Original subtitles

NARRATOR: An Airbus heading from Paris to Cairo disappears over the Mediterranean.

A plane with some 58 passengers on board has gone missing,

it is EgyptAir Flight 804.

NARRATOR: Radar data provides the first clue.

And then they started spiraling.

What is going on in this cockpit?

NARRATOR: The cockpit voice recorder, found deep on the seafloor,

reveals a horrifying detail.

(pilots coughing)

There's a fire!

It has to be one of the worst things that could happen.

(fire extinguisher sprays)

(dramatic music)

NARRATOR: A shocked world demands answers.

We owe it to the traveling public. We owe it to the victims' families.

NARRATOR: The accident investigation stalls.

Then, six years later,

an Italian journalist reports an astonishing new theory.

The people need to know the truth.

PILOT (radio): Mayday, mayday.

(warning alarms) GPWS: Pull up!

(indistinct radio chatter)

(airplane drones)

NARRATOR: A late-night flight to Cairo cruises 37,000 feet over Greece.

Radar check. Looks clear.

- ASSEM: Thank you, Captain. - I like the way that sounds.

NARRATOR: Mohamed Shoukair is in command of tonight's flight.

With more than 6,000 hours of flying time, he's just been promoted to captain.

COX: The initial upgrade to captain is a real pinnacle event for an aviator.

It's something you work years to attain.

Winds are as forecast, no deviation.

NARRATOR: First Officer Mohamed Assem has 2,700 hours of flying time.

He, too, is an ambitious pilot.

Being a pilot in Egypt is one of the most prestigious jobs in northern Africa.

SKOUKAIR: Hi there. Could I have a cup of coffee up here?

- ASSEM: Make that two, please. - SHOUKAIR: Make that two, please.

COX: This was routine flight. This was a normal crew.

Both pilots were very well trained and experienced.

NARRATOR: The pilots fly for EgyptAir,

a state-owned airline and the flagship carrier of Egypt.

BERBERI: EgyptAir is one of the best airlines in Africa

and one of the oldest airlines in the world.

NARRATOR: Flight 804 is two and a half hours

into its journey from Paris to Cairo.

The pilots are flying an Airbus A320.

COX: The A320 is one of the more modern fly-by-wire computer enhanced airplanes.

It's an extremely reliable veteran workhorse

in the commercial aviation industry.

NARRATOR: On board the plane tonight are 56 international passengers:

Egyptian, French, British, and Canadian.

(indistinct chatter)

The five-person cabin crew has a quieter night than usual.

The plane is only half full.

Hello, hello. EgyptAir Flight 804, flight level 370.

(radio) Squawk number 7624.

NARRATOR: Captain Shoukair updates controllers on the flight's progress.

- EgyptAir 804, radar contact. - Thank you very much.

EgyptAir 804, maintain flight level 370 and current heading.

NARRATOR: Greek controllers oversee the airspace Flight 804 is flying through.

SHOUKAIR (radio): Maintain 370 and current heading. Efcharisto poli.

- How's the coffee? - Strong. Just what I need.

COX: One of the challenges when you're flying what they call

the "back side of the clock" - the technical term is a circadian low,

and this is when your body normally would be asleep.

But you're having to press it because you're on duty.

GREEK ATC: Egypt Air 804. Contact Cairo center now on 125.300.

NARRATOR: As Flight 804 leaves Greek airspace,

the controller hands it off to Egyptian control.

(chilling music)

But the pilots don't acknowledge the instruction.

COX: The fact that they missed the call, understandable.

Perhaps they were in conversation and just missed it.

EgyptAir 804, contact Cairo center, 125.300.

NARRATOR: After a second call,

the controller waits for confirmation from the pilots.

There's still no reply.

After the second or third call, that becomes unusual. Something's wrong here.

NARRATOR: Then, Flight 804 disappears from radar.

(tense music)

Cairo, have you made contact with 804?

CAIRO ATC: No, and we don't have them on radar either.

(indistinct conversation)

NARRATOR: As the minutes tick by, there's no word from the pilots.

Flight 804 doesn't arrive in Cairo.

Normally crashes occur during takeoff,

during landing, somebody runs into a mountain.

But at 37,000 feet, not a lot of things that can go wrong.

