Original subtitles

Just another hazy day.

Watch it.

NARRATOR: A high speed collision over the California

desert tears two planes apart.

What the hell were those guys doing up there?

Doc, we're going down.

NARRATOR: Seven years later, a 727 and a Cessna

crash into a San Diego suburb.

How did this happen again?

[non-english]

NARRATOR: When two passenger jets collide in India,

it's the world's deadliest midair collision.

Two fires on the ground, confirm?

NARRATOR: With thousands of flights in the air every day,

investigators need to find out where the system failed

before another disaster occurs.

Forget the red tape.

This is in the interest of aviation

safety and saving people.

WOMAN 1: Ladies and gentlemen, we are starting our approach.

PILOT: We lost both engines.

MAN 1: Mayday, mayday.

WOMAN 2: Brace for impact!

MAN 2: It's going to crash.

NARRATOR: Los Angeles International Airport.

Hughes Airways flight 706 prepares for takeoff.

There are 44 passengers on board.

The flight is traveling from Los Angeles to Seattle

with several intermediate stops.

Welcome aboard, folks.

We'll be getting underway any minute now.

NARRATOR: Former Air Force pilot captain Theodore

Nicolay is in command today.

He has amassed more than 15,000 flight hours.

AIR TRAFFIC CONTROL: Air West 706 Red cleared

for takeoff, runway 24 left.

Climb via heading 250.

Roger, 24 left, climb heading 250.

NARRATOR: First officer Price Bruner

has even more hours in the air than Captain Nicolay.

Weather's there's looking clearer all the way to Seattle.

Throttles are all yours.

PRICE BRUNNER: 80 knots.

NARRATOR: At 6:02 PM, the DC-9 lifts off from LAX.

AIR TRAFFIC CONTROL: Turn right heading 060.

AirWest 706 Red right 060.

NARRATOR: The heading takes the plane west over the Pacific

Ocean before turning northeast towards its first stop,

Salt Lake City.

4 minutes after takeoff, first officer

Bruner contacts a different control center north of LA.

Los Angeles center, good evening.

AirWest 706 red, turn left, heading

040 until receiving Daggett.

NARRATOR: The controller's guide the DC-9 out of Los Angeles.

In addition to AirWest, the radar controller

may have been talking to five or six other jets

climbing out towards the northeast in addition

to a small number of criss crossers back and forth

through the airspace.

NARRATOR: Suddenly, an emergency alarm

warns the controllers that a plane in their airspace

may be in trouble.

ROGER ANDERSON: At this point, we look back.

Where AirWest 706 is, the target's missing.

The radar controller said something like--

Hughes AirWest 706, reset your transponder.

Radar contact lost.

There's no answer.

AirWest 706--

Radio check, how do you hear me?

No answer.

This is getting bad.

Now we've lost the target.

And we've got no communications with the aircraft.

[screaming]

NARRATOR: Moments later, the crew of a nearby military plane

calls in devastating news.

Center, we've just seen an explosion

on the side of a mountain.

NARRATOR: The DC-9 with 49 people on board

has slammed into the California hills.

Did AirWest just explode?

It had crashed for some reason.

And we had no idea whatsoever.

NARRATOR: The National Transportation

Safety Board assigns one of its top investigators to the case.

Yeah, got it.

NARRATOR: Second World War Navy pilot Dick Baker.

San Gabriel Mountains.

NARRATOR: The crash site is in a remote area of the San

Gabriel Mountains, a few miles from the town

of Duarte, California.

In the hours after the crash, witnesses come forward

insisting they saw a mid-air collision between the DC-9

and a fighter jet.

Investigators are stunned.

How did a fighter jet and a passenger plane

end up on a collision course?

OK, thank you.

Bye bye.

NARRATOR: A call from a nearby Marine Corps base

provides a key detail.

El Toro is missing a jet.

NARRATOR: An F-4 Phantom hasn't made it back to nearby El

Toro Marine Corps Air Base.

It's the military's most advanced

fighter, capable of outmaneuvering almost

everything else in the sky.

In the '70s, there was lots of military training going

on in Southern California because there were

clear skies and lots of desert out there

that they could train over.

NARRATOR: Investigators learned the identities of the F-4's two

crewmen, marine pilot James Richard Phillips

and radar intercept officer Christopher Schiess.

Watch it.

