Original subtitles

A luxury jet on its maiden voyage is jolted in midair.

Declare an emergency.

We have a wing tip.

The plane has lost a part of its wing.

It became clear that we were in very, very big trouble.

The crew struggles to land the badly damaged plane.

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

But the trouble isn't over when they hit the ground.

The crew is detained, and questioned by police.

Somehow, this small plane

has triggered the worst crisis in Brazilian Aviation history.

September 29th, 2006, in Sao Jose Dos Campos, Brazil.

Three, two, one! Whoo-hoo!

It's a big day at Embraer headquarters.

The Brazilian aviation firm has just sold a brand new private jet

to ExcelAire, a US charter company.

The price tag, 25 million dollars.

It's a beautiful airplane And it was a beautiful little ceremony

that Embraer had in the hanger just before we got on the plane.

And the guys from ExcelAire we particularly proud.

The Legacy is a modified regional jet.

The cabin, redesigned for comfort,

it can seat up to 13 people

and in its first four years of service,

Embraer has delivered almost 100 of these sleek business jets.

ExcelAire will use the jet to fly customers around the world,

but first, the company has to get the plane up to the United States.

Joseph Lepore and Jan Paladino will be at the controls for the jets maiden voyage.

They've been down in Brazil for a couple of weeks

getting familiar with the new plane.

Joe Sharkey is a reporter for The New York Times.

He's been offered a free ride home.

We were delivering an airplane basically

and my role was hitchhiker, and they kindly invited me along.

The Legacy jet is heading to Manaus in northern Brazil.

A stopover on its way to New York.

Half an hour after takeoff,

the Legacy is flying over the heart of Brazil.

The countryside stretches out below.

The view out of the window is spectacular.

I glanced out and I was amazed...

Just to the horizon. Nothing but treetops.

And I just remember how pretty it seemed.

At ten minutes to 4:00 in the afternoon,

the Legacy jet makes contact with controllers at the Brasilia Area Control center

still nearly 100 kilometers away.

Brasilia-November- 600-X-ray-Lima,

flight level 3-7-0, good afternoon.

75% percent of the country's air traffic

is handled by the controllers in this room.

The traffic volume larger than any other Control Center in the country.

One of the many planes they will be dealing with today is the Legacy jet.

Every flight that's handled by Brasilia ACC

appears on computer screens as a small circle

moving in the direction of the plane.

The computer also displays the plane's actual and planned altitudes.

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

- Squawk ident. - Roger.

Paladino sends out a signal. Controllers use it to confirm

that the data on their screen is coming from the plane they think it is.

Radar surveillance.

An hour later, the flight has settled into a familiar routine.

The mood sort of settled down.

Everybody was working and it was just a very, very calm and peaceful time.

I was transcribing notes from one of the interviews from the Embraer tour.

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

But in the cockpit, Paladino is having trouble

getting back in touch with air traffic controllers in Brasilia.

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

He can't raise controllers on the frequency he used almost an hour ago.

He tries other channels.

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

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

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

After 12 attempts, Paladino finally gets in touch with Brasilia ACC.

This time with a different controller

who provides radio frequencies for future contacts.

Contact one, two, three, decimal three, two.

...two, six...

I'm sorry I did not get the last two.

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

The Legacy loses radio contact again.

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

As the pilots try to restore communication with Brasilia,

the plane continues to power through the sky.

It's just minutes before five o'clock.

Suddenly, there was the loudest bang I've ever heard in my life.

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

What the hell is that?

Just fly the airplane, dude.

Declare an emergency. Sit down back there.

No one is sure what's happened to the jet,

but when Joe Sharkey looks out the window, he's stunned by what he sees.

The end of the wing was chopped off and it was serrated.

It looked like it had been chewed off.

It became clear that we were in very, very big trouble.

ExcelAire vice-president Ralph Michelli

rushes to the window for a look at the damage.

And I said to Ralph, "How bad is it?"

And he looked at me and he said, "It's bad."

With more experience flying this type of plane,

co-pilot Paladino takes over control of the limping jet.

Let me fly the thing, dude, all right?

We are descending, I want to get down.

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

The crew still can't make contact with controllers.

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

Do we have a wing tip?

- No. - Damn it.

The entire tip of the Legacy's wing is breaking up.

