All language subtitles for Air.Disasters.S09E08.Steep.Impact.1080p.PMTP.WEB-DL.AAC2.0.H.264-maldini_track3_[eng]

Grab your ankles.
Head down.

Man: Get out of it!

Man: I can't.
Man: no!

Man: Oh, God! That's it.

Narrator: A plane crash
in Georgia leaves 23 dead,

including a NASA astronaut
and a U.S. Senator.

Man: Anytime there's
a high-profile case,

there's more stress
and pressure on you.

Narrator: In search
of the cause...

Man: We've got to see
what happens in the air.

Narrator: Investigator
Tom Haueter gambles

on a risky hunch.

Tom Haueter: When I first
proposed doing the flight test,

it was not well-received.

Narrator: He puts his reputation

and the life of a skilled
test pilot on the line.

Haueter: EMB-120, do you copy?

Man: Copy.

Man: This was, in my opinion,
a very dangerous maneuver.

Haueter:
What if this airplane crashes?

What if we lose the airplane?

Man: The risks, of course,
is part of the game.

Flight attendant:
Ladies and gentlemen,

we are starting our approach.

Pilot: We lost both engines!

Flight attendant:
Put the mask over your nose.

Emergency descent.

Pilot: Mayday, mayday.

Flight attendant:
Brace for impact!

Controller: I think I lost one.

Man: Investigation starting
into this tragedy...

Man: He's gonna crash!

Narrator: Atlantic Southeast
Airlines flight 2311

cruises at 15,000 feet.

Hank Johnston: It's the Braves'
year. I feel it.

Mark Friedline: Sorry.
I don't want to get my hopes up.

Last year still hurts.

Narrator: At the controls
is Captain Mark Friedline.

The 34-year-old is
an experienced pilot

with almost 12,000 flight hours.

Friedline: We got storm clouds
ahead of us.

Johnston: Yep.
What do you want to do?

Narrator: First officer
Hank Johnston is 36.

He's been flying with
Atlantic Southeast Airlines

for nearly three years.

Friedline:
We're gonna go around 'em.

Tell center we'll go right.

Johnston: Center, ASA 2311.

We'd like to request a deviation
for some weather.

John Maris:
This was a normal day

in the life of the crew.

Nothing untoward had happened,

and I doubt they were expecting
any difficulties

with the flight.

Controller: ASA 2311,
roger that.

Weather deviation approved
at your discretions.

Maintain current altitude.

Johnston: Okay.
Thanks, center. 2311.

Friedline: Let's go...
20 degrees to the right.

Narrator: Today's flight
is a short commuter route

from Atlanta, Georgia,

to the city of Brunswick
on the Atlantic coast.

Friedline: This is Captain
Friedline on the flight deck.

We've got a bit of weather
ahead of us,

but we're gonna go around it and
give you a pretty smooth ride.

Might hit a few bumps,
but nothing to worry about.

We do ask you to return
to your seats

and please make sure your
safety belts are fastened.

Narrator: The Embraer 120
banks gently

as the pilots deviate
around the storm.

Maris: The Embraer EMB-120

is designed
for commuter-type operations.

It takes approximately 30 people
on short haul flights

between city centers.

Narrator: The commuter airplane

is powered
by two turboprop engines.

Maris: Turboprops differ
from jet engines

because instead of using the
exhaust to power the aircraft,

they use a propeller,
which is more fuel-efficient

and is more suited for
these smaller aircraft.

Narrator: Today, there are
20 passengers aboard,

including NASA Astronaut
Sonny Carter.

Sonny Carter:
Thank you so much.

You're a star.

Narrator: As part of the space
shuttle Discovery's crew,

Sonny Carter orbited the Earth
for 120 hours,

circling the planet 79 times.

Frederick Gregory served
with Carter on that mission.

Fred Gregory: Sonny was
not only an astronaut;

he was a renaissance man.

He was an engineer,
he was a medical doctor,

he was a navy pilot.

At a very young age,
he had accomplished things

that even one of which
would have been

an outstanding achievement
for just any other person.

Narrator: Also on the flight is
another high-profile figure,

former Senator John Tower.

