All language subtitles for Mayday.S07E08.Frozen.in.Flight.1080p.AMZN.WEB-DL.DD+2.0.H.264-playWEB_track3_[eng]

Halloween, 1994.

You haven't
heard anymore
from this controller chick, huh?

No, not a word.

A commuter plane
circles outside Chicago,
waiting for clearance to land.

Eagle Flight 184,
descend and maintain 8000.

Maintain 8000.
Eagle 184.

Without warning,
the controls snap to the right.

The plane plunges
straight for the ground.

The behavior of the crew
and the air traffic controllers
would be examined.

Pilots would question
the safety of an airplane.

The airplane
will have a nasty tendency
to go out of control.

Investigators travel
the world for answers.

The crash makes 'Roselawn'
one of aviation's darkest words.

Mayday! Mayday!

It's mid afternoon
on October the 31st, 1994.

American Eagle Flight 4184
left Indianapolis, Indiana,
15 minutes ago.

It's heading to Chicago.

There are 68 passengers
and crew on board.

- Happy Halloween Cowboy.
- Thank you.

Flying through the clouds,
the aircraft begins
to experience some turbulence.

I'm going to keep them
in their seats
in this chop.

No sense in taking chances.

Captain Orlando Aguiar
is in command of today's flight.

It's supposed to be his day off.

He volunteered for this flight
to make extra money.

His wife is expecting
their second child.

Let's see if we can
get above this.

Center any chance Flight 184
can climb to 16,000?

Eagle Flight 184
maintain 16,000.

First Officer
Jeff Gagliano is handling
the flying duties

on this leg of the flight.

He programs
the autopilot to climb
to a less turbulent altitude.

Jeff actually was working
on his dad's ranch in Wisconsin

uh, just before he
came in for that trip
on, uh, Halloween that day.

Getting on a horse
or getting in an airplane,

those were two of the things
that Jeff loved most.

Flight 4184
is an ATR-72.

A groundbreaking
new aircraft built in France.

Cost efficient and comfortable,
the plane has become popular
on short runs.

This flight is just
one of five short hops
the crew will be making today.

It's Amanda Holberg's
first day on the job

as a flight attendant
with American Eagle.

She's paired with Sandi Modaff,
a seasoned veteran.

Aguiar and Gagliano have flown
this route countless times
and know it by heart.

When you're flying
from Indianapolis to Chicago,

you're flying through
some of the busiest, uh,
airspace in the world.

As Flight 4184
approaches Chicago O'Hare,

the pilots begin the descent
to 10,000 feet.

Chicago center.
We have discretion
down to uh, 10,000.

We're on our way down now.

Eagle 184, roger.

In Chicago,
Controller Michelle Willman
is returning from a break

The trainee controller
is still working under
the supervision of a monitor.

She's told that traffic
into O'Hare

is facing potential delays
because of weather.

She will have to be prepared
to put some flights on hold.

Operations into
and out of O'Hare
are handled on a priority basis.

It's not necessarily
a first-come, first-serve basis.

Um, international flights
arriving to O'Hare

because of their fuel status
get priority.

And then the turbo props
come in at the end.

Eagle 184,
hold southeast on Victor seven.

Chicago Center, roger
hold southeast on Victor seven.
Eagle 184.

Flight 4184
must now fly a racetrack shaped
holding pattern

over northwestern Indiana.

Chicago Center, Eagle 184
entering the hold.

Eagle 184, roger.

Aguiar programs
the Autopilot to keep the planes
circling at 10, 000 feet.

I'll go up front to see
if they want anything.

The crew has little
to do as they wait
for Air Traffic Controllers

to give them permission to land.

- Can I get you boys anything?
- I'm good.

Stereo,
you don't have a hard job.

We do have it pretty easy.

Man, this thing gets a real high
deck angle in these turns.

- Yeah.
- We're just wallowing
in the air right now.

You want flaps 15?

- I'll bring the nose down.
- Sure.

I guess
Sandi's going ooh now.

- See y'all.
- All right.