NARRATOR: Remarkably, after the impact,

Lieutenant Schiess was able to eject from the doomed fighter.

Dick Baker.

NARRATOR: The Marines send their own man

to help with the investigation, Lieutenant Colonel Jack Zeich.

Investigators hunt for clues as to how

these two planes collided.

But recovering the wreckage from the remote crash site

will take time.

REPORTER: The first rescue workers had to hike

six miles to get to the scene.

They reported only the tail section intact,

no signs of life.

NARRATOR: A day after the crash, investigators

get a chance to talk to the accident's sole survivor.

The DC-9 hit us like this, his nose to our tail.

Hold on, back up a bit.

Tell me exactly what happened.

NARRATOR: Lieutenant Schiess claims that his aircraft was

not at fault. On the day of the crash,

Schiess was flying in the rear seat of the F-4.

Copy Rick, climbing 15,000.

NARRATOR: 27-Year old Lieutenant Rick

Phillips is in the forward seat, flying the jet.

They're on their way back to home base, El Toro, California.

Climb to 15,000 feet here.

NARRATOR: Schiess uses his radar to scan the ground below.

He would have his head down in the radar scope, doing ground

mapping.

And then the front seater would be primarily visual because he

knew that he lost that extra set of eyes that

was down in the radar, instead of looking

out for other aircraft.

Watch it, Rick!

That's when I first saw the DC-9.

Came out of nowhere and slammed into us.

NARRATOR: 5 seconds later, Schiess ejects.

I got out.

But Rick didn't.

NARRATOR: The F-4 was not equipped with a black box that

can confirm Schiess's story.

And the high speed impact obliterated

the jet, leaving no clues.

Luckily, the team recovers some of the wreckage of the DC-9,

including the black boxes.

But they're badly damaged and offer little help.

Hughes AirWest engineer Dave Knutsen

is brought in to see if the wreckage supports

the young lieutenant's story.

By reconstructing the DC-9 Knutsen

might be able to explain the angle of impact.

Climbing through 15,000 feet.

Just another hazy day.

[explosion]

NARRATOR: 10 days after the crash,

searchers find the nose of the DC-9.

It's a critical piece for the reconstruction.

It reveals a large gash, slicing to the cockpit.

It looks like the stabilizer cut the plane in two.

So if they hit like this--

The F-4 had actually penetrated the DC-9 on the left

side a few feet from the nose.

So frankly, the F-4 hit the DC-9 rather than the DC-9

hitting the F-4.

Watch it, Rick!

Cut off the nose of the airplane.

And that took away all the controls in the airplane.

And some of the observers on the ground

said it was like a falling leaf till they hit the ground.

NARRATOR: Investigators know that Schiess

was wrong about who hit whom.

But why couldn't the pilots see each other

and avoid a deadly collision?

to explain how a DC-9 and an F-4 fighter

collided over California.

They wonder how fast the planes were traveling

at the moment of impact.

The F-4 is coming in at 420 knots from the north,

slightly east.

The DC-9 is coming in at 320 knots from the southwest.

What's the rate of closure?

I was able to calculate the closing

speed of these two planes was roughly 1,000 feet per second.

NARRATOR: In the seconds before the crash,

Lieutenant Schiess likely had his head down, checking

the ground below his radar.

Pilot Philips is likely scanning the instruments.

At 15 seconds, the F-4 is 1/10 of an inch big in the window,

tiny.

10 seconds, 3 tenths of an inch, still tiny.

But maybe now he can see it.

5 seconds, the entire window is filled.

The probability of these two aircraft,

either one, detecting and avoiding the other

was slim and none.

NARRATOR: Investigators suspect the design of the DC-9 cockpit,

with its wide window dividers may have made the visibility

problem even worse.

You can't see it here, nor here or--

NARRATOR: The F-4 would have been hidden--

--or here.

It's completely obstructed.

NARRATOR: --for close to 25 seconds.

Just another hazy day.

Watch it!

NARRATOR: None of the pilots had enough time

to see the oncoming plane.

But air traffic controllers are supposed

to keep planes a safe distance from each other.

So why did they fail to separate the planes?

AirWest 706 Red, turn left, heading

040 until receiving Daggett.

NARRATOR: The controllers revealed to investigators they

couldn't see the F-4 either.

Why did the F-4, the Marine aircraft,

not show up on the radar?

The hell happened?

