Original subtitles

They're the traffic cops of the skies.

Keeping planes on course.

Okay, you're right in the middle of the TCA, sir.

Guiding them to safety.

Avianca 052, look at your TCA chart.

Charlie 2937 descend...

And keeping them apart.

But the system has reached a breaking point.

Where is it?

CO-PILOT: There! On the left!

If there is another major airline accident,

it's going to probably originate

from an air traffic control problem.

Yup, yup. We got it.

There are too many planes.

The tools controllers use to track them are inadequate.

The failing system is putting passengers at risk.

Monitor, vertical.

Now, the race is on to fix it...

Do you see him, Daniel? No.

...before disaster strikes again.

Mayday! Mayday!

Rush hour. John F. Kennedy International Airport.

One of the busiest in the world.

More than 1,200 planes use JFK everyday.

In the sky, they're stacked up for kilometers,

waiting to land.

On the ground, dozens more are waiting to take off.

The constant stream of airliners

can tax the abilities

of even the most experienced controllers.

The "picture", as it's called,

that they have to maintain in their head

of everything they're controlling, where everybody is,

their speed, their altitude, their separation.

Also includes constant back and forth talking to the pilots.

And this is a matrix of information flow in and out of their brains.

It's just amazing to watch.

For the team of air traffic controllers in JFK'S tower,

it's just another day at work.

It's a job that gets more demanding

with each passing year.

On a busy day in most centers

and most departure and arrival controllers,

you're saturated.

You've got people talking as fast as they can.

And that's where errors come in.

Over the last decade,

there's been a 25% jump in traffic at JFK.

And New York's not alone.

It's a trend that concerns some industry experts.

One of the things that I do as an aviation analyst

is try to keep a good lock on what's happening,

watch where the weak spots are in the system.

If there is another major airline accident,

God forbid, it's going to probably originate

from an air traffic control problem.

The solution to the looming crisis is being developed here,

The William J. Hughes Technical Center in New Jersey.

It's the workshop of America's

Federal Aviation Administration.

The center has been involved in every major advance

in air transportation system technology since 1958.

Airport design, aircraft safety and security...

communications, navigation.

Scientists at the William Hughes Center

have tackled aviation's most difficult problems.

Today, this plane is at the heart

of one of the largest projects in the history of the FAA.

They're using it to design a new air traffic system

that will help manage more traffic safely.

A two or threefold increase in the number

of aircraft flying is certainly within the, uh...

within the range of possibility

in the next couple of decades.

Together, test pilots and researchers

need to figure out a safer way to get airplanes

into and out of America's airports.

What they've come up with is a system called NextGen.

NextGen will supply pilots with the tools and information

they need to make many decisions

that are now made by controllers.

At its heart is a sophisticated piece of equipment

that will soon be added, not to towers, but to planes.

To see if it works,

test pilots have to take it for a ride.

We're liberating the airplane to do what it's designed to do

and not constraining it by our management.

Positive rate. Gear up. CO-PILOT: Here it comes.

Researchers have installed a revolutionary navigational computer

in the back of this executive jet.

We're currently flying over Delaware.

It's called ADS-B.

It stands for Automatic Dependent Surveillance Broadcast.

It's a sophisticated GPS receiver that paints a detailed picture

of any plane anywhere near this flight.

So the pilot has what we call situational awareness of what's flying around him.

Uh, the aircraft then broadcasts

that position once a second,

so any other aircraft flying within RF range of that aircraft

now knows its position as well.

There's nothing like this in any cockpit today.

Because it's still experimental technology,

the FAA is testing this system in the cabin of the aircraft.

If tests like this succeed, it will someday be in the cockpit

of every plane in America

and eventually around the world.

Once the ADS-B system is fully operational,

everyone will know where you are, how high you're flying,

and where you're headed.

It's a key piece of the future because it is so accurate.

The computer that researchers are putting to the test today

is the central element in the most significant retooling

of the American air traffic control system in half a century.

Human beings cannot be perfect on a sustained basis,

we can for certain periods of time.

Therefore, we have to expect failure.

People make mistakes.