That affects airflow and is making the plane hard to control.

How you doing? Okay?

As the plane begins to descend,

passengers in the back are worried that the damaged wing is getting worse.

Our main concern was that wing,

but it had taken such a hit

that the structural integrity of the wing was obviously in question.

The leading edge was separated.

With so much damage to the wing, the pilots can't turn sharply.

Too much stress could rip the wing right off.

We were in a position where we realized we were going to die,

I thought of my wife and I thought, "Well, okay, one thing I can do,

"is I can write a note to my wife,"

which I did, I took out my reporter's notebook and I wrote,

you know, a short note saying that I loved her.

Well, you know, just saying what I could.

The Amazon is a bad place to have to land a plane.

It's a dense jungle for as far as the eye can see.

There's nothing down there but trees and I thought,

"Where are they going to put this airplane down?"

Just hours into its maiden voyage, the badly damaged jet is going down.

Paladino and Lepore's flying will soon be analyzed and debated throughout Brazil.

Chart.

The verdict against them will be harsh.

Please answer. November-six- zero-zero-X-ray-Lima.

The crew of the Legacy jet searches desperately

for a place to land their crippled plane.

Captain Joseph Lepore finds a small military base on his chart.

November-six- zero-zero-X-ray-Lima, we have an emergency.

State your emergency.

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

We need to land at Sierra-Bravo-Charlie-Charlie. Is that your airport?

Affirmative.

Do you know how long the runway is?

- Two-six-zero-zero meters. - Standby.

Two-six-zero-zero, that's good, right? Eight thousand feet.

Okay, we're coming in. We're declaring an emergency.

This is November-six- zero-zero-X-ray-Lima.

- Did you see something? - Something hit us.

Twenty-six hundred meters is more than long enough to land the Legacy,

but the crew doesn't know how the plane will respond when it touches down.

The canopy of green.

There was a slash of brown about two miles away.

I heard Joe say there is an airport.

Sierra-Bravo, we see you. We're coming in.

Finding an airport was a stroke of luck

but the crews troubles are far from over.

Now they have to get the damaged jet safely on the ground.

Paladino and Lepore can't configure their plane for routine 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. - Nine.

Extending flaps increases the size of the wing.

Since a bigger wing can generate more lift, pilots can slow down to land.

- You good? - Yeah, I'm good.

With all the damage they have sustained,

the crew doesn't want to put too much pressure on their wing.

They won't be able to extend their flaps until the last moment.

They'll have to land faster than usual.

Everyone sit down back there.

When you land under those sort of circumstances,

you're landing faster than you normally would.

And you get a real appreciation of just how fast an airplane is actually moving.

Because, you know, you're coming down like gangbusters.

I see these trees now, you know, at ground level.

Just sort of looked almost like a movie with one of those moving backgrounds.

And I'm thinking, "I hope this runway doesn't run out."

Got it.

Paladino hits the brakes hard.

Good, good.

You got it.

Hold it.

Then finally, the plane begins to slow.

Whoo!

Good job. Oh, man.

And then finally, we just did come to a halt.

There's that beautiful silence that occurs when the engines are shut down.

Everything was just quiet again.

For more than 25 minutes,

the business jet had flown with part of its wing torn off.

There's also damage to the plane's tail.

Somehow, high over the rainforest,

something tore into the plane.

The bizarre day takes another strange twist.

Because they have landed at a military base,

soldiers confiscate the passports of everyone on board.

And that's the point at which I realized that we were in custody.

But I don't think the others on the airplane

had the immediate sense that this was a custodial situation.

Along with the two pilots,

the jet's passengers are taken to the nearby airbase.

N-six-zero-zero-XL raise your altitude to eight-point-zero-zero.

The emergency onboard the Legacy jet has thrown Brasilia ACC into turmoil

but it's not the only problem controllers there are facing.

Another plane they're expecting to see hasn't shown up.

GOL Flight 1907 should be on radar in Brasilia.

The missing flight is a Boeing 737 with 154 people on board.

It's been in the air for two hours and should be nearing Brasilia

but controllers there can't find any trace of that plane.

Manaus. There isn't any GOL.

- There isn't any GOL with us here. - It's on its way.

They check its status with controllers in Manaus

who were last in contact with the plane.

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

They did not know what was happening.

