All language subtitles for Air.Disasters.S07E05.Hidden.Danger.1080p.PMTP.WEB-DL.DDP5.1.H.264-maldini_track3_[eng]

The Boeing 737
is one of the most popular

passenger jets in the world.

Around the globe,
the plane has carried more

than 12 billion passengers.

It's the backbone of
the aviation industry.

But in 1991,
something happened on board

a 737 that sent shivers
through the world of aviation.

-
-Oh, my lord.

A deadly crash has
investigators scrambling.

There was a time
when I had doubts

that we'd be able to solve it.

It was like he was
tracking a serial killer.

The hunt for answers
will take 10 long,

grueling years.

The fate of the airline
industry hangs in the balance,

and the mystery is
unsolved until more

than 150 people are dead.

Ladies and gentlemen,
we are starting our approach.

Put your mask
over your nose.

Emergency decent.

Brace for impact!

9:40 AM,
March 3, 1991.

After a short 17 minute
trip from Denver,

United Airlines flight
585 is on final approach

into Colorado Springs.

It looks like a
perfect day for flying,

but there's trouble in the air.

Nice looking day.

Hard to believe the
skies are unfriendly.

There's Been heavy
turbulence during the flight

and violent gusts
of wind are forecast

over Colorado Springs.

Never driven to Colorado
Springs and not gotten sick?

At the controls is
52-year-old Captain Harold

Green, a pilot with
20 years experience

and a sterling reputation.

Green's co-pilot
is Patricia Eidson.

At 42, she is one of
the first female flight

officers in United's history.

Flight
attendants, prepare for landing.

At Colorado
Springs Municipal Airport,

air traffic controller
James Rayfield is

ready to bring flight 585 in.

United 585 report
the airport insight.

Got it.

Yep.

Airport inside United 585.

Lower landing gear.

United 585 is cleared for a
visual approach to runway 35,

weather conditions 23, 20
degrees at 16 gusting at 29.

As its
speed decreases,

flight 585 becomes more
vulnerable to the turbulence.

Eidson wants to know
what other planes

have experienced on landing.

Any airports lately of any
loss for gain of airspeed?

Yes, ma'am.

500 feet a 50 knot loss at
400 feet at 50 knot gain

and at 150 feet a
gain of 20 knots.

Sounds adventurous,
thank you.

Starting on down.

Just a mile
from the airport,

retired policeman Harold
Darnell is on his way

to a local flea market.

Half a mile overhead,
Green and Eidson

focus on keeping their speed
constant as they descend.

Wait, a 10 knot change here.

Yeah, I know.

Have a lot of power
to hold that airspeed.

As United 585
approaches the runway,

Darnell feels
something strange.

Oh, what the heck was that?

Out of nowhere,
a powerful gust of wind

strikes his vehicle, almost
blowing him off the road.

I know 10 knot gain.

Pretty flops.

From
the control tower,

James Rayfield can now see
flight 585's final approach.

As the aircraft closes
in on the airport,

the ride gets even bumpier.

Wow.

40,000 feet.

Then, without
warning, the 737

starts to spin out of control.

15, 12.

15.

Oh, no.

Oh my God.

Oh my God.

Oh my lord.

Crash, crash!

Rescue workers
arrive within minutes,

but there is almost
no sign of the 737.

The shattered remains
of the 38-ton jet

lie buried in a fire
blackened impact crater.

The plane, it didn't skate
or bounce

like when a plane comes
in normally and lands,

it just nosed right
in and where it hits,

where it stayed.

There
are no survivors.

All 20 passengers
and five crew members

are killed instantly
by the high speed

impact and exploding jet fuel.

In 10 violent seconds,
Colorado Springs

has become the site of one
of the most mysterious air

crashes in aviation history.

By nightfall,
investigators from the National

Transportation Safety Board
descend on Colorado Springs.

Known to insiders
as tin kickers,

NTSB investigators examine
over 2,000 aviation accidents

a year, at times by
picking through the metal

debris of fallen aircraft.