Tower served four terms
in the U.S. Senate.

A leading republican,
he was an advisor

to presidents Ronald Reagan
and George H.W. Bush.

Friedline: We're still running
20 minutes late.

Johnston: Yep. Well...

Friedline: Couldn't be helped.

Narrator: Before takeoff,
flight 2311 was delayed

due to a mechanical problem.

The crew was forced
to switch planes.

Maris: There was a last-minute
change in the aircraft,

which, while uncommon,
is not extraordinary,

and it would not have
thrown the crew.

Carter: These small planes
do keep you on your toes.

Narrator: The new plane
is running smoothly

as it leaves
the storm clouds behind

and nears its destination.

Glynco Airport is a former
air base with just one runway.

It's used by private planes
and small commuter airlines

flying to the Georgia coast.

The flight attendant prepares
the cabin for landing.

Friedline:
The runway's in sight.

Narrator: The crew is just
five minutes from touching down.

Controller: ASA 2311,
cleared direct to Jeff-1 Glynco.

Report the airport in sight.
Expect a visual.

Johnston: We do have it
in sight, 2311.

Friedline: Slowing
for approach speed.

Maris: The aircraft was normal.

There was nothing unexpected.

Friedline: Gear down.

Johnston: Gear down.

Three green.

Narrator: Then, the captain
notices an unusual sound.

Friedline: That's weird.

Number one seems to be
spinning faster.

The left is... the left is
pulling a bit more.

Bringing power down to the left.

Narrator: Captain Friedline
tries to compensate

for the plane's unexplained
pull to the left.

Flight 2311 is less than
1,000 feet from the ground,

and the plane is getting more
and more difficult to control.

Friedline: What's going on?

You see anything?

Johnston: There's nothing.

Maris: The crew were apparently
caught completely by surprise

by something.

Friedline: What's going on
with this thing?

I can't hold it.

Johnston: Get out of it!

Friedline:
I can't. Come on!

Narrator: The plane
is rolling to the left,

and the crew doesn't know why.

Maris: The crew would have
instinctively applied

opposite aileron, moving
the stick to the right,

to try and prevent the aircraft
from rolling as it was.

Carter: Come on, guys.

Get us out of this.

Johnston:
Come on! God. I can't.

Computer: pull up.

Maris: I think they would
have been preoccupied

with trying to stop the roll,

maybe to the extent
of not knowing

just how much peril
they were in.

Carter: Do what I do.

Grab your ankles,
head down. Okay?

Narrator: Captain Friedline
fights desperately

to save his plane.

Computer: Pull up.

Friedline: Come on!
Johnston: No! No!

Friedline:
That's it. Oh, God!

Narrator: It's no use.

Maris: The aircraft crashed
in the middle of woods,

which would have made the job
of the first responders

and firefighting teams
quite difficult.

Narrator: Rescuers make their
way through the dense brush,

but when they reach
the crash site,

they find no one alive
to rescue.

All 20 passengers and
three crewmembers are dead,

killed at the moment of impact.

Jim Ritter: It was
a catastrophic crash.

There was no chance
for survival.

Narrator: With two high-profile
passengers on board,

the crash of flight 2311 makes
headlines around the world.

Maris:
In this particular accident,

Senator Tower on board, was
a four-term senator, was killed,

which raised the profile
of the accident a great deal,

both from the investigation
point of view

and the public and the media.

Woman: And we are,
at this moment,

beginning the on-scene phases
of the investigation.

Gregory: I was in Spain
when the accident occurred.

When I got on the plane
to head back,

the pilot told me that one of
the astronauts had been killed,

and that his name was Carter.

I was in shock,
because Sonny and I had

had an amazing
relationship for years.

We were like brothers.

Narrator:
Wreckage is still smoldering

when Jim Ritter arrives
at the crash site.

Though an experienced
investigator

with the national transportation
safety board,

Ritter is struck
by what he sees.

Ritter: My God.

There was a lot of fire damage
in the wreckage,

and the airplane was basically
totally destroyed.

Narrator: Ritter realizes
he's facing

one of the biggest challenges
of his career.

Ritter: Anytime there's
a high-profile case,

you're a little more nervous.

