Original subtitles

East of Los Angeles, a calm holiday weekend

is shattered by a devastating explosion.

A neighbourhood is destroyed.

Frank! Angelica!

I turned and saw my house totally on fire.

All the houses behind me were all on fire.

Where are they? Where are they?

Fiery wreckage is strewn for blocks.

Investigators must discover why this airliner crashed.

And find a way to stop it, from ever happening again.

Los Angeles International Airport, LAX,

is one of the busiest in the world.

It's used by 40 million passengers each year.

More than 15-hundred planes take off and land every day.

It's August 31st 1986, Labor Day weekend.

Today, a junior air traffic controller, Walter White,

will be handling some of that traffic.

White isn't a full-fledged controller yet.

He has to put in more time

before he gets his final certification.

Hey Karl, how's it goin'?

Hey. Slow, slow, slow.

It was a long weekend

and it was a beautiful day in Los Angeles.

It absolutely clear outside,

which we call Chamber of Commerce type day.

You want to take a break? Have a Cigarette?

I can sit in for you. Sure. Why not?

That was my normal assigned shift

and Walter came in and asked me if I wanted a break,

wanted to go smoke a cigarette.

And I said sure. Traffic was light. It wasn't very busy.

Uh, it was Sunday morning.

L.A. approach - Good morning.

Well certainly,

any controller is looking to get seasoning, if you will.

Three months, four months, that's a pretty new controller.

Los Angeles approach - Good morning.

I mean it wasn't my time for a break,

Walter wanted to work the sector.

As I remember it correctly,

he wanted to work it for some proficiency time.

He hadn't worked it in a while.

ACL sixty, can you see the runway two-five left?

Roger L.A. Approach. Thank you.

Reduce speed to two-zero-zero, then descend

and maintain 6-thousand.

Two-zero-zero. Descend and maintain 6-thousand.

Thank you. Have a nice day.

Several hundred kilometers to the South -

passengers are boarding an AeroMexico DC-9.

Dr. Donald Wong and his sons are returning

from a highly successful fishing trip.

Jason, Jason. I think we should put it up in the kitchen.

They caught an enormous sailfish...

Your mom would love it there.

...which they plan to display back home.

Labour Day weekend was the last weekend

before school was to start.

Um, Donald decided that it would be fun to take the boys

fishing down in Mexico, to go deep sea fishing,

which he'd only done one other time in his life.

This would be a, like, father-son bonding weekend.

And it was also the first time

that they had traveled without me.

Just east of L.A.,

the suburban city of Cerritos wakes up slowly.

In the 1970's this bustling community had been

one of the fastest growing in Los Angeles County.

My husband had been working out of town all week

and he was coming home for the weekend.

And that Sunday morning I decided,

let's just stay home and not go to church.

I'm going to go out

and get your favourite things for a good breakfast.

Javier, go and take a shower. I'll be back in a bit.

And I left to go to the grocery store.

In the home was Alex. He was fourteen.

His twin sister, Angelica.

Uh, she was asleep, he was asleep still.

And Javier - that was my sixteen-year-old -

and my husband.

As Estrada leaves on her errand,

AeroMexico Fight 498 is just twenty minutes from L.A.

Captain Antonio Valdez-Prom is acting as Co-pilot

as they approach the city.

First Officer Jose Valencia is piloting

this leg of their journey.

Ready when you are Captain.

About 22 kilometers south of LAX

sits the Torrance airport.

Operating in the mammoth shadow of LAX, Torrance serves

private planes and amateur pilots.

It's one of several small airports that operate near L.A.,

a region that has over 6-thousand weekend flyers.

Fuel set. Flaps set. Okay. We're all set for takeoff.

At the end of a busy summer William Kramer,

his daughter Caroline

and wife Kathleen are finally taking to the skies.

Piper 4891, all clear for takeoff.

Good morning Piper 4891. This is Torrance tower.

You're clear for takeoff on Runway five... right.

They're heading to Big Bear Lake...

Rolling tower.

...about 2-hundred kilometers northeast.

A meticulous man,

William Kramer is an executive for an engineering company.

Six years ago, at the age of forty-seven, Kramer bought

his first airplane, a stylish and swift Piper Cherokee.