It's a lesson the airline industry has learned the hard way.

A lesson that fundamentally shaped

how planes travel across the skies today.

In the few years in which they have been operating,

the airlines have discovered that their efforts

to improve comforts and services have...

After the Second World War,

Americans were traveling by air in booming numbers.

The earliest air traffic controllers stood next to runways.

They waved flags to guide planes in.

As traffic increased,

pilots also began to use radios

to stay in touch with airports.

The first air traffic control towers

were built as more and more flights had to be handled.

Airports have become very busy places.

And air traffic was beginning to overwhelm controllers.

June 30th, 1956.

Los Angeles International Airport.

TWA Flight 2 lifts off eastbound for Kansas City.

Airline flying in the '50s was, uh, was really amazing.

It was something you dressed up for.

Only people who could afford a fairly high price could actually fly.

The TWA Flight is a Lockheed Super Constellation...

one of the most advanced commercial airliners of its time.

You won't find any pilot who doesn't think the Super Connie

is one of the sexiest airplanes ever designed.

Just minutes behind TWA Flight 2,

United Airlines Flight 718

takes off from the same airport on its way to Chicago.

The system to track both of the planes is far from high tech.

The air traffic control center consisted of a room

with a map spread out on a table

and the air traffic controllers

were moving markers on that map to indicate

where each airplane was and its last known position.

The pilots radio their positions to company dispatchers.

Controllers use this information

to get a rough idea of their flight paths.

They were on radar for a while in Los Angeles,

but once they got outside that area, there was no radar.

They were flying under visual flight rules.

The rule is called see and be seen.

So, I see you, you see me,

we stay apart, and we're responsible for our own separation.

And except for a few radars in certain parts of the country,

controllers didn't really know where the airplanes were.

They were estimating on their reports.

As the two planes get closer to the Grand Canyon,

the distance between them disappears.

Both captains were used to showing the Canyon off on a clear day.

They could move the airplane to the left, move it to the right a little bit,

point out the Canyon to people

and get them to ooh and ah.

The United Flight closes in on the TWA plane from the right,

unaware their paths are about to cross.

People on one side of the DC-7

would have been able to see the oncoming Constellation.

Would have seen an airplane against an azure sky,

with fluffy clouds, coming closer and closer.

And they would have felt the impact.

The Grand Canyon is a graveyard

for 128 passengers and crew of two airliners

which crashed on peaks little more than a mile apart.

None survived.

It was the worst commercial air disaster in history.

The Grand Canyon crash created huge banner headlines across the nation

and a lot of pressure on the government to do something.

We needed radar.

We needed to buy it and get it deployed

throughout the United States immediately.

We had to change the system. And we had to do it fast.

The crash killed 128 people

and changed the world of air traffic control forever.

Following a lengthy investigation,

the stark conclusion was that the crash happened

because the two planes were outside of so-called controlled airspace.

TWA and United collided over the Grand Canyon

primarily because neither they nor the control system

had the ability to know where both of those airplanes really were.

Once the planes left the small area

being monitored by controllers,

no one was paying attention to where they were.

The "See and Avoid" principle is a fraud, and it always has been.

The fact is the faster you go, it's a big sky,

you've only got 180 degrees of peripheral vision,

and you can't see and avoid everything up there.

In the wake of the Grand Canyon accident,

American airspace was blanketed by radar.

Planes were more stringently confined to air corridors, highways in the sky.

The air traffic control system we have in the United States today

was designed with the Grand Canyon accident in mind.

That crash determined how far apart airplanes should be spaced

and where radar dishes and air traffic control centers should be built.

It also resulted in the formation

of the Federal Aviation Administration, The FAA.

But now, 50 years later,

the system needs to change again.

Today, the system falls short of the public's expectations,

being congested...

slow...

clunky...

unpleasant.

As planes fly faster and higher,

it becomes harder for controllers to track their movements.

I think, in many respects, we're in a, uh,

a very similar situation to where we were in the '50s.

The system has to change massively.

And the change must happen soon

before we are faced with a major air accident

that could take the lives of hundreds of people.