There's more stress
and pressure on you

to come up with a cause
for the accident.

Narrator: The pressure is on
to figure out what happened

aboard flight 2311.

Narrator:
In Glynn county, Georgia,

investigators search for answers

at the crash site
of flight 2311.

Several people
at a nearby trailer park

saw the plane go down.

Man: It had come right over
top of the house,

and it got real loud.

It was coming right over
these trees here,

and then it got extra loud.

Ritter: The eyewitnesses saw
an extreme left roll angle

from the airplane,

and so we knew that it was some
kind of catastrophic failure,

a very abrupt failure that
would have been difficult

for the flight crew to overcome.

Okay.

Let's start here and work
backwards to first impact.

I want a record of everything.

You need to look
at the crash site

to collect
the physical evidence.

That's the most important aspect

of any aircraft investigation.

Maris: Investigators
look at the wreckage

to try and evaluate the sequence
of events leading to the crash.

They look for the two wing tips,
the tip of the tail,

the tip of the nose.

Narrator: A survey of
the crash site soon confirms

those key pieces are
among the wreckage.

Ritter: That tells us that there
was no in-flight breakup

and that the airplane
stayed intact

until it collided
with the ground.

Can you get a shot of this wing
for me, please?

Narrator:
For expert investigators,

the size and shape of
the impact zone is also a clue.

Maris: If an aircraft,
particularly through trees,

has a long swathe
cut through the trees,

the investigators get an idea
that the aircraft hit the ground

approximately flat
in a shallow descent.

In this case, the wreckage
was very concentrated,

which indicated the aircraft
hit the ground

at a very steep angle.

Ritter: We need to get some

measurements on these trees.

Narrator: Investigators hope
the broken trees will shed light

on witness statements about
the way the plane was flying.

Man: I seen it fly overhead
and, you know,

it looked like it was making
a wide right turn,

but it was unusual because
when it turned out,

it... the nose started heading
toward the ground,

and I was right up toward
the entrance of touchstone,

and I heard the explosion and
seen the fire and the smoke.

Ritter: When the plane crashed,

it sheared the tops off of many
of the trees in the woods there,

and so one of the things
that we did

was we measured the heights
of the trees

where the tops were sheared off,

and that was able to give us
a fairly good idea

of the roll angle,
which was a large left roll.

In the plane you would have
felt light in your seat.

You would have turned
obviously to the left

at almost 90 degrees.

Johnston: Get out of it!

Friedline: I can't. Come on!

Ritter: It would have been
a traumatic experience.

Carter: Come on, guys.

Get us out of this.

Ritter: What could
make it roll so far over?

When the airplane rolled
to the left,

it could really only be
due to two things.

Perhaps the pilot wanted
to roll to the left,

or there was a malfunction that
the pilots couldn't counteract.

What have you got for me?

Narrator: Ritter examines

airport flight records.

He's looking for anything
that might have triggered

the deadly roll.

Ritter: Clear skies on approach.

Almost zero traffic.

There were no other airplanes
in the area to avoid.

It was a nice, clear day,

so we didn't really
have an explanation

for why the airplane rolled
so violently to the left.

Narrator: Ritter won't be
getting an explanation

from any onboard
flight recorders.

At the time of the crash,

commuter planes weren't
required to carry them.

Investigators will have to solve
the mystery of flight 2311

without one of their
most useful tools.

Ritter: Not having those
made the physical evidence

all the more important.

What have you got for me?

This is the third one.

Narrator: The engines have been
badly damaged in the crash.

The propeller blades
have been torn off.

Did flight 2311 suffer
some kind of engine failure?

It's too soon to say.

One thing Ritter does know

is that the pressure
he's feeling from the media

is not about to let up.

The deaths of Senator Tower
and Astronaut Sonny Carter

are sure to keep the
investigation in the spotlight.

Ritter is determined not to let
the pressure get to him.

Ritter: Sometimes
we feel pressure

to do an investigation quickly,

but for the most part, it's
more important to get it right,

and so I would rather
take the time

and have a good analysis
of the evidence

before they come out
with a probable cause.

We won't find our answers here.

