All language subtitles for Air.Disasters.S02E05.Alarming.Silence.1080p.PMTP.WEB-DL.DDP5.1.H.264-maldini_track3_[eng]

For investigators
trying to solve a plane crash,

the most important tool
can be the black box.

It records every detail
in the cockpit.

Look at this.

Where's Charlie at?

And tells
investigators about

vital conversations.

Damn, it's starting
to rain.

Northwest 255,
runway 3 center,

clear for takeoff.

But in the crash

of northwest airlines
flight 255...

I have never been
to an accident of that scale.

...it wasn't what
investigators heard on the tape.

TCI was un-set.

It was what
they didn't hear...

It's checked.

That would lead
to an astonishing conclusion.

Ladies and gentlemen,

we are starting our approach.

We lost both engines!

Put the mask over your nose.

Emergency descent.

Mayday, mayday.

Brace for impact!

I think I lost one.

Investigation starting...

He's gonna crash!

Detroit, Michigan.

August 16, 1987.

It's 8:00 p.m., and the city
is sweltering.

Nearly 16 miles from downtown,

Detroit metropolitan airport

is one of the busiest airports
in the united states.

More than 1,100 airplanes

pass through its four runways
each day.

Today, one of those is
northwest airlines flight 255,

bound for Phoenix, Arizona.

Captain John Maus is in command.

A Las Vegas native, 57-year-old
Maus is a veteran pilot.

His first officer is 35-year-old
David Dodds of Galena, Illinois.

Why don't you tell them
we're ready to go.

Both have years of experience

on this type of aircraft.

The MD-80 is also known
as the super 80,

and is the second generation
of the dc-9.

The MD-80 was
quite a bit longer,

it had more powerful engines.

It could carry more people.

For that reason it was a better
moneymaker for the airlines

than the dc-9 was.

Look at this.

The sky
between Detroit and Phoenix

is filled with storms.

Several are moving quickly
towards the airport.

There's a line here.

For the crew,
it's been a long day.

And another one here
about 25 miles wide.

Well, if we get
out of here pretty quickly,

we won't have a delay.

They've already flown
from Minneapolis, Minnesota,

to Saginaw, Michigan,
and then Detroit.

Phoenix is their next stop

on the way to Santa Ana,
California.

If we wait till
after the storm's here,

there will be delays
going over to Waterville.

If they're delayed
by weather...

They may not make
their final destination.

Let's get out of here
before it starts raining.

The plane's 149 passengers

are also eager to leave.

Paula Chican and her family
have been visiting relatives.

They're heading home to Arizona.

Her daughter Cecilia
is only four years old.

Looks like the bags
are all in.

Why don't you tell them
we're ready to go.

Ramp 255 at delta 15...

Flight 255 is running
half an hour late.

Northwest 255,
clear to go.

Okay, we're clear
to push.

Let's do the checklist.

Brakes.

Set.

Windshield heat is on.

Boost pumps, we've got six.

Cabin pressure controller,
checked.

Auxiliary hydraulic pumps
and pressure,

on and checked.

Damn, it's starting
to rain.

To beat the storms,
they need to leave immediately .

Sign beacons.
They're all on.

Before start checklist
is complete.

Flight 255 begins
moving from the gate

to the runway.

Northwest 255...

But because
of the weather...

Northwest 255, now exit
at Charlie runway 3 center.

...the ground
controller gives them

a last-minute runway change.

Ok, out to Charlie
for 3 center, northwest 255.

Charlie for 3 center right.

Okay.

Ladies and gentlemen,

we're currently number one
for departure.

We should be rolling
in a couple minutes.

Flight attendants
be seated, thank you.

It's blacker than hell
out there.

Where's Charlie at?

By the time they get
to the new runway,

they're 45 minutes
behind schedule.

Northwest 255,
runway 3 center,

clear for takeoff.

Within 17 seconds,

144,000 pounds of passengers
and aircraft

hurtles down runway 3C.

But moments before liftoff,

Maus discovers he can't engage
the auto-throttle.

It won't stay on.

TCI is unset.

His computer
isn't in takeoff mode.

They're on now.

Ok.
Oh, ho ho ho...