NARRATOR: Investigators examined the radar equipment

used at the control center.

What they discover is alarming.

It was nothing more than World War II technology.

And temperatures generated by this equipment

would cause the equipment to drift drastically.

NARRATOR: To better understand what the controllers could

and could not see, investigators test the technology

by flying an F-4 along the flight

path on that fateful day.

Did the outdated radar pick up the F-4?

Was that something there?

The F-4's traveling almost 500 miles an hour.

The F-4 does six runs.

But the controller can barely track

the fast, stealthy fighter.

It might have been a plane, maybe not.

It could just be interference that was

shown frequently on the radar.

A single blip means absolutely nothing.

We have to have a history of blips

to see that it's actually traffic.

NARRATOR: Investigators conclude it would have been almost

impossible to detect the fighter jet

as it streaked across the sky.

He's all alone.

And no one knows he's there.

NARRATOR: To make matters worse, in 1971,

military pilots were not routinely briefed

on civilian air traffic routes.

RICK PHILLIPS: We should stay clear of traffic

if we cut east of Los Angeles.

NARRATOR: Schiess tells investigators

that they hoped to avoid commercial air

traffic by skirting the city.

Unintentionally, they flew into one

of the airport's busiest lanes.

Why did the F-4 crew not get ahold of an air traffic control

guy to let them know where they were and what they were doing.

The terminal area charts would show those departures.

But the military doesn't have those

because they don't operate out of Los

Angeles International Airport.

NARRATOR: Investigators uncover a dangerous flaw in

the American aviation system.

The military and civilian control centers don't

communicate with each other.

Bang.

NARRATOR: The pilots had no idea they

were flying toward each other at the same altitude.

Would we have done anything different?

No, absolutely not.

It was just something that happened.

We could not have changed it, not us.

NARRATOR: The exhaustive investigation

produces two separate reports, one civilian and one military.

They cover every detail of the deadly accident.

How military and civilian authorities

failed to communicate they had planes

flying in the same airspace.

Was that something there?

NARRATOR: How controllers couldn't track

the supersonic fighter jet.

And why the crew of a DC-9 44 passengers on board

never saw them coming.

The reports led to important changes

in the rules governing aviation.

Military pilots, as a result of this accident, everybody

had to be on radar control.

And that means being controlled by radar

operators on the ground.

NARRATOR: Military pilots are now

advised of all restricted air traffic

zones near commercial airports.

And the restricted airspace at busy airports

is expanded to include more of the surrounding area.

Hughes AirWest was sold in 1980 and eventually

folded into Northwest Airlines.

But the legacy of the company's deadliest accident endures.

TODD CURTIS: One of the things that came out of the Hughes

AirWest F-4 midair collision was a need

to have better communication between the aircraft that

are flying and with air traffic control.

Tragically, it wasn't one that was implemented

perfectly in the future.

NARRATOR: Seven years later, California residents

face another disaster as two planes collide over San Diego.

NARRATOR: Pacific Southwest Airlines flight 182

is on an early morning run down the coast of California

from Sacramento to San Diego.

Approach PSA 182 coming out of 95 descending to 7,000.

Airport is in sight.

NARRATOR: First officer Bob Fox is at the controls

of the Boeing 727.

Captain Jim McFeron has been with the airline for 17 years.

PSA 182, clear visual approach, runway 27.

Thank you, cleared visual approach 27.

NARRATOR: There are 128 passengers on board, including

30 Pacific Southwest employees.

An approach controller at a facility north of the airport

monitors flight 182.

APPROACH CONTROLLER: --11,000 until further advised.

The approach control facility is quite busy.

And that's stressful because you're

handling so many different airplanes in the same airspace.

NARRATOR: When the controller spots

a Cessna flying ahead of the 727,

he makes sure they can see it.

PSA 182, traffic's at 12 o'clock,

three miles out, 1,700.

Got it.

Traffic in sight.

OK, sir.

Maintain visual separation.

Contact Lindbergh tower 133.3.

Have a nice day.

OK.

Visual separation means that the pilot has another aircraft

in sight and acknowledges it.

Got it.

Once the visual approach is accepted by the pilot,

he's then responsible for maintaining

separation from that traffic.

NARRATOR: With the plane now less than five miles

from the runway, a controller in the airport's tower

takes over to guide the flight in for landing.

PSA 182, cleared to land.