So in that particular case, that was a bit of a mystery.

NARRATOR: As day breaks,

Egyptian, French, and Greek ships and aircraft search for the plane

north of the Egyptian coast.

(news music)

So here is the breaking news tonight.

A plane that reportedly has some 58 passengers on board has gone missing.

A plane with some 58 passengers on board has gone missing.

It is EgyptAir Flight 804. It was en route from Paris to Cairo.

NARRATOR: Families gather at Cairo Airport, hoping for news.

One day after Flight 804 disappears, search teams find debris from the plane.

BERBERI: Around the same time the aircraft went down,

in Europe, we faced a lot of terrorist attacks

in France, in Belgium, and in other parts.

I thought that this could be a terrorist attack.

The question inevitably being asked here in Paris

is whether or not the plane was sabotaged.

- BEA INVESTIGATOR: Any survivors? - None have been found.

NARRATOR: An investigation into the crash of Flight 804 is launched.

- 66 people are feared dead. - And time is running out.

NARRATOR: The case falls within the jurisdiction

of the Egyptian Civil Aviation Authority Investigation Directorate.

The Bureau will do whatever it can to assist.

NARRATOR: Investigators from France's

Bureau of Investigation and Analysis for Civil Aviation Safety, the BEA, assist,

because the A320 is built in Europe and French nationals were on board.

What do we know so far?

Very little, I'm afraid. It was at cruise, and then it was gone.

COX: It's a worldwide news event, and so the pressure's on,

and as an investigator, you have to say,

"No, we're gonna do this methodically and properly."

ECAA INVESTIGATOR: The current and tide could scatter debris

hundreds of kilometers from the point of impact.

NARRATOR: But satellite images show an oil slick on the water.

COX: If you find an oil slick,

there is a high likelihood that the airplane impacted the water in this area.

The more you can narrow the search down,

the higher the likelihood you'll find the wreckage on the seafloor.

Hopefully the ROVs will find it soon.

NARRATOR: The oil slick lies on water 3,000 meters, or nearly 10,000 feet, deep.

Sophisticated undersea technology and expertise are needed

to explore such extreme depths.

TECHNICIAN: Anything?

NARRATOR: BEA investigators lead an advanced dive team

in the hunt for the wreckage of Flight 804.

Their ships are equipped with sonar units

capable of detecting the pingers on black boxes.

BENZON: Underwater searches actually have a good side and a bad side.

They kind of slow things down,

and allow investigators to kind of get their act together a bit.

It allows them to accept wreckage gradually, rather than in a big pile.

And that's a good thing. Other than that, on the bad side, it takes a long time.

Did you pick up on anything unusual?

NARRATOR: As the search for the plane continues,

the investigation on shore gains pace.

They were passing through Greek airspace.

EgyptAir 804, maintain flight level 370 and current heading.

NARRATOR: Can the Greek controller who last handled the flight

provide investigators with any clues?

COX: In the early days of any investigation,

you want to interview the air traffic controller.

Did the crew make any ATC communications

advising that they had a mechanical problem?

Maintain 370 and current heading. Efcharisto poli.

He spoke to us in Greek. He sounded very relaxed. It was all very routine.

- Any emergency calls? - No. None.

LEARMOUNT: There had been a conversation between the aircraft

and the Greek traffic control only moments before this event took place.

It's completely inexplicable as to why communication would suddenly stop.

NARRATOR: Investigators don't know if there was a malfunction

or something more sinister, like an act of terrorism.

This should fill in some gaps.

NARRATOR: Using radar and satellite data,

investigators reconstruct the plane's flight path after contact was lost.

ECAA INVESTIGATOR: It's making a left turn. Now it's making a right turn.

BEA INVESTIGATOR: They're dropping altitude fast.

NARRATOR: After a sudden left turn,

Flight 804 spirals downwards until it hits the sea.

COX: If you have a problem, you want to get towards an airport.

So you would not want to circle on your way down.

Maybe there's problems with the controls?

BEA INVESTIGATOR: Maybe.

But he'd have time to tell the ATC.

NARRATOR: The spiral flown by EgyptAir Flight 804

raises some troubling questions.

LEARMOUNT: A spiral descent is what will eventually happen to an airplane

if it's completely left alone by the pilots and not controlled by an autopilot.