Let's get what we can
back to the hangar--

wings, tail, engines,
instruments.

Narrator: The question now--

can he find enough evidence

to solve the mystery
of flight 2311?

Narrator: Investigators begin
the painstaking task

of sorting through the wreckage
of flight 2311.

They're searching for
any evidence that might hint

at why the Embraer 120 rolled
sharply to the left and crashed,

killing everyone on board.

Ritter: Alright, guys.

Let's start with the ailerons.

Narrator: They wonder
if one of the plane's

flight control surfaces
was malfunctioning.

Maris: Control surfaces
are the moveable flaps

typically at the back of the
wings, the tail, and the fin,

which allow the pilot
to roll the aircraft,

to pitch the aircraft,
and to yaw the aircraft--

the three motions
an aircraft can do.

Narrator: They need to examine

every component
of the flight control system.

Ritter: What you're looking for
is continuity of the controls.

Are the hinges all intact?

All the actuators are
in their proper position?

Were the control surfaces
themselves

in a reasonable position
at the time of impact?

Ailerons look good.

When we examined
the control surfaces,

we didn't find anything
unusual at all.

Everything checked out normally.

So if the control systems
were all working,

why would a plane do this?

Left bank almost 90 degrees,

then almost straight down.

Maybe the engine?

Without the black boxes,

it's basically a process
of elimination.

We analyze all
of the physical evidence

and come up with
the most compelling scenario

that matches that evidence.

Alright. Let's see what
we can find in here.

Narrator: If one of the plane's
two turboprop engines failed,

it might explain why the plane
went into such a steep roll.

Ritter: We wanted to look
for any indications

of an engine problem,

so we retrieved both the left
and the right engine

and their propeller systems

and took those back
to the laboratory

for further examination.

Narrator: Investigators soon
find some telltale evidence--

leaves and branches
inside the engines.

Ritter: When we find vegetation
in the engines,

that tells us that
the engine is operating

because it's sucking in air

and it's pulling in the leaves
and the vegetation,

and that's an indication
that it's making power.

This one was spinning
to the very end,

no doubt about it.

We confirmed that both engines
were operating

right up until
the moment of impact.

Computer: Terrain.

Friedline: That's it.

No!

Narrator:
With engine failure ruled out,

Ritter turns his attention

to the other main part of
the plane's propulsion system.

Ritter: Let's take a look
at these propellers.

Thank you.

Narrator: Tom Haueter
is an NTSB investigator.

Haueter: When we started doing
testing of the propeller system,

we didn't know where
it was gonna lead us,

but it was something we had to
eliminate, if nothing else.

Narrator: Deep inside
the propeller unit,

investigators uncover
an important clue.

Ritter: Ah-ha!

There you are.

We have a witness mark.

Take a look.

Narrator: There's a small mark

where two parts
of the propeller mechanism

slammed together on impact.

The witness mark might be enough
to tell investigators

how the propellers
were operating.

Ritter: You can literally
match up the scratch marks

between both pieces,

and you'll know what the angle
of the propeller blade was

from that measurement.

Mark this one...

22 degrees.

Narrator: The Embraer 120
has what's called

a constant speed propeller.

The blades spin
at a steady rate in flight.

When the pilots need more power,
the blades twist,

changing their angle to take
a bigger bite out of the air

and provide more thrust.

Friedline:
Slowing for approach speed.

Maris: And in flight,

it acts like the automatic
transmission in a car.

It's as if it's changing gears
to match the engine load,

the speed, whether the plane
is climbing or descending,

and it does so constantly
and automatically

without intervention
by the crew.

Narrator: There are witness
marks inside both propellers.

Ritter: Now, this one...

Looks like three degrees?

Narrator: The marks tell Ritter
the exact angle of the blades

when the plane slammed
into the ground.

Ritter: We immediately
noticed the difference

between some of the blade
angle measurements

for the left engine
versus the right engine.

These guys had a big problem
with their left propeller.

The blades were almost flat.

Narrator: The left side
propeller blades

are at a dangerously low angle--

one that is never used
during flight.

At three degrees,
the blades are so flat,

they would act like a wall,

blocking the flow of air the
plane needs to maintain lift.