A coroner has marked
the location

of human remains in red.

NTSB investigators marks
scraps of metal in yellow,

looking for clues
to help them solve

the mystery of flight 585.

Like investigating
a mass murder,

it's a tough job walking
onto a crash site.

Among the investigators
assigned to the case

is Malcolm Brenner,
a specialist

in human performance.

His job will be to
find out if the crash

was caused by pilot error.

The area
was cordoned off by police,

and there were
salvation army trucks.

I got a cup of coffee, a cup
of hot chocolate, or something

and I thanked them for it, and
they said, no, no, thank you.

And they had this
look in their eyes

like, oh my God, you have
to go into this site.

Clues to
the fate of United 585

lie mangled in a
deep black hole.

The fuselage is crushed
like an accordion

in the impact crater.

The rest of the plane is in
pieces spread over an area

smaller than a football field.

There was a lot
of fire damage.

There had been a
fire afterwards,

and it was all contained in a
relatively small area,

which just initial impression
it can be a sign

that the airplane was intact.

If there was a midair
explosion or something came off

the airplane, you would expect
that to be a much larger site.

My first sense that it
was going to take some time

to investigate the
accident was the damage

that we saw in the parts.

When they're burned
and broken, the process

always takes longer.

The National
Transportation

Safety Board begins
a painstaking

investigation into the crash.

Engine turbines, hydraulic
pressure gauges, the cockpit

voice recorder, and
in-flight data recorder

are all carefully
extracted from the site,

photographed, and sent
to the lab for analysis.

An important step
in the investigation

is the analysis of the
cockpit voice recorder.

With pilot error a factor
in 70% of air disasters,

Malcolm Brenner's
job is to see what

role pilots Green and
Eidson played in the crash.

This crew was--
and I felt this at the time--

was one of the more
impressive crews

that I'd ever dealt with.

There was a little bit
of tension release,

a little bit of humor.

The captain said--

Never driven to Colorado
Springs and not gotten sick?

The first officer suggested
that they add extra speed

as a safety margin.

The captain agreed with it.

It was good interaction.

- Got it.
- Yep.

Airport insight, United 585.

Lower landing gear.

This is a sense
of an excellent crew

caught randomly, if anything.

So, again, that was
my first impression

is that this would
be consistent more

with a hardware situation.

As more about
flight 585 becomes known,

mechanical failure
becomes a serious suspect.

Just seconds before it crashed,
the plane rolled onto its back

and spun wildly out of control.

Investigators wonder
if the sudden motion

was caused by the plane
losing an engine or a wing.

From the state of
the aircraft on site,

it's clear that it was intact
at the time of the crash.

What investigators don't
know is if the engines

were still working at impact.

Technicians examine
the engine turbines.

They discover dirt
has been drawn

deeply into every crevice.

These blades were clearly
spinning and sucking

in air at the time of impact.

The engines may have been
running but technicians

aren't sure how well.

The plane's hydraulic
pressure dials are destroyed,

the glass covers broken.

The indicator needles
have been snapped off

by the force of the impact,

but even these ravaged dials
tell a tale.

-15 flops.
-15.

On closer
inspection, investigators

find a critical mark.

At the moment of impact, a
dent was made on the face plate

by the jar indicator needle.

It proves that when
flight 585 crashed,

its engines were
running normal.

With engine failure
ruled out,

there seems to be only one other
mechanical explanation for why

flight 585 suddenly rolled over
and then fell out of the sky.

It appears increasingly
likely that the plane

had suffered a
catastrophic problem

with its flight controls.

Investigators quickly become
suspicious of the rudder

at the back of the tail.

We focused in, after
eliminating other flight

control surfaces
that we thought

could contribute
to the role,

we start looking into
the rudder.

Bring that up so I
can take a look at it.

Investigators
begin their examination

of the rudder on site, but
the violence of the crash

makes the job
extremely difficult.

Almost nothing left.