The crew needs
to let the airline
know about their delay.

It could affect the rest
of the day's schedule.

Crews use text messages
to communicate with dispatchers

so they don't tie up
radio frequencies.

Should I let 'em know
how much fuel we got?

Sure.

Space, F U E L, is that...

We've got uh, 3600 pounds.

Well, folks, once again,
this is the captain.

I do regret to inform you
that Air Traffic Control

has put us into
a holding pattern up here.

We're holding for approximately
20 minutes out of Chicago
at this time.

I do apologize
for all the delays.

That's much nicer,

flaps 15.

I'm sure once they let us
out of the hold
and forget they're down,

we'll get the overspeed warning.

I can't hold anymore, man.

I'm doing circles up here, yeah.

We got plenty of gas.
We could be up here
for a long while.

- Hey, bro.
- Yeah.

I'm getting busy
with the ladies back here.

Ooh.

Yeah, so if I don't make it
up there in the next say,
15 or 20 minutes,

you know why.

Ok, I'll uh, when
we get close to touchdown,
I'll give you a ring.

Oh, nah, I'll be up right now.

You uh, you haven't heard
any more from this
controller chick, huh?

No, not a word.

Eagle Flight 184
descend and maintain 8000.

Down to 8000. Eagle Flight 184.

Eagle Flight 184 uh,
should be about 10 minutes

uh, till you're cleared in.

Thank you.

The flight
is allowed to descend.

Are we out of the hold?

No, we're just
going down to 8000.

Then a warning.

I knew we'd do that.

The plane
is going too fast to fly
with its flaps extended.

Well, I was trying
to keep it at 180.

Galliano retracts the flaps.

There's
a strange sound coming
through the fuselage.

Suddenly,
the control column
turns sharply to the right.

The controls won't budge.

The plane is falling
from the sky.

The pilots begin
to recover control.

But then it happens again.

Mellow it out,
mellow it out!

Terrain. Pull Up.

- Terrain.
Doesn't pull.

Terrain. Pull Up.
Terrain. Pull Up.

It was coming down
too steep to even try to land.

It was coming down at a,
I mean, a sharp angle,
a real sharp angle.

Flight 4184
has crashed into a field

just outside Roselawn, Indiana.

Oh my God
they're dead, they have to be

for the speed that
it was coming down.

Hundreds of volunteers arrive
at the crash site to offer help.

But there's nothing they can do.

There was not much
to see of any airplane,
you, you couldn't see no,

no cabin or anything
of the airplane,

there just wasn't
anything left of it.

Both pilots,
the two flight attendants
and all 64 passengers are dead.

The Roselawn crash
would soon become

one of the most important
accidents in aviation history.

It will lead investigators
to new conclusions
about a string of older crashes.

The morning
after the crash
of American Eagle Flight 4184,

a team from the National
Transportation Safety Board

is on the scene
just outside Roselawn, Indiana.

Greg Feith
is the lead investigator.

The morning
that we arrived
at the accident site

it was cold, it was overcast,
It was one of those
drizzly, dank days.

All you could smell
was the Jet-A
or the kerosene fuel

and because it was muddy
and wet, you had that odor
or that aroma of dirt

and so with all of those
smells, that I mean, that really
evokes some emotion there.

And now you have to walk
through that field and actually
start to do your job.

The crash site
is soaked in jet fuel
and hydraulic fluid.

Human remains
are scattered everywhere.

The site is declared
a bio hazard.

With 4184, it was one
of those types of accidents

where there was very little
left of the airplane.

Investigators know that the way
the wreckage is spread out

can tell them
how the plane hit the ground.

Because there was a fan
shaped debris pattern

and it was spread out
over a very large area,

we knew that the impact
was very shallow,
but at a very high speed.

The airplane's
two flight recorders
are found intact in the tail.

They're taken
to the NTSB labs for analysis.

The data on the recorders
could provide the clues

investigators need
to solve the mystery.

But extracting
the data takes time.

In the meantime, investigators
look for the location
of key pieces of wreckage.