Clamp, 100 knots.

At 195 miles per hour...

V-1, rotate.

...the pilots angle the plane's

nose up for liftoff.

Then something else goes wrong.

Just under 50 feet
from the ground,

the aircraft begins rolling
from side to side.

Tower,
lifeguard copter, 102.

It rolls left
and strikes a light pole.

Out of control, flight 255
slams into the ground,

skids along a highway

and disintegrates when it hits
an overpass.

I prayed
that everybody made it,

but I thought it was
just a small plane

because it happened so quickly.

I didn't know
it was a bigger plane.

And it was just awful.

I saw the plane
come through the viaducts,

it was a big fireball.

When we got dispatched, it was a
rainy Sunday night.

And then he said,
there is an airliner down,

and our mood
kind of just changed

and the one guy looked at me,
Dan, and he said,

"well, I hope it's a small one".

And when we pulled up,
we saw the cockpit

and the word "west"
written on the fuselage,

and we looked at each other,

and he said, "it looks
like a big one".

There's a trail
of scorched bodies and debris

more than a half mile long.

Just minutes after impact,
paramedic Tim Schroeder

is on the scene
looking for survivors.

I had never been
to an accident of that scale.

We were struck by the magnitude
of what we were seeing,

the large scale of it,

it was just, it was
almost overwhelming.

From the little
that's left of flight 255,

it is unlikely they'll find
anyone alive.

And I buddied up
with Dan,

and we both started
entering the wreckage.

It was probably
a minute went by,

and Dan actually heard a noise.

He asked me a couple times,
you know, do I hear anything,

and I said no.

And then finally I heard it.

And there was more like
a faint cry.

When I turned my head
to the right,

I saw an arm
underneath the seat.

One, two, three, lift!

She was covered
in some blood and some soot.

Somehow,
four-year-old Cecilia Chican

has survived the crash.

But she's badly injured.

Tim Schroeder races her
to the hospital.

We have a four-year-old girl

found alive in the wreckage.

She has a very weak pulse.

If Cecilia survived,
perhaps others have as well.

Rescuers spend hours
looking through the wreckage

for more survivors.

But their efforts
will be in vain.

We actually
covered anything

that was a body or a body part
with a yellow blanket.

It was just nothing
but like a sea

of yellow blankets,
basically.

Northwest airlines said

154 passengers and crew
aboard the plane

died in the crash.

Both captain Maus
and first officer Dodds

are killed in the crash.

Two other people died when their
cars were hit by the plane.

This is the second deadliest
airplane disaster

in U.S. History.

Recovering
in the hospital

with serious head wounds

is flight 255's lone survivor,
four-year-old Cecilia Chican.

Despite her injuries,
doctors say she will live.

Maybe god was
on her side that night.

Within hours of the crash,

investigator Jack Drake

and his team from the national
transportation safety board

begin looking for clues.

Drake is a former navy pilot

who's been involved in hundreds
of crash investigations.

You know when
you're at a crash site

because you get this combination
of burned plastic and kerosene

and sometimes combined
with fire retardant foam

that has, has its own
distinctive odor.

You know you've arrived
when you smell it.

Drake and his team

treat the crash site
like a crime scene.

They set out to examine
every piece of wreckage

to discover what went wrong.

They have
responsibilities

for looking at different parts
of the wreckage debris

and do qualitative analysis
of those parts.

We always look
for the recorders first.

They're frequently referred to
as black boxes,

although they're usually orange.

Since the 1960s,
commercial jetliners

have been required to carry
flight data and voice recorders.

The devices must be able to
withstand an impact of 3,400 GS

and temperatures as high
as 2,000 degrees Fahrenheit.

The cockpit voice recorder
is intact,

but the flight data recorder

suffered some damage
in the crash.

They may hold the only clues

that can help solve
this accident.

Both recorders are sent
to the NTSB lab

in Washington, D.C.

John Clark is Drake's
flight performance engineer.

His first task is to make a map

of the debris left behind

by flight 255.

When I first
started seeing the wreckage,

it, uh, your mind
immediately starts turning

to sorting out
where it hit, how it hit.

Not where the wreckage ended up,

but those first few inches where
the airplane was coming down.