Most of
the plane's parts

are too crushed or
burned for testing,

but a vital component is
still reasonably intact,

the Power Control Unit or PCU.

Used constantly during flight,
especially during landings,

the PCU performs like
a car's power steering.

When the pilot pushes
on a rudder pedal,

the PCU uses hydraulic fluid
to convert gentle movements

of a pilot's foot into the
pressure needed to move

the 737's enormous rudder.

The heart of the
PCU is something

called the duo-servo valve.

Cheap like a soda
can, it has two slides

which glide past one
another,

directing the flow of
pressurized hydraulic fluid

that moves the rudder.

The server valve
is very unique

that it is in effect
two valves in one

and that, that
creates a whole range

of interactions that
don't occur in a more

conventional hydraulic valve.

When a technician
opens the power control unit,

chips of metal
are found floating

in the hydraulic fluid.

It's a disturbing find.

These particles
could cause the servo

valve to jam, making
it impossible to work

the plane's rudder.

It's a chilling prospect.

Could a microscopic fault
bring down a 38-ton jet?

It's difficult for
Phillips to tell.

While more intact than
much of the wreck,

the PCU and duo-servo
valve are both damaged.

To test what he does have,
Phillips travels to California

to the labs of Parker
Hannifin where the rudder

control unit is made.

The curious metal chips
floating in the PCU's chambers

are dismissed.

Phillips is told that
filters keep them out

of the delicate servo
valve that directs fluid

and moves the rudder.

Nothing else is
found that could

explain any sudden movement
of the rudder on flight 585.

We didn't have any absolute
indication or information

that we could point to that said
the rudder power control unit,

the servo valve, or any
part of that flight control

system caused that accident.

Philips still
suspects a mechanical problem

but with no conclusive
evidence that the PCU or servo

valve caused the crash.

He is forced to sign
off on the tests.

It's a farce.

With
Philips at a dead end,

only bad mountain weather
remains a primary suspect.

An expert on weather related
aviation accidents,

Greg Salotollo, is
trying to determine

if heavy winds on the day
of the crash were a factor.

There is a
history of events where there

have been airplane
accidents attributed

to mountain waves of rotors.

In 1966, a BOAC
707 near Mount Fuji

disintegrated in a
mountain wave and rotor.

High winds crashing
over mountain peaks leaves

so-called wind rotors in
the lee side invisible,

highly turbulent downdrafts
that come plunging down

with devastating power
and are extremely

dangerous to aircraft.

We found a great
deal of evidence

looking at the
surface upper air data

and talking to
witnesses in the area

that roters were a possibility.

The explosion was
right over there.

Salotollo's
hears several eyewitness

reports of bizarre
mountain weather

on the day of the crash.

One of the most intriguing
is from Harold Darnell.

Oh, what the heck was that?

Whose
truck was struck

by a powerful gust of wind just
moments before 585 crashed.

But as Greg Salotollo
combs through his evidence,

the theory that a wind rotor
knocked the plane from the sky

is getting less
and less likely.

A nice looking day.

Hard to believe the
skies are unfriendly.

Wind rotors
are areas of extremely

low barometric pressure.

So if flight 585 did
pass through one,

its altimeter reading would
have spiked as the plane

was blown suddenly upwards.

There's no evidence that
we saw that on the flight

data recorder of 585.

What the
flight recorder

did show was a fast and
deadly drop in altitude

as the plane fell to apart.

It's been 21 months

since the investigation
into the crash

of United Flight 585 began,
almost two years in which

the NTSB has studied
the crew, the weather,

the rudder, and thousands
of other pieces of evidence.

They've come up empty handed.

For only the fourth
time in its history,

the NTSB releases
a report which

doesn't reach a conclusion.

The cause of the crash of
Flight 585 is undetermined.

We had put a lot
of time and effort

in into the investigation,
and we just weren't

sure what had happened.

It was like he was
tracking a serial killer.

He was frustrated that
they had not solved 585.

He did not want that
to happen again.