NARRATOR: Did something prevent the pilots from operating the plane's controls?

Investigators hang their hopes

on the recovery of the black boxes from the wreckage.

But what remains of the plane

is somewhere 3,000 meters, or nearly 10,000 feet, under water.

COX: 3,000 meters of water is a very, very challenging environment,

under immense pressure.

NARRATOR: A surface vessel uses hydrophones

to scan the sea for a specific frequency

being transmitted, or pinged, by the black boxes.

If the transmitter is not buried in either wreckage or in the seafloor,

you can pick it up from a pretty good distance out.

NARRATOR: It's a race against time.

The pingers on the black boxes only have battery power to transmit for 30 days.

Look. Is that it?

NARRATOR: Two weeks into the search,

investigators track a frequency that matches the pinger's.

TECHNICIAN: That's gotta be it!

NARRATOR: The team deploys a remotely operated submarine,

equipped with cameras and robotic arms, to confirm the find.

Technicians control the submarine through a tether that extends from the ship.

Okay. It should be… right there.

Here's the plane!

NARRATOR: They find the wreckage, but now must locate the flight recorders.

COX: They're looking for the flight data and cockpit voice recorders.

Those are key pieces of evidence in the investigative process.

Okay, slowly, slowly.

I see it! There!

NARRATOR: Using the submarine's robotic arms, the team extracts the black boxes.

These things are gold to an investigator, and to be able to go down that deep,

and in those cold, frigid, dark waters and pick things out selectively, that's magic.

(indistinct chatter)

Here's what they've found so far.

NARRATOR: In Egypt,

investigators study the debris field mapped from underwater footage analysis.

It looks like a fairly contained area.

It doesn't seem like the plane exploded.

If it came apart midair, the debris would be scattered further apart.

NARRATOR: The destruction of the plane likely occurred on impact with the water,

not while in the air.

So the plane was intact through a 37,000-feet descent. That's a long time.

Why didn't the pilots tell the controllers what was going on?

BENZON: There's a saying in aviation.

During an emergency, you need to first aviate,

and then you navigate, and lastly, you communicate.

The cockpit voice recorder should help.

(distant alarm) (muffled shouts)

NARRATOR: Investigators wonder what was happening

in the cockpit of EgyptAir Flight 804 in the minutes before it crashed.

LEARMOUNT: There have been a couple of cases

where pilots have deliberately done something to cause the aircraft to crash,

and to achieve their own suicide by it.

NARRATOR: Just 10 months earlier, a pilot on a Germanwings Airbus

deliberately crashed into the French Alps, killing 150 people.

LEARMOUNT: But this didn't look like one of those.

It really looked as if the aircraft was out of control. The question then is,

why on Earth was it, from normal, regular flight, suddenly out of control?

ECAA INVESTIGATOR: We've got data. It's from EgyptAir.

NARRATOR: Airbus and EgyptAir provide them with a source of evidence.

- What are they saying? - There were a bunch of ACARS messages.

NARRATOR: A digital datalink system called ACARS

sends short messages from the aircraft to ground stations via satellite.

The ACARS messages are one thing that the investigators will go look at early,

because they know the airplane is transmitting.

Is there anything unusual in those transmissions?

(alarm) What's that?

Eleven messages in total.

NARRATOR: EgyptAir gives the investigating team a full list of transmissions

from Flight 804's Aircraft Communications Addressing and Reporting System, or ACARS.

BEA INVESTIGATOR: It looks like the first four messages

are minor maintenance messages during engine startup.

But these seven messages occurred within a three-minute time span.

(alarm) What's that?

NARRATOR: The fault messages reveal a crew confronted by a series of warnings

three hours and 17 minutes into the flight.

Anti-ice right window.

It starts on the right side of the plane with the right window anti-ice system.

- SHOUKAIR: What's going on over there? - I don't see anything.

The second message is from the right-side windows, too.

NARRATOR: The first two ACARS messages tell investigators

there was a problem with the windshield panels on the right side of the cockpit.

COX: The sensor in the sliding window

is primarily to determine the temperature of the window,

so that the heating elements can maintain the desired temperature.

BEA INVESTIGATOR: Check out this third warning. Smoke in the lavatory.