Haueter: At certain speeds
and certain regimes of flight,

if the propeller
goes flat enough,

you have a situation where
you can't control the airplane.

Narrator: Investigators
study the mechanism

used to control
the left propeller.

Ritter: Will you look at this?

Narrator: They make
a disturbing discovery.

Ritter:
It's completely worn down.

Narrator: The teeth on a key
piece of the gear mechanism,

known as the quill,

are almost entirely worn away.

Investigators
may finally have the lead

they've been looking for.

Ritter: This is what
it's supposed to look like.

Narrator:
With its teeth worn away,

the quill can't lock
onto the gear system

that controls the angle
of the propeller blades.

The discovery might explain
why the propeller blades

slipped to such
a dangerously low angle.

Ritter: Once we noticed that the
quill teeth were severely worn,

we started theorizing
what would happen

in that type of situation,

and it was pretty clear that

control of the propeller
blade angles could be lost.

And that really was
a eureka moment for us,

because now we had
a serious malfunction

that we could examine.

Ritter: This could

definitely be it.

Narrator: Ritter digs
into manufacturing reports,

trying to find out how such
a vital part could have failed.

But what he finds
only adds to the mystery.

The quill teeth are made

of an extremely durable
case-hardened metal.

Ritter: They were definitely
made to last.

Narrator: It's hard to imagine
what could have caused

such rugged teeth
to wear down so badly.

Ritter: Something
didn't work as planned.

Let's find out everything we can
about every one of these pieces.

Narrator: Ritter is certain
he's found the critical clue--

worn-down teeth on the quill
that could have allowed

the propeller blades to slip
to a dangerous angle.

But he soon learns there's
a big problem with his theory.

The manufacturer says
it's impossible.

Engineers at Hamilton Standard
included a fail-safe feature

when they designed
the propeller.

It should be impossible for the
blades to go flat during flight.

Maris: Manufacturers
have to demonstrate,

through a number of means, that
their systems are fail-safe.

Haueter:
All the tests and research

that had been done
before this said

even if
you have a disconnect,

that will not result
in an accident.

Narrator:
If there's ever a problem

with the mechanism
controlling the angle,

the blades are designed
to move on their own

to what's called
the feathered position.

Haueter:
The feathered propeller blade,

the leading edge of the blade
is directly into the wind,

so that's the most minimal drag,

no thrust,
but very little drag.

Narrator:
A feathered propeller

can't endanger
the safety of the flight.

Maris: If this rod disengaged
because of any cause,

the propeller should
go to feather,

which would result
in the loss of the engine,

and the crew would be able
to cope with that

and land on one engine,
as they are trained to do.

Friedline:
The runway's in sight.

Ritter: This has got to be it.

This has to be
connected somehow.

Narrator: But Ritter
isn't convinced

by the manufacturer's
assurances.

His gut tells him the worn quill
did allow the propeller blades

to move to a dangerous angle.

But without flight data,

his investigation
has hit a wall.

He has no way to prove the quill
brought down flight 2311.

Friedline: What's going on?

Can you see anything?

Johnston: There's nothing.

Ritter:
Tom, welcome to the team.

Haueter: No problem, Jim.
Glad to help.

Narrator:
With the investigation stalled,

Tom Haueter joins Jim Ritter
to hunt for answers

in the crash of
Atlantic Southeast flight 2311.

Haueter: I was a little nervous
about this one

in that when I first
jumped into it,

I didn't really know
what was going on

other than it was basically
at a standstill

and they were looking for me
to get it moving.

What do we have?

Ritter: I think everything
we need to know

is right here on this table.

Haueter: You have a part of
the propeller control assembly,

and the teeth on the gear
are essentially gone.

That's very unusual.

Could that have been
a part of the accident?

We didn't know.

Narrator: Haueter and Ritter
study the design

of the propeller mechanism.

Ritter: Tom, look at this.

Haueter: We don't see anything
obviously wrong with the crew.

We don't see anything wrong with
the structure of the aircraft.

We don't see anything wrong
with the engines

and the flight control system,

but we do have a severely worn
Transfer Tube

and quill arrangement.

Is it possible that this
could have resulted

in the loss of control?

