Original subtitles

A routine landing...

Ladies and gentlemen,

we are starting our approach to DFW.

You're in good shape.

...turns into a sudden fight to the death.

You're going to lose it all of a sudden.

There it is!

A passenger jet mysteriously falls from the sky

and rockets towards a busy highway.

Push it up. Push it way up.

Delta, go around!

Hang on! Son of a...

It's gonna crash!

A mysterious force brings down a plane,

claiming 137 lives.

In the wreckage lies the one clue that can stop it from killing again.

August the 2nd, 1985.

Dallas, Texas.

It's a very hot day, even by Texas standards.

See you all tomorrow.

Temperatures soar to 101 degrees.

Rain coming.

Should cool things down a bit.

In the late afternoon,

William Mayberry is heading home from work.

The day's heat and humidity are having an effect on traffic

at Dallas Fort Worth International Airport, DFW.

Roughly the size of Manhattan, DFW is the biggest airport in the world.

It's also one of the busiest.

The heat has triggered some afternoon thunderstorms at the airport,

creating a backlog of planes waiting to take off.

American 631, you are cleared for takeoff.

Air traffic controller Gene Skipworth is in the tower today.

He's been working there for 14 years.

With him, his controller, Mike Porter.

Skipworth was not asking for help.

Nothing seemed unusual other than the fact that

we were starting to get busy

and aircraft were starting to pile up.

One of the many planes heading towards Skipworth's control

is Delta Airlines Flight 191.

Weather is 6,000 scattered to 1,000 scattered.

Visibility, 1-0. Temperature, 101. Wind, calm.

- A hundred and one? - A hundred and one degrees. Yes, sir.

Captain Ed Connors and First Officer Rudy Price

are two of Delta Airlines' most experienced pilots.

Second Officer Nick Nassick is the other member of today's crew.

The crew is flying a six-year-old L-1011 TriStar.

The L-1011 is billed as one of the safest planes in the sky.

There are 152 passengers and 11 crew members on board.

They're scheduled to land in Dallas just before 6:00 in the evening.

Good afternoon, ladies and gentlemen.

This is your captain speaking.

Hope you're enjoying your flight so far.

Traffic is backing up at Dallas.

All total, we'll be about 10-15 minutes late getting to the gate.

Please let us know if there's anything we can do to make your flight more comfortable.

The delay bothers Chris Meier.

He's a frequent business traveler who's in a hurry

to get home to his family for the weekend.

I'd been down in Florida, Fort Lauderdale

for the last two weeks,

and it was a Friday afternoon,

and I was due to go home on Flight 191.

One of IBM's best known executives is also on the flight.

Don Estridge led the development of the IBM PC.

He and his wife are traveling to Dallas for a family visit.

963 turn right, heading 620.

En route from Florida to Texas,

Delta 191 will be in communication

with several controllers.

...turn you into Blue Ridge, it'll be about zero-one...

Every aircraft is guided along its flight path

by a series of regional air route traffic control centers.

They direct each plane's speed and altitude.

One-Niner-One, descend and maintain one-zero-thousand.

Join the Blue Ridge, 010, radial and inbound.

We have a good area there to go through.

Captain Connors has some concerns

about the route he's been given.

He sees a storm cell along that path,

and he doesn't want to fly through it.

Well, I'm looking at a cell at about a heading of 2-5-5.

It's a pretty good-sized cell,

and I'd rather not go through it.

I'd rather go around it, one way or the other.

I've had about 60 aircraft go through this area out here. 10-12 miles wide.

They're getting a good ride. No problem.

Well, I can see a cell now, about heading 240.

When I can, I'll turn you into Blue Ridge.

It'll be about the 0-1-0 radial.

0-1-0. Roger.

We're going to hold you to that.

Captain Connors gets his way.

He's given permission to fly around the storm.

Once past it, he'll line up for a landing on Runway 17 Left.

I'm glad we didn't have to go through that mess.

Friday afternoons are a busy time at airports.

The afternoon rain is making this Friday even busier.