The technology onboard the FAA flight

might be the solution to the overtaxed air traffic control system.

Test pilots regularly take to the skies

to help researchers prepare

the new system for America's airliners.

The beautiful thing about ADS-B is,

is it gives the pilots in the cockpit

and the air traffic controllers basically the same picture.

ADS-B is more than a map of other planes.

The idea is to show pilots what now only air traffic controllers can see...

data about the planes that are in a pilot's airspace.

With ADS-B, you'll see who that other aircraft is.

You'll see an identifier on it.

You'll be able to see planes on runways.

You'll see planes in the traffic pattern.

And you'll get a better feel for what's going on around you.

Especially if you're at an uncontrolled airport.

We can also see map information.

We can see navigational aids.

We can also see other airports.

Giving pilots all that information in the cockpit

will allow them to make decisions

about how to get to their destinations quickly and safely.

The current system relies on radars

for the detection and tracking of aircraft.

And radar was a great technology in 1940,

but fundamentally, it's very sloppy.

Today, ground-based radar bounces radio signals

off an airplane to calculate its position.

It can be off by as much as two miles.

That's why we keep aircraft three miles or more apart,

because we're just not that confident of the solution.

With NextGen,

an onboard GPS unit will constantly receive signals from a GPS satellite.

This will tell pilots where they are

down to within a few hundred feet.

With a more accurate picture of airspace,

airliners will be able to fly closer together.

The FAA hopes this will help relieve the congestion at busy airports.

Today, only controllers have an accurate picture of air traffic.

They use this information to guide pilots around potential problems.

The pilots themselves have no way to independently confirm

where they are in relation to all other flights.

They must rely on controllers to tell them.

The weakness of the system was exposed

years before NextGen tests began.

Labor Day weekend, 1986.

Aeromexico 498, traffic ten o'clock. One mile...

Approach Controller Walter White

guides Aeromexico Flight 498 in for a landing

at Los Angeles International Airport.

The airspace around LAX is very tightly controlled.

It's called the TCA, the Terminal Control Area.

As Aeromexico Flight 498 closes in on the airport,

Walter White sees a plane he does not expect on his radar.

Uh, one approach on a flight from Fullerton.

Cruising altitude is 4,500.

- We'd like following. - Okay. You're are right in the middle of the TCA, sir.

Grumman six-six-Romeo,

I suggest in future, you look at your TCA chart.

There was an aircraft that was east of the airport

which he became involved in.

That was what they called a violator.

In many cases,

the air traffic that was crawling across his screen,

even with transponders, were not reporting altitudes.

Walter White hustles the small plane

out of the controlled airspace.

You just had an aircraft pass

right off your left above you at 5,000

and we run a lot of jets right through there at 3,500.

But White doesn't realize that there's another plane

dangerously off course.

We should be able to see the ocean by now.

Take a look at the map and look around the 405...

A Piper Cherokee

is cutting across the approach to LAX,

oblivious to the danger.

The Aeromexico Flight is just minutes from landing.

Aeromexico 498.

Los Angeles Approach.

This can't be!

The jet plunges towards Cerritos,

a suburban community of Los Angeles.

Aeromexico 498. Los Angeles Approach.

I'm sitting there talking with the two departure controllers,

and not really thinking.

I hear Walter say something like...

I think I lost one.

Aeromexico 498, Los Angeles approach.

That immediately got everybody's attention.

So I looked at the radars,

and could hear him calling Aeromexico 498.

...498, Los Angeles approach.

The crash devastates the community of Cerritos.

Fifteen people on the ground are killed in the disaster,

along with all 64 people on the Aeromexico jet.

The Piper Cherokee is found in a nearby schoolyard.

All three people on the small plane have been killed.

The fact of the matter is

that the Cherokee flew into the TCA

and hit the DC9 in restricted airspace without a clearance.

The National Transportation Safety Board questions Walter White

about what he saw on his radar display.

At any time, did you see the Piper Cherokee on your scope?

No.

No, sir.

The Piper's target was not displayed.

It is my belief that it was not on my radar scope.