Narrator: They discover that
shortly before the accident,

Hamilton Standard started using
a harder, more abrasive coating

on a key part known
as the Transfer Tube.

Its grooves mesh-like clockwork
into the teeth of the quill.

The change had
an unexpected consequence.

Haueter: It turned it
into a giant file.

Ritter: So the splines
on the Transfer Tube

were much harder and rougher
than the quill teeth,

and it was almost
like sandpaper,

so the tube was actually

wearing down
the teeth on the quill.

Narrator: The discovery explains
the worn teeth on the quill.

The design of the propeller
should ensure

it snaps to a safe position,

even with the worn part.

Ritter: The propeller
manufacturer believed

that they had
a fail-safe condition,

so that even if they had
this problem,

the propeller blades
would be slowly driven

to the feather position.

Narrator: In spite of what
all their data says,

the investigators want
to see for themselves.

They set up a test at
the manufacturer's facility.

Ritter: We had an engine
and a propeller combination

mounted in a test cell.

Maris: In order to determine
that something is fail-safe,

the engineers use a combination
of mathematical analysis,

very structured analysis,

testing in a laboratory,
as you can imagine,

and by these methods,

Hamilton Standard
convinced themselves

that this propeller would fail
in a safe direction,

i.e., towards feather.

Narrator: Jim Ritter's doubts
about the fail-safe design

may be confirmed
in just a few seconds.

The technician flips a switch
to free the Transfer Tube

from the teeth on the quill.

But as the test unfolds,
instead of moving to flat,

the propeller blades move to
the safe feathered position.

The fail-safe system performs
exactly as it was designed to.

It suddenly seems
that investigators

are on the wrong path
altogether.

Ritter: So, when we tested
the quill with the worn teeth

at the manufacturer's facility,

we found that the propeller
blades went to feather,

so at that point,
we were basically stumped.

Haueter: Can you play it again?

Narrator: The test results leave
Ritter and Haueter wondering,

could there be some other factor
that they've overlooked?

Haueter: Hold on.

That's it.

It's bolted to the ground.

The question I raised,

well, in flight, the aircraft
is in turbulence,

it's bouncing around.

There's different vibrations.

With the aircraft on the ground

or an engine mounted solidly
to the ground,

the airplane doesn't
behave the same.

There's different
vibration modes.

Is it possible that could change
the outcome of the analysis?

Haueter: I think we need
to see it in the air.

Ritter: Definitely.

Maris: One of the problems
with doing testing

in a laboratory environment,
which is very controlled,

is that you can't always
anticipate what will happen

when you go out
into the real world.

Carter: These small planes
do keep you on your toes.

Maris: Imagine, for example,
an orchestra that rehearses

in an acoustically perfect
concert hall

and then performs outside
with random noises,

without the sound controlled.

You can see how one might miss
important factors

about the sound.

Haueter: We've got to see
what happens in the air.

I said, "Well, the only way
to really know

is let's do a flight test
and find out."

Let's do something to absolutely
determine this is the case,

'cause we were at a point
in the investigation

we need to start
eliminating things.

Narrator: The investigation
into the crash of flight 2311

moves to Embraer headquarters
in Brazil.

Ritter:
We really wanted to look at

what would happen in flight,
in an actual flight

with the same malfunction?

Narrator: Tom Haueter meets with
representatives from Embraer

and propeller manufacturer
Hamilton Standard.

The team immediately starts
preparing for the test flight.

Haueter: Thank you
for doing this.

When I first proposed
doing the flight test,

it was not well-received
by almost everybody.

People saw no need.

Why are we spending the time,
the money?

Why are we doing this?

Would you mind if
I used that table?

Is that okay?

But I pushed hard.

I thought, "Well, we need
to really prove this."

Narrator: Embraer's chief
test pilot, Gilberto Schittini,

has agreed to put
the investigators' theory

to the test.

Gilberto Schittini: The risks,
of course, is part of the game,

so you have, always have
to reduce your risk

as much as possible,

but you cannot avoid it,
so you just accept it.