Twenty three-niner, down to 6-18-96.

The main priority for the controller on duty

is to keep the incoming planes a safe distance apart.

He wants them at least 4.5 kilometers from each other.

That distance allows enough time for the violent air turbulence behind one plane

to die down before the next plane touches down.

Right now, Connors and Price are getting too close

to the plane just ahead of them,

a corporate Lear jet.

Delta 191 heavy, turn left ten degrees.

Reduce speed to 1-8-0.

To put some distance between the two planes,

the controller asks the Delta crew to slow to 180 knots.

Delta 191...

330 kilometers an hour.

Wilco.

Ten degree flaps, please.

You're listening to Dallas 105 FM.

It's a wet one out there, folks, so drive carefully.

Heading home along Highway 114,

William Mayberry will soon be passing DFW.

Flight 191 is now just 50 kilometers from the foot of the runway.

Ladies and gentlemen,

we are starting our approach to DFW.

Please make sure your seats are in the upright position

and your seat belts are securely fastened.

The crew begins their final descent into the Dallas Fort Worth area.

Attention, all aircraft listening.

There's a little rain shower just north of the airport...

Connors now switches radio frequencies

and contacts a local DFW airport traffic controller

for approach instructions.

As the passengers and crew of Flight 191 prepare for their landing,

a deadly force takes shape in their path.

Critical decisions and missed information conspire against them.

The crew will soon be engaged in a 47-second struggle,

which will become one of the most important moments

in the history of modern aviation.

August the 2nd, 1985.

The crew of Delta Airlines Flight 191

has been skirting a line of heavy storms

between Florida and their destination, Texas.

Thirty kilometers from the Dallas Fort Worth airport,

First Officer Rudy Price notices rain ahead.

We're going to get our airplane washed.

What?

We're going to get our airplane washed.

It seemed like the closer we got in to DFW,

the worse the weather got.

And we was turning in to the...

the rain instead of going around it.

and the pilots never said anything about the bad weather.

Delta 191 is still closing in on the Lear jet ahead of it.

Price and Connors need to slow down even further

to put some distance between the two planes.

Delta 191 heavy, reduce speed to 150.

Speed to 150.

Nine kilometers from Runway 17 Left,

Delta 191 is handed over to another controller,

Gene Skipworth, for final approach and landing.

Zero-nine-zero, at five... Gusts to one-five.

Tower, Delta 191 heavy, out here in the rain. Feels good.

Delta 191...

Skipworth tells the crew

to expect a manageable crosswind of up to 15 knots.

Winds, 090 at five, gusts to 15.

Thank you, sir.

First Officer Price will be at the controls for the upcoming landing.

Pilots and co-pilots routinely alternate flying duties.

As Flight 191 is coming in to land,

William Mayberry is just north of the airport.

He's caught in the same storm that Price and Connors

are just beginning to fly through.

Before landing check.

- Landing gear? - Down. Three green.

Flaps? Slats?

Thirty-three. Thirty-three. Green light.

The crew suddenly notices that they'll be flying

into more than a bit of rain.

Lightning coming out of that one.

What?

There's lightning coming out of that one.

- Where? - Right ahead of us.

A thousand feet. I'll call them out to you.

All right.

We're not getting any bad warnings

from the weather, or from

other pilots, which we rely on as they come through it.

Uh...

They...

They need to report to us, and they do, if they have...

turbulence, or they have trouble

on final, or ran into anything abnormal.

The Lear jet ahead of Flight 191 lands safely.

Connors and Price are now less than a minute behind.

Without warning, the intensity of the storm increases.

The L-1011 is being pounded by a driving rain.

I knew we was getting ready to land.

But at the same time,

you felt a surge.

Like the pilots was revving up the engine for something.

The plane's air speed is increasing for no apparent reason.

Watch your speed.

Price pulls back on the throttles to slow the plane down

and maintain it at the requested 150 knots.

The plane is just 180 meters from the ground.

You're gonna lose it all of a sudden.

There it is.

Then the plane drops rapidly.