182, cleared to land.

Gear down.

NARRATOR: Suddenly, first officer

Bob Fox spots a distant plane.

There's one underneath.

I was looking at that inbound over there.

[explosion]

[screaming]

Tower, we're going down.

This is PSA.

OK, we'll call the equipment for you.

[tense music]

Get over here.

NARRATOR: The approach controller's radar

reveals that the 727 has collided with the Cessna.

Jesus Christ.

[explosion]

REPORTER: Hundreds of people watched in horror as the two

planes collided and crashed into a quiet San

Diego residential neighborhood.

NARRATOR: 144 people are dead, including 7 on the ground.

22 homes are destroyed.

It's the biggest airline disaster

in American history to date.

The PSA accident in 1978 I think

was the lynchpin when the United States government and aviation

world in general figured out we have

to do something about this.

NARRATOR: Two hours after the crash,

NTSB investigator Wally Funk arrives from Los Angeles.

WALLY FUNK: The accident scene was horrendous.

There was so many bits and parts and pieces

around, not only the aircraft but the homes.

NARRATOR: Funk needs to confirm that the wreckage

of a small plane found six blocks away

is in fact what collided with the 727.

We had paint transfers.

We had pieces and parts from the two different aircraft.

Yes, this was an absolute midair collision.

There's no doubt about it.

NARRATOR: But how did these two planes end

up on a fatal collision course?

We had to visualize from a very mangled mess of metal

where the two came together.

NARRATOR: Fortunately, the 727's black boxes

are recovered from the crash site

and rushed back to Washington, DC for analysis.

Meanwhile, senior NTSB investigator Phillip Ho

joins the team.

He's eager to speak with the approach controller.

Can you show us the two flight paths?

So the 727 was flying east to do a turnaround

and land on runway 27.

And the Cessna was flying northeast.

But it was miles ahead of the 727.

They should have missed each other by over a mile.

NARRATOR: To verify the approach controller's account,

investigators review a transcript

of his conversation that day.

It confirms that both pilots knew each other's positions.

PSA 182, traffic's at 12 o'clock, three miles out 1,700.

Got it.

NARRATOR: But if both planes knew of each other,

why did their aircraft collide?

Investigators question why the approach controller didn't warn

the pilots when they were dangerously close,

especially since his radar would have sounded a proximity alarm.

Didn't you get any warning?

We did.

We ignored it.

Well, when the alert sounded, I mentioned it to my supervisor.

[alert noise]

Alarm again.

I talked to both planes.

PSA 182 has confirmed a visual sighting of the Cessna.

We're not expected to contact the pilots if they're

flying by visual rules, not to mention,

we get about 13 alarms a day.

NARRATOR: The approach controllers overlook the alert.

But they contact the Cessna and remind them of the nearby 727.

Traffic in your vicinity.

PSA jet has you in sight.

He's descending for Lindbergh.

NARRATOR: But at that exact moment, the planes collide.

Get over here.

Investigators now interview the tower

controller to better understand why he also

failed to warn both pilots.

They discover he relied on an even less sophisticated radar.

The tower controller did not have the collision alert system

at the time.

When the controller saw the planes

within a mile of each other, he made contact, warning the 727.

PSA 182, traffic 12 o'clock, one mile.

I think he's passing off to our right.

Yeah.

If the pilot says he's passing off to our right,

this implies that he's still maintaining visual separation.

It was his responsibility.

And you would not worry about it.

NARRATOR: After talking to both controllers,

investigators still have no answer to the key question

in the midair collision.

Who crashed into whom?

Now, let's have the next acetate please.

NARRATOR: But when they calculate

the two planes' actual radar tracks,

the answer becomes clear.

The 727 has rear ended the Cessna.

The Cessna never passed off to the right.

He was always in front of PSA.

I was looking at that inbound over there.

NARRATOR: The 91 ton aircraft, flying at 160 knots,

slammed into the much slower and lighter Cessna.

The PSA crew, when they acknowledged

they had the Cessna in sight, at that moment

became responsible for keeping the airplanes separate.

NARRATOR: So how did the veteran 727 crew lose sight of a plane

directly in front of them?

review the recovered cockpit voice

recording of PSA flight 182.

All right, hit it.

NARRATOR: They hope the pilots' conversation will explain how

they lost sight of the Cessna.

BOB FOX: Were we clear that Cessna?