Clark looks for ground scars

and other impact marks

and interviews witnesses

to piece together where
the plane fell and how.

And that kind of
gives you a sense

of those last moments,

what the airplane was doing
when it hit the ground.

Clark begins to understand

the final moments of flight 255.

According to witnesses,
as it lifted off,

it couldn't climb and flew
in a nose-high position.

V-1.

Rotate.

The nosehigh position
could indicate that the plane

didn't have enough power
to get off the ground,

that it didn't have enough speed

or that high winds prevented it
from lifting off.

Witnesses provide investigators
with a critical clue.

You saw fire coming
from the engine?

Several, including
an air traffic controller,

saw flames coming from the
plane's engine before the crash.

The engines become the first
focus of this investigation.

They looked for evidence
of an internal failure.

Investigators soon learn

that less than a month earlier,

one of the plane's engines
was damaged

when it was hit
by a foreign object.

It was repaired and was
being monitored by mechanics

to see how it performed.

The team studies
the remains of the engine

for clues that it had
either caught fire

or shut down on takeoff.

Despite what the witnesses saw,

they find no evidence of fire
or of a massive breakdown.

The information suggested

that the engine operation
had been normal.

Clamp, 100 knots.

The flames were the result

of the fuel tank rupturing

after the plane hit
a light pole.

The fire didn't cause the crash.

If Drake and his team
are to solve this mystery,

they need to be certain
about what happened

during the last few seconds
before flight 255 crashed.

Well, I think the, probably the
best physical evidence

is what was on
the flight data recorder.

But NTSB technicians
can't recover

all the information
from the recorder.

They send it to the manufacturer

to see if they can recover
the lost data.

While he waits for news
about the flight data recorder,

Jack Drake looks more closely
at the weather

on the night of the crash.

There was some convective
or thunder showertype activity

that had moved through the area.

And its impact on the accident
required a lot of analysis.

Drake wonders how
the storm affected flight 255.

He listens to the cockpit
voice recorder for clues.

He discovers
the menacing weather

was a concern to the crew.

Let's get out of here
before it starts raining.

Jesus, look at this.

Drake sees that there
were several storms

along the flight path,

and they were getting closer
to Detroit.

There's a line here
and a line between these two.

Uh-huh.

And another one here
about 25 miles wide.

Thunderstorms can create

a very Dangerous threat
to pilots.

Since there was
severe weather in the area,

we always worry
about microbursts.

Microbursts occur

when columns of air
shoot down to earth.

As a plane passes through,

winds batter it
from all directions,

making it difficult to control.

In a microburst condition,
you can get very shifting winds

and also vertical winds

that try to push the airplane
into the ground.

So you can get
loss of air speed,

a very rapid rise in air speed,

and then also actually push
the airplane toward the ground.

And it requires
very aggressive flying

on the part of the flight crew.

This unusual weather condition

had killed before.

In 1985 a microburst

brought down a delta airlines
flight in Dallas,

killing 137 people.

At the Time
of the Detroit accident,

there was no device at airports

to accurately detect
microbursts.

Instead, pilots relied
on reports from other crews.

Jack Drake discovers
that 27 minutes before liftoff,

captain Maus and
first officer Dodds

received such a warning.

Ground, this is 722.

You just had
a microburst out here,

the dust just exploded
down there.

Satellite images
taken at the Time of the crash

and weather data from
the airport's sensors

show that there were storms
near the airport

at the time of the accident.

There's no evidence
of a microburst.

Wind and rain, but nothing that
could be a microburst.

But around the time
of the crash,

the airport's sensors did record

a dangerous gust of wind
on the runway,

powerful enough to set off
alarms in the tower.

Upon further investigation,

Drake discovers that flight 255
was still at the gate

at the time of that alarm.

So the winds couldn't have
brought the plane down.

Sign beacons.

But they did have
a huge effect

on captain Maus's flight plan.

The crew's pre-flight
dispatch package stated

they would take off
from runway 21 left.

But with the sudden change
in wind direction,

ground control sends flight 255
to runway 3C,

the shortest of three
available runways.

Northwest 255, now exit
at Charlie runway 3 center.