The first things
we typically look for

are the four corners
of the airplane.

The NTSB's Bob Swaim
leads that search.

You're looking
for the nose and the tail
and the two wing tips,

because if you can tell
where the four corners
of the airplane are,

you get an initial idea
of whether the pilot
was in control or not.

The plane's
four corners
are far from each other.

The nose and cockpit
are completely destroyed.

This tells investigators
that the plane hit
the ground nose first,

in a shallow but rapid descent.

Mellow it out,
mellow it out!

The fact that
the plane wasn't
in a steep descent on impact

indicates that the pilots
had some control

in the final seconds
before the crash.

They just ran out of room
to pull up.

Investigator Bob Swaim
meanwhile, has recovered
some of the plane's instruments

including its
Attitude Director Indicator.

Also known as
the artificial horizon.

It's a key instrument that tells
pilots if they're flying level.

If it malfunctioned,

it could have misled
the crew and caused them
to make mistakes.

We had a pretty good idea
of the attitude
of the airplane at impact,

so it would really help
at that point
to see if the pilots

had the same view
of the flight that we found
as they hit the ground.

Can you get
the lights for me please?

A lot of the cockpit pieces
use a fluorescent paint,
or something similar,

and when they contact
each other little, little bits
of the paint transfer.

If we look at those
with a black light

we can see things that
the naked eye cannot see.

There's a good imprint here.

The force
of the impact
has left tiny scratches

on the shattered instrument.

Swaim discovers that
the attitude indicator
seems to have been working.

Its final readings show
the plane was leveling off.

The instrument coincides
with the plane's
actual position on impact.

It indicated that at least
the flight instruments

that the pilots would
have been looking at
were appropriate,

they were proper,
that the pilots
had something to fly by.

The discovery means
that the pilots knew their plane
was diving towards the ground.

Investigator Greg Feith
is getting a clearer picture
of the flight's final seconds.

Now he wants to know
about the history of this flight
before it fell from the sky.

One of the elements
of the investigation, of course,

was to look
at Air Traffic Control.

Eagle 184 hold southeast...

Feith learns that
Flight 4184 had been
in a holding pattern

southeast of Chicago
for 39 minutes before the crash.

When we looked
at the Air Traffic Control
records,

we found that the flow rate,

that is the number
of airplanes that were going
into Chicago O'Hare at the time,

had to be reduced
because of the weather
moving through the area.

Well, folks, I do regret
to inform you
that Air Traffic Control

has put us
into a holding pattern up here.

And because of the reduced
rate into Chicago,

we knew that 4184
was going to have to hold
for a very long period of time.

I do apologize
for all the delays.

One of the aspects
that we found was that
one of the controllers

in the facility
was relatively new,
they were considered a trainee.

Had an inexperienced controller
put Flight 4184 in peril?

Chief investigator Greg Feith
wants to know more about
the weather conditions

along the holding pattern.

I want weather data,

pilot reports,
atmospheric conditions,

Doppler radar
or anything you can find.

Flight 4184
wasn't the only plane
circling O'Hare that day.

Several other planes
were also on hold.

They all landed safely.

Interviews with the pilots
of some of those planes

give investigators
an important clue.

One after another,

they all experienced icing,
some as much as
three quarters of an inch.

Many of the pilots
report the same thing.

Ice.

Dr. Marcia Politovich works
at the National Center
for Atmospheric Research.

She's one of the leading experts
on icing, and the danger
it poses to aircraft

It essentially changes
the shape of the wing
while you're in flight.

It creates drag,
it reduces lift,

it causes performance
and handling problems

and it's just not
a good thing to have.

Investigators examine
weather records
from the day of the crash.

They find a disturbing pattern
of reports of icing all along
a cold front near Chicago.

But the reports describe
the icing as
light to moderate.

Perhaps the size
of the commuter plane
was a factor in this crash.

Different planes
respond to icing differently.

A large plane will respond
differently than a small plane.

Uh, reasons for that are both
environmental and having to do
with the airframe itself.