(warning bell, continuous) (passengers murmur)

There is smoke in the avionics bay as well.

(alarm)

We've got trouble. Something's wrong.

NARRATOR: Critical computers are located in the avionics bay.

BENZON: Smoke in the avionics bay, that could get you in trouble real quick.

NARRATOR: Just two minutes after the smoke warnings,

the pilots discover that their primary flight controls are failing.

We've got an SEC problem.

NARRATOR: The SEC computer manages the spoilers and elevators,

which move up and down to change the plane's pitch and roll.

COX: If the crew knew this, there is yet another piece of evidence

that there's something seriously wrong in the avionics bay.

If they are losing flight controls, that could explain the slow, spiraling descent.

Let us move to the backup.

(alarm beeps)

NARRATOR: The A320 flight control system was designed

so that if one system failed, the backup system would still operate.

LEARMOUNT: If one fails, fails totally,

the other system will give them enough control to get the aircraft back to base.

There aren't any warnings on the other flight control computers.

NARRATOR: The ACARS messages tell investigators

Flight 804 was in serious trouble in the final minutes before it crashed--

All pointing to one thing.

There is a fire at the front of the plane.

LEARMOUNT: There's nothing that could happen on an airplane

that is more chilling and more dangerous than fire on board,

because fires can spread very rapidly,

and they can do tremendous damage to control systems.

NARRATOR: After analyzing the ACARS warnings,

the investigators grapple with the devastating implications of the discovery.

Maybe they were too busy fighting the fire to call air traffic control.

You must get the fire out quickly. You just cannot allow it to spread.

NARRATOR: Now investigators face more difficult questions.

LEARMOUNT: The investigators want to discover exactly where it started.

The whole reason for the investigation is to prevent this happening again.

Alright, let's have a listen.

NARRATOR: Investigators turn to the CVR

in the hopes it might reveal more about the fire on board.

GREEK ATC (CVR): EgyptAir 804, maintain flight level 370 and current heading.

SHOUKAIR (CVR): Maintain 370 and current heading.

The BEA helped the Egyptians by downloading the data.

But then the BEA had to hand the cockpit voice recorder over to the Egyptians.

(pilots coughing)

SHOUKAIR: There's a fire!

(alarms) (coughing)

The crew's statement of the word "fire" indicates that they have evidence,

hard evidence, that there is a real-time fire that they need to contend with.

Thank you.

NARRATOR: After listening to the CVR,

the Egyptian investigators report their findings

to France's Bureau of Investigation and Analysis, or BEA.

I'm afraid our suspicions have been confirmed.

The pilots are on the recording saying there's a fire on board.

Any idea where it started?

- It's spreading! Where's it coming from? - SHOUKAIR: I don't know!

(coughing)

No, there's no indications.

Well, we'll have to find out another way. When are you coming back?

I'm sorry, I need to stay in Cairo.

COX: Why was there a fire? The crew states the word "fire." Why? Where?

NARRATOR: Seven months into the international investigation

aided by the BEA,

the Egyptian government suddenly releases a statement to the media.

The Egyptians believed that this was some form of sabotage involving an explosive.

NARRATOR: The Egyptian government believes an act of terrorism

may have brought down EgyptAir Flight 804.

By law, the investigation is handed over to Egypt's state prosecutor.

It's out of my hands. You must understand.

The Egyptian authorities advanced the theory

that there was an explosion on board.

That is certainly something to be considered,

but you provide the evidence for everyone to see.

BEA INVESTIGATOR: Can we see your forensic report?

The case is with state investigators now. I'm sorry.

There's too much room for error here. Are you sure it's not a false positive?

The tests are conclusive.

BENZON: The BEA and Airbus tried their best, said "Hey, we're here to help,

we're here to help, we're here to help," and they were ignored.

(sighs) Okay.

To say, "well, we have evidence and we're not gonna discuss it any further"

flies in the face of the International Civil Aviation Organization agreements

that have been made by countries worldwide.

NARRATOR: In Milan, Italy,

aviation journalist Leo Berberi follows the case closely.

BERBERI: The Egyptian investigators started talking about an explosion aboard

as a result of a terrorist attack,

and when asked to provide proof, they didn't provide any.

