Original subtitles

FE. KRICK: Power set.

[Explosion]

NEWSCAST (Archive): A TWA Flight 800 has exploded in mid-air.

NARRATOR: The sea is on fire.

BOB: It was a horrible thing.

NARRATOR: 230 lives are lost.

Eyewitnesses give a frightening account.

AL: A lot of them thought they saw missiles.

JAMES KALLSTROM: My gut said it was an act of terrorism.

NTSB INVESTIGATOR: All right. Let's get to it.

NARRATOR: The search for the truth will pit crash investigators

against the nation's most respected crime detectives.

JAMES KALLSTROM (Archive): Microscopic explosive traces of unknown origin.

AL: The criminal aspect kept coming up over and over.

NARRATOR: To make their case, the NTSB will attempt

the unthinkable.

NTSB INVESTIGATOR: We're gonna rebuild the entire plane.

JAMES WILDEY: It really looks like an impossible job.

[♪ theme music ]

[♪ theme music ]

♪

AIR TRAFFIC CONTROLLER (Archive): Heavy turn here. Go left on Bravo today.

NARRATOR: It's a hot summer evening

at John F. Kennedy Airport in New York.

AIR TRAFFIC CONTROLLER (Archive): If you look off your left, eight o'clock.

NARRATOR: Trans World Airlines Flight 800

is almost an hour late for departure.

The Boeing 747 jumbo jet is carrying 212 passengers,

many of them now growing impatient

for the flight to Paris to get underway.

CAPT. KEVORKIAN: Are we gonna start placing bets

on when we actually push off?

NARRATOR: Captain Ralph Kevorkian is an experienced pilot,

but this will be just his second training flight

as a 747 captain.

BOB: All airline pilots, including captains,

are checked at least twice yearly in flight procedures

and how well they coordinate with their crew,

anything having to do with flying.

And it's just another safety measure

that the airlines go through.

CAPT. SNYDER: Twenty dollars on us getting out of here

before sundown.

CAPT. KEVORKIAN: I'll take that bet.

NARRATOR: Captain Steve Snyder has been flying with TWA

for over 30 years.

Tonight, he's conducting the line check on Captain Kevorkian

while also acting as the first officer.

Janet Christopher is one of fourteen flight attendants

on the big jet.

JANET: It'll be much cooler when we're in the air.

NARRATOR: She's doing all she can to make passengers

comfortable during the ongoing delay.

JAMES KALLSTROM: She was very, very senior,

the head stewardess on the airplane that evening.

JANET: It shouldn't be much longer.

Let me check with the captain.

JAMES KALLSTROM: Janet was on that plane that evening

because she switched with another stewardess

'cause she wanted to be home that next weekend

'cause her son Charles was gonna be given his Eagle Scout.

JANET: The crowd's getting a bit restless. Any news?

CAPT. KEVORKIAN: I haven't heard anything yet. They're still looking.

NARRATOR: The reason for the delay is that a piece of luggage

is on board but its owner is not.

This is a red flag for airline security.

JAMES KALLSTROM: We were at a very high state of alert

in the United States leading up to this

and we had all kinds of threats coming in.

Not specific to aviation but I mean real bona fide threats.

NARRATOR: The bombing of Air India Flight 182 a decade ago

was a wake-up call for the entire industry.

Terrorists checked a bag packed with explosives

onto a jumbo jet bound for Delhi. 329 people died.

Since then, all checked bags must be matched

to seated passengers before any flight can depart.

CAPT. KEVORKIAN: Your old man tell you it was gonna be

this exciting to fly with us, Ollie?

FE. KRICK: Oh yeah. It's a thrill a minute, just like he described.

NARRATOR: Flight engineer Oliver Krick is a new recruit

with only six flights under his belt.

His father is also a TWA pilot.

BOB: The flight engineer was only 25 years old.

It had to be pretty exciting for him to be a flight engineer

on the queen of the skies, the 747.

CAPT. KEVORKIAN: You wanna get in on this, Richard?