Large jets generally
fly above the dangerous
conditions inside a cloud.

But the ATR-72 can't do that.

A smaller plane
can't fly as high.

They're stuck in the icing
environment for longer.

They may not have
de-icing equipment.

And if they get in trouble,

they may not have enough
excess power to get out of it.

Investigators discover that Flight 4184's
holding pattern

took it through layers
of cloud repeatedly.

Each time it would have been
exposed to icing conditions.

4184 we knew had been
holding in an icing event,

there were layers of clouds
that they have been
flying in and out of.

Steve Frederick
was flying out of Chicago
on the morning of the crash.

He flew through the same
treacherous weather.

Each time that I went
through that cold front

during that day,
the weather was intensifying,

the ice was getting worse
and I was getting
more and more concerned.

Frederick asked
his captain to pass on
a warning about the weather,

so that other pilots would be
alerted to the danger.

I found out a little bit later
that my captain
had never warned dispatch

and these pilots never got
the warning about the ice
that was out there that day.

And there's no feeling
in the world that can compare

to how badly
I felt at that moment.

Greg Feith
knows that controllers
had put several other planes

into a holding pattern
near Chicago.

But they all landed safely
after coming out of the hold.

This means the controller
had not put Flight 4184
in jeopardy.

She acted correctly,
given the information
she had about the weather.

One of the issues
about Air Traffic Control

is that the controllers
can't just look
at their radar screen

and identify areas of,
of precipitation

or icing conditions readily.

The controllers don't know
that an airplane is sitting
in icing conditions

unless the pilot provides them

with what they call a Pirep
or a Pilot Report.

So if, if the crew in this case,
4184, doesn't provide
that information

to the controller,
then the controller doesn't know

that an icing event actually
is occurring out there.

Feith and his team
wonder if the flight crew
simply didn't realize

they were flying
into icy conditions.

The plane's cockpit
voice recorder
provides the answer.

Can I get you boys anything?

Stereo,
you don't have a hard job.

We have it pretty easy.

Hey, bro.

I'm getting busy
with the ladies back here.

Ooh.

At first glance,
the crew's behavior
seems unprofessional

and undisciplined.

The first officer
was listening to some music.

We knew that there were a lot
of non-aviation things going on.

One of the most contentious
elements was how did that affect
the crew's performance

and their awareness
to the situation
that was starting to develop.

That's much nicer now,

flaps 15.

Showing some ice now.

I'm sure
once they let us
out of the hold and forget...

But nine minutes
before the crash

the crew had noticed
their plane was picking up ice.

The pilots must have been aware
they were flying through
an area of aircraft icing.

You haven't
heard any more
from this controller chick, huh?

No, not a word.

Then, two minutes
before the accident,

another remark draws
the attention of investigators.

We still got ice.

I see what you mean.

The crew
knew about the ice.

Now investigators need to know
what they did about it.

The ATR-72 is equipped
with sophisticated
de-icing devices.

It's crucial to know what
the crew did about
the ice buildup on their wings.

This time,
the flight's data recorder
provides the answers.

Almost 17 minutes
before the crash

something sets off
the master caution warning.

It could signal a problem
in one of the plane's systems.

It could also mean
the electronic ice detector

is picking up
the presence of ice.

The flight data recorder
shows investigators that
in response to the alert,

Captain Aguiar turned
the plane's de-icing system
to its maximum setting.

The NTSB's Charley Pereira
looks into the performance
of the ATR-72.

The icing, uh, alert system
had sounded aurally
and they heard it,

and they activated
protection systems
on the airplane,

and at the time of the accident,
uh, the de-ice systems were on.

The complete ice
protection system
on the ATR-72 airplane

consists of a combination
of what we call anti-icing

which are hot surfaces that
don't allow the ice to form.

The windshields
and the propellers are also
heated on this airplane

and then they have
de-ice systems which
are on the leading edge

of the wings, what you call
pneumatic boots.

