to remove them again
before takeoff.

Investigators find that
the Birgenair pitot tubes
were never covered.

And somehow,
the uncovered pitots
had become blocked.

Recovering the tube
from the ocean floor,

is the only way for
investigators to answer
a pressing question.

What blocked
the pitot tubes?

Nobody knows for sure.

The evidence is 7000 feet
down in the Atlantic Ocean.

But even if
the pitot tubes were blocked,

how could it have caused
the crash of a modern jet,

and the death
of 189 people?

It's not like a car
where you have only
one speedometer.

In this kind of an aircraft,
you have a total of
three airspeed indicators,

and there is a flight
data computer,

which is computing the velocity
in relation to the ground.

I'd like to welcome you all
this afternoon.

As you know,
I'm Bob Macintosh.

Using information
from the black boxes,

the NTSB pieces together
a real time animation,

from lift off to the final
moments of Flight 301.

This is the indicator.

The captain actually
realized that his speed
indicator was not working.

- Is yours working?
- Yes, sir.

The big question for
investigators is,

how could one faulty
airspeed source
result in a crash?

He realized at a time
that he could have aborted.

He could have turned back.
But he chose to continue.

Investigators analyze
the Captain's every move,

and find that he allowed
a small error to escalate,
and ultimately overwhelm him.

Rotate.

Positive climb, gear up.

Moments after liftoff,

Captain Erdem's
airspeed indicator
appears to be working.

That means
it is at odds.

But investigators
suspect the gauge is responding
to changes in altitude.

Climb thrust.

As the plane climbs
through the thinning atmosphere,

the air trapped
inside the tube expands,

causing a buildup
of pressure.

Inside the cockpit,

this causes the airspeed
indicator needle to deflect.

Even though altitude is causing
the increase in pressure,

the sensors mistakenly read it
as an increase in airspeed.

So, at this point,
the takeoff is standard...

Captain Erdem
may have had five separate
sources of airspeed to rely on,

but investigators noticed
that when the trouble started,
he wasn't flying the plane.

Center autopilot on, please.

- Center autopilot has command.
- Thank you.

The autopilot was.

And unless the crew
reconfigures it,

the autopilot gets
its airspeed information
from only one source.

Remember, the autopilot
gets its data only from
the Captain's pitot tube.

The one that was blocked.

The data shows that the trouble
on Birgenair Flight 301

began when
the autopilot took over.

Right after
the autopilot is engaged,
the plane's nose begins to rise.

Investigators suspect
that the crew didn't realize

that the blocked pitot tube
was feeding the autopilot
faulty information.

The computer registered
that the plane
was traveling too fast,

and raised the nose
to slow it down.

It soon rises
to 15 degrees.
Then it stays there.

Raising the nose works
like an air brake.

It slows the plane
by creating drag.

The autopilot is programmed
to never bring the nose higher
than about 15 degrees.

Any higher and the plane would
slow down too much and stall.

The autopilot's
a pretty smart guy.

He already knows
he's got all the power that
he's going to get for the climb.

The only thing
for the autopilot to do
is raise the nose.

And it raised the nose
of the airplane to
its limits of authority.

But the autopilot
was reacting
to faulty information.

Moments later, it sent out
two different warnings.

Rudder ratio.
Mach airspeed trim?

That the plane
was traveling too fast
to be controlled safely.

The airplane begins
picking up warnings,
rudder ratio.

A variety of things
that the airplane is
sensing problems.

Okay, there is
something crazy here.
Do you see it?

Yes,
there is something crazy.

Mine shows only
200 now,
and decreasing, sir.

Both of them are wrong.

Investigators realized that Captain Erdem
wrongly concluded

that both airspeed indicators
were malfunctioning.

In fact,
his First Officer's gauge
was always correct.

The plane was traveling
much too slowly.

What can we do?

Captain Erdem no longer knows
which instruments to trust.

Let's check
the circuit breakers.

As they saw
these caution lights,

they decided they were
going to start pulling
some circuit breakers.

But that would be
rather strange.

The actions of trying to
reset circuit breakers

is something's that pilots
of older generation's aircraft

have learned via
experience of sometimes
being able to get

an errant system
back functional.

Resetting the circuit breakers
turns off the alarm.

But that needle
continued to climb around
the clock face,

until it activated
the overspeed warning.

The autopilot system
sent yet another warning,

that the plane
was traveling too fast.

But the reality
was just the opposite.

The plane was
slowing down.

At this point,
the overspeed indicator is on.
They're going too slow.

They think
they're going too fast,
and confusion has set in.

Let's pull the airspeed.

That's when Captain Erdem
made the gravest error of all.

You can see
that he now pulls back
on his throttles.

Investigators realize
that at the plane's
already slow speed...