Wings west fifty-two twenty-five,

Los Angeles approach depart Seal Beach, heading three- two-zero.

Expect a visual approach runway two-five left,

report airport in sight. Thanks.

Walter White's job as Arrivals Controller

is to make sure incoming planes keep well clear of each other.

He's directing them to land on one of two runways.

Confirm terminal search, runway two-five left. Thank you.

Southeast of LAX, the crew of AeroMexico Flight 498 is

still a few minutes from their first contact with Walter White.

But in the skies above Los Angeles,

a deadly series of events is about to unfold.

Dozens of people who have never met

will be bound together forever,

in a tragedy that will affect everyone who flies.

August 31st, 1986. Labor Day weekend.

All clear for takeoff, Torrance.

Just south of Los Angeles,

William Kramer and his family

are finally on their way for a long awaited holiday.

Ok, just an hour to go and we're in Big Bear Lake.

They're reporting visibility of fourteen miles today.

Pretty good.

As the Torrance airport recedes behind him,

Kramer begins climbing to 3-thousand metres

on his way northeast to Big Bear Lake.

Several kilometers away, a half-full DC-9 from Mexico

is approaching Los Angeles International Airport.

Less than 2-thousand metres below them,

Theresa Estrada is driving home

with the groceries for a holiday breakfast.

Her husband and three children

are waiting just a few blocks away.

That's it. Holidays are over.

PSA seventeen sixty-five,

Los Angeles approach toward, one mile southbound...

It's not a busy morning and one-by-one,

Arrivals Controller Walter White guides his planes in safely.

At eleven forty-seven a.m.,

he gets his first call from AeroMexico Flight 498.

VALDEZ-PROM: Los Angeles Approach, good morning.

This is AeroMexico four-nine-eight.

AeroMexico, four-ninety-eight,

Los Angeles Approach.

Two-five left final approach course.

Do you have information uniform?

AeroMexico Flight 498 is now officially

inside what's known as the Terminal Control Area - or TCA.

Sometimes referred to as the birdcage, the TCA is a complex

piece of three-dimensional airspace around the airport.

It's restricted air space that's normally

found around heavily congested airports or hub airports

where the traffic density's extremely high and you

need to control the access into and out of that airspace.

AeroMexico, four-ninety-eight,

traffic ten o'clock, one mile northbound, altitude unknown.

VALDEZ-PROM: Roger, four ninety-eight.

AeroMexico, four-ninety-eight, reduce

speed to one-niner-zero, then descend and maintain 6-thousand.

As the AeroMexico plane descends,

William Kramer and his family continue climbing.

I hope it's like this when we get to Big Bear.

We should be able to see the ocean by now.

Hon, take a look at the map,

and look around the four-oh-five, and see

if you can see any, any kind of landmarks that we can use.

Oh, what am I looking for?

Walter White is keeping his eye

on the AeroMexico jet when his attention is abruptly

drawn to another plane that's just appeared on his radar.

It's not one he's expecting.

Uh, one approach six-

six Romeo is on a flight from Fullerton.

Cruising altitude is 4-thousand, 5-hundred. We'd like following.

The pilot of a small Grumman Tiger asks White

to help guide him through the crowded Terminal Control Area.

Pilots are supposed to contact LAX

approach before they enter the controlled airspace.

This pilot could be in the path of incoming traffic.

But before White can deal with the private plane,

he gets a call from the AeroMexico DC-9.

VALDEZ-PROM: Uh. what speed do you want?

We're reducing to, uh, two niner zero...

no, no to one niner zero.

Uh, okay. You can hold what you have sir.

White decides to give the AeroMexico jet

the runway closest to their gate.

Uh, change in plans, sir. Stand by.

VALDEZ-PROM: Roger, four ninety-eight.

With the DC-9 on hold, White turns to the intruder.

Grumman six-six Romeo,

squawk four-five-two-four remain clear of the, uh, TCA.

White tells the pilot of the Grumman to use

a unique radio channel.

But he seems confused.

Four, five, what were the other two numbers?

Four. Five. Two. Four

Grumman six-six Romeo.

Are you at 4-thousand, 5-hundred right now?

Negative. We're at 3-thousand,

4-hundred and climbing. Ok.