Uh, they're like rubber
inflatable chambers
that you blow air into

and they expand
kind of like a balloon
and that cracks the ice

and the ice flies off
the airplane.

The flight
data recorder shows

that after he activated
his de-icing system,
Captain Aguiar,

also pushed the throttle
forward slightly,

increasing the plane's speed.

This increased the speed
of the air moving over
the plane's wings,

making it harder
for ice to settle there.

The pilots had done everything
they could to deal
with ice buildup on the plane.

But were the anti-icing systems
actually working?

The shattered remains
of that de-icing system

are now the main focus
of the investigation.

The airplane
was designed in France

by a group of French
and Italian companies.

The de-icing system
was part of that design.

So the components were made
by small French vendors.

who were located
around the countryside,

and then they were assembled
there in Toulouse
into the final airplane.

Bob Swaim arrives
in France with pieces
of the de-icing system.

I brought some pieces
from Flight 4184 to look at.

The key component
to the de-icing system
is probably not

the black rubber boot
that you see on the airplane,

but the timer that's inside
the airplane, or the timers

in the valves
that control those boots.

The force of the crash
has left telltale markings
called index marks.

They show the position
of the valves
at the time of impact.

Swain compares them
to the original blueprints.

Does anything seem
out of the ordinary?

The trip to France
has led to yet another dead end.

There was nothing wrong
with the plane's
de-icing system.

Thanks a lot. I appreciate it.
Thank you.

Investigators are puzzled.

Showing some ice now.

If the crew knew
they had ice on their wings

and their de-icing system
was working,

why did the plane crash?

Other pilots think they know
the answer
and decide to speak out.

Their decision will dramatically
change the course
of this investigation.

Three weeks
after the crash
near Roselawn, Indiana,

American Eagle pilot
Steve Frederick
distributes a warning.

It says the ATR-72 fleet
operated by American Eagle,

is dangerous
in icing conditions.

It claims American Eagle pilots
have pleaded with the airline

and regulators to do
something about it,
but to no effect.

I drafted and,
and distributed a brochure

in Chicago O'Hare Airport,

which essentially warned people

about the problems
with the ATR aircraft and made
an outreach to the public

in order to try and get
something done
because nothing was happening.

Steve Frederick
has more than
a professional interest

in the crash of Flight 4184.

Co-pilot Jeff Gagliano
was his close friend.

They graduated
from flight school together.

Galliano's death
has hit him hard.

He made the comment one time

that he would probably wind up
dying because of ice in an ATR.

And it was eerily prophetic.

A month
after the crash.

Pilot frustration over
the ATR's airworthiness
boils over.

A group of a dozen pilots
refused to fly,
citing risky weather.

The airline is forced
to cancel flights

and then Steve Frederick
goes one step further.

He voices his concerns
on a US Network morning show.

We were told
this airplane will try
and kill you if you get too slow

in ice the the airplane
will have a nasty tendency
to go out of control.

When I came back to flying
after my appearance
on Good Morning America

I was summarily suspended
without pay.

The public protest
leads investigators to wonder

if the ATR-72 has
a deadly vulnerability to ice.

Merci.

Investigator Charley Pereira

visits the ATR's
French manufacturer Aerospatiale

to learn more
about the plane's history.

We embarked on a research effort
to try to identify

all previous ATR-42 and 72
uh, roll control uh, incidents.

He finds
a disturbing pattern.

And, and about 5, 5 of those
were found to be similar,

uh, after the fact in our review
to the Roselawn case.

One such incident
took place in December 1988

in Mosinee, Wisconsin.

An American Eagle ATR-42
had been preparing

to land in icy conditions
at Central Wisconsin airport.

The airplane was on approach

uh, in severe icing conditions

um, described as
freezing drizzle
and freezing rain.

Captain Mike Bodak
was the pilot that day.

We were just on the last
two legs of our trip

before we'd be done with work.

And uh, we were doing
our descent.

um, everything
was proceeding normally.

Negative ice, just wet.

I'll call the flight Center
to let them know
we're turning inbound.