It's as though an invisible force is pushing it to the ground.

Push it up!

Push it way up!

Way up! Way up! Way up!

The crew is pushing the plane's jet engines to their full power,

but can't get more speed, or get the plane to climb.

So I pulled my seat belt tight as I could,

but at the same time, you could hear a pin drop.

Nobody was talking.

But I mean, you got dead silence.

As suddenly as it began, the crisis seems to end.

The plane stops falling and begins to pick up

some of the speed Connors and Price have been fighting for.

That's it.

But before the crew can take another breath, the plane drops again,

rocking violently from side to side.

And then, it dips wildly to the right.

And I just knew we shouldn't be that close to the ground that soon.

Hang on to the son of a--

About two kilometers from the runway, it plows into a field

and rockets towards Highway 114.

When we hit the ground, it felt like you was in a car

running over railroad tires. It was real bumpy.

The crew somehow manages to get the plane back in the air.

At that moment, Gene Skipworth catches sight of Delta 191.

He's gonna crash!

Delta, go around!

But it's too late.

The plane's engines slam into William Mayberry's car

on Highway 114.

He is killed instantly.

The plane hits the ground again north of the runway.

It's traveling more than 350 kilometers an hour.

I must have caught sight of him just at the last millisecond,

and he cartwheeled into the tank in just an instant.

And then, of course, there was...

Fire. Not a ball of fire, but a wall of fire.

It seemed like it was only a few seconds. Five seconds at the most.

I don't know how long it was.

We was... Everything was stopped.

The resulting explosion is so powerful

that the rear section of the plane is blasted backwards,

away from the fireball.

Then all of a sudden you look up,

and it's just nothing there.

It's... Everything's gone.

You just see the whole big picture outside.

Like the plane just opened up.

Remarkably, the tail section containing the last ten rows of seats

is relatively intact.

People just thrown around on the ground.

Some with clothes on, some without clothes on. Some were burned.

It was something that

you can't describe unless you were there to see it.

It is something that you will never get out of your mind.

Help! Over here!

Hang in there. Help's on the way.

Then, as suddenly as it had started, the rain stops.

It takes firefighters less than a minute to get to the crash.

And when I arrived on the scene,

I truly believed that there wasn't anybody

that had survived this plane crash,

'cause there was just devastation everywhere.

What I hadn't pulled up on at the time,

was the wing section, which is the portion

of the aircraft that carries the fuel.

So there was a large amount of fuel and a large amount of flames.

The front of the plane has all but disintegrated.

I knew I had to get out there.

At the time, I was a stringer for Time magazine.

Worked with them on a part-time basis.

Called their Atlanta headquarters for this portion of the country.

They said one word. "Go."

Firefighters need only a few minutes

to get the raging fire under control.

They then turned their attention to pulling survivors from the plane.

It wasn't until the fire started to subside a little bit

that I saw the tail section

where there was some hope of some people surviving.

There were these two women that were walking through the smoke.

Ladies! Ladies, clear the area.

Get out of the way. Clear the area.

And it kind of surprised me.

So I knew that there was hope and that there were people out there.

Only 27 people survived the crash.

I had seen death before as a medic in Vietnam.

But it had never been aimed at civilians,

and certainly not on a mass casualty situation.

And certainly not this suddenly.

I could tell how bad it was.

You could see and smell and feel the death.

We felt like we did everything that we could, and we were just,

you know, we were just pleased that there were survivors.

I was scheduled to sit on... off Seat 15A.

And I told them that wouldn't be no good,

'cause that was a non-smoking section.

I was a smoker, so I had to be in back.

That probably saved my life.

Captain Connors,

First Officer Price,

and Second Officer Nassick are killed.

So are five other crew members and 128 passengers.

IBM's Don Estridge and his wife are among the dead.

In the tower, there was silence for probably one to two minutes.

Of the... Except for just an occasional transmission.

But basically it's just quiet

and you just sit there stunned,

and wishing you could do anything to take it back.

This is a monumental crash.

Investigators from the National Transportation Safety Board

arrive at DFW, determined to find the cause.