But almost two
years after the report on 585

is released, the
killer strikes again.

At 7:00 PM on a clear
windless day,

US Air flight 427
is nearing Pittsburgh.

Captain Peter Germano and
first officer Chuck Emmett

are getting ready for
their final approach.

Folks from the flight deck,
we should be on the ground

about 10 more minutes.

Sunny skies, a little hazy.

Flight attendants, please
prepare for landing.

I ask you to check the
security, your seatbelt.

Thank you.

US Air at 309 descend
and maintain 6,000.

As they close
in on the airport,

the pilots are on the
lookout for another flight

about six miles ahead of them.

Looking for the traffic,

turning 100, US Air 427.

I see the jet stream.

As they pass
through the turbulence left

behind the other flight,
their jet suddenly

and alarmingly rolls left.

Hold on, hold on.

Oh, my, shoot.

Nothing the pilots
do seems to have any effect.

What the heck is this?

What the hell?

Shoot!

God, God.

427 emergency.

Oh, shoot.

Whoa, whoa.

Oh, God, no.

Rescue
crews arrived quickly,

but the fate of flight
427 is tragically clear.

There is no hope for the
132 passengers and crew.

The human carnage is so bad.

Authorities declare the
crash site a biohazard.

US Air 427 accident was
the first US accident where

biohazard suits were used and
it made it more difficult.

They were uncomfortable.

They were hot.

And to this day, when I put
on a pair of rubber gloves,

for any reason, I'm
instantly transformed back

to the site in Pittsburgh.

Captain John Cox,
a 737 pilot and flight system

specialist with the Airline
Peloton Association,

is asked to join the
team investigating

the crash of Flight 427.

As coroners attempt to
collect human remains,

NTSB lead investigator
Tom Haueter

already knows his
hunt for clues

will be long and painstaking.

When we first arrived
at the crash site--

well, first of all, there
was no aircraft there.

There were only bits and
pieces of the airplane.

It wasn't really
recognizable as an airplane.

With the help of
eyewitnesses, information

from the flight data recorder,
and the cockpit voice

recorder, investigators
begin to quickly see

some striking
similarities between 427

and the unsolved
case of United 585.

In fact, they seem to be
mirror images of each other.

On final approach, United
585 rules right,

while US Air 427
rolls to the left.

I got slip.

Hang on. hang on.

Both crews
are caught by surprise

and after just a few
terrifying seconds,

both aircraft plummet
straight to the ground.

As the investigation continues,
the list of

similarities grows.

427's engines were also
attached and functioning

at the time of impact.

But for all the
similarities, there

is one important difference.

Unlike United 585, as US Air
427 approached Pittsburgh,

weather conditions
were dead calm.

Folks from the flight deck,
we should be on the ground

about 10 more minutes.

Sunny skies a little hazy.

As he did in
the case of United 585,

Greg Phillips will
once again lead

the investigation into
the mechanical aspects

of the crash.

Almost immediately, he
makes a promising discovery.

Miraculously, much of US
Air 427 tail and rudder

appear intact.

The hydraulic devices
inside the tail

have also sustained
very little damage.

Philips and Haueter
prepare to send the parts

to the manufacturer,
Parker Hannifin,

for testing as
soon as possible.

They need answers.

Pressure on the NTSB
to solve the accident

is growing quickly.

Not only are the crashes
of flights 585 and 427

disturbingly similar,
both of them

involve the same kind of
airplane, a Boeing 737.

But with serious questions
being raised about the plane's

safety, billions of
dollars, untold lives,

and perhaps the airline
industry itself are at risk.

We couldn't
live with the fact

as investigators of having
two unsolved 737 accidents.

The airplane is
in too much use,

too why to use
around the world.

It carries too many
people every day.

Unsolved was not an
acceptable answer.

To find their
killer, the NTSB can't

afford to rule anything out.

From the possibility that
a collision with birds

brought flight 427 down to
strange even bizarre theories.

They looked at
electromagnetic interference.

They got calls from
people saying it

might be Russian death rays.