Deep in the Amazon,

those who were on the ExcelAire jet are also struggling to figure out what happened.

We hit something, man. That's all I know.

Maybe it was a condor.

Are you kidding? It was 37,000 feet.

Well, maybe it was a military jet.

No, I think a plane must have exploded.

And we flew through the debris field.

No, there would have been more impact.

As they're trying to piece together the day's strange events,

the group gets some shocking news.

A GOL flight has crashed.

It's the plane that's been missing.

I just heard

737 went down in the Amazon right where we were.

What?

It was like a thunderclap.

The world changed immediately.

Joe and Jan were just stricken.

I don't think I've ever seen two more anguished men in my life.

The GOL flight crashed right where the Legacy lost a piece of its wing.

It can't be a coincidence.

Approximately 100 kilometers from the military base,

the wreckage of GOL Flight 1907 has been found.

The greatest difficulty involved the fact

that the plane fell straight down.

When it hit the ground the trees covered it up, making it hard to get to.

The shattered remains of the plane litter the jungle floor.

The news hits controllers in Brasilia extremely hard.

They had just realized that the worst thing

that could happen in their control happened.

People were crying. A lot of people had to be dragged out of the room.

Things were not under control in the room.

Over the next several days,

troops pour over the scene of the GOL crash.

The dense jungle slows their progress.

To walk about one kilometer in the forest took us about an hour.

A makeshift helicopter landing pad is carved out of the jungle.

It's becoming increasingly clear that no one has survived.

One hundred and fifty-four people are killed.

At the time, it's the worst crash in the history of Brazilian aviation.

What had happened in the skies above the Amazon?

Investigators face a mammoth job.

Colonel Rufino Ferreira is in charge of the investigation into the GOL crash.

An investigator always has to keep an open mind.

You can't start with any pre-conceived ideas.

When we arrived at the location of the accident,

the only thing we knew for sure was that we had found plane that was missing.

The wreckage of the GOL jet is spread over more than two kilometers.

The widespread debris tells investigators

that the plane ripped apart before crashing to the ground.

The aircraft disintegrated during the fall. It hit the ground in pieces.

There was practically no damage caused by the impact with the ground.

The plane had already fallen apart.

On October 2nd, just three days after the crash,

the plane's flight data recorder is found.

Most of the cockpit voice recorder is also recovered, except for one critical part.

In this accident, the impact was so strong that the modules separated

from the recorder.

Modern voice recorders don't use tape.

Conversations are recorded digitally onto a memory module.

But that part of the GOL CVR has broken free.

Without it, the rest of the cockpit voice recorder is useless.

While the search for the module continues,

Ferreira looks at the information

from the 737's flight data recorder.

He learns that the plane was flying at 37,00 thousand feet.

It was on course and flying level at its assigned altitude.

Then, without warning, the plane pitched over and plummeted toward the ground.

Whatever happened, it was sudden and catastrophic.

The data recorder tells Ferreira that the plane spun 11 times before it hit the ground.

Manaus, I can't see GOL.

There isn't any GOL with us here.

It's on its way.

- So it's already in my area? - For over half an hour.

Police investigators want to know what Air Traffic Controllers

can tell them about GOL Flight 1907's final minutes.

There was no Mayday.

In fact, we never had contact with the GOL jet.

Controllers say there was no warning that the jet was in trouble.

It simply vanished.

Colonel Ferreira studies Air Traffic Control data from the day of the accident.

There is no sign of the GOL flight.

But the readings from the smaller Legacy jet capture his attention.

It seems to be flying erratically.

Instead of keeping to a single altitude,

the radar shows it flying up and down dangerously.

Perhaps the private jet pilots were testing out their new plane

by climbing and descending quickly.

They may have collided with the GOL jet as a result of their reckless flying.

When that information leaks out to the country's newspapers,

it makes front page news.

Population thought it was unjust that a smaller aircraft

was able to make an emergency landing

while the larger aircraft

with 154 people just fell into the Amazon and everyone died.

Neither Lepore nor Paladino are officially charged

but they are confined to a hotel room in Brazil while the investigation continues.

Ferreira interviews the two pilots about what they did and what they saw.

Look we are proceeding northwest on course to Manaus at 37,00 feet.

- Okay? We attempting to contact Brasilia Control... - Were you changing altitude?