I hear in the tail a sound
like that.

It just got louder and louder.

We have no idea
what is occurring.

I thought initially
a propeller blade
may have come off.

It was as if the steering wheel
wasn't connected to anything.

The plane stalls.

Its wings can't generate enough
lift to keep it in the air.

As I see I'm not getting
any of the airplane back,

I come up on the power levers
all the way.

The engines
are really trying to fly.

And at this point I'm getting
some of the airplane back.

So I make a forward motion
to try and break the stall

and it's still going,
"terrain, terrain"

and I don't have
the airplane back yet

and my first officer says...

Props.

And I say, "max rpm."

Terrain. Terrain.

And he throws the props
from 86 to 100 percent.

And instantaneously boom,
we fly out of the stall.

Whoo!

The plane
is less than 1200 feet
above the ground.

Captain Bodak has learned
a sobering lesson about the ATR.

There was no warning.

The plane stalled
without any warning.

Planes do have warnings
for stalls.

But in this case
there was no warning.

I got the first warning
that I was in a stall was,
I was in a stall.

But other pilots
weren't as lucky.

An ATR-42
operated by an Italian airline

was flying over the Alps
enroute to Germany
in October 1987.

The plane lost control
and crashed in the mountains,

killing all 37 people onboard.

Ice was the main factor.

But the final report
blamed pilot procedures.

For investigators
it's really important
to look back

at historical information
about any airplane.

You want to look for trends.

What they would find
is a troubling detail
with this plane's history.

Did any of your studies
uncover a wing design flaw?

Charley Pereira
wants to know if the engineers
who built the plane

could explain why
an ATR-72 would go
so badly out of control.

To his surprise, he learns
they knew that it had
a susceptibility to icing.

You've seen the flight data
from the accident flight.

Where would the ice
have formed to cause that?

When I asked
one of their oldest
most senior aerodynamicists

who couldn't speak
any English at all,

what he thought would be
the shape and location

of an ice accretion
that could cause uh,
the behavior that we saw

on the flight recorder
for the Roselawn airplane.

He drew up the airfoil section
and a little shape

just behind the de-ice boots
and said this was it,

and the translation
was that this is what
will cause the problem.

Aft of the de-icing boot.

Investigator Charley Pereira's beginning
to understand how ice can affect

the wings
of the French-built plane.

If the ice built up
behind the boot

the crew would have
no way to clear it.

We still got ice.

And even
a small amount of ice

can have a devastating effect
on an airplane.

Ice can disrupt
the smooth movement
of air over the wing.

But how could so much
ice buildup behind the boot?

Investigators contact
Dr Marcia Politovich
for assistance.

The NTSB called us uh,
to help them analyze

weather conditions in this case.

Her research shows
that the pilots of Flight 4184

likely flew into something
they've never even heard of.

Something even more dangerous
than ordinary ice.

Now based
on the weather analysis,
it looked to us

like the kind of icing
that plane encountered

was from super-cooled
large drops.

Now large is relative,

what we're talking
about large here is about
the size of a human hair.

Super-cooled
large droplets

are about 100 times
smaller than a raindrop.

They form inside storm clouds
when the temperature
is near freezing.

But the drops don't freeze
until they come into contact

with something solid,
like the wing of an airplane.

Conditions that day were ideal
for the formation of these
tiny freezing droplets.

We had all the clues
that we needed.

A warm cloud top, minus eight
to minus 12 degree Celsius.

We had drizzle formation
near the top that was probably
encouraged by some wind shear

near the cloud top.

And very little ice in the cloud

from what we could tell.

On every lap
of its holding pattern

Flight 4184 flew through layers
of clouds that hid
a small but lethal element.

They just put that poor guy
in the wrong place
at the wrong time.

Investigators learn
that super-cooled large droplets

have a distinctive way
of accumulating
on an aircraft wing.

Ordinary ice accumulates
on the leading edge of the wing,

where de-icing boots
can get rid of it easily.

But SLD act differently.

These super-cooled drops hit
the wing and slide back
over it before freezing.