One of our field investigators would have been on scene

trying to locate the flight data recorder

and the cockpit voice recorder,

which is a...

you know, very important part of the investigation.

Investigators begin looking for evidence of mechanical failure.

They examined the wreckage for clues that the plane was not responding

to the pilot's command.

It's essential...

in any approach, or departure accident

to establish what the airplane's configuration was.

To assure that it was not a factor in the accident.

But everything was normal on this aircraft.

Investigators turn their attention away from the plane...

and to the skies.

After any accident

in commercial aviation, there are theories galore.

A couple of them prevalent that evening...

First, that lightning had struck the airplane.

Secondly, that it had been hit by a mini tornado.

There's lightning coming out of that one.

Where? Right ahead of us.

15 different witnesses including flight crews

report seeing lightning as Flight 191 was descending towards the runway,

The investigators have to consider the possibility

that Flight 191 was hit by lightning.

Lightning is always something that you have to investigate

to determine the possibility that lightning disabled

some part of the airplane.

In 1963, a Boeing 707 was struck by lightning.

The lightning ignited the fuel in the plane's tank.

The plane crashed.

Eighty-one people died.

There had been a handful of similar crashes since then.

Key pieces of wreckage from Flight 191

are taken to the NTSB lab in Washington, D.C.

Bud Laynor is the investigator in charge of examining the wreckage,

as well as the data from the plane's cockpit voice recorder.

Sometimes to might be very difficult to find,

to, to determine where the airplane

might have been struck by lightning and where the exit point was.

Lightning coming out of that one.

Where? Right ahead of us.

If the plane was hit by lightning,

there would be evidence left behind.

A device called a static discharge wick

is attached to the trailing edge of an airplane's wings.

It redirects static electricity into the outside air

instead of into the plane, where the charge could cause a fire.

If the plane was hit by lightning,

one of the pieces that would be visibly damaged

is the static discharge wick.

Nothing there.

With lightning ruled out, investigators go looking elsewhere.

They would soon discover the real culprit.

It had actually been caught on tape.

A Delta Airlines L1011 crashes after entering a storm near Dallas.

One hundred and thirty-seven people die.

Investigators rule out mechanical problems and lightning

as causes of the crash.

Nothing there.

The NTSB's Bud Laynor

turns his attention to the plane just ahead of Delta 191,

the corporate Lear jet.

He learns that it was less than a minute ahead,

and flew through the very same storm.

After we had passed about 5 miles

from the end of the runway,

we entered a rain shower.

What we thought was a light rain shower,

it had turned out to be the heaviest rain.

I've ever seen before, or since.

In spite of the rain,

Rufus Lewis managed to land his plane safely on Runway 17 Left.

When we broke out of the clouds, we were high and hot.

So we had to use all of the runway

at DFW Airport.

We landed, we're able to turn off at the end of the runway.

So why was the much larger L-1011

unable to land just moments later?

Delta 191 Heavy, reduce speed to 150.

To put some distance between Delta 191 and the Lear jet

the controller had asked Price to slow his plane several times.

When Laynor plots the bigger plane's speed...

Then down to 150.

...he finds that it was coming in to land at 150 knots.

Delta 191 heavy, reduce speed to 150.

Investigators consider the possibility

that Flight 191 had been traveling too slowly for a safe landing.

If you don't have a lot of extra energy,

you don't have anything to trade in case you get in trouble.

So it's... A lot of times, in adverse conditions,

the pilots should...

they add another ten knots for mom and the kids.

Crews don't have to follow

a controller's speed request if they think it's unsafe.

Price did reduce his speed.

He knew this plane extremely well.

He had actually helped to rewrite the L-1011's operating manual.

If the captain decided that 150 knots was too slow,

they would have told the controller it was too slow

and they wouldn't have flown it.

Laynor consults the airplane's manufacturer

and interviews other L-1011 pilots.

He concludes that neither the controller

nor First Officer Price made any errors regarding speed.

Delta 191 heavy, reduce speed to 150.