You're right in the middle of the TCA, sir.

Grumman six-six-Romeo,

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

You just had an aircraft pass right off your left

above you at 5-thousand,

and we run a lot of jets right through there at 35-hundred.

Well, what do you suggest I do now?

As the crew of AeroMexico Flight 498 continue

to close in on the airport...

VALDEZ-PROM: Landing lights.

...their DC-9 is rocked by a violent shudder.

What was that?

AeroMexico four-ninety-eight,

Los Angeles approach.

First Officer Valencia tries

desperately to control their dive.

AeroMexico four-ninety-eight,

Los Angeles approach.

VALDEZ-PROM: This can't be. I saw a huge explosion.

Just the red vibrant colours of a, of fire.

Just huge explosion, like the way a bomb might hit the ground.

White is getting no response

from the AeroMexico jet.

AeroMexico four-ninety-eight,

Los Angeles approach.

And now he can't find it on his radar screen.

I'm sitting there talking with the two departure

controllers and, uh, not really thinking.

And I hear Walter say something like,

I think I lost one.

AeroMexico four-ninety-eight, Los Angeles approach.

That immediately got everybody's attention.

So we looked at the radars and you could hear him

calling 'AeroMexico four-ninety-eight.'

Uh, called him several times on the radio.

Where was AeroMexico?

At this point we still weren't absolutely sure

what had happened.

White calls to an incoming jet for help.

American three-thirty-three heavy...

I want you to take a look around at eleven o'clock.

I just lost contact with a DC-9, let me know

if you see anything down there please.

Uh, eleven o'clock, uh, five miles. What altitude?

He was last assigned six.

He's no longer on my radar scope,

American three-three- three heavy.

Okay, uh, I see a, uh, very large, uh, smoke screen

off on the left side of the aircraft, about eleven o'clock.

I went down the street to go to my house

and I saw a woman's head and her

body had been cut in a diagonal and she was just laying there.

There was nothing but debris

and fires sporadically all over the place.

I could see fire in the whole neighbourhood.

Nearby, an engine from a local fire station had been

on a training exercise led by Fire Captain, Larry Hambleton.

All of a sudden, one of the firemen tapped me

on the shoulder and said,

'There's a big column of smoke, you know, off to our left.'

So I picked up the mic and made a guess at the, uh, address.

I'm responding to a large fire north of ninety-one,

north of Carmenita.

They came back and, uh, said,

'Well, we've got a report of an airliner down.'

So I upgraded the response

to, uh, basically triple what I initially asked for.

I'm calling for a third alarm

and two air squads east of one eight-three and Carmenita.

As we approached, I realized that, in addition

to the, uh, aircraft parts in the street, there were people,

body parts, which changed the complexion of the whole thing.

Set up a perimeter.

Hello? Hello? Can anybody hear me?

At Los Angeles approach, Walter White,

deeply shaken by the crash, is relieved of duty.

I remember watching Walter get up

and walk out of the room by himself.

And, you know, something inside of me was just, you know,

saying, 'this is not right, this is not right.

Somebody's gotta go with him.'

Tony, he can't go out alone.

I could have been sitting there just as easy as him.

And I don't know

if I'd have done anything different than he did.

If you're out in this area you'll see a large

plume of black and white smoke about three miles

west of Fullerton airport, not far from...

Helicopter news crews are quickly on the scene.

There was a lot of fire in front of me.

And my house was just totally on fire.

Frank! Angelica! Javier! Angelica!

And I saw my neighbour, Where are they?

I said to her, 'Rose, where's my family?

What happened?' And she goes,

'Oh, honey. Your family's in here. They're over here.

We're looking for you.

Where are they?

And, within myself,

all I could do is thank God that they were safe and sound.

she took me into her home and I saw Alex.

Alex! Alex! What happened?

Where's Angelica? Where's Angelica?

I don't know.

Where's Javier? Where's Papa?

I don't know mom. I'm sorry.

And he started crying right away and said,

'Mom, I'm sorry.

I'm the only one that came out alive.'

And all I could do was hug him.

Pieces of fuselage have torn through nearby

homes setting them on fire.

The tail section of the jet has been catapulted

more than a block from the crash site.

Hello? Is there anybody in here?