Twenty bucks. Easy money.

NARRATOR: Richard Campbell completes the cockpit crew.

He's on board to help train the young flight engineer.

Passengers wait as the minutes tick by.

GATE AGENT: TWA 800?

CAPT. KEVORKIAN: TWA 800. Go ahead.

GATE AGENT: We're reconciled. Passenger was on board the whole time.

CAPT. KEVORKIAN: Are you kidding me? Roger that.

CAPT. SNYDER: Hey, you owe me twenty.

CAPT. KEVORKIAN: Yeah, yeah. We'll settle up in Paris.

Ladies and gentlemen, from the flight deck

thank you all so much for your patience.

We've been cleared to go.

We'll be pushing back from the gate shortly.

♪

Takeoff thrust.

NARRATOR: Finally, at 8:19 pm, TWA Flight 800 is airborne.

♪

AIR TRAFFIC CONTROLLER: TWA 800, amend the altitude.

Maintain one-three thousand, 13,000 for now.

CAPT. SNYDER: TWA 800 okay, stop climb at one-three-thousand.

CAPT. KEVORKIAN: Stop climb one-three-thousand.

NARRATOR: Altitude reassignments are a routine part

of the climb out from JFK.

BOB: The airspace around New York City

is probably one of the busiest in the world.

You have not only JFK, you have La Guardia,

the Liberty Airport, Teterboro, and they all

have to mesh together air traffic control-wise.

AIR TRAFFIC CONTROLLER: TWA 800, climb and maintain one-five thousand.

CAPT. KEVORKIAN: Climb thrust.

CAPT. SNYDER: TWA 800, climb and maintain one-five thousand

leaving one-three thousand.

CAPT. KEVORKIAN: Ollie. Climb thrust.

FE. KRICK: Power set.

♪

JANET: [Gasps]

♪

CAPT. KEVORKIAN: Talk to me. What do you have for us?

NARRATOR: Without warning, a powerful explosion

tears the fuselage apart.

BOB: In the front of the airplane that broke off,

the centrifugal force had to be just horrendous

as the nose fell down.

[Screaming and chaos]

NARRATOR: The front third of the plane is gone.

What's left continues skyward engulfed in flames.

[Screaming]

JAMES KALLSTROM: It went up at least another thousand feet,

maybe fifteen hundred feet, you know,

and flames pouring off of it.

♪

[Screaming]

BOB: It had to be horrible for the passengers.

You'd have a 250, 300 knot wind all of a sudden

blasting them in the face. It was a horrible thing.

AL: The TV had shots of pieces of wreckage on fire

floating on the ocean.

NARRATOR: Debris from TWA Flight 800 litters the water

nearly 75 miles east of Manhattan.

NEWSCAST (Archive): 212 passengers, 17 crew.

212 passengers, 17 crew.

NARRATOR: Search and rescue aircraft scan the sea.

A media swarm descends on Long Island

where dozens of witnesses are describing what they saw.

WITNESS (Archive): Me and my cousin Joe, we was over by the dock over there

and we was over there crabbing and, uh, he says

yo, Darren, look in the... look up in the air,

there's a big ball of, uh, fire.

AL: You had boats coming in with pieces of wreckage on 'em

and some bodies being brought right in there

and all sorts of press people all over the place and police.

PRESIDENT CLINTON (Archive): The National Transportation Safety Board, the FAA

and the FBI are on the scene of the crash.

As of now no survivors have been found.

NARRATOR: With a nation in shock, investigators begin

the painstaking task of piecing together what happened

to TWA 800.

♪

By the next morning, it's clear

that none of the 230 people aboard TWA 800 have survived.

♪

It is the third deadliest airline disaster

in U.S. history.

The NTSB's lead investigator, Al Dickinson,

faces an urgent task.

AL: It was extremely important for us to find out what happened

because there were so many 747s flying at that time.

The NTSB will lead the investigation

while the FBI launches a parallel criminal inquiry.