JIM MCFERON: Supposed to be.

BOB FOX: Oh yeah, before we turn down land,

I saw him about 1 o'clock.

Probably behind us now.

Stop it.

NARRATOR: 35 seconds before impact, the PSA crew think

they've passed the Cessna.

It was right in front of them the whole time.

NARRATOR: Investigators wonder if something

was preventing the pilots from seeing the much smaller plane.

The 727, when it's flying in level flight,

is a slightly nose up condition.

So that the pilots, as they look out,

they're looking over the nose of the airplane.

Was the nose of the aircraft high?

And they didn't see the Cessna, they

may not have realized the Cessna was as close as it was.

NARRATOR: The team conducts a visibility study to determine

how long the PSA crew could see the Cessna

through their windscreen.

After measuring and photographing each pilot's

view, they plot the Cessna's location on the photos

in 10 second intervals.

What they find is surprising.

The PSA crew could see the Cessna for a much longer period

than they expected.

170 seconds of clear view.

NARRATOR: How did the pilots lose track of a Cessna

when it was in view for almost 3 minutes?

Searching for answers, investigators

go back further in time on the cockpit recording.

AIR TRAFFIC CONTROLLER: Traffic at 12 o'clock, three miles out,

1,700.

Got it.

Traffic in sight.

NARRATOR: 85 seconds before impact,

the 727's pilots spot the Cessna flying ahead of them.

OK, sir.

Maintain visual separation.

Contact Lindbergh tower, 133.3.

NARRATOR: The crew must now keep the Cessna in view

while performing other tasks in preparation for landing.

Lindbergh, PSA 182, downwind.

The wings need to be configured.

The landing gear must be lowered.

Systems have to be adjusted.

So it's a busy place.

NARRATOR: But at this critical moment,

no one is keeping an eye on the Cessna.

Is that the one we're looking at?

Yeah, but I don't see him now.

The Cessna should be right here in front of them.

The Cessna was visible just at about the windshield level

of PSA.

And it's really incredible.

Somehow, they lost sight of it.

OK, can you show me how you normally

adjust your seat, please?

NARRATOR: To better understand how the PSA crew lost sight

of the Cessna, investigators take another look

at the cockpit visibility.

Pilots come in all sizes and shapes.

They learn quickly to adjust the seats to the position that's

comfortable.

Some pilots want to sit lower so they can

see their instruments better.

NARRATOR: When they recalculate the Cesnna's location

on the windshield based on the crew's seat positions,

they make a shocking discovery.

Instead of 3 minutes, the crew would only have seen

the Cessna for 5 to 10 seconds.

Even if the crew had leaned forward to check for the plane,

investigators believe the smaller plane may have been

camouflaged by the background.

They become harder to see.

And the terrain makes it even more so.

Is that the one we're looking at.

Yeah, I don't see him now.

NARRATOR: The fate of flight 182 now

depends on the captain clearly communicating this

to the tower.

I think he's passed off to it right.

NARRATOR: The controller would have been

able to see that the Cessna had not

passed the 727 on his radar.

So why didn't he take action?

AIR TRAFFIC CONTROLLER: OK, we had him there a minute ago.

NARRATOR: Investigators compare two separate recordings

of the conversation between the captain and the controller.

OK, Chris, let's hear the cockpit first.

JIM MCFERON: I think he's passed off to our right.

Passed.

I thought I heard passing before.

Double check that, please.

JIM MCFERON: I think he's passed off to our right.

He's still saying pass.

Let's compare it with the tower because I

think I heard passing.

NARRATOR: Investigators make a startling discovery.

BOB FOX: He's passing off to our right.

Passing, I was right.

It does sound like passing.

NARRATOR: Radio static caused the radio

controller to hear the word "passing," not "passed."

The air traffic controller heard it as he's

passing off to our right.

That indicated that they still have visual contact with him.

You would believe that the pilot

was being able to maintain the separation.

It was his responsibility.

And you would not worry about it.

NARRATOR: In the spring of 1979, investigators finally

conclude who was at fault.

The determination of the board's report

is very clear that the crew obviously did not

see the aircraft, the Cessna, in time

to divert it away from a catastrophic accident.

NARRATOR: Recommendations in their report

focus on improving the air traffic

control system in San Diego.

PSA 182 also helped fuel the search for new technology.