...pulling back on
the throttles
was disastrous.

The crew got the most
severe warning that
a plane can send out.

And that's when he gets
the stick shaker.

God! God!

He's got
a tactile sense coming through
his flight controls

that literally shakes
the stick and says,

you've got to
lower this nose.

In a matter of seconds,
Captain Erdem was first warned

that his plane
was traveling too fast,

and then that it was
traveling dangerously slowly.

They're in direct opposition
of each other.

And two warnings that you
would never expect to get,
one right behind the other.

The autopilot

is programmed to
always disconnect when
the stick shaker activates.

It's up to the pilot to get
the plane out of a stall.

Once the autopilot
reached its limits
of authority,

it said,
"I've done all I can do.
I'm out of here."

When the autopilot
disengaged,

Captain Erdem suddenly
found himself
in control of the plane,

at the moment of
his greatest confusion.

You watch the plane
at the top of the screen.

The cockpit
recordings lead investigators
to a stunning conclusion.

A.D.I.

Captain Erdem
may not have recognized that
his plane is about to stall,

but the Relief Pilot
behind him did.

A.D.I.

This additional pilot
intervened to say
"A.D.I., A.D.I.!"

In other words,
look at the A.D.I.
and put yourself

where you would normally see
the nose of the aircraft.

Five degrees nose high,
ten degrees.

So when the reserve pilot says
"A.D.I." he is attempting to
focus the captain's attention

to roll and pitch which
are becoming problematic.

The relief pilot
wanted Captain Erdem

to recognize that
the plane's nose was pitched
dangerously skyward.

Investigators can hear
First Officer Gergin trying
to convey the same message.

Nose down.

At this point, the first officer
actually trying to lead
the captain to some solutions,

but not actually take
control of the airplane.

What the 757
desperately needed was airflow
over the wings to generate lift.

The only way to get that
was to point the nose down
and dive.

What puzzles investigators
is that the First Officer

had a control column
identical to the Captain's.

He could have pushed it
and brought the nose
down himself.

He may have been able
to save the plane.

But he didn't.
Instead, he and the other
Turkish crew member

continued offering suggestions
to their more experienced,
but overwhelmed Captain.

Not climbing.
What am I to do?

You can level off.
Our altitude's okay.

But the recording shows that
Captain Erdem ignored

valuable advice
that could have
saved the plane.

And in the Birgenair case,
there's a case of a
relatively junior First Officer,

looking at one of
the most senior captains
on the airline.

It is not
culturally appropriate

for him to say,
"I am going to take
the airplane away from you."

Instead, he tries
to assist the captain,
to lead the captain,

but leave
the captain in command.

Other cultures,
other training,
other airlines,

may very well have
required the First Officer

to physically take control
of the airplane.

I think the social atmosphere
in the cockpit will prevail

to revere age and experience
to the point where it...
it can kill somebody.

And in this case,
it looks like it did.

The flight data
recorder reveals that instead
of pushing the nose down,

Captain Erdem tried to get
more speed from his engines.

At this point,
the crew goes to full power.

Thrust levers! Thrust!

At the angle
the plane was falling,

the engines couldn't
get enough air.

Applying full power
was more than
they could handle.

The left engine
quit first,

With the right side
at full throttle,

the airliner swings around
as though it's left wing were
caught on a branch.

The airplane goes into
a classic full stall,
where the nose drops,

it falls on a wing,
which is now a very life
threatening condition.

The 757 itself
makes the situation worse.

Like many modern jets,
it uses a so-called
swept wing design.

The wings angle slightly
backwards to reduce drag
and increase fuel efficiency.

But the design
has a downside.

One of the characteristics of
swept wing jets is they get
less and less stable.

They're they're much harder
to fly as they approach stall.

Sir, pull up!
What's happening?

What's happening?

To maintain control
of a swept wing jet,

with no more altitude
than they had
in this condition

is very, very problematic,

and they are not successful,
and the airplane
goes into the water.

Investigators now know why Birgenair
Flight 301 crashed.

What they can't understand
is why the flight ever left
the ground.

Eighty knots.

My airspeed indicator's
not working.

At 80 knots,

if the pilot and co-pilot's
instruments disagree,
takeoff should be aborted.

V-one.

Investigators are troubled
that the captain took off

knowing he had
malfunctioning instruments.

If something is not
functioning correctly,

it doesn't matter what it is,
one should abort the takeoff
at 80 knots.

This decision
on the part of the captain
has been criticized.

But there is a very short
time window for this decision
to be made.

Members of
the investigative team
in Puerto Plata

try to find any clues
that might explain

why Captain Erdem
didn't abort his takeoff.

It was raining that night.

Perhaps he was worried that
he wouldn't be able to stop
his speeding plane in time.

Procedurally,
he's required to stop.