JAMES KALLSTROM: You know, people think this is

the exclusive jurisdiction of the NTSB. That's not correct.

If it's a criminal matter

we have to get out there right away.

AL: We're used to a large area.

They're used to a crime scene that they can tape off.

Try taping off a couple miles worth of area out in the ocean.

It's impossible to do. So they had to learn that things

are handled a little bit differently.

NARRATOR: Both agencies are hoping for quick results.

But TWA 800 will turn into one of the longest

and most challenging investigations ever conducted.

An abandoned aircraft plant on Long Island

becomes a massive hangar for thousands of pieces of aircraft

debris being pulled from the ocean floor.

NTSB INVESTIGATOR: Yeah. You can take that just down over there.

AL: It was a perfect spot for us to put every bit of wreckage

we recovered. I mean there's piles of it.

NTSB INVESTIGATOR: Nice to see you.

JAMES KALLSTROM: I just wish it was under better circumstances.

NTSB INVESTIGATOR: I think I should show you something. Come with me.

NARRATOR: Investigators have matched the seat numbers

with the passenger and crew manifest.

They're able to determine who sat where,

including flight attendant Janet Christopher.

JAMES KALLSTROM: Her and her husband were very close friends

of my wife and I. And I happened to be in their wedding.

NTSB INVESTIGATOR: This was almost certainly Janet's seat.

♪

JAMES KALLSTROM: You look at a seat

and then you put someone that you care very much for

in that seat. It's very emotional.

NARRATOR: The FBI believes they may already have an explanation

for the disaster over Long Island.

Three years earlier in 1993, terrorists drove a bomb

into the World Trade Center.

Just over a year before, Timothy McVeigh

bombed the federal building in Oklahoma.

Now, the mid-air explosion of TWA 800

is also being linked to terrorism.

AL: It was all over the news how people thought

they saw something going up to hit an aircraft.

A lot of 'em thought they saw missiles.

JAMES KALLSTROM: There were a lot of people

that wanted to do us harm back in 1996, a lot,

and the FBI and other people on the national security front

believed it was an act of terrorism without question.

JAMES KALLSTROM: I'm sure this was a bomb

and that we'll find the evidence of that in this wreckage.

Just keep me posted.

NTSB INVESTIGATOR: All right. We'll go through it.

AL: Jim Kallstrom has a, a strong personality.

JAMES KALLSTROM: Agent.

AL: And even though he didn't say he's in charge

you got the impression from him

that he was really running the show.

JAMES KALLSTROM: Well, you know, I'd be lying to you

if I didn't tell you there was some professional tension,

and there always is.

NTSB INVESTIGATOR: All right. Let's get to it.

BOB: We tried to keep an open mind as much as possible,

and that would mean considering something like a missile

until we had some, some honest proof that that did not occur.

BOB [Archive]: Excuse us.

NARRATOR: Seven days into the investigation,

the ocean salvage team makes a major find -- the black boxes.

AL: Recovering the CVR and the FDR is very important

in every investigation.

The trouble is you never know what you're gonna get.

BOB: We sent them immediately down to Washington, D.C.,

to be read out after we found them.

NARRATOR: Technicians are able to recover the data,

but it gives investigators little to go on.

CAPT. KEVORKIAN: TWA...

NARRATOR: They hear no cockpit alarms or signs of panic from the crew.

BOB: Normal conversations in the cockpit.

Normal readouts on, on the flight data recorder

up until the point where a sharp noise was heard

and then nothing after that.

NARRATOR: NTSB investigators spend weeks carefully searching

for any sign of foul play.

They study wreckage from almost every part

of the 230-foot long plane.

AL: Pretty much the whole time we were there we were

looking for something that would support

any kind of missile or bomb.

NARRATOR: They find no signs of an explosive device.

NTSB INVESTIGATOR: No pitting. No cratering. Nothing.

JAMES WILDEY: We didn't find the, uh, soot patterns

in a radiating pattern that might have been from a bomb.