Three years after the accident, a safety device

called TCAS, or Traffic Collision Avoidance System,

is developed and later installed in all passenger aircraft.

TODD CURTIS: All airliners are now

equipped with fairly sophisticated

collision avoidance systems.

They have the ability in the cockpit to get instant feedback

to avoid other airliners, including

instructions as to what they should

do to avoid that airliner.

279, good day.

NARRATOR: Unfortunately, in some corners of the world,

aviation developments don't come soon enough.

In 1996, tragedy strikes again when two passenger

jets collide over India.

[screaming]

New Delhi, a gateway to India.

Just past 6 o'clock, Saudi Arabia Airlines Flight 763

takes off into the sunset.

Gear up.

Gear up.

Clear on left.

NARRATOR: Captain Khalid Al-Shubaily powers the Boeing

747 away from the runway.

His copilot, Nazir Khan, handles all radio communication.

289 passengers on board are traveling

to Duran, Saudi Arabia.

279, good day.

NARRATOR: Shortly after takeoff, approach controller VK Dutta

guides the plane away from the airport.

Saudi 763 approaching flight level 100.

Roger, climb flight level 140.

Clear to climb 140, Saudi 763.

NARRATOR: After reaching 14,000 feet,

the crew request permission to continue their ascent.

Roger, maintain flight level 140.

Standby for higher.

NARRATOR: In order to coordinate incoming and outgoing traffic,

Dutta wants the Saudi flight to stop climbing.

Saudi 763 will maintain 140.

NARRATOR: The controller is concerned about another plane,

a Kazakhstan Airlines Aleutian 76

passenger jet which is coming in for landing

at Indira Gandhi airport.

He wants it to pass 1,000 feet above the Saudi flight

before landing.

After that, he'll have the Saudis continue their climb.

Kazakh 1907 now reaching 150, 46

miles from Delta Papa November.

Roger, maintain flight level 150.

Identify traffic 12 o'clock reciprocal, Saudi Boeing 747.

NARRATOR: Dutta warns the Kazakh flight of the nearby Saudi jet.

PILOT: How many miles?

Traffic is at 8 miles level 140.

NARRATOR: But seconds later--

[screaming] --a massive explosion

tears through the Saudi jet.

[shouting]

Both the Saudi and Kazakh flights have vanished

from the controller's radar.

Saudi 763?

Kazakh 1907, report position.

So I run the sweep again.

They were not there at all.

[tense music]

NARRATOR: A call from a nearby US Air Force pilot

confirms the worst.

Two distinct fires on the ground.

Two planes have gone down over Charkhi Dadri.

NARRATOR: In the hours following the horrific collision,

recovery teams find the wreckage of the Kazakh and Saudi

aircrafts 4 and 1/2 miles apart.

The two planes were carrying 349 people.

There are no survivors.

It's the worst midair collision of all time.

The death toll is terrible.

It's terrible if it's several hundred.

It's terrible if it's even one person.

But what has to be true, no matter

how many people are killed in an event,

is what are we going to do about it?

NARRATOR: The next morning, captain

KPS Nair is one of the first investigators on the scene.

I was just horrified.

It is something which I can't explain.

NARRATOR: Investigators have two separate crash

sites to examine.

But they know one cause will explain both accidents.

Thankfully, the black boxes from both aircraft are found.

While investigators wait for the data to be recovered,

they focus on conversations between the two planes

and the air traffic controller.

Hi, I'm VK Dutta.

Have a seat.

NARRATOR: They want to know everything that Dutta

did on the night of the crash.

Was traffic heavy?

Evenings are always busy.

NARRATOR: Unlike most modern systems,

Dutta's radar doesn't track a plane's altitude.

Instead, controllers write a plane's last reported position

on a strip of paper.

VK DUTTA: This is the Kazakh one.

And this is the Saudi one.

Kazakh 1907, now reaching 150.

NARRATOR: Dutta was supposed to ensure

that the two planes were 1,000 feet apart

as they approached each other.

Roger, maintain flight level 140.

Standby for higher.

NARRATOR: To confirm Dutta's instructions,

investigators review the air traffic control transcripts.

They learned that Dutta gave the two

planes the proper directions.

Roger, maintain flight level 140.

Standby for higher.

NARRATOR: Since his radar system doesn't display altitude,

there was no way for him to tell if the planes followed

his orders.