Ok, out to Charlie
for 3 center, northwest 255.

Charlie for 3 center, right.

Ok.

Controllers try to have planes

take off into the wind.

The additional wind
flowing over a plane's wings

gives it more lift and
helps it get off the ground.

Taking off into the wind
is safer,

but taking off
on the shorter runway

now means first officer Dodds

must recalculate
the plane's takeoff weight.

If there is
a runway change,

you have to determine
if the weight of the aircraft

will permit it to accelerate
and climb out safely.

And this varies, depending
on the length of the runway,

temperature,
altitude of the airport.

Perhaps first officer Dodds

made a mistake
in his calculation.

4044? How can we be
that light for a full airplane?

If he did,
it could explain why the MD-80

wasn't able to make it
off the ground.

Runway 3C simply wasn't
long enough.

Using calculations
based on average weight

of luggage and
passengers on board,

Drake's team confirmed
Dodds' estimate.

The plane weighed
144,047 pounds,

well below the allowable limit
for runway 3C.

It should have been able
to get off the ground.

Drake's investigation
has hit another dead end.

He and his team are running out
of possibilities.

Until technicians can decode

the damaged
flight data recorder,

the team must rely
on the physical evidence

that's been found
at the crash site.

But when investigators study
the cockpit's center console,

they're forced to consider
an almost unimaginable cause.

Is this the way
it was found?

To get the plane
off the ground,

the flaps on the wings
should have been extended

to the 11-degree position.

But the way the flap handle
is damaged

suggests the plane's flaps were
retracted when it crashed.

The pin had left a mark.

This happens
because the aircraft

comes to a very sudden stop
and the handle jangles around

and, and it's
a metal-to-metal contact

that's exaggerated
by the impact.

Won't stay on.

That indicator was
that the flaps were zero

or fully retracted,

and the slats were
retracted as well.

Flaps and slats
are extensions

that slide out of the back
and front of the wing.

They make the wing bigger,

which increases the amount
of lift they can provide.

They must be extended
for takeoff.

If the slats are retracted, for
the most part,

with today's modern jets,

the airplane is not capable
of flight.

...is not capable of flight.

If the crew tried to take off

with the flaps retracted,

it would be
an astonishing blunder.

V-1, rotate.

But a pilot
who was lined up

directly behind flight 255
on the runway

is certain the plane's flaps
were extended.

And you're sure
the flaps were extended?

Pilots in other aircraft

that were close to the point
where the takeoff had begun

were telling us
that they thought

the flaps and slats were
deployed to a normal position.

Investigators
can't be sure whether the flaps

were extended or not.

The clues they need
lie somewhere

in the sea of debris
recovered from the crash site.

Eventually investigators
find the evidence they need

inside a section
of the plane's left wing.

Each component
of the slat system

has its own drive system,

and one of those
was interrupted

by the light pole that passed
through the wing.

18 feet of the left wing
was severed.

The cable
controlling the slats

was sliced in two when the wing
hit the light pole.

Based on where
the cable was cut,

investigators can tell
whether the slats and flaps

were extended or retracted.

It severed two cables,

and if you lined up
those two severed ends,

it corresponded with the slats

being in the full
retracted position.

It looks
increasingly likely

that the crew never extended
their flaps.

Only the damaged flight data
recorder can verify this.

Fortunately technicians
have finally been able

to rescue all its data...

A digital history
of flight 255's performance

until the moment of impact.

As expected, the FDR confirms

what the evidence has been
showing investigators.

The flight data recorders told
us that the flaps and slats

had not been extended.

It's a major breakthrough.

Drake now knows
what brought down flight 255.

But the flight data recorder

doesn't answer
a more troubling question.

So, why weren't
the flaps deployed?

For some reason,
a seasoned crew

forgot one of the most
basic steps involved

in getting an airplane
off the ground.

Two months
after the crash,

northwest airlines flight 255's
sole survivor, Cecilia Chican,

is released from the hospital.

We can't be sure
why the little girl survived.

She's a very little girl
buckled into a big seat.

And she was more protected

than adults that might have been
sitting around her.

So she was very lucky.

Jack Drake needs
to know what contributed

to the death of her family
and all the other victims.