We didn't find this micro-cratering

where a hot piece of metal are impacting other pieces of metal.

NTSB INVESTIGATOR: It wasn't a bomb.

JAMES WILDEY: No piece had any evidence of a bomb at all.

NARRATOR: Investigators know the plane exploded in midair,

but they are convinced this was not a terrorist act.

JAMES WILDEY: In a way it made the Safety Board's job

much more difficult because we had to now determine

what happened if there was no bomb or missile

that caused the airplane to come down.

NARRATOR: They hope an analysis of the debris field

can provide some answers.

BOB: In an in-flight breakup whatever comes off first

may have something to do with the origin of the problem.

They divide the ocean crash site into three zones.

The Red Zone, nearest the airport,

is where the first pieces of wreckage hit the water.

The Yellow Zone is where the front third of the airplane

landed. The Green Zone contains everything else.

Investigators scour the debris from the Red Zone.

JAMES WILDEY: We had to take these pieces

and develop a sequence that showed that these pieces

would have been the first ones that came off.

NTSB INVESTIGATOR: What is this thing? Can we get a closer look at this?

BOB: The wreckage recovery started to teach us some things.

NARRATOR: They check Boeing schematics to try to identify

exactly what part of the plane they're looking at.

NTSB INVESTIGATOR: Huh. A keel beam from

the center wing section of the plane.

JAMES WILDEY: Well the keel beam runs underneath

the wing center section fuel tank and back through

the landing gear compartment.

NARRATOR: They pour through other Red Zone wreckage

feeling that they may be on the trail of a breakthrough.

NTSB INVESTIGATOR: Give me a hand with this.

NARRATOR: They soon find pieces with telltale scorch marks.

ROBERT: It had actual heat damage

that had compressed it and wrinkled it.

NARRATOR: The scorch marks and damage point to an explosion.

Now they must determine where it came from.

NTSB INVESTIGATOR: A piece of span-wise beam from the center wing fuel tank.

In the same place we found the keel beam.

NARRATOR: It's a discovery that changes the direction

of the entire investigation.

NTSB INVESTIGATOR: I think this could be it.

The explosion must have started somewhere inside the fuel tank.

ROBERT: Our first pieces came from inside

of the center wing fuel tank, and I mean right in

the heart of it.

[Explosion]

[Gasp]

CAPT. KEVORKIAN: Ollie!

♪

NARRATOR: The NTSB is certain they're making progress.

But five weeks into their investigation,

the FBI makes a shocking announcement.

JAMES KALLSTROM (Archive): As a result of scientific analysis conducted

by federal examiners, microscopic explosive traces of

unknown origin have been found relating to TWA Flight 800.

ROBERT: One of our problems right from the beginning of this

is that the FBI and others didn't have the experience

that we had and they were thinking bombs, missiles

and all sorts of other bad things.

NARRATOR: The statement directly contradicts the evidence

found by the NTSB.

JAMES WILDEY: I knew for a fact that this was not caused

by a bomb on the airplane.

NARRATOR: The FBI tests show traces of RDX and PETN,

chemicals used to make plastic explosives,

the same chemicals used in the bombing of Pan Am Flight 103

eight years earlier.

For the FBI, the evidence points in just one direction.

JAMES KALLSTROM: You know, we represent the American people,

you know, so we don't speculate.

We try not to speculate about it but, yes,

my gut said it was an act of terrorism.

[Screaming]

JAMES KALLSTROM (Archive): There's a chance, in our view a good chance,

but there's a chance this is a criminal act.

This is an act of terrorism.

NARRATOR: The NTSB employs the nation's best

air crash investigators.

Suddenly, it seems their work is in question.

AL: My thoughts about the fact that the criminal aspect

kept coming up over and over, it was frustrating.

NARRATOR: With their reputation on the line,

they decide to attempt something

that has never been done before.

NTSB INVESTIGATOR: We're gonna put all this back together again.

We're gonna rebuild the entire plane.