They considered everything.

There were a
couple of witnesses

who gave reports
of the aircraft

suddenly descending and
hovering before it blew up.

We discounted those.

But the
investigation's

primary suspect is the
duo-servo valve, part

of the power control
unit that moves

the 737's rudder and a suspect
in the crash of United 585.

Parker Hannifin made the valve.

At its lab in
California, investigators

look inside the main cavity of
the US Air power control unit.

Just like in the
earlier crash, they

find tiny chips
of metal floating

in the hydraulic fluid.

But once again, Parker and
Boeing repeat their claim,

filters designed
to stop any debris

from interfering with
the delicate metal

slides have done their job.

Investigator Greg Phillips
wants to be absolutely sure.

If the chips were
blocking the slides,

they would have left tiny
scratch marks behind where

they rubbed against the metal.

But Phillips can't find any.

Another pass.

OK.

Philips
has technicians

put the servo valve from flight
427 through as many tests

as he can think of,
trying to find a weakness.

If he can find one, it
could explain why two planes

were ripped from the sky.

But he comes up empty.

What that unit passed all

its operational test,
there wasn't any indication

that it had failed, and it
operated within the parameters

we expected it to.

Once again,
the investigators

are forced to shift their
focus back to the pilots.

By studying the plane's
flight data recorder,

investigators know
that the jet's rudder

was deployed fully
to one side, what's

called rudder hard over.

We were definitely
focused on a rudder,

on hard over rudder, full
rudder input for about

20 seconds.

It can be caused
either by hardware,

something unknown
in the hardware,

or it can be caused
by pilot input.

First officer Chuck
Emmett, who was flying 427

did indeed step down
hard on his rudder,

and then held it
there while the plane

plummeted toward the Earth.

It raised a grisly question,
was he trying to fly

the plane into the ground?

And looking at this
and being a pilot

myself is like this doesn't
seem like rational behavior.

What the hell is this?

Human performance
specialist Malcolm

Brenner listens
closely for evidence

on the cockpit voice recorder.

What the hell?

In this case, they
had microphones right

by their mouths, and you can
hear as well as in real life

or better, you can
hear breathing sounds.

Yeah, I sees the jet stream.

The cockpit recordings

indicate that flight 427's
troubles began at the moment

it flew through the jet
wake of a Delta Airlines 727

that had just passed
in front of them.

Both pilots are
startled by the wake.

I sees the jet stream. Whoa.

The first officer breaks
off at the end of a sentence.

I see the jet stream,
za, and there's

no more discussion of the
jet stream or anything else.

They both focus.
Something happened here.

Captain says, sheez.

Sheez.

It was such a
smooth flight that it

was a momentary jolt that
they just hadn't anticipated.

And with that, the pilots
got on the controls

and immediately put
in a rudder input.

Sheez.

The cockpit recorder even

records the thumping sound
of the jet stream turbulence

as 427 flies through it.

As flying 427 encounters
the turbulence,

Rener hears something unusual.

First officer Emmett
begins to grunt.

Ah. Ah.

The grunting is unusual.

The controls are
designed so that pilots

don't need to grunt.

They're specially designed
around human capabilities.

So to have someone
grunting is typically

a sign of an emergency.

By matching data
from the flight recorder

with the crew's
voices, Brenner is

able to confirm that Emmett's
grunts begin a split second

after he pushed down on
the rudder pedal and three

to four seconds after the
wake turbulence affected

flight 427.

What the hell?

On their own, the
cockpit voice recordings

proved very little,
but it seems

clear that the crew wasn't
trying to crash their plane.

Something happened, which
took them by surprise,

but nothing they
did seemed to help.

What the hell is this?

It's been
almost two years

since the crash
of Flight 427, and

the investigation has stalled.

Now, two 737s have gone down
in startlingly similar ways,

and investigators
still don't know why.

We were all frustrated
as months wore into years.

What were we missing?

We were going up against
an aircraft that had

an incredible safety history.