And that was welcomed with a lot of skepticism from the aviation community.

COX: Are there chemical residue that is consistent with an explosive?

BENZON: If it had been a bomb, nobody claimed responsibility. (chuckles)

That makes the entire exercise of bombing an aircraft pretty damned useless.

Ah! Our own forensics are in.

NARRATOR: Air accident investigators from France's BEA

independently look into the terrorism theory.

They test materials from the crash for explosive residue.

Negative for traces of explosive.

NARRATOR: They can't find any evidence to support the bomb theory.

The information they had denied what the Egyptians were suddenly claiming.

There's gotta be a connection here.

NARRATOR: Unconvinced by the Egyptian government's bomb theory,

BEA investigators hunt for the source of a fire

they're certain ripped through Flight 804.

(alarm) (coughing)

There's a fire!

The right window heating element is first.

NARRATOR: They look for a pattern to the ACARS messages

- to explain the cause of the fire. - There has to be something in common.

And that's the big question: What could trigger this?

BEA INVESTIGATOR: Then smoke in the lavatory and avionics bay.

It's moving from front to back.

The order matters in that you may be able to say the fire is increasing.

It's also propagating, it's moving.

So it's affecting different parts of the airplane.

BENZON: The last warning the ACARS system processed

had to do with a flight control problem. That was a very serious one.

Everything seemed to kind of center in on the avionics compartment.

The avionics bay is packed with wiring.

Maybe some wires arced and ignited.

COX: The A320, like a lot of modern jets, is a fly-by-wire airplane.

So the computers actually control the flight control position.

If you were to lose all electricity in the airplane,

maintaining control becomes very, very challenging.

(alarms) (coughing)

My belief was that this was an avionics bay fire.

The smoke penetrated, probably via the floor or the floor panels,

penetrated into the forward lavatory.

NARRATOR: Did faulty wiring in the avionics bay ignite a fire on board?

Sounds like Swiss Air 111.

NARRATOR: On Swiss Air 111, arcing in the wiring of the plane's entertainment system

was identified as the source of a tragic onboard fire that killed 229 people.

As soon as I heard about the ACARS messages about smoke in the avionics bay,

I immediately thought of Swiss Air triple-one.

NARRATOR: Did an electrical fire start in the avionics bay

- on board EgyptAir Flight 804? - A fire can happen on board any aircraft.

They can be caused by a variety of things,

but very often they're triggered by some kind of an electrical fault.

NARRATOR: If there was faulty wiring on an A320

that crashed into the Mediterranean, it would have grave repercussions.

LEARMOUNT: If that were the cause, you can inspect the rest of the fleet

and make sure that the same chafing is not happening in the rest of the fleet.

NARRATOR: But without the assistance of the Egyptian Civil Aviation Ministry,

there's no way to determine the cause of the fire.

The BEA's investigation stalls due to lack of evidence.

It's really vital to have a final report

because that's the only way to improve aviation,

to avoid making the same mistakes.

(crowd chatters indistinctly)

NARRATOR: Six years after the crash of Flight 804,

there's still no official report

nor conclusion to Egypt's criminal investigation.

(phone rings)

BERBERI: Pronto.

NARRATOR: In March of 2022, aviation journalist Leo Berberi gets a huge scoop.

BERBERI: After years that I was harassing people

involved directly in the investigation,

someone in France had some news for me about that flight.

I'll meet you there.

NARRATOR: Aviation journalist Leo Berberi of Corriere della Sera

meets a trusted source

who offers another explanation for the crash of EgyptAir Flight 804.

We met, and the person handed me the document.

(intrigue music)

NARRATOR: Berberi learns from the confidential source

details of an investigation launched by the French judiciary,

staffed with a team of technical experts

appointed to analyze the available evidence.

BERBERI: The French judiciary involved five experts in aviation and in accidents,

probably some of the best in the world,

and handed them all the documents, all the data they had about that flight.

NARRATOR: The aim is to determine if the accident

constituted involuntary manslaughter.

The French government started the investigation in Paris,

because there were French citizens among the victims on that flight.

NARRATOR: Berberi confirms the report with the French judicial investigation,

who had secured copies of the cockpit voice recorder.