He, uh, was positive

that the aircraft was not there for him to see.

But when investigators finally get

the air traffic control radar records,

they conclude the Piper should have been visible.

We were able to determine

that the aircraft that collided

with Aeromexico was there to be seen.

Controllers had been complaining

about the radars for a long time.

We had reported problems with the radar

not picking up targets several times.

You may lose one target, you may lose two targets.

It may not be presented for one sweep.

Did you see the Piper Cherokee

- on your scope? - No, sir.

But that doesn't mean that the target isn't there.

A blind spot is only an instantaneous thing.

It's not a continuous thing.

He was looking at one and trying to keep it clear.

Lost track of another one that just happened to be at the same altitude

as the approaching Aeromexico jet.

It was a one in a billion chance,

but that one in a billion came up that particular day.

The collision over Los Angeles

drew attention to weaknesses

in the radar systems used by air traffic controllers

and led to some much-needed improvements.

Mode C Intruder is an automated program

that is now incorporated

in all our major radar facilities.

That, if an aircraft should inadvertently intrude,

the controller will now be given

a visual and an aural alert,

thus giving him time to provide

a timely warning to the pilot.

After the collision over Los Angeles,

radar systems at the airport were upgraded.

The next generation of air traffic management will only use radar

if the GPS system fails.

NextGen is also targeting another weakness in the current system,

the radio.

Today, pilots and controllers use radios to talk to one another.

We're now descending to one-niner-zero...

The system depends on clear, precise language.

Misunderstandings are common.

And they've caused some of the most tragic air disasters in history.

As the FAA test flight flies high west of Atlantic City,

its radio keeps the pilots in touch with controllers.

Vector for sequence for the downwind runway 22.

Okay, 1-0-0, clear for the ILS.

But in the air traffic system of the future,

pilots and controllers will communicate less frequently.

The controller and the pilot can now work together

to resolve issues instead of wasting a lot of time

explaining what the issues are.

Mistakes can be made for a number of reasons.

English is the international language of aviation.

But pronunciation, accent and emotion alter the way any language is spoken.

Nowhere is this better understood

than in the air traffic control tower

at John F. Kennedy International Airport.

If you listen on any control frequency,

you're going to hear a lot of people say, "Would you say that again?",

"Say again, over, please."

The airspace above JFK

is frequented by one of the most international

collections of pilots in the world.

Maintaining clear radio communications

can prove challenging to controllers here.

There's pressure, because that's the business they're in.

The business is moving passengers from A to B.

That's what the airlines are paid,

and the controllers are paid to help that work.

When pressure mounts,

small misunderstandings can have enormous consequences.

January 25th, 1990.

In the skies over New York...

Avianca 052, expect further clearance time in 20 minutes.

I think we need priority. We are passing out of fuel.

Avianca 052, roger, how long can you...

Avianca Flight 52 is trying to land in New York.

But a driving rain is delaying air traffic into and out of the area.

The flight began in Colombia.

On its way to New York, it's been routed through a series of holding patterns

by air traffic controllers.

Bad weather is delaying landings all along the Northeastern Seaboard.

There was a system moving through the Great Lakes moving East.

There were a couple other systems converging.

And a lot of times, they'll converge in the New York Area there

and the whole Northeast will go down.

Is it okay if I send four more your way?

Casino, I'm back in the hold again.

I got full in the stack and there's no end in sight.

Avianca 052, I might be able to get you in right now,

stand by.

Thank you.

They were progressively moving towards JFK,

and they were held in the air for three times.

This certainly would put some stress on the crew,

uh, as to fact they want to go from A to B.

They don't want to fly in a racetrack for an hour, just holding.

Avianca 052, roger.

And what's your alternate?

We said Boston, but we can't do it now.

We'd... We'll run out of fuel.

The pilots are growing increasingly desperate

for clearance to land.

Avianca 052, just...

They've used up almost all of their fuel while waiting their turn.

...set him up for his alternate.

- What is his speed now? - I'm not sure, to be honest.

Slow him to 180 knots and I'll take him.

