Original subtitles

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.