He finds an important clue
on the cockpit voice recorder.

It shows that the last-minute
runway change

caused confusion in the cockpit.

Once the aircraft
began to taxi...

It's blacker
than hell out there.

Northwest 255, now exit
at Charlie runway 3 center.

...other activities
were introduced

that had the potential
to cause distractions.

Did he say 3 center?

3 center, yeah,

that's why I was thinking
we had to go that way.

I was thinking 2-1.

Well, they made
a wrong turn,

which might have been confusing,

because they had to go
a different route.

Where's Charlie at?

Right at the end
of this ramp.

I think Charlie was...

No, it is Charlie.

You sure?

I think so.

The crew got lost
on the way to runway 3C.

Ground, northwest 255,
I guess we went by Charlie.

We're going to 3 center right.

Northwest 255,
affirmative,

make a left turn at foxtrot.

They finally got
to the runway, 45 minutes late.

Ladies and gentlemen,

we're currently number one
for departure.

Should be rolling
in a couple of minutes.

Flight attendants be seated,
thank you.

But Jack Drake finds
something missing on the CVR.

It seems the crew overlooked
a very important step.

We're ok for
the center runway, aren't we?

Damn.

Before they got lost,

the crew of flight 255 performed
a number of checklists.

But possibly due to the
confusion of the runway change,

they seemed to have completely
neglected the taxi checklist.

They apparently didn't
consider the checklist,

and key in the checklist

is the configuration
of the aircraft for departure.

And the flight data recorder
showed that was never done.

There are hundreds of
small steps for a crew to take

to get a passenger jet
off the ground.

Most of them are covered
by checklists.

The checklist is a means
by which you ensure

that important items are
positioned or done properly.

Transponder.

Instead of doing it
by memory

and having the possibility
of a lapse of memory,

flight crews use a very rigorous
and regimented procedure

of following the checklist...

Cabin pressure
controlled.

To verify that each switch, each
dial, each lever

is in the proper position

before taking the runway
for departure.

The first item
on the taxi checklist is flaps.

One of the things

that would have been included
in their checklist

was to configure the slats
and flaps for low-speed flight.

But because
they didn't run the checklist,

the crew never set their flaps
to the takeoff position.

I think Charlie was...

No, it is Charlie.

You sure?

I think so.

They hadn't done
this checklist

at the time they normally would,

and as the activities piled up

that were
potential distractions,

they were further and further
away from the point

at which they would normally
perform that function.

Their mindset was probably
that they had completed it.

A modern jetliner shouldn't

allow a crew to take off

without warning them
their flaps are fully retracted.

The pilots got an indication

that their plane wasn't
properly configured.

During takeoff they couldn't
activate the auto-throttle

because their computer
wasn't in takeoff mode...

Another step covered
by the taxi checklist.

It won't stay on.
TCI is unset.

This should have
alerted them

that they didn't perform
the checklist.

If it had occurred
to them at that point

that we might have missed
something else on the checklist,

that could have led
to a rejected takeoff.

There, on now.

100 knots.

Okay.

Apparently
that didn't happen,

and so the takeoff
was continued.

...with disastrous results.

An alarm should have sounded

when the pilots tried
to take off

with their flaps retracted.

But for some reason
investigators can't hear it

on the cockpit voice recorder.

When it activates,
it alerts the crew

that the aircraft is not
in a configuration

that's safe for takeoff.

Maybe it went off,
but we just can't hear it.

Technicians analyze
the cockpit voice recorder

for more clues.

And they find something unusual.

Stall.

Stall.

This warning
is alerting the crew

that the plane
is about to stall.

But it should be coming from
two speakers in the cockpit.

Stall.

Technicians notice
it's only coming from one.

Stall.

Stall.

As the airplane
lifted off,

there was a stall warning,

and it has a typical
characteristic of a sound

like "stall-all",

because there are
two annunciations,

and the purpose of that
is to provide redundancy.

But that redundancy
wasn't there.

We had a single "stall".

I went to an MD-80 sitting
on the ramp at Detroit.

And a captain took us through
the process of checking out

to demonstrate
those different sounds.

Let's start
with the config warning.

The takeoff
configuration warning

is what would have alerted them
about the flaps and slats.