Maris: The mindset
of a test pilot is one

not perhaps of heroic bravery,

but certainly one wants
to be unflappable

in the face of danger
and unusual situations,

because you're not
very productive

if you're terrified by
the goings-on in the cockpit.

Narrator: Schittini
will fly an Embraer 120

that has been modified
to recreate the failure

on flight 2311.

Haueter:
So, we've modified the quill.

The teeth have been worn down
just like flight 2311.

Narrator: A worn quill
will be placed

inside the propeller unit.

Haueter: This was potentially
very high risk,

because once we disconnected
the Transfer Tube in flight,

the pilots would have no way
to control the propeller.

We put a pitch lock here.

It won't go past 22 degrees.

Narrator: A mechanical lock
has also been added

to stop the propeller from going
flatter than 22 degrees.

Haueter: It would be too
dangerous in the flight test

to have the propeller blade
go all the way to flat pitch.

You'd lose control
of the airplane.

That was almost guaranteed.

If the blades move
to 22 degrees,

then we know that they would
have gone flat.

All good?

Narrator: The propeller blades
don't need to go completely flat

to prove that Haueter's
on the right track.

Schittini:
This was a high-risk test.

We had to take extra precautions

in order
not to repeat the accident.

Narrator: Real-time data will
tell the team on the ground

whether the propeller blades are
going safely towards feather

or moving dangerously flat.

Haueter: Everything says that
if you have a disconnect,

the normal frictional drag
within the system

will cause
the components to rotate

towards the feather position,

but will that really happen
in flight the same way?

Narrator:
They're about to find out.

Haueter: We were comfortable
that this test

could be safely accomplished,

but there's a difference

between believing
it can be safely accomplished

and knowing.

Narrator:
As the test plane climbs,

Schittini takes it
over an unpopulated area,

just in case.

Haueter: There was a potential

for a severe
controllability problem

such that the pilots might
have to abandon the aircraft

and parachute to the ground.

Narrator: The propellers
have been set

to a normal angle for flight--

around 30 degrees.

Haueter: EMB-120, do you copy?

There was a lot on the line,
in terms of the fact

that what if this
airplane crashes?

What if we lose the airplane?

Certainly
I'm the investigator in charge.

I'm the one, you know, who's
basically running this test.

This could be all
my responsibility.

Schittini: Copy.

We are ready to disengage
the prop.

Haueter: Basically they would
pull the lever

that would disconnect
the propeller control system

from the propeller

and see what happens.

Narrator: The most dangerous
part of the test flight

is now under way.

Schittini: I just thought that,
well, it's happening.

Let's do what we have to do and
get this airplane on the ground.

Maris: This was, in my opinion
a very dangerous maneuver,

because after all,
they didn't know

what the outcome
was going to be,

and they already knew
the aircraft wasn't controllable

under certain circumstances.

Schittini: Propeller blade angle
is causing no problems.

No control issues.

We were thinking about
the test to do and nothing else.

You have to focus on the job
that you have to do ahead,

and once you focus you forget
about everything else.

Narrator: As soon as the
propeller quill is disengaged,

the blades begin doing what
they were designed to do--

moving towards
the feathered position.

Haueter: As it starts
drifting towards feather,

we thought, "Okay.

Well, this test is
gonna be a bust.

It's just gonna prove what
everybody said it would do."

You could see it in their faces.

They didn't say anything,

but you could just, you know,
hear the relief.

Narrator: The propeller blades
keep moving

toward the fail-safe position.

For Tom Haueter, Brazil is
a long way to come for failure.

It seems like the test

that he hoped would solve
the mystery of flight 2311

is going to leave
the investigation

back at square one.

Narrator: With the cause
of the Atlantic Southeast crash

still unknown

and the entire investigation
on the line,

the Brazilian test flight
takes a dramatic turn.

Schittini: We saw that
the RPM was increasing slowly,

but it was increasing,
so we knew that the propeller

was going in
the wrong direction.

Narrator:
As the flight continues,

the blades begin drifting
in the opposite direction,

towards the dangerous
flat position.

Haueter: Ah-ha.

Here we go.

Ritter: The aerodynamics,
the vibration,

the actual in-flight loads
on the propeller

are something that you just
can't predict in a test.