No.

I was on the plane.

Had the plane been flying erratically

or doing loop-de-loops or whatever it was,

I think I would have had a pretty good story for The New York Times.

Did you say you were flying at 37,00 feet?

Yes, that's right.

Flight level three-seven-zero. We never moved from that.

When he reviews the information

from the Legacy's flight data recorder,

Ferreira confirms the pilot's story.

Although the ground radar shows the Legacy flying wildly,

the data from the plane shows that it didn't change altitude at all.

But there is something shocking about the Legacy's path.

The business jet was flying north to Manaus,

the GOL flight south from Manaus.

Ferreira can see that both planes were flying at the same altitude.

Thirty-seven thousand feet. He makes a horrifying discovery.

For some reason, the two planes were on a collision course.

Air traffic is typically routed along specific corridors

through the sky.

Essentially, highways in the air.

But planes traveling in opposite directions

are supposed to be separated by at least 1,000 feet.

HANS-PETER GRAF: The airway system,

for instance, between Brasilia and Manaus is very simple.

It makes airplanes fly northbound, maintaining even levels

and airplanes flying southbound maintaining odd levels.

But somehow the Legacy Jet and the GOL 737

were traveling down the same ariel highway in opposite directions.

For long minutes, they were heading straight for each other.

It seems more and more likely that the two planes collided.

At the crash site, workers find support for this incredible theory.

The left wing of the GOL flight is recovered.

Investigators discover that about halfway along the wing, it's sliced clean through.

None of the other wreckage is sliced this way.

The precise nature of the cut tells Ferreira that this is not damage

that was caused by impact with the ground.

The damage on the left wing clearly shows

that it was caused by a collision with another plane.

The badly damaged wing would have sent the 737 into a spiral dive.

The pilots would have had no way of controlling it.

The sudden spiral motion would have pulled the plane apart.

It's the reason the wreckage is spread over such a wide area.

Ferreira finds the most conclusive evidence

of a collision on the Legacy's damaged wing.

On the Legacy, we found very small pieces of paint

that came from the GOL wing.

Together the planes had a combined speed of 1,600 kilometers an hour.

At that speed, the wing tip of the small jet easily sliced through the 737.

Colonel Ferreira now understands what caused the GOL jet to crash.

But he doesn't know why.

How had the two jets ended up in the exact same airspace without anybody noticing.

Investigators in Brazil now realize that they are dealing with something very unusual.

A mid-air collision is a very rare event in aviation.

And it should not have happened with two very modern new aircrafts.

The situation becomes more complicated

when investigators study a critical document.

The Legacy's flight plan.

Flight plans are filed by using a standard form

which is the same all over the world.

The form will contain the flight number

as well as requested flight level or altitude.

According to this document,

when it collided with the GOL flight,

the executive jet wasn't expected to be at 37,000 feet.

The Legacy's flight plan called for the jet

to fly at 37,000 feet only until it reached Brasilia.

Then descend to 36,000.

But the collision took place 850 kilometers northwest of Brasilia.

Well past point where the Legacy

was supposed to descend.

So why hadn't the Legacy followed its flight plan?

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.

I don't know where you are getting the information from.

We followed the rules.

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

Colonel Ferreira needs to check the story that the crew is telling.

He wants to know exactly what they were told by controllers

when they took off from Sao Jose Dos Campos.

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

ATC permission for Manaus flight level three-seven-zero.

The Legacy's last instruction was to fly all the way to Manaus

at 37,000 feet.

The pilots obeyed that instruction even though it differed from their flight plan.

Air Traffic Control always can deviate from the flight plan

because they have best knowledge of the actual traffic situation.

Leaving Manaus, the GOL jet was also cleared to fly at 37,00 feet.

Both planes were assigned the same altitude by controllers

at opposite ends of the country.

...decimal two.

Once we were certain that both planes were flying at the same altitude,

we knew for sure there would be a lot to investigate

on the side of Air Traffic Control.

Ferreira turns his attention to conversations

between controllers in Brasilia and the Legacy jet.

The cockpit voice recorder from the Legacy

gives investigators a remarkably detailed look

into what happened on the private jet.

The brand new Legacy jet has a state of the art recorder

that captures two hours of conversation.