As I surveyed the houses

and the crash site around me, it was a very surreal experience

to, to stand right there for, probably four or five minutes

before anybody else showed up and not see another living soul.

I have got wreckage all over the place.

There are no survivors. Just fatalities.

I had dealt with death, one,

one or two or three people in a residential fire.

But never a whole airliner full of people.

Let's go to work, guys.

I don't think I ever saw a whole, a whole human being.

I gave them the job of finding body parts and wrapping them,

recovering them with yellow rescue blankets.

No matter where it was, ever so small or whatever,

you know, a hand or a torso or a leg or whatever.

That became, life to us, and it was treated with respect.

My memory of the incident is in a muted shade of brown.

It's not black and white. It's not vivid colour, you know?

The grass isn't green, the houses don't have paint.

It's all some muted brown shade.

I'm told that that's my brain's way of taking something

violent and horrible and softening it a little bit

so I can live with it and deal with it.

The whole corner of this neighbourhood

has been torn apart.

Yellow sheets mark the bodies.

I count one, two, three, four, five, six, seven, eight,

nine, ten, eleven bodies right now.

Oh gosh. This neighbourhood has been just devastated.

Sixteen houses have been damaged.

Many of them completely destroyed.

At Los Angeles International Airport, Mary Wong is

waiting for her husband and two young sons.

I went to the airport to pick them up, um, around noon.

And, uh, waited in that area outside of customs

and waited and waited.

And probably, you know,

you're thinking customs might take a little while

but about maybe twelve-twenty or twelve-thirty I started seeing

a man walk around with a pack on his back with a green cross.

We were taken up to a lounge upstairs and on the

elevator up I looked at the man and I said, 'They're dead.'

I said, 'I just know they're gone.'

In Cerritos,

emergency workers are shocked by another grisly discovery.

In the playground of a local school,

they find the wreckage of a Piper Cherokee Archer.

Remarkably intact, the plane's canopy is sliced off.

Its three occupants are found still belted into their seats.

William Kramer and his family are dead.

All the passengers

and crew on AeroMexico Flight 498 are also dead.

In addition, fifteen people on the ground have been killed.

It's a horrifying situation.

Two planes have crashed into a California neighbourhood.

Something's gone terribly wrong in the skies above one

of the busiest airports in the world.

Now investigators have to find out exactly what's happened.

On the last day of August in 1986, a lazy

Labour Day weekend is shattered by an enormous explosion.

Two planes crash in L.A. County, destroying several homes.

It is a grisly scene -

bodies are scattered throughout a devastated neighbourhood.

Eighty-two people are dead.

Fifteen people on the ground have been killed.

Another sixty-seven have died in the tangled

wreckage of the two planes involved.

Investigators from the National Transportation Safety Board

arrive that night.

They include experts in human performance, flight systems,

and air traffic control.

From the beginning, investigators are focused

on the fact that there are two planes on the ground.

It suggests a disturbing conclusion -

that this was a mid-air collision.

The idea that this had been a mid-air collision

was already conveyed to us before we even launched

out of hanger six back when we got the word.

They saw two wreckages coming down.

Um, and that's the way it got conveyed to us.

With that idea in mind, John White

and his team must painstakingly examine the wreckage.

It's more of now documenting where the major

pieces were and then looking at the, uh, pieces to see

if you can, uh, determine how the aircraft,

what angle the aircraft may have come together at.

Propeller marks on the tail of the DC-9 and paint

from the Piper Cherokee - reveal how the planes crashed.

It looks like, uh, the Piper collided at the tail

section of the DC-9 and the horizontal stabilizer came off.

Uh, and once that happened,

you could no longer control the pitch of the DC-9.

The descending DC-9 and the climbing Cherokee

met at a ninety degree angle.

Their combined speed was 4-hundred

and fifty kilometres an hour.

The impact tore off the airliner's tail section.

Discovering how the planes collided is the first step.

The more important question to be answered is why?

To piece together the tragedy,

investigators examine the DC-9's flight data recorder.

It helps them pinpoint the exact location,

and altitude of AeroMexico Flight 498.

The DC-9 was inside the Terminal Control Area -

the controlled airspace of the Los Angeles airport.

It was right where it was supposed to be.