NARRATOR: They hope to reconstruct the entire downed 747

piece by shattered piece.

It may be the only way to prove to the world

that TWA 800 suffered no bomb damage anywhere.

It will be a Herculean task.

JAMES WILDEY: There's a picture taken from above in the hangar

of all these pieces laid out on the floor,

and there are literally tens of thousands of them,

and it really looks like an impossible job.

NARRATOR: NTSB investigators believe it was an exploding fuel tank

that took down TWA 800.

But they still don't know what sparked the blast.

AL: If you find evidence of an explosion in a fuel tank,

you have to look for what could cause an explosion to start

in there and you work backwards.

NTSB INVESTIGATOR: We need to prove three things:

The fuel was flammable, the explosion has to be

powerful enough to rupture the tank and, finally,

something created the spark to ignite the fuel.

Let's start with the first one: Flammability.

♪

NARRATOR: Jet fuel in its liquid form is not flammable,

but when heated the fuel starts to vaporize.

When combined with oxygen already present in the tank,

this vapor can become highly flammable.

At the altitude where TWA 800 exploded, almost 14,000 feet,

jet fuel needs to reach 96 degrees Fahrenheit

before it can ignite.

There's just one problem.

BOB: The manufacturer said, well,

it never gets that hot in there.

NARRATOR: According to Boeing, the fuel tanks housed

inside the wings would never get hot enough

for the fuel to vaporize.

On the day of the fatal flight, the temperature at JFK Airport

hit 87 degrees Fahrenheit, well below the flashpoint

for jet fuel. The NTSB's theory may be wrong.

Investigators examine the design schematics of the aircraft.

An intriguing detail catches their attention.

AL: I remember learning that the placement of

the air conditioning units were underneath the center tank,

and those generate a fair amount of heat.

BOB: They cool the aircraft, but the packs themselves

get quite hot during that procedure.

NARRATOR: On TWA 800, the air conditioning units

were working extra hard to keep the cabin cool

on a hot evening.

BOB: The air conditioning packs underneath

the center wing fuel tank had been operating for I believe

several hours prior to takeoff.

AL: And we all looked at each other and thought,

boy, is that design correct?

NTSB INVESTIGATOR: I wonder.

NARRATOR: Could heat from the units have boosted

the temperature inside the tanks to a dangerously high level?

NTSB INVESTIGATOR: There's only one way to find out.

Air conditioning on.

AL: We had to prove to ourselves that the temperature

inside the tank would be flammable,

because if we couldn't prove that, how was it gonna explode?

BOB: The only way we were going to determine

the actual conditions inside the fuel tank

was by performing a flight test.

NARRATOR: They decide to reproduce the exact conditions

of the accident flight.

NTSB INVESTIGATOR: All right. Let's start it up.

NARRATOR: The same type of plane, the same fuel load and,

most importantly, exactly the same air conditioning units.

BOB: We preheated the center wing tank fuel

by running the packs for hours.

Boeing engineers installed, oh gosh, it must have been two

or three dozen different types of sensors inside the tank,

probes to measure temperature, pressure, vibration.

NARRATOR: It's a risky undertaking, filled with uncertainties.

♪

BOB: We knew that one of the requirements

to have a fuel air explosion inside the tank

would be a high temperature, but we didn't know

how high the temperature got inside a tank.

NARRATOR: The test flight reaches the same altitude as TWA 800.

NTSB INVESTIGATOR: Holy crow.

NARRATOR: The temperature readings are terrifying.

ROBERT: These air conditioner packs were getting

up to 350 degrees.

350 degrees is about what you turn your oven to

to bake a chicken.

NTSB INVESTIGATOR: This is off the charts.

NARRATOR: The temperature in the tank hits 127 Fahrenheit,

30 degrees above the flashpoint.

BOB: It was a bit disconcerting because we were in a sense in

an aircraft that was identical to the accident flight.

Now if you're gonna ask me whether I would do it again

I'd probably say no.