The CVR was probably the most important component

in the investigation.

At ten minutes to 4:00,

the crew is told to change radio frequencies and get in touch

with the controller monitoring their flight.

Change frequency to one-two-five-zero-five.

Decimal one, I'm sorry, one-two-five-zero-five, good day.

Good day.

At this point, the Legacy jet

is approaching Brasilia, but the crew never receives

any instructions regarding their altitude.

Brasilia-November-six-hundred- X-ray-Lima level three-seven-zero,

good afternoon.

November-six-hundred- X-ray-Lima.

When the Legacy overflew Brasilia at flight level three-seven-zero,

according to the flight plan it should have been

descending to three-six-zero.

But Air Traffic Controllers simply forgot

to give the order to the Legacy to descend to three-six-zero.

The pilots would have assumed they were meant to stay at three-seven-zero,

37,000 feet.

No airplane should ever change altitude

without receiving instructions from Air Traffic Control.

To discover why controllers didn't give that crucial instruction,

Colonel Ferreira takes a closer look at the technology

used to monitor the traffic over Brazil.

So can you call up the Legacy jet screen for me?

On the radar's screen we see the altitude,

speed and the transponder information of each plane.

Each flight has an individual code

assigned to it that helps controllers track it.

Underneath that, there are two separate numbers.

On the left, the plane's actual altitude.

On the right, the altitude the plane is supposed to be at according to its flight plan.

So here the number changes to three-six-zero.

As the Legacy jet passed over Brasilia,

the number on the right, the planned altitude, changed.

The computerized system automatically updated it.

According to the flight plan, at this point

the plane was supposed to descend to 36,000 feet, three-six-zero.

To my knowledge,

only Brazilian Air Traffic Control system is using this kind of design.

In other parts of the world,

this update has to be done manually.

The computer changed a single number

which led to a critical error.

Without much experience with the computerized system,

the controller mistook the new planned altitude

for the plane's actual altitude.

The system changed it automatically

from authorized altitude to the planned altitude

which made the controller believe the Legacy was flying at three-six-zero.

Police investigators talk with the controller who was on duty

when the number changed on the screen.

It was shortly after that I went on break. Lucivando relieved me.

He tells police about a critical mistake on his part.

You have five aircraft.

The Legacy is at three-six-zero.

Before leaving, he handed his flights off to another controller,

telling him where he thought the Legacy was flying.

I believed it was at three-six-zero, and that is what I told him.

When the new controller took over,

the one being relieved gave him the Legacy's altitude information

according to the flight plan. Three-six-zero.

But the jet was actually flying 1,000 feet higher

right in the path of the GOL flight.

Colonel Ferreira studies transcripts of conversations on board the Legacy,

and finds that the crew was having their own difficulties during the flight.

How much longer, guys?

That is a good question, Ralph.

The crew seems unfamiliar with some of the jet's advanced systems.

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

Where's the one that gives us total time?

My impression is that the pilots were trying to learn

their aircraft systems during the flight.

Investigators also uncover a breakdown in communications.

Brasilia-November-six-hundred- X-ray-Lima,

flight level three-seven-zero, good afternoon.

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

- Squawk ident. - Roger.

After a brief conversation between

the Legacy jet and Brasilia ACC,

Colonel Ferreira notices something extremely unusual.

Radar surveillance. Radar surveillance.

For almost an hour, the Legacy pilots don't talk to anyone on the ground.

They stayed 57 minutes without attempting

any contact with Air Traffic Control,

which seems like a lot of time.

After 57minutes, they tried to call 12 times without success.

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

Paladino did try to get hold of ground control,

but he couldn't get through.

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

He then tried the backup frequencies listed on his navigation charts.

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

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

His only contact, a single garbled message.

Sorry, say frequency one more time

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

Both pilots and Air Traffic Controller

should have been more concerned of maintaining two way contact

all the time.

This is their duty.

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

Had pilots and controllers spoken,

they might have discovered that the Legacy was flying north

in a corridor reserved for southbound traffic.

As the public learns about the mistakes in the Air Traffic Control center,

there is growing pressure to make some changes.

We wanted to understand what had happened to these people.

Inside the control room, the controller should have been able

to see on their radar screens

that these two airplanes were flying in a collision course.

Brazilian Air Traffic Control is one of the last in the world

to be run largely by the country's military.