Mostly there and there, as close as you can get it.

NARRATOR: One of the planes must have drifted

from their assigned altitude.

But which crew is responsible for the fatal collision?

Investigators in India catch a break when engine pieces

of the Saudi aircraft are found near the beginning

of the debris field.

It reveals that they were some of the first pieces

to come off the plane after the collision.

KPS NAIR: The significant point of contact

was between the tail end of the IL 76

and the wing portion of the Boeing 747 of Saudi.

NARRATOR: The tail of the Kazakh plane

appears to have pierced through the left wing of the Saudi jet.

Surprisingly, the Kazakh flight wasn't

above the Saudi jet when they collided,

as air traffic controllers thought.

Between two aircraft, the requirements

specify a vertical minimum separation of 1,000 feet.

NARRATOR: Investigators wonder which plane

was at the wrong altitude.

Unfortunately, the recovered cockpit instruments

provide little help in verifying the aircraft's

positions at impact.

I can't find anything.

Too much damage.

I agree.

Look at this.

NARRATOR: Having learned all they can from the crash site,

the fate of the investigation now

lies in what details are stored in the flight data recorders.

Three months later, data from both

the Kazakh and Saudi black boxes is successfully downloaded.

In order to avoid any suggestion of bias,

the boxes are analyzed in England

by the experts at the Air Accidents Investigation Branch.

NAZIR KHAN: 279, good day.

NARRATOR: They concentrate on the data

from a Saudi flight 763 first.

Saudi 763 approaching 140 for higher.

Roger, maintain flight level 140.

Stand by for higher.

Saudi 763 will maintain 140.

NARRATOR: Both the CVR and the flight data recorder

reveal that the Saudi pilots received

clear instructions from the controller

and followed them meticulously.

It had leveled at its assigned altitude of 14,000 feet

and continued to fly level.

NARRATOR: But when investigators examined the Kazakh's flight

data, they discovered that it descended to just over 1,000

feet below assigned altitude, putting it within 10

feet of the Saudi flight.

To understand why the Kazakh plane was below its assigned

altitude, investigators turn to the cockpit voice recorder.

AIR TRAFFIC CONTROLLER: Kazakh 1907, report level passing.

Passing 240, Kazakh 1907.

NARRATOR: Because the Aleutian is a modified military plane,

it has another unusual feature, a position for a radio

operator in the cockpit.

Egor Repp handles all communications

for the Kazakh flight.

As they near the airport, Repp gets in touch

with approach controller Dutta.

I told Kazakh to descend and maintain flight level 150.

That is 15,000 feet.

VK DUTTA: Kazakh 1907, now reach 150.

NARRATOR: It's 1 minute before impact.

And the Kazakh plane is in position 1,000 feet

higher than the Saudi plane.

But investigators know that instead of leveling off,

the plane continued to descend.

As it does, Dutta issues a traffic

warning to the Kazakh pilots.

Identify traffic, 12 o'clock reciprocal Saudi

Boeing 747 and 10 miles.

Likely to cross in another five miles.

Report if in sight.

NARRATOR: He tells them to watch out for the Saudi flight.

But the Kazakh jet just keeps flying lower.

Ahead?

Ahead.

NARRATOR: Suddenly, the radio operator recognizes

the plane is flying too low.

Keep to 150.

Do not descend.

Accelerate.

NARRATOR: But his warning comes too late.

Get to the 150, because after 140.

NARRATOR: Investigators are stunned.

Why weren't the pilots monitoring their altitude?

Report 8 miles.

NARRATOR: They go back to earlier in the recording.

While Repp communicates with the ground,

neither the pilot nor co-pilot confirm

the altitude instructions.

Switch on, engine inlet--

NARRATOR: The pilots are busy discussing arrival procedures.

Repp appears to be the only one focused on their altitude.

Pull up the level.

What level were we given?

NARRATOR: The final report points the finger squarely at

the crew of the Kazakh plane.

The Kazakh pilots' failure to maintain altitude

led to the deaths of 349 people.

Investigators are also critical of the outdated radar that

was being used in New Delhi.

Today, new radar systems allow controllers across the country

to see an airplane's flight number, altitude, and heading,

preventing midair collisions from ever happening again.

It's not a matter of who did something wrong.

It's a matter of how can we change

the way we do business to make sure this can't happen again.

Not that it is unlikely, but that it can't.