It was really-- everything
you could see for 30 years,

this has been a great airplane.

We were trying to
prove that there

was something wrong with
the straight A student.

Unsure of
where to look next

and with the trail of
evidence getting colder,

investigators need a break
in the case and fast.

East wing 517,
you're clear for landing.

On June 9,
1996, Captain Brian Bishop

is on final approach to
Richmond, Virginia, when

without warning,
his East wind jet

rolls sharply to the right.

We didn't know
to what extent,

but we knew we had a
problem with the rudder.

I turn the yoke the
opposite direction stood

on the opposite rudder pedal.

The pedal didn't move for me.

For over
30 seconds, the 737

flies in a
precarious right bank

as Bishop fights to keep
it from rolling over.

Then, suddenly, the unknown
forces holding the jet let go,

snapping the wings
back to horizontal.

In a matter of seconds,
it released itself

and went back to normal.

We had started the checklist.

Almost before I could finish
the sentence,

all of a sudden
there was just a wham.

For a second time,

the 737 is pushed
on its side again.

For 30 more harrowing
seconds, the 737

takes on a life of its own.

Then, once again, as quickly as
it began, the rollover stops.

After the second time, I
looked at the first officer

and I said, declare
an emergency.

Tell the controller we have
flight control problems.

As they slow down
to land, the risks increase.

If a third rollover
occurs, they won't have

enough airspeed to recover.

I did at some
point tell my first officer

to look out the window
and find a dark spot.

It was nighttime,
and we were looking

to avoid a neighborhood
or a populated area.

And he very calmly
responded that,

hey, here's a spot over here.

But there
is no third rollover.

Bishop brings Flight
517 in high and fast

and lands safely.

Taxing in is when
I realized my legs were shaking.

We got the aircraft
to the gate,

and I did pick
up the PA to make

an announcement to try
to explain what had

just happened to these people.

I'm picking up the microphone,
I realized there was nothing

I could say to make this
any better and probably

for the first time
in a long time,

I was at a loss of words, so
I simply put the microphone

down and let it go at that.

But Bishop won't
remain speechless for long.

By the next day, the
investigation team

has arrived in Richmond.

There were a lot
of FAA, lot of NTSB,

and they all wanted to
talk to us very badly.

It gave the NTSB a tremendous
break because suddenly they

had a 737 that had, had a rudder
incident that was intact,

and they had
a pilot who was alive

and who could talk about it.

NTSB investigators
quickly determined

that what happened
on board East wind

Flight 517 is alarmingly
similar to events

in flights 427 and 585.

If they can discover why
Bishop's 737 rolled over,

they may be able to
crack two mysterious

and fatal accidents.

And when we said, well,
what happened they said,

there was something wrong
with the rudder pedal.

The pedal wouldn't go down.

I was standing on
the rudder pedal,

and I couldn't
get it to go down.

My God.

With Bishop's
first person testimony,

investigators immediately
zero in on East

winds rudder controls.

The power control unit is
removed, inspected, and then

tested again and again.

To the frustration of everyone,
the unit performs perfectly.

After a five-year
hunt for clues,

a third mysterious
event on a 737

and a live pilot as a
witness, Tom Haueter

still lacks the evidence
he needs to crack his case.

He decides to push his chief
suspect, flight 427's rudder

controls, a little harder.

One fellow mentioned a test
they had done in the military

of a thermal shock where if
you had the actuator being very

cold and put in very
hot hydraulic fluid,

it would cause it to
react in strange ways.

So we put together a
thermal shock test,

and this test was
extreme to say the least.

On August 26, 1996
in Valencia, California,

NTSB investigators gathered
to watch the torture test

of US Air 427 PCU.

After soaking it
and dry ice, the PCU

is blasted with nitrogen gas
to simulate the minus 40 degree

temperatures at 32,000 feet.

Then, it's quickly
injected with

superheated hydraulic
fluid and given

the command to start working.

As we were
standing there listening

to the actuator move left
and right left and right.