Since they're run by the military,

they're run by the Brazilian Air Force.

We did not have complete access to information except for what was released.

As fingers are pointed at controllers,

many of them come forward with stories of overwork and poor training.

They complained that they weren't well trained in English language

which is the international aviation language.

Also, they had complaints about their equipment.

In fact, the controller who incorrectly reported the Legacy's altitude

had been on the job for only a year.

A valuable piece of the puzzle is still missing.

Investigators still don't know what happened

during the final minutes of the GOL flight.

Soldiers have been scouring the Amazon jungle with metal detectors

looking for the plane's missing memory module.

Almost a month after the crash, they find it.

Colonel Ferreira hopes to hear some reason

why the GOL crew wasn't able to avoid colliding with an oncoming jet.

GOL one-niner-zero-seven, contact Brasilia ACC

on one-two-five-decimal-two. A good flight.

Thanks very much, Brasilia one-two-decimal-two,

GOL one-niner-seven.

There are no alarms before the collision,

no warning that they were flying straight for another jet.

Pilots rely on Air Traffic Controllers to keep other planes out of their path.

They spend much of their time monitoring their instruments,

not the skies ahead.

At the speed they're traveling,

they'd only have to look away for a few seconds to miss an approaching plane.

There were no issues of communication

and no misunderstanding between the pilots and the Air Traffic Control.

Keep calm.

They had no idea what had just happened to their plane

and fought until the end to regain control.

For less than a minute,

the pilots struggle for control

- but there's nothing they can do. - Keep calm!

But why were there no warnings?

Both planes were equipped with a safety feature

designed to prevent exactly this type of accident.

Ferreira now needs to know why that system failed.

Earlier in the investigation, strange radar images

suggested that the Legacy pilots were flying wildly over the Amazon.

Now those suspicions have vanished

but Ferreira revisits the fluctuating radar data

to understand why neither plane knew the other was coming.

You see, the altitude is very insignificant.

To try to understand this last piece of the puzzle,

Colonel Ferreira returns to the radar display

that Air Traffic Controllers saw the day of the crash.

Instead of displaying just the expected altitude and the actual altitude,

the letter "Z" appears between them.

The "Z" on the Air Traffic Controller's screen

Indicates that the airplane he's looking at has lost its transponder.

Modern commercial aircraft are equipped with transponders.

Like small radio stations,

they broadcast information on the plane's altitude and flight number.

This information is received by computers on the ground

and instantly displayed on the screens of Air Traffic Controllers.

In Brasilia, if the transponder fails,

so-called primary radar takes over automatically.

Signals are sent out from the ground but hit the target and return.

Those readings are wildly inaccurate.

Primary radar only is passive indication

of anything that is flying through the air space.

The difference of the actual altitude

in the primary radar system might differ.

Several thousand feet.

The inaccuracy of the radar tracking the Legacy jet

explains why its altitude appeared to be rising and falling.

Investigators discover that the transponder

wasn't sending out signals for more than 50 minutes before the crash.

But controllers didn't notify the pilots.

That may be because they didn't notice the subtle change.

The way in which the information is displayed

to the controller does not visually alert him to the change.

There are no flashing lights

that would tell the controller that the plane has lost its transponder.

There's an even more critical role played by the transponder.

It doesn't just beam information to controllers on the ground

but to other planes as well.

All commercial aircraft are equipped with a warning system called TCAS,

the Traffic Collision Avoidance System.

TCAS gives a relative position of other airplanes

within range of your own airplane.

TCAS picks up a signal from an oncoming

plane's transponder and issues a warning if it's too close.

If either plane's transponder is off, the system won't work.

What the hell is that?

Ferreira discovers that the Legacy's transponder was working early in the flight

and after the collision.

But for more than 50 critical minutes, it was silent.

How had a state of the art jet just off the factory floor

developed problems with its transponder.

The failure of the transponder certainly contributed to this accident.

And we had to find out what caused it to fail.

Investigators examine the Legacy jet's transponder unit.

They discover that the system which controls it had a troubled history.

It had been installed on a different plane but removed because it wasn't working.

It was repaired and then placed on the jet that was sold to ExcelAire.

Investigators have the system tested

but even with its suspicious past,

after the crash, they can find no obvious problems with the plane's transponder.