This plane should have been able to land at 150 knots.

Speed to 150.

Bud Laynor still doesn't know

what slammed Flight 191 into the ground.

But soon he finds the clues he needs on the plane's flight data recorder.

It logs every adjustment pilots make to the plane's controls.

The device also records external elements

like temperature, wind speed, altitude, and air pressure.

Whatever Connors and Price were fighting,

there's a good chance it left its fingerprints on the flight data recorder.

This flight data recorder gave us several parameters we didn't have before.

Engine power, longitudinal acceleration...

And those kinds of parameters

really enabled us to do a more in-depth analysis.

The plane's data recorder has documented

a combination of rapidly shifting winds.

Then it shifts to a down draft.

In a matter of seconds,

the plane was hit with strong winds from the front,

then from above, and then from behind.

There you have it.

For Bud Laynor, that sequence could only mean one thing.

A microburst.

A microburst is a violent shaft of air falling from a storm cloud.

Back in 1985, few people knew more about encounters

between microbursts and airplanes than John McCarthy.

If you're at the kitchen sink and you turn on the water

and it goes straight down and it splashes out in all directions.

And that's kind of what a microburst is,

except that it is extremely bad news

if you're an airplane flying through it at low altitude.

A plane first faces a strong headwind, which lifts the plane skyward.

Then a downdraft, which slams it towards the ground.

Finally, the microburst delivers its most dangerous punch, the tailwind.

And you would get a rapid descent,

a loss of lift and a rapid descent towards the ground,

and easily crash the airplane.

A plane's wings need a steady flow of air moving over them.

That's what gives them their lift.

By inhibiting that flow, the tailwind reduces lift.

There's no better recipe for a microburst

than the weather conditions at Dallas Fort Worth

on the day of the crash.

It had been extremely hot all day,

and hot air rises.

When that hot air meets the cold moisture in the storm clouds,

it cools instantly and rushes violently back to earth.

A microburst.

It is a tiny thing.

Meteorologically speaking, compared to a... a big storm,

or a snowstorm or a hurricane, it's just a... like a needle in a haystack.

At its maximum strength, it's...

It's no more than two miles across.

And it lasts no more than 15 minutes.

So, if you look at that little space and time window, it's very small.

And so the probability of hitting one is low.

The odds may be slim, but planes do fly into microbursts.

In 1975, an Eastern Airlines flight

landing in New York flew into a microburst.

It slammed the plane into the ground, killing 113 people.

Then, in 1982, a microburst killed another 153 people

when it struck a Pan Am 727, taking off from New Orleans.

It was clear that 136 people on Flight 191

had become the latest victims of a microburst.

Investigators had their culprit.

Unbelievable.

And thanks to Flight 191's advanced data recorder,

they could paint a remarkably accurate picture of it.

The killer had essentially been caught on tape.

But what the flight data recorder doesn't explain

is how such an experienced crew fell victim to a killer...

You're in good shape.

...they were all trained to overcome.

When Laynor compares the pilot's actions

to the actions of the microburst,

Watch your speed.

He uncovers details of a fight to the death.

A fight that the Delta pilots almost won.

...lose it all of a sudden.

There it is.

He seemed to know what he was going to hit.

Watch your speed.

The increase in air speed prompted First Officer Price

to reduce power to his engines.

Power that he would desperately need in just a few seconds.

You're going to lose it all of a sudden. There it is.

When Price and Connors entered the downdraft...

Push it up. Way up.

...they were less than 250 meters from the ground.

The captain knew the characteristics of a microburst.

He'd obviously been given an introduction to wind shear

and microburst characteristics in his flight training.

When Connors and Price encountered the microburst tailwind,

there was very little they could do.

They had insufficient speed and altitude with which to maneuver.

If a pilot encounters a strong tailwind at 3,000 meters,

he can point his nose down and dive to pick up speed and generate lift.

It's called trading altitude for airspeed.

But that trade wasn't available to Price and Connors.

They were just 150 meters off the ground when the tailwind struck.