Flaps.

Flaps.

Flaps.

Can we get
the stall warning to sound?

Stall-all.

Stall-all.

He activated
the stall warning system

by a test switch,
and it said "stall-all".

The voice
on the left channel

is slightly different
from the voice on the right,

as it should be.

But that's not what Clarke heard
on flight 255's voice recorder.

Can you make it
sound like this?

Stall.

Stall.

To get
a singular "stall",

he had to pull power
to one side or the other.

And one way he demonstrated that

is he pulled
the P40 circuit breaker.

The circuit breaker
is the electrical switch

that protects the circuit
from damage caused by overload.

The P40 circuit breaker

is an important one
in this investigation.

It handled both
the failed takeoff warning

and the stall warning systems.

What struck me was, he said,

I hear people doing it.

I, of course,
don't do it myself,

but let me show you how.

And he reached around
behind him,

around behind the seat,
and down low,

and pulled the P40
circuit breaker without looking.

And then when he ran
the stall warning system,

we got the singular stall.

Stall.

Stall.

It's a major clue .

Clark could only reproduce

the strange-sounding
stall warning

by pulling the same
circuit breaker

that's connected
to the takeoff warning.

This tells investigators
that the breaker was tripped

when flight 255
tried to take off.

Then John Clark
notices something else

about the P40 circuit breaker .

You could see
smudge marks around the decals

on each side
of the circuit breaker.

They looked like finger marks
where oil had built up

and dirt and grime
over the years.

So it told me that
that circuit breaker

was being used routinely
by a lot of pilots.

Can you tell me
why that is so worn?

It turned out

that the take-off configuration
warning

could be a nuisance to pilots.

If you're doing
a single engine taxi,

you have to push
the throttle up further

to get up power to taxi,

and you would set off
the takeoff warning system.

So they would pull the
circuit breaker to silence it.

It's irritating.

It's a warning.

It's meant to alert you.

And if it's going off
routinely all the time,

it gets on their nerves,

and so apparently pilots

were routinely silencing
those takeoff warnings.

Investigators suspect
that the crew of flight 255

tripped the breaker to avoid
the irritating takeoff warning.

And then, with the added delay
from the runway change

and the impending storm,

they proceeded to take off

without doing
the taxi checklist.

That might explain
why the alarm didn't sound

when they tried to take off
with their flaps retracted.

We don't know if the pilot did
pull that circuit breaker

on that particular flight.

There was certainly one error
and the potential for two.

I think the extensive use
of the circuit breaker,

because of the smudge marks
around the circuit breaker,

and the pilots' statements,

I think it's highly likely
that he did.

It appears
the downing of flight 255

was caused by pilot error.

Now, investigators
can accurately piece together

what happened that night
in Detroit.

But it would take
another shocking accident

for the airline industry
to learn its lesson.

Jack Drake's team
has discovered

what caused the crash
of flight 255

but cannot prevent it
from happening again.

One year later in Dallas,
delta flight 1141

tried to take off
without their flaps extended.

The investigators who had been
working on the northwest crash

are stunned.

I was very frustrated
to learn

that another airline
had done the same thing

in a different aircraft type
about a year later.

The delta crash would uncover

potentially deadly flaws

in the checklists

commercial pilots
are trained to follow.

The delta and northwest crashes
killed 170 people

and had eerily similar causes.

In both disasters, the workload
in the cockpit increased...

Jesus. Look at this.

Northwest 255, now exit
to Charlie runway 3 center.

If we get out of here pretty
quickly, we won't have a delay.

And in both,
the pilots failed to perform

vital elements
of their checklists.

It is very unusual for a crew
to not perform a checklist.

They have done it hundreds
upon hundreds of times.

Brakes.

Windshield heat, is on.

Cabin pressure controller
is checked.

The normal procedures were
a little bit out of the norm.

And as a result,
it got overlooked.

To prevent this
from happening again,

aviation officials
turned to a government agency

that knows the importance
of clear procedures...

- Four, three...
- Discovery, you're go.

... two, one.

NASA.

...ready to go.

Alright.

Jack Drake and his team

wanted the U.S. Space agency

to help create checklists

that decrease the odds
of items being skipped.