After more than an hour in holding patterns,

controllers finally give the pilots

of the Avianca flight permission to land.

Avianca 052 descend and maintain 3,000.

Descend and maintain 3,000.

But in this critical hand-off

from one controller to another,

no one mentions that the plane is running out of fuel.

Avianca 052 heavy,

contact Kennedy Tower one-one-niner point one. Good day.

It was extremely important that Avianca 52

landed on their first approach to JFK.

The voice recorder revealed that the Captain was certainly

quite concerned about the fuel state.

At JFK, only one runway is being used for landings.

Weather at the airport is making approaches difficult.

Avianca 052 heavy,

Kennedy tower two-two left,

you're number three, following seven-two-seven traffic

on a niner mile final.

Avianca 052 heavy, roger.

Avianca 052, say airspeed.

One-four-five knots.

Are we clear to land? No?

Yes, sir. We are clear to land.

Standby.

The Avianca crew, when they felt that they were being handed off

to an approach controller now and given a heading

and a lower altitude,

I'm sure In their minds they thought,

well, they even commented on a cockpit voice recorder.

"We're being handled," or, "We're being taken care of."

Four kilometers from Runway 22L

and with fuel running dangerously low,

the flight hits ferocious winds.

They were getting, like, 60 knots of wind on the nose,

and then, as they descended on down

through about 500 feet to the ground,

they were down to 20 knots.

So that's a 40-knot change in 1,000 feet of elevation.

That's a lot.

- This is the wind shear. - A dramatic change

of winds throws the aircraft off its descent path as it makes its approach.

- Glideslope! - Glideslope.

Glideslope. Glideslope.

The runway. Where is it?

- I don't see it. Pull up. Pull up.

The plane is thrown towards the ground by the winds.

Pull up. Pull up.

The airplane was about 200 feet above the ground,

about two miles from the runway,

which was well below the glideslope and very dangerous.

So, the airplane almost crashed on its first approach.

Give me the landing gear up! Landing gear up!

When you get a missed approach,

it changes the whole ball game.

Request another traffic pattern.

Executing a missed approach. Avianca 052 heavy.

The fuel tanks aboard Avianca Flight 52

are all but empty.

Another approach on the airport will be nearly impossible.

Controllers in New York will have to try once more

to get Avianca Flight 52 safely to the ground.

...to one-eight-zero

on the heading, and we'll try once again.

We are running out of fuel!

These guys were out and they didn't say, "We were out."

And he allowed the approach control to vector him

way out in the original pattern

and 15 miles north to the outer marker again.

Advisor, we are in an emergency! Did you tell him?

Yes, sir! I already advised him.

But the First Officer neglects to use the word "emergency"

in his radio transmissions to the tower.

He only mentions that his fuel is low.

...zero-five-two heavy, contact approach on one-one-eight point four.

Approach Avianca 052 heavy...

And it was apparent from the voice recorder transcript and tape,

that the Captain was not understanding

the First Officer's radio communications that were being made in English.

Flame out! Flame out on engine number four!

The engines quit when they're finally starved of fuel.

Flame out on engine number three!

Show me the runway.

We just lost two engines and we need priority please!

Avianca zero-five-two,

turn left heading two-five-zero.

Without engine power,

Avianca Flight 52 crashes into a residential neighborhood on Long Island.

Avianca zero-five-two, radar contact lost.

Yes. Hello, I live in Cove Neck in Oyster Bay

and there is a plane crashed in our yard in front of our house.

Eighty-five of the 158 people onboard survive the crash.

Throughout the night, rescue workers pull them from the wreckage.

Investigators from the National Transportation Safety Board

arrive within hours.

They remove the cockpit voice recorder from the wreckage.

The condition of the aircraft was

really astonishing to see that that much of the structure

was left in the condition that it was in.

It hit right on a, about a 28-degree embankment.

And with the wings and all the other trees, it only slid 28 feet,

so it hit and stopped instantly.

The NTSB investigation reveals

that controllers didn't transmit

vital information to one another.

Radio communication,

one of the most vital parts of air traffic control,

failed the passengers and crew.