The only way for them to gain airspeed was from their engines.

Push it up! Way up!

Co-pilot responds, the airplane stabilizes.

I can say that most pilots would say,

"Well, we're through with that," and...

it's going to... Rain's going to stop. We're gonna land.

Momentarily, their efforts seem to pay off.

Their air speed increases, their plunge is halted.

But with Flight 191 less than 150 meters from the ground,

this particular microburst delivered the ultimate blow.

A fierce crosswind that forces their plane to bank dangerously to the right.

Turn the son of--

Combined with the microburst's other winds, the crew was defenseless.

TOGA!

TOGA is Take Off, Go Around mode.

And what it means to a pilot

in that regime of flight

is, first, abandon the approach.

We're no longer going to try to to land this airplane.

We want to do everything we can now to survive

the wind condition that we've entered.

The skill and experience of the pilots

were no match for this microburst.

It was too big,

it's winds too powerful and unpredictable.

The entire fight lasted only 47 seconds.

The pilots of Delta Flight 191

did their very best to recover from this situation.

And it didn't work out.

Investigators were left with one perplexing question.

Why had Connors flown into the storm in the first place?

Prior to 1985, the radars on board the aircraft

were built to detect thunderstorms.

191...

Essentially, heavy areas of precipitation.

They were not effective, they were not even designed to detect a microburst.

So those radars were essentially useless at low altitudes

for looking into microburst phenomena.

Microbursts are invisible,

but they generally emerge from storm clouds.

That's why pilots are trained not to fly into storms if they see lightning.

It's a pretty good sized cell.

And I'd rather not go through it.

I'd rather go around it one way or the other.

When I can, I'll turn you into Blue Ridge.

It will be about 010 radial.

010. Roger.

Captain Connors was not a risk taker.

He was known as a cautious pilot.

I'm glad we didn't have to go through that mess.

It's hard to blame the air crew.

Their job is to avoid thunderstorms, and...

There's probably a forecast for thunderstorms every day at Dallas in the summertime.

Which ones do you avoid?

And it's, you know... It's a very difficult problem.

Earlier in the flight, Connors had flown around bad weather,

Investigators can only conclude that he underestimated

the storm in his path at the foot of Runway 17 Left.

When you're in a landing sequence

at an airport like Dallas or Atlanta, or Chicago,

and you see other airplanes ahead that are landing uneventfully,

you might get the impression that there's a thunderstorm there,

but I'm going to pass through it very quickly

and it's not gonna be a factor for me.

Airports like DFW

have sophisticated systems in place to provide weather information to pilots.

A thunderstorm at the end of a runway

is the kind of threat they were designed to identify.

But this deadly storm managed to foil those systems.

As Flight 191 was approaching the airport,

the weather at DFW was changing very quickly.

Attention, all aircraft listening.

There's a little rain shower just north of the airport.

Captain Connors heard that part of the message,

but then he switched his radio frequency

for his final landing instructions.

The Delta crew never heard the last part of this message about weather ahead.

There's a little bitty thunderstorm sitting right on the final.

There was an observation two minutes before the accident

that there was a wall of water at the threshold of the runway.

It's been my contention that that information

would have been very important to the flight crew.

Radar readouts from the day of the crash indicate

that the storm cell Connors and Price flew into

grew out of nothing in a matter of minutes.

This is two minutes before the accident.

The readout shows the beginnings of a weather cell

at the foot of Runway 17 Left.

This is three minutes after the accident,

that we have a new cell

right at the threshold of the runway

that wasn't evident in the previous picture.

This explains why Rufus Lewis was able to land his Lear jet.

The microburst was just beginning to form when he was approaching the runway.

Many people think that there was a huge vertical development

that the pilots recognized, and they just decided

to go fly through it anyway,

and I maintain,

and I think the evidence proves it,

that that was not the case.

They didn't recognize this,

this new developing cell.

They did get into the storm beneath the cell.

But it was heavy rain. They weren't worried about that.

Then the hammer fell.

It was too late.

It's small, it's the length of a runway, roughly,

and it doesn't last very long.