INVESTIGATOR: All we were told is the pilots reported a fire

but didn't mention its location.

Let's see what they said.

NARRATOR: The investigators began their analysis

by looking for answers to the main question:

how did a fire start on Flight 804?

We had a lot of questions, a lot of theories, but no answers.

COX: The word "fire" that is on the voice recorder

indicates this was something other than an explosion.

(yawns)

- Tired? - ASSEM: I'm okay.

(hissing)

Stop. Do you hear that?

Play it again.

- SHOUKAIR (CVR): Tired? - ASSEM (CVR): I'm okay.

(hissing)

INVESTIGATOR: Looks like there's something on channel three.

Can you isolate it visually?

The cockpit voice recorders not only can record voices,

but they record noises in the cockpit, which can tell us another story, too.

NARRATOR: Investigators isolate the channels.

(hissing)

On one of the channels, they hear something unusual.

What's that sound?

They worked on that audio,

changing the sound spectrum to reduce the low frequencies.

This could allow them to hear clearly something

coming from one of the microphones of the pilots.

It's like… a whispering sound.

Can you pull the library of sounds? (hissing)

NARRATOR: Investigators compare the sound to similar sounds

in a database of cockpit noises.

INVESTIGATOR: Not… not this one. Not that one either. Um, play that one.

(static)

No. That's not it. What about this one?

(hissing)

That's it! It's the oxygen mask.

(hissing)

NARRATOR: Was oxygen leaking from a mask in the cockpit?

Says here that if not stowed properly, it's going to leak.

Now the closest oxygen mask to channel three is this one,

right behind first officer's seat.

SHOUKAIR: Hello, hello. EgyptAir 804, flight level 370.

Squawk number 7624.

NARRATOR: The implication of the discovery is immediately clear.

That's fuel for the fire.

(alarm)

In an oxygen-enriched environment, the potential for ignition goes up,

and the severity of the ensuing fire post-ignition goes up.

NARRATOR: An oxygen leak can feed a fire, but it can't ignite one.

Investigators wonder what could have started the fire.

I need reports from cases with in-flight fires.

NARRATOR: Are there other cases where a similar fire brought a plane down?

One of the early things you do is,

has the fleet seen this before, or anything similar to it?

Have there been flight deck fires? And there have.

NARRATOR: In June 1983, an onboard fire ripped through an Air Canada DC-9

and forced the pilots to make a harrowing emergency landing.

American investigators theorized that a lit cigarette in the lavatory

was one of the possible causes.

Perhaps the pilots were smoking.

Smoking regulations for pilots in Egypt, what are they?

NARRATOR: Smoking has been banned on most airliners around the world for years.

Unbelievable. (chuckles)

NARRATOR: EgyptAir did not allow smoking on board, except in the cockpit.

BERBERI: It was allowed in 2016 to smoke in the EgyptAir's cockpit

with the authorization of the captain.

(dramatic music)

NARRATOR: With no ban on smoking for pilots at EgyptAir in 2016,

French judicial investigators put forth a theory

that focuses on the pilots of Flight 804.

Listen to this. The ashtrays were replaced before the accident.

NARRATOR: The Egyptian Pilots Association insists that the pilots were not smokers.

According to the Egyptian authorities and the Egyptian media,

the pilots weren't smokers.

But according to other pilots that I interviewed, they were smokers.

NARRATOR: Studying maintenance reports for the aircraft,

investigators make an important discovery.

It's not just the ashtrays that were changed.

They replaced the FO's oxygen mask.

And it looks like it was left in emergency mode. This is just what we need.

The first officer's oxygen mask was changed three days before the accident.

According to the experts,

the oxygen mask was set improperly on an emergency mode.

NARRATOR: When an oxygen mask is left in emergency mode,

it feeds oxygen at a higher pressure,

releasing more oxygen than when it's in normal mode.

COX: I can see where it could, depending on the position,

initiate flow out of the hose into the mask and then into the environment.

Aren't the pilots supposed to check the oxygen masks at the start of each day?

BERBERI: Pilots are supposed to check that setting

unless someone else on the first flight of that day has already done that.

But that doesn't mean that you can't do that again.

GREEK ATC (radio): EgyptAir…

NARRATOR: French judicial investigators speculate

that the leaking oxygen saturated the cockpit air,

increasing the potential for a sudden fire.

