Original subtitles

All that is left of Ethiopian Airline’s Flight 409

lies at the bottom of the Mediterranean Sea.

This accident was very unusual, very unlikely

Everybody was shocked that we had a major crash in Lebanon

A 737 fell from the sky , just minutes after leaving Beirut

Now, rumours of a terrorist attack are spreading through the streets.

They speculate that the plane could be hit by a bomb

and investigators are struggling to understand the plane's bizarre flightpath.

Often, the best approach is the Sherlock Holmes approach...

Eliminate everything you know didn't happen

What is left...

...is probably what did happen

The evidence leads to a finding, so controversial

some still refuse to believe it.

ALARM IN THE COCKPIT

This is a true story

It is based on official investigations and eyewitness reports

Heading for disaster

It is just past midnight...

...at Rafik Hariri International Airport in Beirut, Lebanon

The fuel is good

The load is calculated.

In a typical departure,

the flight-crew reviews its load, reviews the fuel, reviews the route

then runs through the checklist to get the airplane underway.

Captain Habtamu Negasa has been flying with Ethiopian Airlines for over 20 years

and has more than 10,000 hours in the cockpit

check is complete

Check complete no problems.

The First Officer is far less experienced

Allulah Beyene

is a recent graduate of the Ethiopian Airlines Flight Academy

Tonight, there are 82 passengers aboard the 737.

They are preparing for an overnight flight to Addis Ababa, Ethiopia.

Many passengers are Lebanese.

Some are Ethiopians returning home after working abroad.

There is also an undercover security officer on-board tonight's flight.

The flight security officer is there post 911 to intercept anybody

who attempts to interfere with the flight-crew.

Beirut Airport has seen its share of trouble

It was the site of the 1983 barracks bombing

that killed 241 American servicemen.

More recently,

all 3 runways were destroyed by Israeli missiles during the Lebanon War of 2006.

Today, the rebuilt airport is again open to flights from around the world.

Beirut Airport is a very busy, very well put together civil airport.

Its only difficulty is presented by the mountains directly to the East.

The Lebanon mountains rise sharply from the coast,

forcing all flight to take off towards the Mediterranean Sea.

Flight 409's flight-plan calls for it to head South West,

then, make a U-turn towards a navigational checkpoint called CHEKKA.

Ethiopian 409, the wind is nearly calm, cleared for take off Runway 21

The Air Traffic Controller gives 409 its final take off instructions.

Immediate right turn to CHEKKA

Cleared for take off runway 21 immediate right turn to CHEKKA, Ethiopian 409.

The left side is clear

The right side is clear

The captain sets his radar to display the weather.

While the first officer monitors the terrain

The weather that night had mixed clouds with bases from 2000 ft

overcast up to 20,000 ft

and there were scattered thunder storms in the area.

Take off thrust: set.

The 737 accelerates down the runway.

Speed increasing

Do you see that?

Rotate

Ethiopian Airlines 409 lifts off, just after 2:30 AM

Their take off procedure and the initial part of the take off

seemed entirely routine and ordinary, and well executed.

Gear up.

Heading select.

Check

The captain begins banking the plane to the right as he climbs.

The tower controller bids the crew goodbye

and hands the flight off to a colleague

Ethiopian 409, good morning, climb flight level 29,000 ft

The area controller instructs Flight 409 to climb to 29,000 ft

Flight level 290, Ethiopian 409.

But the weather ahead is becoming fierce.

There is lightning in the area, you see the flashes

You are beginning to feel turbulence.

Sir, I suggest that, due to the weather, you follow heading 270 to be at the clear

21?, say again

Confirming 210

Just a few minutes into the flight, something is going wrong.

An alarm warns the crew that their turn is becoming dangerously steep.

The airplane is being banked beyond its normal operational limits.

Captain Negasa is struggling to correct the problem

He veers back to the left,

towards the thunderstorm the controller wants him to avoid.

As you enter heavy precipitation

the cockpit can become very noisy

with a tremendous whoosh.