But high speed aborted
take-offs are something
that are very serious,

and that flight crews trained
to avoid high speed
aborted takeoffs if possible.

And we certainly looked
at the parameters
of the runway

to ensure that there
was adequate runway
in that particular situation.

Careful measurements
are taken.

Investigators conclude that
at 80 knots, when he first
noticed the problem,

Captain Erdem had enough
runway left to bring
his plane to a stop.

He could have aborted
his takeoff.

There's also the question
of the hastily
assembled crew.

Investigators now wonder
if the last minute nature
of the crew's call

could have influenced
their decision to take off.

Birgenair started
with a crew that probably
didn't expect to fly that night.

They didn't have
adequate rest.

They got out to the aircraft and
perhaps were rushed in some
of their planning.

Investigators consider
the possibility that the crew,

who had been away from home
for more than two weeks was
simply too eager to get home.

Zero eight three zero one.
Thank you.

- Good flight.
- Good flight.

This is the homesick factor,

where the minor problems
are ignored in order
to get back home.

But investigators will
never know what was going
through Captain Erdem's mind

when he opted
to continue his takeoff.

In this case,
the airplane is accelerating
rapidly enough.

The First Officer responds...

V-1.

...which is the commit
to fly speed.

And by training,
now the decision window
has closed.

They need to fly.

Rotate.

And immediately thereafter,
they're airborne.

Once the plane
was in the air,
its blocked pitot tubes

caused Captain Erdem to make
a series of critical mistakes.

But how were
the tubes blocked
in the first place?

Investigators will find that
the death of 189 people

was caused by something
the size of a paperclip.

Investigators now know that
a blocked pitot tube

led to a series of conflicting
warnings that confounded
Flight 301's Captain.

Now they want to know
how those same warnings
would affect other pilots.

We went to a flight simulator
and in the simulator,

we tried to recreate the
conditions of what happened

On the night of
February 6th, 1996.

Gentlemen, stand by.

The simulator
showed investigators that
an overspeed warning,

followed by a stick-shaker
warning caused even the
most seasoned pilots to freeze.

The contradictory warnings
were potentially dangerous.

When the stick shaker
activated,
it was very unnerving.

It's really overwhelming.

That would tell me that
Mach airspeed warning horn,

combined with the stick shaker
was a tremendously mind-boggling
experience to a line pilot.

As a result,
the FAA issues a directive

that simulator training for
all airline pilots must include
a blocked pitot tube scenario.

The flight crew within
Birgenair was faced with
a large number of warnings,

that kept coming and each
warning added complexity
to the environment.

There's a lot of
warning lights going off.

This captain is in
a condition that is
deteriorating now very rapidly.

So there is a dramatically
increased demand on the captain
to fly the airplane.

The FAA asks Boeing to change
some of those warnings.

Those changes
include the addition
of a new warning,

which tells both pilots that
their instruments disagree,

and the ability for pilots
to more easily silence
troublesome alarms.

Finally,
Boeing modifies its planes,

so that pilots can easily choose
which pitot tube the autopilot
is using for airspeed readings.

All told,
more than 1400 Boeing planes
worldwide are affected

by the new directives.

One final question remains.

What had blocked
the plane's pitot tubes?

Investigators conduct an
extensive search for Birgenair
Flight 301's pitot tubes.

They are never found.

But at Puerto Plata's airport,
they don't have to look far
to find the likeliest suspect.

It's not ice,
and it's not dirt.

We know that the area
around Puerto Plata

Has a lot of bees,
and wasps, and...

and animals,
and birds, and insects
that like to build nests.

One of the insects
is well known to pilots flying
out of the Dominican Republic.

It's called
the Mud Dauber wasp.

Bug experts
tell investigators

about an extraordinary
connection between the wasps
and a pitot tube.

When a Mud Dauber is looking
for an area to build its nest,

it's looking for a site,

a place that's
more or less tubular.

When the Mud Daubers
make their mud nest,

the mud, when it dries,
hardens and condenses.

It gets hard.

Mud dauber wasps
are squatters that make
their nests in available places.

Like crevices in homes,
or even the pitot tubes
of planes.

That the plane was stopped
for so long, 25 days,

was enough time for any species
of the Mud Dauber to build
its nest in the pitot tubes.

Investigators can
only conclude

that Mud Dauber wasps blocked
the uncovered pitot tubes

that fed the captain's
airspeed indicator, which
caused it to malfunction.

They didn't put
covers on the pitot tubes.

So, at some point in time,
extended time,

there was an opportunity
to get something like
a Mud Dauber

in that pitot tube.

Investigators have
their answer.

On February the 6th, 1996,

a tiny insect led to
a series of mistakes
that brought down an airplane,

and changed the design of
the world's most successful
series of airliners.