But the Kramer's Cherokee was also inside the TCA.

With all of the jets taking off and landing at LAX,

private planes must first get permission to enter this area.

Piper 4-8-9-1, all clear for takeoff, Torrance.

William Kramer was a newcomer to Los Angeles.

But investigators learn that he was well

aware of the limits imposed by the TCA.

He knew that it was restricted airspace.

And in the cockpit of Kramer's Cherokee, the confirmation.

Investigators find a map

of the Los Angeles Terminal Control Area.

Investigators make another puzzling discovery.

They learn that the Kramers' proposed flight plan took them

from Torrance, to Long Beach, then up to Ontario and finally

to Big Bear Lake, at a cruising altitude of 3-thousand metres.

That plan keeps him well out of the TCA.

The fact of the matter is, the Cherokee flew into the TCA

and hit the DC-9 in restricted airspace without a clearance.

So how had Kramer flown into danger,

and why hadn't he let anyone know?

On the ground in Cerritos, one possible answer emerges.

Heart disease runs in Kramer's family

and the initial autopsy results show a major blockage.

Are you alright, Bill? Yeah, yeah. I'm fine.

Kramer may have suffered a heart

attack on the flight, leaving the plane without a pilot.

Samples of William Kramer's heart tissue are sent

to the Armed Forces Institute of Pathology for testing.

If he suffered a heart attack,

it might explain why he didn't call in to L.A. approach.

It's totally possible

that he could have had the heart attack, fell back,

pulled the airplane up and that's why

he didn't try and avoid the DC-9.

But no matter why Kramer was

flying in restricted airspace, Air Traffic Controller

Walter White should have been able to see him.

Kramer's plane should have appeared on White's radar.

Before being questioned by investigators,

White reviews the radio calls from that morning.

He needs to be sure of what he said... and what he saw.

Richard Wentworth was one of the investigators

who talked to White.

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.

NTSB investigators aren't satisfied

with White's memory.

While the radar data is being analyzed,

news arrives from the Armed Forces Institute

of Pathology about William Kramer's heart.

Are you alright? Yeah, I'm fine.

Results from a detailed study of his body

show that, while he had advanced heart disease, William Kramer

was not fighting a heart attack before the collision.

Investigators must find another explanation for why the Kramer's

flight went into the Los Angeles Terminal Control Area.

While he had submitted a flight plan, small planes

like Kramer's Cherokee don't have sophisticated instruments.

Like most private pilots,

Kramer was navigating by landmarks like freeways.

That meant keeping an eye both on the landscape below

and the airspace around him.

Ah that's definitely the four-oh-five...

Where is it again?

John Andrews is an aviation expert who testified

about the circumstances of the Cerritos disaster.

The, uh, pilot of the Piper

was navigating by visual landmarks,

possibly attempting to follow, uh, parallel to a freeway.

And that he had become, uh,

confused about which freeway he should have been following.

New to California, perhaps bewildered

by the tangle of freeways below him, Kramer may have

flown into the Terminal Control Area, without knowing it.

There are no lines on the ground that says the TCA

starts here and at this altitude.

You have to look at a chart. You have to interpret that.

Investigators are now confident they can explain

why Kramer was inside the controlled airspace of the TCA.

But when he finally gets a look at the air traffic control

radar record, Richard Wentworth is convinced that

Walter White should have been able to see the Piper.

We were able to determine that the aircraft

that collided with AeroMexico was there to be seen.

So why hadn't White reacted to the Kramers'

plane, if it was on his radar?

When Walter White came to work that day,

the Arrivals station was being controlled by Karl Grundmann.

Hey Karl. How's it goin'?

Hey. Slow, slow, slow.

Grundmann believes that long standing radar

problems were the reason White didn't see the Kramers' plane.

Controllers had been

complaining about the radars for a long time.

We had reported problems with radar, uh,

not picking up targets several times.

When radar signals strike a target--

they bounce back to the receiver.

But if buildings or mountains interrupt the radar,

the return signal can disappear.

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. I think I lost one.

There were also holes that were just

because the radar was old.

It was just not as accurate as it might have been.

It was not state of the art equipment, that's for darn sure.

There's an effect called flicker, when a

computer becomes overloaded, the scope will flicker every now

and then, targets will drop out or can drop out.