Trying to avoid those kinds of mistakes is a key component of NextGen.

Radio communication will largely be replaced

by an exchange of electronic data.

Automation is extremely important.

And in the future, it's going to be able

to get rid of the type of errors that occur

when you put massive pressure on a human being

to be 100% perfect.

With the elimination of radio chatter,

air traffic control towers of the future will be very quiet places.

Controllers on the ground will still be needed

to move planes in and out of airports.

But with more accurate information at their disposal

and less need to talk to pilots,

they'll be able to handle far more flights than they do today.

On board the FAA's flight,

the new GPS-based technology gets the ultimate test.

Without any warning from Air Traffic Controls...

Do you see them yet, Daniel?

CO-PILOT: No, I don't see them yet.

- There he goes! - There he is!

They notice another plane just 400 feet below.

In the back of the jet,

the NextGen system detects the other plane.

Had the system been in the cockpit,

it would have shown the pilots its precise location.

Without it, they rely on a piece of technology

called TCAS to warn them of the danger.

Using signals transmitted from plane to plane,

the Traffic Collision Avoidance System

warns pilots when other planes are too close.

A TCAS gives the pilot a traffic advisory

at 45 seconds before the potential collision.

And then, at approximately 25 seconds or so

before the potential collision,

a resolution advisory is given

to actually tell the pilots

to climb or descend to avoid the altitude of the other aircraft.

Normally, air traffic will call that to us.

- Yeah. - But they didn't even call the traffic.

- No. - So that TCAS helped a lot.

TCAS can help pilots of approaching planes avoid collisions.

But with the new system,

pilots will be able to prevent their planes

from getting dangerously close in the first place.

You know, with ADS-B, we're going to be able to see that traffic on the display.

So the avionics can have smarts built into it to

warn the pilot when he's approaching another aircraft.

Today, the system works perfectly.

The pilots of the test flight see the danger and avoid it.

TCAS can help pilots avoid a collision,

but having it onboard is no guarantee

that an accident won't happen.

September 29th, 2006.

A small business jet flies high above the Brazilian countryside,

The pilots will fly to Manaus in Brazil,

before taking off again for New York City.

CO-PILOT: [ON RADIO] Brasilia, November six-zero-zero...

In the cockpit, co-pilot Jan Paladino

is having trouble maintaining radio contact

with air traffic controllers.

...November six-zero-zero, X-ray Lima.

He tries different channels,

but still no one responds to his radio calls.

Brasilia, November six-zero-zero...

It's unusual for pilots and air traffic controllers

to be out of contact for such an extended period of time.

Brasilia, November six-zero-zero X-ray Lima.

November six-zero-zero X-ray...

Finally, after 12 attempts,

Paladino gets through to controllers.

Contact one, two, three,

two, six, decimal 45.

Sorry, say frequency one more time for November six-zero-zero X-ray Lima.

But Paladino can't understand the garbled radio transmission.

Brasilia November six-zero-zero X-ray Lima.

Then, the signal disappears altogether.

The jet follows the Brasilia air corridor en route to Manaus.

But traffic along this corridor

runs in both directions.

...six-zero-zero X-ray Lima.

The airway system between Brasilia and Manaus

is very simple.

It makes airplanes

fly northbound maintaining even levels,

and airplanes flying southbound

maintaining odd levels.

A little more than two hours into the flight, disaster strikes.

The concussion itself seemed to affect every atom in my body.

The end of the wing was chopped off

and it was serrated. It looked like it had been chewed off.

The Legacy Jet has struck an oncoming Boeing 737...

Keep calm! ...GOL Flight 1907.

With 154 people onboard,

the GOL flight spirals out of control.

The pilots of the smaller jet don't know what they've hit,

- but their business jet is still flyable. - Sit down back there!

I got it. I got it. Just let me fly the thing, dude.

- All right. - We're descending. I want to get down.

Okay, it's yours. It's yours.

The crew locates a runway at a military base in the middle of the jungle.

November six-zero-zero X-ray Lima declaring an emergency.

We need to land at zero bravo Charlie Charlie, is that your airport?