Now this is the layout now of the standard one on the Legacy jet.

Colonel Ferreira does notice

something potentially dangerous about the design of the Legacy's cockpit.

If a pilot uses the built-in footrest during flight,

his toes can come in contact with the buttons

on the transponder.

Show me what it looks like in standby mode.

And when the transponder does go into standby,

it would be difficult for a pilot to notice.

There's no alarm.

A small yellow warning light is the only indication

that the transponder isn't on.

It was not easy for the pilots to detect that

because it's not hooked up with the central warning and alert system.

But the pilots of the Legacy jet

do not remember using the plane's footrest.

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

Time...

Investigators suspect that one of the pilots

may have turned the transponder off by mistake.

The most probable scenario is that by accident,

one of the pilots temporarily turned off the equipment

as he tried to familiarize himself with the technology on board.

However, the transponder went off. At a critical moment,

the crew had no last-ditch safety system

to warn them that they were flying right at a 737.

Even though TCAS system on the GOL plane was working,

there was no signal from the approaching jet for it to receive.

Closing in on each other at 1,600 kilometers an hour,

the pilots never saw each other coming.

Brazil's Air Traffic Control system

would undergo some radical changes as a result of the collision.

But those changes would not come without a fight.

The investigation into the crash of GOL Flight 1907

has uncovered dangerous problems with Brazil's Air Traffic Control system.

Brasilia-November- six-hundred-X-ray-Lima,

level three-seven-zero. Good afternoon.

Two planes were assigned to fly

at the same altitude in the same airspace.

Radar surveillance.

Overworked and inexperienced controllers in Brasilia

neglected to instruct the Legacy jet to descend to 36,000 feet.

You have five aircraft.

The Legacy is at three-six-zero.

Then they mistook the Legacy's planned altitude for its actual altitude.

To make matters worse,

the Legacy pilots, unfamiliar with Brazilian airspace,

were unable to make contact with controllers on the ground.

And somehow the transponder

which broadcasts their location in the sky, went silent...

...which controllers in Brasilia failed to notice.

Keep calm.

Keep calm.

A multi-billion dollar ATC system designed to keep planes apart

had failed to detect two planes on a collision course.

One by one, a series of human errors occurred

and all of the defense systems that exist to avoid these errors were defeated.

A month after the crash of the GOL passenger plane,

controllers begin a work to rule campaign.

They want to draw attention to problems with the system.

Once they did start working to the rules

and not stretching them anymore,

this triggered what we called the aviation crisis in Brazil.

At a certain point, maybe 40% of flights in all of Brazil

had over an hour delays.

Following the crash and the work slowdown,

changes start being made.

There has been a lot of changes in Brazilian aviation after the accident.

Specifically with regards to Air Traffic Control.

Because the Air Force had to admit that they had a shortage of controllers,

and also there's a higher degree of accountability.

In the United States,

the Federal Aviation Administration

issues two recommendations as a result of the tragedy.

Pilots flying Legacy jets are warned of the possibility

that putting their feet up in the cockpit

could accidentally turn off the transponder.

And manufacturers are told that an alarm should sound

if the TCAS system shuts off.

The controllers who are involved in the crash

are charged with varying degrees of manslaughter.

But those criminal charges worry people who were closely involved with the disaster.

An investigation like ours which focuses on prevention

suffers huge setbacks when there is pressure to lay charges.

By blaming people, we might be creating a culture

where people will not come forth and be honest about failures and mistakes.

And when we try to hide that, things get swept under the carpet.

And soon enough, they'll come out again.

No controller leaves his home in the morning

thinking he's going to crash a plane.

And so the criminalization only interferes with investigations

that can prevent further accidents.

More than two months after the crash,

the crew of the Legacy jet is finally allowed to return to the United States.

Joe and Jan barely got out of the country.

There was an attempt to hold them

under what I thought was a cobbled together

initial criminal charge of "failing to ensure the safety of Brazilian skies".

While we are grateful for the safe return of Joe and Jan

and everyone aboard the Legacy,

we are all saddened by this tragedy

which took many innocent lives.

More than a year after the accident,

the Legacy jet that survived a mid-air collision was still at the airfield in the Amazon.

Its maiden voyage cut short by a tragic series of technological and human errors.