It's something that actually
had to be flown.

Narrator: Schittini remains
smooth and precise

on the controls.

Schittini: Reducing speed.

Easy does it.

We started feeling
a rolling moment to the left

and a yaw moment to the left.

Narrator: The blades go as flat
as this test will allow,

22 degrees.

For Haueter, it's a victory.

The risky test flight
has paid off.

His theory about the crash
is back on solid ground.

Haueter: The Hamilton Standard
and the FA people

just went white.

I mean, they were just shocked.

You could tell that
everything they believed

had just been thrown
out the window.

That's as flat as
they're gonna get.

Schittini: Do you have
what you need?

Haueter: Affirmative.

We have everything we need.

Schittini:
Okay, we're going back.

Once the test part is finished,
it is finished.

Don't stay around
looking for trouble.

Go back home.

Haueter: Good work.

Thanks very much.

Seeing the data right then,
it took a load off.

I said, "Okay, wow."

I mean, we now know
what happened.

It was obvious.

Looks like you have
some work to do.

Ritter: Hello.

Narrator: The team has just
one more question to answer

before they can explain
the crash.

What happens when blades
go completely flat?

Ritter: In the flight test,

they were only able to go

to a blade angle
of about 22 degrees

for safety reasons.

Start it.

But during
my flight simulations,

I went down to flight angles
as low as three degrees.

Anytime.

Narrator: In a flight simulator,

Jim Ritter recreates
the fatal propeller malfunction

aboard Atlantic Southeast
Airlines flight 2311.

Ritter: As the blade angle
got to very low values,

the airplane was essentially
uncontrollable.

Narrator: The simulation
allows him to experience

what the test pilot couldn't.

Haueter: Flight tests proved

we could have a blade
go to flat pitch.

The simulator proved
you'd lose control if it did.

Ritter: Thanks.

That was... helpful.

You could say that
the simulator testing

was kind of like the final
piece of the puzzle.

Narrator: Investigators finally
understand the full story

behind the deadly crash.

Ritter: When the flight crew
began preparations for landing,

the teeth on the quill
were worn down,

but still operational.

Friedline:
Slowing for approach speed.

Narrator: Preparing for landing
put renewed pressure

on the already worn teeth
in the quill.

They could no longer hold.

Once the teeth gave way,

the propeller blades were free
to drift to a different angle.

As the turbulence of flight

and mechanical vibrations
from the engine

shook the propeller,

the blades moved to
a dangerously flat position.

Ritter: The fail-safe failed.

The propeller's design couldn't
hold the blades at a safe angle,

and the plane became less
and less controllable.

Friedline: What's going on?

You see anything?

Johnston: There's nothing.

Friedline: What's going on
with this thing?

I can't hold it.

Johnston: Get out of it!

Friedline: I can't.
Come on. Come on!

Haueter: For a while,
you can kind of fight this,

putting in control movements
with the wheels, the rudder,

but, unfortunately,
they were in a situation

where it didn't matter

if you were the best pilot
on the planet.

You were not going to be able
to control that airplane.

It's going to roll over.

It's gonna dive
towards the ground.

Maris: Ironically, human error
is almost always underneath

the causes of an accident,

even if it wasn't the pilot
or a mechanic.

In this particular case,
an engineering change was made,

which, well-intentioned,
actually, did not work out.

Johnston: No!

Friedline:
That's it. Oh, God!

Johnston: No.

Haueter: The worn quill teeth

was a time bomb
waiting to go off.

There was nothing they could
have done to save that plane.

What I really felt was, "Okay,
now that we know it,

we've got to tell
the rest of the world

and get operators to start
changing their equipment,

like, right now."

The fail-safe system
doesn't work.

Narrator: After the accident,
additional safeguards were added

to prevent this
type of failure--

a change that affected
not only the Embraer,

but several other
turboprop aircraft as well.

The FAA also ordered
more frequent inspections

of propeller quills.

Haueter: The most important
thing we have learned

from the accident at Brunswick

is assumptions.

You cannot rely on assumptions.

It was assumed that ground tests
were as good as flight tests.

That one assumption
unfortunately turned out

to be fatal for some people.