(alarms)

The French report concluded that the aircraft went down

because there was something, most probably a cigarette,

that, with the contribution of the oxygen leaking from the first officer's mask,

started a fire that wasn't stopped or couldn't be stopped.

NARRATOR: Leo Berberi breaks the story that the French judicial inquiry

has a very different theory from either the Egyptian government

or France's Bureau of Investigation and Analysis for Civil Aviation Safety.

It's a theory questioned by many experts.

LEARMOUNT: Just imagining that this mask is filling the cockpit

with a high percentage of oxygen is ridiculous,

because the feed, even when it's at full blast,

is intended to be enough feed to the pilot's face, like this.

In the cockpit, that would have been minimal.

(alarm) Let's move to the backup.

To me, frankly, this is a bit of a stretch.

NARRATOR: Officially, the ignition source for the onboard fire

remains an open question.

Families of those lost in the tragedy still have no firm answers.

The Egyptians maintain that this was an act of terrorism.

Two alternate explanations remain on the table: the cigarette theory…

…and the faulty wiring theory.

What caused Flight 804 to crash remains a mystery.

But one fact is clear. Whatever happened could happen again.

It's absolutely vital that we find out what caused the fire on this airplane.

Aviation does not do well with mysteries. We never have.

ASSEM: It's spreading!

- Where is it coming from? - SHOUKAIR: I don't know!

(pilots coughing)

I'm taking us down.

NARRATOR: The Egyptian government has since banned smoking in the cockpit.

As of 2022, there still isn't an official report.

LEARMOUNT: I think we know that there's a lot more information

that has been gathered about Flight 804 than has been released.

NARRATOR: An incomplete investigation leaves behind an incomplete story.

Multiple unanswered questions tarnish the case.

(alarm) What's that?

NARRATOR: But there's agreement that the crisis began suddenly,

escalated rapidly, and forced the pilots to act fast.

While the plane is cruising at 37,000 feet,

first signs of a crisis become apparent.

LEARMOUNT: Things had started going wrong.

(alarm) There's a fire!

You need to get the airplane on the ground now.

Too many things are failing, too many warnings are coming up.

ASSEM: It's spreading! Where's it coming from?

SHOUKAIR: I don't know! (pilots coughing)

(alarm blaring)

NARRATOR: The warnings would have spurred the pilots into action,

but the situation worsened.

It's getting increasingly smoky.

They're going to be increasingly having trouble with breathing.

ASSEM: Blower override. (coughs) Cabin fans off.

NARRATOR: The pilots would have followed the procedures for smoke in the cockpit

in an attempt to isolate the source of the smoke.

Electrical bus tie, auto.

(Shoukair coughs) ASSEM: Try to start the APU. (coughs)

NARRATOR: The electrical emergency configuration

would have shut down most of the aircraft's systems,

leaving the pilots with only some basic controls to bring the plane down.

COX: This is what you do if there's a fire.

It has been a proven safeguard in airliners for quite a long time.

(Shoukair coughs)

NARRATOR: It seems the fire grew…

(coughs) I'm taking us down.

NARRATOR: …and spread into the passenger cabin.

There is a fire extinguisher in the flight deck.

So, where's the fire? What's the intensity of the fire? Where's it progressing?

NARRATOR: Every second the fire burns, the more damage the plane sustains.

The situation in the flight deck would be chaos,

because it's becoming increasingly difficult

for the pilots to know what they are fighting against.

SHOUKAIR (yells): I can't see!

(extinguisher huffs)

(cries of panic)

NARRATOR: The cockpit of Flight 804 was likely engulfed in flames

as the pilots tried to save their plane.

How exactly the pilots tried to fight back the fire

is another one of Flight 804's unsolved mysteries.

If nobody knows about what went wrong in a particular accident,

how can they change their own programs? How can they devise their aircraft better?

NARRATOR: If mistakes were made by EgyptAir or by Airbus,

they remain unpublicized.

Airbus has not made any changes to the design of the A320

as a result of this accident.

COX: It's been a large number of years since this tragedy happened,

and we still don't know why.

We owe it to the traveling public. We owe it to crew members.

We owe it to the victims' families.