So, it's something that can happen so quickly

that many accidents have occurred because nobody knew it was there.

The storm arrived at the foot of Runway 17 Left virtually unannounced,

but once there, it attracted a lot of attention.

Pilots on the ground, as well as trained weather observers,

saw the worsening storm,

but they all saw it too late to warn the crew of Delta 191.

The storm did show up on a radar screen

at the Fort Worth Air Traffic Control Center.

But at the time of the crash,

the meteorologist on duty was in the cafeteria,

on a meal break.

If the flight crew had had any idea

that there would be a severe event in front of them,

they would have missed the approach.

Investigators conclude that the Delta crash

was caused by the pilot's decision

to continue their approach into the storm.

A decision that was made because the crew wasn't warned about the hazard.

In 1985, there were basic systems at airports

that could detect dangerous winds,

but they could not reliably detect a microburst.

On the ground, there were systems

called low level wind shear learning systems,

that primarily looked for differences of wind speed

around the airport, on the airport.

Unfortunately, these sensors tend to be spaced so far apart

that a microburst could actually exist in between them

and escape detection, or at least detection in time

to warn a pilot of a threat.

But a microburst detection system

to overcome this problem had been developed.

It was being tested in Denver and working very well.

What we found out is that Doppler radar,

which is on the ground, is incredibly effective

in detecting microbursts, and in fact, it can detect

about 98% of a microburst.

Conventional radar uses radio waves to measure precipitation inside a storm.

Doppler also sends out radio waves.

But by measuring the frequency of returning waves,

Doppler can also calculate the movement of the winds inside a storm.

And if you look through the Doppler radar,

you see a part of it that's going away from the radar,

and a part that's coming towards the radar.

And if it's small, It's absolutely a microburst.

It can be nothing else.

So it has what we call

an unambiguous signature of a microburst,

which means we got it.

Since Doppler radar could see a microburst,

controllers could use it to warn crews of their presence.

The Denver research resulted in an important new system at airports.

Terminal Doppler Weather Radar.

When the system detects dangerous conditions,

it relays a warning to air traffic controllers...

who can then alert pilots.

Flight 236, microburst alert.

Five-zero knot loss, one mile final. Say intentions.

After the crash of Delta 191,

The Federal Aviation Authority, the FAA,

hurried to install Terminal Doppler Weather Radar at high risk airports.

Dallas Fort Worth was one of the first.

The domes containing the specialized radar

are now a common fixture at major airports around the world.

But radar on the ground can't get the warning to the pilots fast enough.

We also have an issue of ground-based systems in that

it takes time to communicate the threat to the crew.

The system has to detect it on the ground.

It would typically go to a control position

in the control tower, and be relayed by voice to the pilot,

which can introduce a delay of 10, 15, 20 seconds, which could be very critical.

Planes also needed on-board microburst detection.

A team from NASA began developing such a system

by flying into the most dangerous microbursts, they could find.

LANGLEY CO-PILOT: Here we go. Here we go.

By risking their own lives,

they would eventually save thousands of others.

Delta Airlines Flight 191

is the latest in a string of crashes attributed to a microburst.

Since 1964,

microbursts were shown to be the cause of 26 accidents

claiming more than 500 lives.

The public is unnerved.

Politicians are demanding answers.

The killer has to be stopped.

The body count is building,

and this ca... this particular crash tipped the scales

as far as the federal government was concerned.

The crash of Delta 191 showed that seconds count

when planes encounter a microburst.

We're gonna lose it all of a sudden.

There it is.

Increasing alert times...

Push it up!

...could save more lives,

especially if a microburst detector was mounted right on the plane.

If you can provide the airplane with 10, 15, 20 seconds

of advanced warning, pilots push the throttles up,

they build air speed, they build altitude, they build energy.

It's like money in the bank.

By the time they get to the microburst

during a recovery, they can survive.

Aviation experts had to find a way to give all pilots

those critical 20 seconds.

To develop that technology,

they would embark on a high-risk, unprecedented research project.