Affirmative. The pilots

of the executive jet attempt an emergency landing.

Here we go. Hold it.

Let's dump the flaps at the top of the flare.

Right. So give me nine on the flare.

- Could you give me nine. - Yeah, you've got nine.

Everyone, sit down back there.

When you land under those sort of circumstances,

you're landing faster than you normally would.

You're coming down like gangbusters.

Good. You got it.

Hold it. You're good.

Whoo! Oh, man.

Good job. Oh, man!

At Brasilia Air Traffic Center,

controllers have lost track of GOL Flight 1907.

Manaus. There isn't any GOL.

I can't see anything here.

It's on its way.

So it's already in my area?

For over half an hour.

Anxiety was high and controllers were confused about what to say.

They didn't know what was happening.

Troops locate the wreckage of GOL Flight 1907

deep in the Amazon jungle.

There are no survivors.

Investigators learned that the Legacy Jet and the GOL Flight

were flying along the same air corridor in opposite directions.

One thousand feet of altitude is supposed to separate them.

Investigators interview the pilots of the business jet.

We were proceeding northwest, on course

to Manaus at 37,000 feet.

Okay? We were attempting to contact Brasilia control...

Did you say you were flying at 37,000 feet?

Yes, that's right. Flight level three-seven-zero.

We never moved from that.

The pilots of the executive jet filed a flight plan

in which they would fly at 37,000 feet

until they reached Brasilia.

There, they would descend to 36,000.

The flight plan calls for you

to descend to three-six-zero at Brasilia.

- Why didn't you? - We weren't told to.

Before we took off, we were cleared for three-seven-zero

all the way to Manaus. That's what we did, sir.

Air traffic control can always

deviate from the flight plan,

because they have best knowledge

of the actual traffic situation.

We were not told to descend and we did not descend.

Once we knew for sure that both planes were flying

at the same altitude,

we knew there would be a lot

to investigate on the side of Air Traffic Control.

Can you call up the Legacy Jet screen for me?

On the radar screen, we see the altitude, the speed

and the transponder information of each plane.

Images show investigators what air traffic controllers saw

on their radar screen before the accident.

One symbol stands out.

The "Z" on the air traffic control screens indicates

that the airplane

he's looking at has lost its transponder.

Roger.

Transponders give controllers

exact information on the altitude of the flights they monitor.

Investigators learned that the transponder aboard

the Legacy had been turned off,

possibly due to the captain's inexperience with the new jet.

Still working out the kinks on how to work this flight management...

Without information coming from the jet's transponder,

the air traffic computer displays the altitude

the plane is supposed to be at, according to the flight plan.

But it's actually flying 1,000 feet higher,

right in the path of the GOL flight.

The Brazilian controllers did not verify the Legacy Jet's real altitude.

Nobody did anything from the ground,

which is where we expect it to happen,

to save these two airplanes from being head on at the same altitude.

...zero X-ray Lima.

Back over Atlantic City, pilots are preparing to bring

their test flight in for a landing.

Today, the flight has to stay within tightly confined boundaries

set out by air traffic controllers.

But when all aircraft are equipped with ADS-B, that won't be the case.

If the aircraft could fly

on a path that was optimum for them,

and optimum for the traffic system,

we could use a lot more of the airspace

than we do today.

We're going to have airplanes

flying directly where they need to fly,

and computers keeping them apart.

At the FAA, researchers have been designing systems

that get flights from A to B in a whole new way.

Right now, there's no way for controllers to know

the exact location of a plane.

That's why flights are confined to pre-set highways

to keep them from colliding.

With GPS-based NextGen,

a pilot can follow any route he chooses,

provided there aren't any other planes in his path.

He can choose a much more direct route to his destination.

If we could have airplanes going in all directions

and more efficiently directly to where they want to go,

we would be able to double, triple, maybe even quadruple

the number of aircraft that we could safely handle

in the skies at one time.

By charting their own route,

ADS-B will allow pilots to keep a safe distance from other planes

without having to stick to a pre-set highway in the sky.

Maintaining that distance is important,

because even the best technology

can't keep airplanes apart.