We reviewed that data.

We had no evidence that there were any

malfunctions of any systems in Los Angeles.

There is another possible explanation.

If the Cherokee had appeared on the radar -

White still could have missed it.

Investigators focus on the other plane in the sky that day -

the Grumman Tiger.

Private planes are required to contact air traffic control

if they are entering the Terminal Control Area.

But the Tiger was already deep into the TCA

before it radioed Walter White.

Uh, one approach six-six Romeo

is on a flight from Fullerton.

Cruising altitude is 4-thousand, 5-hundred. We'd like following.

Grumman six-six Romeo.

Are you at 4-thousand, 5-hundred right now?

Negative. We're at 3-thousand,

4-hundred and climbing.

Okay, you are right in the middle of a TCA, sir.

There was an aircraft that was east of the airport,

which he became involved in.

That was what they called the violator.

Grumman six-six-Romeo,

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

You just had an aircraft pass right...

The problem with the conversation

between the controller and the pilot of the Grumman

is that it went on too long.

Why were you so mesmerized by the Grumman?

I thought he posed a risk.

This occurred during a critical time at which

the two aircraft to the southwest of his display,

which was the AeroMexico and the Cherokee, were merging.

But even if the Cherokee's signal did

appear on White's radar-- and even if he had seen it--

investigators discover that White still would not have

had all the information he needed.

Radar signals only show controllers

that a plane is in range.

Transponders on planes can broadcast other information--

including height and speed.

But at the site of the Cherokee wreckage, investigators

discover the plane's transponder is a basic model.

It only sends out information on the plane's direction.

It provides no information about the plane's altitude.

So these controllers were pretty much

used to see a little triangle, which represented a VFR aircraft

with no altitude readout, traversing all over the place.

And, unless they learned firsthand from the pilot,

they had an expectation that the aircraft would not

intrude into that airspace.

Grumann six-six Romeo. Squawk four-five...

Investigators believe that

White's divided attention-- perhaps made worse by an

older radar system-- explains why air traffic control never

warned the DC-9 of the danger posed by Kramer's Cherokee.

Find any landmarks that we might be

able to use as a visual.

But there's another mystery that hasn't been solved.

Studying the radar records from the day--

NTSB investigators are startled by what they find.

Neither the crew of the DC-9s, nor the pilot of the smaller

Cherokee took any evasive action before the crash.

Both pilots appear completely unaware of each other.

Why hadn't the pilots of either airplane, reacted?

Visibility was over 20 kilometres.

How could two planes collide in the clear blue sky?

To try to get a better sense of what was

happening inside the AeroMexico cockpit, investigators

listen to the airplane's cockpit voice recorder.

VALDEZ-PROM: Los Angeles approach,

this is AeroMexico four ninety-eight.

The flight crew had put

Walter White on their overhead speakers.

The microphone for the cockpit voice recorder was

right beside the speakers.

approach, depart Seal beach heading three two zero.

Much of what the pilots said

was drowned out by White's voice.

The radar information paints a puzzling picture.

It indicates that, for more than a minute,

the Kramer's Cherokee was there

to be seen by the AeroMexico crew.

And if the Kramers had looked out their right side window,

they would also have seen the Aero Mexico jet.

But neither plane altered its course.

Neither plane took any action to avoid the deadly collision.

Investigators believe that

if William Kramer was indeed lost - and using the highways

as a guide - he might never have seen the approaching DC-9.

The window he would have been looking out was the pilot's

window - but the DC-9 was coming from the other direction.

This would have been a very unfortunate, uh,

situation, because the DC-9 was approaching from the far right

side and, in fact, could not be, could only be seen out the

passenger's window, which was on the right side of the aircraft.

For the crew of the DC-9,

the very size of the much smaller Cherokee could have

prevented them from seeing the plane before it was too late.

In some cases,

when a small aircraft is closing very rapidly,

by the time the aircraft becomes large enough for you

to easily see it, it's almost too late to avoid the collision.

Uh, the FAA generally, uh, has taken a,

sort of as a rule of thumb, that you need about twelve

seconds in order to see an aircraft, decide that it's

a threat and then execute an avoidance maneuver.