NTSB INVESTIGATOR: Okay. Let's get back down to the ground.

NARRATOR: Investigators are now certain the fuel

in the tanks of TWA 800 did become flammable.

But before they can take the next step

in their investigation, another media firestorm hits.

PIERRE (Archive): 154 people living in the Long Island area

where the missile testing was going on

saw one or two missiles rising in the air,

and a number of them saw an explosion in the air.

NARRATOR: President John F. Kennedy's former press secretary,

Pierre Salinger, claims he has proof that a missile hit TWA 800

and that the missile was fired by the U.S. Navy.

♪

PIERRE (Archive): The missile fired down TWA 800.

NARRATOR: Journalist Pierre Salinger releases

unverified radar images showing a foreign object

in the night sky.

He claims the USS Normandy, a guided missile cruiser,

accidentally targeted the 747.

No matter how far-fetched the claim may seem,

the FBI must investigate.

JAMES KALLSTROM: We had to look at the military

because the military has assets to shoot down aircraft.

As the head of the office, I wouldn't take anything

off that board till someone could prove to me that

that wasn't the cause, or couldn't have been the cause.

NARRATOR: While the FBI examines Salinger's extraordinary claim,

NTSB investigators continue reconstructing the downed plane.

They hope the task will ultimately

put the missile theory to rest.

At the same time, they work to prove their own theory,

that the explosion started in the tank.

NTSB INVESTIGATOR: Okay. So we've proved flammability.

Now for the second challenge: Can the tank rupture?

ROBERT: One of the contentions from the industry

was that if we had an explosion in the fuel tank

the airplane was so strong it would contain it.

It wouldn't be a problem.

We wouldn't structurally fail the fuel tank or the fuselage.

NARRATOR: According to Boeing, the tank can withstand

up to 25 pounds per square inch of pressure.

Investigators need to know if the TWA blast

could have exceeded those limits.

They create a scale model of the center wing fuel tank.

BOB: We did some what we call quarter scale testing

of different fuel/air mixtures.

We built a replica 1/4th of the size of the fuel tank

with baffles and everything in it like the fuel tank.

NTSB INVESTIGATOR: Gentlemen. Levels good?

NARRATOR: They fill the tank with the same ratio of jet fuel

as on TWA 800. Then they heat it to the same temperature.

♪

[Explosion]

The results are clear.

JAMES WILDEY: The study showed that if the fuel/air

vapor mixture was ignited that it could generate

more than 50 pounds of force per square inch.

NARRATOR: It creates double the amount of explosive force

the tank was designed to withstand.

BOB: The tank simply wasn't strong enough

to contain the full scale of this explosion.

NTSB INVESTIGATOR: Okay. I think this tells us what we need to know.

NARRATOR: NTSB investigators need one last critical element

of proof before they can be absolutely certain about

what caused one of the worst air disasters in U.S. history.

BOB: Once we determined that the fuel tank became hot enough

to sustain a flame

and once we determined that the fuel tank itself

was not strong enough to contain an explosion

we needed to try to figure out an ignition source.

NARRATOR: While the NTSB team is confident they're on the right track,

the FBI is seeing signs that the Navy missile theory

won't hold up.

JAMES KALLSTROM: You know, one of the first things I did

in talking to the Pentagon was to ask them to give me

all military assets.

JAMES KALLSTROM: So there's no way anything was fired from that ship.

That's helpful. Thank you.

JAMES KALLSTROM: We interviewed the entire crew.

We looked at all their ordinance that was on the ship that day

and of course we also found out that TWA Flight 800

was not in the range of the USS Normandy, so case closed.

NARRATOR: Though Pierre Salinger's controversial theory

is now discredited, it continues to gain traction in the media

and among the general public.

MALE [Archive]: The Navy is a suspect. The Navy is a suspect.

Why should they be involved in the investigation?

NARRATOR: The monumental reconstruction of TWA 800

might be the only way to put all the rumors to rest.