Asaf Degani was a research
scientist working with NASA.

After the accident,
he took on the project

of improving a flight crew's
pre-takeoff procedure.

We looked for any research

that was done on checklists
or procedures in general.

And, in fact,
we couldn't find anything.

So Degani had to
start from scratch.

But there are dozens of
different checklists to examine.

Most of the ones on flight 255
were printed on a single card.

They listed the tasks
the crew had to carry out,

but didn't give them
a way to keep track

of what was
and what wasn't done.

At the time
of the northwest crash,

there were several types of
mechanical checklists in use.

The U.S. Air force used
a scrolling checklist.

Once a checklist item
is completed,

the pilot scrolls
to the next one.

American airlines used a system

that allowed pilots
to cover up completed items

with a plastic slide,

so only the non-completed items
would be displayed.

Asaf Degani set out
to see first hand

how pilots were using
checklists.

He wanted to make it less likely
for pilots to make mistakes.

He sat in cockpits and observed
42 different crews in action.

Degani concludes that many
checklists were badly designed.

There's a certain flow

by which you go about
checking things.

And the idea
is to prevent the case

where you're doing
one thing here, one thing there.

A checklist should have
a certain flow

which is a logical flow

and not one which is
kind of random.

Degani also finds a much more

serious problem with checklists:

If pilots are interrupted,

they sometimes forget
where they left off.

Transponder, checked.

And there's many cases

where people would do
a, b, c, d, e,

an air traffic call would come,

they'd have to respond to it,
and that's an interrupt.

Northwest 255, now exit
at Charlie runway 3 center.

They will go back
to the checklist

and skip a certain item

and continue on the list

assuming that
the whole list was done.

People were very concerned
about that.

To ensure
no steps are missed,

airlines train their pilots

to return to the top
of a checklist

following the interruption,

and start over.

Again, Asaf Degani
sees a problem.

And we found
that if checklists

are very, very long
and meticulous,

that's overburdening the crew,

and they sometimes
will not want to start again

from the beginning.

To address the problem,

Degani suggests changes
across the airline industry.

One of our
recommendations from the study

is to try to take
long checklists

and chunk them to small pieces,

so that if
an interruption happens,

then doing another
four or five items,

you know, it's not a big effort
as opposed to doing 20.

Degani
even made recommendations

about the typeface
that airlines use

so they can be
more easily read by pilots.

Perhaps the biggest advance
to checklists

is the move from paper
to computers.

Since at the time

computer technology
was coming into the cockpit,

it made a lot of sense to think
about electronic checklists.

Today, Degani and his team

are studying smart checklists

that keep track
of checked items.

They provide pilots
with a visual indication

of where they are on the list ,

and in some cases,

verify that the task has been
correctly carried out.

Electronic checklist shows you

which item was completed
and which item was not.

Computerized checklists

are now slowly making their way

into the cockpits
of commercial airplanes.

They make it far less likely

that an accident
like northwest 255

could happen again.

The FAA also ordered
a modification

to the alarm system
of all commercial jetliners

to prevent nuisance alarms.

The takeoff warning
was redesigned

so it could not sound

unless the plane
was actually taking off.

Jack Drake went on

to investigate
hundreds of accidents

over a 26-year career
with the NTSB.

The crash of flight 255
taught him a valuable lesson.

This one
is a worldwide example

of the importance
of following checklists,

and configuration being
completed correctly

on every takeoff.

And so it became something

that was a part
of the training curriculum

in virtually every airline
around the world.

The case of northwest 255
is no different.

It's a series of events...

runway change, task saturation,
an overlooked checklist,

a failed
takeoff warning system...

Put all of those together,
those links in a chain,

and you end up
with the accident.

If you were to break
any one of those links,

the accident wouldn't
have happened.

Flight 255
will also be remembered

for its lone survivor,
Cecilia Chican.

She's never spoken publicly
about the death of her family.

But she's stayed in touch

with the people who
rescued her that day.

She's full of life,
and the conversations we have,

it's more about you know,
her sports and her, her husband

and her vacations.

She just said maybe one day

she'll come out and tell
the world what Cecilia is doing.