This forms a ridge
behind the boots, out of reach
of the de-icing system.

So, as 4184 was flying
in that type of environment,

rather than
the water droplet freezing
on the protected surface

of the de-ice boot,
it actually ran
behind the de-ice boot

and froze on the metal surface.

The pilots
can't get a good view
of their wings from the cockpit.

They would have been
utterly unaware
of the danger taking shape.

For the pilots,
when they looked
out their side window,

they would see the outer
portion of the wing.

They definitely could not see
the top of the wing,

where this ice ridge
was starting to form.

For Greg Feith,
the investigation
is coming to a head.

His investigators
think they know
why Flight 4184 crashed,

but they can't prove it.

To make matters worse,
the plane's manufacturer

suggests that the Roselawn crash
wasn't caused by an ice buildup

but by poor piloting.

The NTSB thought
it was an aircraft problem.

And the French
aircraft manufacturer

thought it was a pilot problem
and not their
particular product.

Feith wants to know
if there had been

problems with ice on
ATR-built planes in the past.

He finds troubling similarities

between some incidents
dating back decades.

Using data
from flight data recorders,

investigators look
at aileron movements
from Flight 4184

and compare them
to the other incidents.

They discover that
on all those flights

the aileron deflected
in exactly the same way.

There's no input
at all from the pilots.

We knew that all
of these ailerons
were being commanded

to move not by the pilot
but in fact
the disrupted airflow

created by the icing event
that the airplane
had encountered.

The physics
of ice buildup explains

why the control column
on Flight 4184
snapped to the right

Air turbulence
on the wing was so powerful

that it lifted the aileron,
which caused the plane to roll.

Since the aileron is attached
to the control column
by a cable,

it jerked the control yoke
to the right.

The force of the turbulence
pulling on the aileron
was so great,

that even two pilots
trying to counter steer

weren't able to bring
the aileron back down.

The forces were determined
to be about 250 pounds.

So for the pilot,
it would have been trying

to roll against 250 pounds
of aerodynamic force.

Worse, the ATR's
control yoke doesn't have
power steering,

so those forces are transmitted
directly to the pilots.

The pilots could not fight back
against the air
pulling on their aileron

For chief investigator
Greg Feith,

super-cooled water droplets
that left a ridge of ice

on the wings
are now the prime suspect.

But how to prove it?

Now,
the real analysis began
because we had to understand

what was going on
in-flight with the airplane.

We had good flight,
data recorder information.

It only told us what happened,

it didn't tell us
why it happened.

We had to try and model
this icing event some way.

At the time
of the crash, NASA
was just beginning

to study the effect
of super-cooled
large droplets on airplanes.

Back in 1994 pilots
didn't know what SLD

or super-cooled
large droplets were.

There was very
little information
in the pilot community

and there was actually
very little information

in the aviation industry
about SLD.

Investigators first
turn to NASA for help.

Together they launch
a daring experiment.

They use a US
Air Force tanker plane

to create a cloud
of super-cooled water droplets.

An ATR-72
flies behind the tanker.

Yellow dye in the water
shows investigators

how the droplets
cover the plane.

The test should solve
the final mystery.

How had ice caused Flight 4184
to go so badly out of control?

One of the primary purpose
this is applying the ATR-72

in behind the tanker
was to understand

how the ice accumulated
on the airplane.

But more importantly,
the effect of that ice

in varying configurations
of the airplane,

on the flight control surfaces,
that is the ailerons.

Investigators make
a startling discovery.

A seemingly harmless action
meant to increase
comfort on the plane

may have led to disaster.

- Can I get you boys anything?
- I'm good.

While American Eagle Flight 4184

was holding,
Captain Orlando Aguiar notices

that the nose
is tipped quite high.

Man, this thing gets a real high
deck angle in these turns.

Yeah.

Captain Aguiar knows
that the plane's high nose angle

was producing
an uncomfortable tilt
in the passenger cabin.

You want flaps 15?

- It'll bring the nose down.
- Sure.