In the case of the collision in Cerritos,

by the time the aircraft became large enough to see,

you were down very close to that twelve-second limit.

In case after case of mid-air collisions,

we find out that the aircraft gave no indication that they

saw each other until the time they actually collided.

The design of the cockpit windshield may also

have contributed to the disaster.

It's possible that, during part of the approach,

at least for one of the pilots,

the aircraft was actually behind the centre post.

And, unless the pilot moved his head back and forth,

uh, to clear that air space,

unless he had a reason to do that, it's possible

the aircraft was obscured during part of the time in which

he might have had a chance of seeing the other aircraft.

The disaster over Cerritos revealed several

tragic weaknesses in the air traffic control system.

One of the most glaring; was that pilots could not be

relied on to see and avoid each other.

They'd need new technology to keep a mid-air

collision from happening again.

A small California neighbourhood is

rocked by a terrifying plane crash.

Eighty-two people are killed

when a private plane slams into a large passenger jet.

The devastation is enormous.

More than a dozen houses are damaged--

several leveled completely.

The NTSB report makes it clear that there are glaring

problems across the air traffic system.

And these concerns must be addressed before,

inevitably, there is another midair disaster.

The FAA, which regulates the airline

industry in the United States, acted swiftly to improve safety.

A new kind of transponder was required for smaller planes.

The kind that might have helped air traffic controllers

recognize that the private aircraft posed a danger.

If you had an aircraft that flew under a controlled

air space, you would have a transponder and you would

be required to have altitude encoding or reporting.

That way it would be no mistake as to

whether you had an intruder or not.

A new system, called Mode C intruder was also

developed, to warn Air Traffic Controllers.

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 oral alert,

thus giving him time to provide a timely warning to the pilot.

Range check. VALDEZ-PROM: Seatbelts.

Even for the most diligent pilot,

the old strategy of see and avoid had serious limitations.

Those limitations would be addressed with the most

important innovation of all.

The major technological innovation that came out

of the Cerritos midair was the congressional mandate that all

air carrier aircraft operating within the United States would

be outfitted with T-CAS, traffic collision and avoidance system.

John Andrews worked on the team that developed T-CAS.

The T-CAS - Collision Avoidance System -

which was under development, uh,

quite possibly could have prevented this accident.

T-CAS gives the pilot a traffic advisory at forty-five

seconds before the potential collision.

VALDEZ-PROM: Hey Maria, everything ok back there?

And then, at approximately twenty-five 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.

Today, commercial airlines

around the world use T-CAS.

The pilot of the Grumman Tiger,

the so-called third pilot whose actions may have played

a part in the crash was eventually charged for flying

into controlled airspace in a careless and reckless manner.

For Walter White,

the effect of the disaster over Cerritos could not be overcome.

Walter came back, uh, to the TRACON and I think it

was probably a month or so later.

And I can't give you exactly how long he stayed there

but it wasn't very long.

And he just got up and said 'No, no thank you.'

Uh, and as far as I know, he didn't talk to airplanes again.

Within a year of the incident,

the old radars at LAX were replaced.

In Cerritos memorial garden now marks the day of the disaster.

Mary Wong has since remarried,

but the pain of returning home that day will never go away.

There's nobody here. The house is empty.

Derek was already living in an apartment in San Diego

and here I was.

I was no longer a mother, except to Derek

and I was no longer a wife.

And so it shattered my whole world.

Days after the disaster, Mary Wong met

one of the few people who could fully understand her loss.

I went to the memorial service and it

was very important to me to try to meet somebody else who

had gone through this.

And I knew from reading stories that Theresa

had lost her husband and two children.

And so I saw someone there who I thought was Theresa.

She says, 'Are you Theresa Estrada?'

I said, 'Yes I am.'

She says, 'Well my mar, my name is Mary Wong

and, uh, she says...

I said, 'I lost my husband and children also.'

I, I just wanted to grab her

and hug her because she was feeling what I was feeling.

So we had an immediate connection and we've

maintained our friendship over these twenty years.

Everyone who flies to day has been

affected by the mid-air collision over Cerritos.

The disaster led to historic improvements in aviation safety.

Since the full adoption of the T-CAS system, there has not

been another mid-air collision in the United States.