July 2002.

Bashkirian Airlines Flight 2937 cruises

westbound through the night sky for Barcelona.

The Tupolev 154M carries 69 people.

Most of the passengers are Russian children traveling on a summer holiday.

Meanwhile, a DHL cargo aircraft

travels north towards Brussels.

The two flights are supposed to pass each other over Lake Constance

in southern Germany.

Climb flight level...

But air traffic controllers have failed to notice

that both flights are at the same altitude.

The controller is distracted by another flight.

At a second station, he assists a late arrival.

Two-nine-three-seven.

What is your present heading?

Present heading is...

It was a standard practice

at the ATC company that at night,

one air traffic controller was responsible for controlling

the entire airspace of ATC Zurich.

Aboard the Tupolev, the pilots have spotted an intruder...

- Look. Look at that. - ...and it's closing in fast.

Five hundred meters.

Onboard the DHL cargo plane, the TCAS computer

is issuing an urgent warning.

Descend.

The system is designed to warn pilots of an oncoming flight.

Increase descent.

And what to do to avoid collision.

Six hundred.

TCAS descent!

When the air traffic controller returns to his position,

he sees the conflict.

The flights will cross paths in less than a minute.

Descend flight level three-five-zero.

Expedite. I have crossing traffic.

The Russian captain obeys the controller's

instruction to descend.

But his TCAS system is telling him to climb.

Climb. Climb. - It says climb.

The Russian crew has 35 seconds to decide whether to obey

- the air traffic controller or the computer. - Descend level three

- five-zero Climb. Climb.

- Climb. - Descend level

three-five-zero. Expedite descent.

He's guiding us down.

We're not accustomed to not trusting controllers.

In civil aviation,

there were lots of situations when pilots didn't follow

instructions of the controller,

and that led to plane crashes or other accidents.

Expedite descent level

- to three-five-zero - Under pressure,

with just seconds to decide,

the Russian pilots follow the controller's direction.

At the same time, the DHL jet is also descending.

Increase descent.

Increase descent.

Increase!

He's going below us.

Increase climb.

- Increase climb. - Where is it?

Here on the left!

- Climb! - Climb!

Descend! Descend hard!

Bravo Tango Charlie two-nine-three-seven.

Bravo Tango Charlie.

Both flights crash near Lake Constance in Germany.

Seventy-one people are killed.

There are no survivors.

The collision leaves air traffic experts at a critical crossroads.

If I have to summarize the advice that we gave the world,

if a warning comes from ACAS,

pilots should immediately follow it at all times.

If the Russian pilots had followed the computer's instructions,

the accident would not have happened.

With the benefit of hindsight, you always ask yourself, "Could we have done more?"

And an accident is a wakeup call for everybody.

The disaster highlighted the potential value

of automated systems.

And proved again how fatal human errors can be.

It's an important lesson for the developers of NextGen.

Technology can provide humans with information,

but can't control what they do with it.

...before landing?

Over Atlantic City, the FAA jet is on its final approach.

Runway is clear. Bring the flaps to 16...

Its two-hour test flight has brought

NextGen one-step closer

to being installed on commercial airplanes.

Nice job, guys.

CO-PILOT: Two reverses.

Speeds at 90. I got the yoke.

When ADS-B is everywhere

and the data is being displayed in the cockpit,

that will allow the airlines to fly

hugely more efficiently.

Over the past 50 years,

air traffic control has evolved tremendously.

Human error...

technical difficulties...

and poor communication...

have taken the lives of hundreds of people

and uncovered deadly weaknesses in the current system.

Today, those weaknesses are one step closer to being fixed.

I think the NextGen system, as it has evolved now,

is really going to be excellent.

It's going to start in the direction that we need to go

for the future.

The elements that make up NextGen

will be introduced slowly over the next decade.

Piece by piece, the whole new system

of air traffic control will take shape in the US,

and ultimately around the world.

That's what airplane people do.

They react to the challenge and develop a new way of flying.

If NextGen lives up to its promise,

that new way will mean fewer delays

and ultimately, fewer accidents.