It stopped, and it was
not commanded to stop.

Systems
investigator Greg Phillips

now asks that the
valve be taken apart

and scanned for scratches.

They find none.

Look at that.

Doesn't leave a trace.

It is a crucial
breakthrough to solving

an almost perfect crime.

They have proven that the valve
which controls the rudders

can jam but no evidence
is left behind.

Tom Haueter and
his team have now

found that a small hydraulic
valve that controls the rudder

of the world's most
popular commercial jetliner

can jam in the
right circumstances.

It's an ominous
discovery but incredibly,

there's another shocking
surprise in store

for the investigators.

The most important
breakthrough

came when a Boeing
engineer examining the data

from that test
discovered some numbers

that indicated the
valve at that point

had actually reversed.

Whoa.

It is a
stunning revelation.

Not only can the
servo valve jam,

but it can then
function in reverse.

It means that any time a pilot
tries to correct a rollover

by pushing on the rudder,

the rudder might turn in
the opposite direction,

causing a fatal accident.

And the reversal is
like driving your car.

You turn it to the
right, it goes left.

You're not going to figure
out this failure mode

until you go off the road.

And in these cases, that's
the pilots were faced with,

something so unusual that
they didn't understand

what was happening.

What the hell is this?

They had evidence now

that the valve was unique,
that the valve not only

could jam but would reverse.

427 emergency.

That would explain why the
first officer, Chuck Emmett,

would keep his
foot on the rudder

pedal because he's thinking,

why isn't the plane going right,
and he's feeling

the plane go to the left.

To the very end,
Chuck Emmett pushes hard,

hoping his rudder will help him
pull out of his deadly spiral.

Tragically, he has
no way of knowing

that he's steering his aircraft
straight into the ground.

Never
driven to Colorado Springs

and not gotten sick?

Flight attendants,
prepare for landing.

Satisfied that
they've determined the cause

of the crash of
US Air Force 427,

the NTSB turns its attention
to the unsolved case

of United 585.

Another turnout game.

Going back
to Colorado Springs,

and you could
follow a progression

of what the captain was doing.

He's close to the
ground and suddenly

underwrote a reversal.

He puts in a little
bit of pedal.

The pedal violently
pushes his leg back.

-15 fly.
-15.

But a reversal certainly fits
what I know about this crew

and how it fits.

We were able to
show the failure mode.

It matched the flight data
recorder from each aircraft.

It felt like a glove.

So we now had a lot
more information

we could apply to United 585.

And based on that, we
redid the accident report.

-Oh, my God!
-Oh, no!

From rudder
reversal to impact

took less than 10 seconds.

585's flight crew
had no chance to save

their plane or passengers.

In the aftermath of
the investigation,

sweeping changes
were made to improve

the safety of the 737 and
the entire aviation industry.

New training protocols were
designed to help pilots react

to unusual in-flight events.

In the 737 fleet,
pilots are now

trained on how to react
to both rudder hard overs

and reversals.

Oh!

The scenario,
the US Air 427 accident,

if the crew had the information
that we have today, I

believe they would
have landed safely

in Pittsburgh that evening.

The FAA also
directed Boeing to redesign

the rudders duo-servo
valve to eliminate

the potential for reversal.

Boeing spent hundreds
of millions of dollars

to replace the valves
on thousands of 737s

around the world.

One thing we don't
like of the safety board

is to have an
undetermined accident

because then we can't make
a change to improve safety.

So out of US Air
427, United 585,

we have a much safer 737 fleet.

It took NTSB
10 kickers, 10 years

to solve the mysterious crashes
of flights 585 and 427,

the longest investigation in
aviation history.

There are still some
people in aviation who don't

think the NTSB got it right.

But I became convinced
after talking

to many, many, many people,
pilots engineers,

people at Boeing,

and spending a lot
of time with the investigators

that they did get it right.

Since the replacement
of the 737 servo valves,

there hasn't been
a similar crash

of the most popular, most
profitable plane in the world.