They would fly a 737 into the most severe microbursts they could find.

We did a very careful risk analysis

of all the possible dangers that could occur.

And initially, you know, the first reaction was,

"You want to do what with an airplane?

"You want to fly it through a microburst?"

In the summer of 1991,

NASA modified a Boeing 737

and went hunting for microbursts.

The idea was to identify onboard technology

that could warn pilots of a microburst in their path.

The airborne solution brings detection right into the cockpit,

so the pilot sees exactly what's in front of the aircraft,

and when the alert is given, there's no time delay.

230... Ground speed 234...

The NASA researchers were testing three separate systems

for detecting microbursts.

Modified Doppler Radar housed in the 737's nose,

a laser radar under its forward cargo bay.

and a side-mounted infrared device

to measure changes in air temperature.

Each of those systems was wired to banks of computers in the plane's cabin.

A spotter on the ground could find a microburst

and quickly direct the plane towards it.

Roger, Control, 515.

We're rolling.

Roger, we understand your roll.

C-D-W-R NASA Control.

- Range. - Range, 45 miles.

Ground speed, 240.

- Here we go. - Take it straight ahead.

Take it up left about 10 degrees, 15 degrees.

Well, when you spot a microburst, it was all business.

It was, "How do we get there? How do we get to the right altitude,

"the right airspeed, the right position?

"When to begin data collection?"

So people were quite busy during these flights.

Yeah, it was exciting. We wanted to find them.

We wanted to penetrate them.

With every microburst,

the three onboard detection systems were put to the test.

Researchers on the plane could instantly see

which instrument was doing the best job of picking up the microburst ahead.

Behind the flight deck,

we had palettes of equipment

where the radar engineers,

the laser engineers, the data recording engineers

could sit and ensure that each system was performing as expected.

Ground speed, 234.

Dead ahead, maybe one degree to the left.

- Let's go straight through this one. - Here we go.

Take it straight ahead.

We started with very, very weak microbursts.

Again, we had the ground-based radar

telling us what we were about to go into.

So we started with very weak microbursts, gained experience,

then gradually worked up to stronger and stronger ones.

You would see the rain begin to fall and you would feel a sinking feeling.

It'd be a little settling, a little like an elevator starting down.

A few minutes here before we touch down, what you see...

So any apprehension that the crew may have had initially about going through them,

was actually replaced later with joy at finding them.

LANGLEY CO-PILOT: Here comes the center of the target, right...

now.

Two hundred and forty-two on the ground speed.

Wind's gone away. Look for a tailwind.

I'm watching.

Lost some altitude there, too.

There. The wind's gone around the tail at 10 knots.

Good, strong, downdraft in the middle of it.

Just sucked 100 feet in almost no time at all.

A good performance decrease, too.

We were about 850 and we dropped to 750. Beautiful.

The Langley researchers flew into dozens of microbursts

over the course of their research.

The project proved

that the forward-looking Doppler Radar was the only system

that could consistently give pilots advanced warnings of a microburst ahead.

What we found was that the Doppler radars

could detect an extremely wide variety of microbursts.

Lightning coming out of that one.

If the crew of Delta 191 had a system to warn them of microbursts,

they could have boosted power to their engines and started climbing

before they encountered it.

That might have given them

the speed and the altitude which they sorely lacked

when they began their battle with the storm.

The Langley flight tests had, in effect, tamed the microburst menace.

After the NASA tests,

the FAA certified a Doppler-based warning system for planes.

Today, Forward Looking Doppler Radar is standard equipment

on commercial flights around the world.

The good news out of all of this tragedy is

so many things have now happened,

from radar to ground-based systems, to airborne systems

and especially to training for pilots,

we think that microburst accidents

are a thing of the past.

If there is one crash that we can look back on now

and say, "This made things safer, because we learned from it."

It was Delta 191.

The changes made after the crash of Delta 191

have saved countless lives.

Captain Connors and First Officer Price

lost their fight against a microburst.

But their struggle did manage to expose and disarm

an invisible killer.