But as the complex crash investigation drags on,

there are growing fears that another disaster

could be just around the corner.

BOB: It became kind of obvious to most of us

that the fuel tank had exploded,

and that, I think, gave us a sense of urgency because

if it happened one time it could happen again.

NARRATOR: Passengers flying on 747s every hour of every day

may be in danger.

NTSB INVESTIGATOR: Okay. We've proven the first two.

Now we're at the final, most important condition.

AL: The final question that we had to answer was:

What caused the spark? We knew it was flammable.

We knew the tank was destroyed,

but we didn't know where the spark started.

NTSB INVESTIGATOR: Without a spark, there wouldn't be

an explosion in the first place.

♪

ROBERT: You rule items out until you're left with

some core potential causes to look at.

It's kind of the Sherlock Holmes approach.

We spent months and months

eliminating potential ignition sources.

We looked at whether something may have come in

through the vent system such as a stroke of lightning.

BOB: Some folks thought that perhaps a meteorite

had struck the aircraft.

NARRATOR: More than a year after the crash,

investigators still don't know what could have caused

a spark in the center wing fuel tank.

In desperation, they turn to something

they thought was a dead end.

NTSB INVESTIGATOR: How about the CVR? Let's go back to the CVR.

♪

NARRATOR: When investigators first listened to

the cockpit recording, they didn't hear anything

that might explain the explosion.

They decide to listen to it again.

NTSB INVESTIGATOR: Maybe we've missed something. Everybody listen closely.

Okay. Play it.

AIR TRAFFIC CONTROLLER: TWA 800, amend the altitude.

Maintain 1-3,000, 13 thousand for now.

CAPT. SNYDER: TWA 800, okay. Stop climb at one-three thousand.

CAPT. KEVORKIAN: Stop climb one-three thousand.

AL: It was a pretty nonchalant takeoff and climb.

FE. KRICK: Fuel one-seven-nine. Estimated time of arrival 6:28 am.

AL: And the only thing that was a little bit different

was one of the crew members mentioned

that the fuel flow indicator was erratic.

CAPT. KEVORKIAN: Look at that crazy fuel flow indicator there on number four.

AL: And he only mentioned it once and then

it apparently calmed down and they kept climbing.

ROBERT: The airplane has a half dozen electrical generators

and it has all sorts of fans and motors and pumps

that use this electricity.

The background noise captured by the cockpit voice recorder

is kind of like a static hum.

NTSB INVESTIGATOR: Wait. Stop. Play that back.

Let me see that waveform. Blow it up.

ROBERT: In the last one second of the flight

before the explosion, we had two dropouts

in that background noise, that background hum on the

CVR recording. That electrical noise had gone somewhere.

NARRATOR: Investigators are on the verge of a major discovery.

NTSB INVESTIGATOR: There was a short circuit somewhere in the plane's wiring.

NARRATOR: A short circuit is an abnormal connection

between points of an electrical circuit

where current is not supposed to flow.

The dropout on the CVR can only be explained

by this type of fault.

ROBERT: We knew we had a short circuit somewhere.

What we did not know is where the energy came from

specifically.

NARRATOR: They begin the enormous task of examining

all of the 747's wiring.

ROBERT: We had 180 miles of wire to work with.

We had wire all over that hangar.

NARRATOR: After hours of examining the plane's wiring,

investigators begin to notice a disturbing pattern.

NTSB INVESTIGATOR: The condition of these wires is abysmal.

ROBERT: We had cracks in the insulation. We had chafes.

AL: When it was discovered that these wires were brittle

and falling apart basically and shouldn't have been,

that was very important.

NTSB INVESTIGATOR: Let's see the fuel indicator system.

NARRATOR: They check wiring schematics to see where

the wires for various aircraft systems are routed,

including the fuel system.

ROBERT: The fuel quantity indicating system

has an extensive amount of wiring in the fuel tanks.

♪

NARRATOR: Following the wiring, investigators

make a stunning discovery.