Extending the flaps
would have the effect
of lowering the plane's nose,

making the ride
more comfortable.

I guess
Sandi's going ooh now.

When investigators
duplicated this maneuver,

they found that it had
a dramatic effect

on where the ice reach formed
on the plane's wing.

the flaps made the icing
problem even worse.

by exposing more
of the upper surface
of the wing

to the oncoming water droplets

and that's one of the reasons
why we got um, the ridge of ice

where we got it
was because of the flaps 15
configuration.

That's much nicer now,

flaps 15.

The crew
of Flight 4184

is unaware that a ridge of ice
more than a centimeter high

has built up on the
surface of their wings.

Eagle Flight 184 descend
and maintain 8000.

Down to 8000. Eagle Flight 184.

The ice buildup
has no effect on the flight

until First Officer Gagliano
begins his descent to 8000 feet.

I knew we'd do that.

The descent increases
the plane's airspeed.

This triggers a warning
from the flight computer,

telling the crew
they're flying too fast
with the flaps extended.

Well, I was trying
to keep it at 180.

Gagliano now
retracts the flaps.

But the routine gesture
has a dramatic effect
on the plane's aerodynamics.

When they retracted
the flaps as they started
their descent down to 8000 feet,

the airplane pitched back up
into a very nose-high attitude.

Airflow over
the ice-laden wing
was disrupted

when those lifted back up.

That created the turbulence
that pulled up the ailerons,

sending the plane into a roll.

The plane stalled,
and tumbled from the sky.

Damn.

Had this crew
had about two to 3000
more feet of altitude,

there's a high probability
that they would have been able

to salvage or recover
the airplane
before it struck the ground.

The NTSB
has uncovered a deadly flaw
in a popular airplane.

There's a growing concern
that unless something is done,

this kind of accident
would soon happen again.

Investigators conclude
that problems
with the ATR's wind design

make it vulnerable
to this menace.

The agency that regulates
US aviation
takes drastic action.

We are going to issue
an Air Worthiness Directive
this afternoon,

that will preclude the operation
of these aircraft

into known icing conditions.

The FAA
takes swift action

banning all models
of the aircraft
from flying in icy conditions.

This throws regional airlines
like American Eagle into chaos.

Public concern over the safety
of ATR airplanes grows

in the aftermath
of the Roselawn crash.

The most controversial charge,

that the FAA had relied
on the French authorities

to test and certify the aircraft
then rubber-stamped the results.

Therefore, the ATR-72 was never
really tested by the FAA

in any way, shape and form

as though
it was manufactured here.

The plane's
French builder proposes
to fix the problem

by making
the de-icing boots wider,

so they cover
a larger part of the wing.

The company also rewrites

operating procedures,
forbidding pilots
from using the flaps

or flying on autopilot
in icing conditions.

In response, the FAA issues
an amendment
to their earlier directive,

loosening operating restrictions
on the ATR's.

Most airlines decide
not to take any chances.

They move their ATRs
to the south,

where a warmer climate
would reduce the risk of ice.

The crash at Roselawn
set off a flurry of new research

into aircraft icing
and the conditions
that produce it.

There's a lot
of weather data out there.

Satellites, radars, surface ops,

and it just keeps
getting bigger and bigger

the collection of data.

New techniques
in forecasting
are being developed

to show pilots where icing
is likely to occur

and help them avoid it.

But we're working on ways
to get it to the people
who need it.

Uh, dispatcher at airlines,

um, meteorologists at airlines.

And now even
into the cockpit itself.

Many of those
changes will take time
to come into effect.

Pilots like Steve Frederick
think that time will cost lives.

The problem that exists
is that there is no technology
available today

to the pilots or anyone
on the ground to accurately
forecast or predict

where these situations
of bad ice are going to occur.

Once these airplanes have been
exposed to the bad ice,

it's too late because these
are no longer airline pilots,

they're test pilots.

And that airplane can fall out
from under them
and their passengers

without any warning
and in the blink of an eye.