NTSB INVESTIGATOR: That's crazy.

NARRATOR: The discovery of bundled wires

in a crumbling electrical system is a major step

in the NTSB's search for a deadly spark.

ROBERT: In going to the cockpit, the fuel quantity wiring

is tied into bundles with wiring that go to the aircraft lights

and all sorts of other aircraft systems.

NTSB INVESTIGATOR: Those wires carry a ton of energy.

ROBERT: These cabin light wires, they were up to 350 volts peak,

and they were co-routed with these five volt

DC low power wires that went to the fuel quantity probes

in the fuel tank.

AL: If you have cross currents into these wires

it sets you up for something drastic could easily happen.

NTSB INVESTIGATOR: This was certainly a short circuit.

ROBERT: It was more than enough to create a short circuit

that would go into the fuel tank and ignite the vapors.

NTSB INVESTIGATOR: And now we have all the conditions

for a fuel tank explosion.

NARRATOR: The full sequence of events is now clear.

While idling at the gate for two and a half hours,

the air conditioning system heats the fuel

in the center wing tank.

The liquid fuel turns to vapor, its temperature rising

well above the 96-degree ignition point.

The flammable fuel and air mixture

is a disaster waiting to happen. All it needs is a spark.

In the plane's aging electrical system,

high voltage wires are bundled with low voltage ones.

Some are so worn they can short circuit.

High voltage surges travel where they were never designed to go.

CAPT. KEVORKIAN: Look at that crazy fuel flow indicator there on number four.

NARRATOR: In the blink of an eye, a deadly spark

reaches the fuel probe inside the center wing tank.

AL: And then it blew up.

[Explosion]

CAPT. KEVORKIAN: Talk to me! What do you have for us?

♪

[Screaming]

NARRATOR: The NTSB's explosion theory is now rock solid,

and their ambitious reconstruction of TWA 800

is finally complete.

♪

BOB: There were thousands and thousands of parts

on this very sturdy structure.

It was an amazing thing for us to see.

JAMES WILDEY: I was really pretty proud of the definitive nature

in which we were able to show where

the airplane break-up began.

NARRATOR: The FBI finally agrees with the NTSB

on what happened to TWA 800.

♪

JAMES KALLSTROM: It brought us to the conclusion

the center fuel tank blew up, which was a huge finding,

and we were very, very confident and to a very high level

that that was true.

♪

AL: People have said that the FBI

should have pulled out sooner, but it's their business.

They, they can do what they want. They have guns, so...

It was a nice feeling when they eventually said,

you guys were right.

NARRATOR: After more than four years of investigation,

the NTSB recommends in its official report

that all Boeing 747s undergo a review and repair

of older wiring.

Significant design modifications are also advised, including

the addition of insulation between the fuel tanks

and the air conditioning system.

Though investigators have found the cause

of the TWA 800 disaster, one question lingers.

How did bomb residue get on the wreckage?

BOB: We think that the residue probably was placed on there

during the wreckage recovery.

A lot of military folks were out helping us.

Perhaps that residue came off boots or clothing

or something like that, and eventually the FBI agreed.

NARRATOR: Investigators also believe that witnesses

who thought they saw a missile

were actually seeing the flaming remains of the plane

curling skyward.

JAMES KALLSTROM: The fuel in the, in the wings still kept

the engines going for some time.

So they did see things going up but they were looking at

TWA coming apart.

ROBERT: The conspiracy type people were still out there

saying we were wrong. We knew we were right.

And I got tired of arguing with people

who had their minds made up.

So I just turned away from TWA and didn't talk about it

for a long time.

AL: TWA 800 was the most complex, hardest investigation

that I had ever been involved in.

I'm just glad we had the expertise to get through it all.

BOB: Even though it took quite a while, we think all the effort

and all the complications involved were well worth it.

[♪ bugle playing taps ]

JAMES KALLSTROM: We had ceremonies out in Long Island

every year for a while.

You know, those were very emotional things,

so that's what I'll always remember.