The controller sees that Flight 409 is starting to veer back towards Beirut

He warns the pilots again that they need to turn.

Ethiopian 409,

follow heading 270, turn right heading 270

At this moment,

the controller was probably the most concerned with the fact

that the crew had overshot its heading, would be conflicting with inbound traffic

and had to be moved away from a possible conflict with terrain

What? Heading 270

What heading did he say?

270, set

The cockpit fills with a disturbing sound

The control columns vibrate warning them that the plane is about to stall.

What is it?

Go around

Go around

The captain pushes the throttle all the way up

to go around-power

Ethiopian 409, follow heading 270, sir

Follow 270 Turn right heading 270 now.

Whenever a controller tells a pilot to do something NOW

the controller is telling the crew that they are in immediate danger.

The speed is going down

Ethiopian 409, you are going into the mountain turn right now heading 270

He was worried that the crew was going to fly the airplane into the hills

behind Beirut Airport

but their situation is even more dire.

The chaotic motion of the plane is torture for passengers.

It's horrible,

you are feeling a 3 g load is pushing down in your seat

as if you are getting squashed

Some of them were silent some of them were screaming.

Ethiopian 409 Beirut

Ethiopian 409, Beirut.

We've lost an aircraft, Ethiopian

We don't know what has happened and we don't know its position.

Ethiopian 409 has plunged into the Mediterranean Sea 5 minutes after take off

The evidence needed to explain the crash is sinking fast.

Within minutes of the crash the Lebanese military issues a distress call

to all available ships in the area.

Local boats, as well as foreign warships,

join the search.

My first reaction was: this accident is very unusual...

...very unlikely...

...that really required a very good investigation

to see what we could learn from it.

It is the first major commercial aircraft accident in Lebanon

in nearly 35 years.

Within hours of the crash,

the Lebanese Civil Aviation Authority dispatches Hamdi Chaouk

to take charge.

As soon as I reached the airport,

I had to try to manage the environment of the accident

The hardest part is how to deal with all the search and rescue

of major parties, from Defence to the Interior Ministry to all the parties

We have never done this before.

A former pilot, he is one of the few experienced investigators in the country.

So, we are going to make this search area right here on this grid

We have ships here, here and here

Mohammed Aziz is his second in command

First of all,

we wanted, if by any miracle anybody had escaped, to be able to pick any survivor

especially that the first hours say discovered to our sweet bodies

most probably they were thrown out of the plane when it crashed.

Have you any sign of wreckage?

Negative, Nothing.

Chaouk is under great pressure to locate the wreckage fast.

so, you want to answer very important questions to the family:

why my relative died.

It will cost your head as an investigator always: I want to know the truth

But the storm Flight 409 was trying to avoid

is still raging

The major deterrent to this search and rescue operation was bad weather

High waves on the sea and so on

So, this makes the Search & Rescue operation difficult

Could the storm have been fierce enough to bring down a 737?

There were thunderstorms West of the airport

Thunderstorms can be very dangerous.

They can interrupt the flight and the airplane structure

and they complicate the safe operation of the airplane.

In rare cases,

a lightning strike can damage the electronics that control the aircraft

While a lightning strike on an airplane is not uncommon,

it usually doesn't create damage to the airplane,

It can, under some circumstances

At the same time, rumours are spreading quickly.

Flight 409 was the target of a terrorist bombing.

When you live in a country like Lebanon, every now and then you have fighting,

you have explosions,

and the first thing that comes to mind when you loose an aircraft just like that is

maybe there is an explosion on-board the flight.

As day breaks, wreckage begins to wash up on shore.

Navy ships recover floating debris

and some human remains.

It is painfully obvious there are no survivors.

The Lebanese army have recovered 7 bodies

82 passengers and 8 crew are dead.

Most of the plane is still missing.

Without more wreckage,

investigators may never know what brought down Flight 409.

At Beirut Airport,

they question witnesses who lend support to the sabotage theory.

the controllers who were on duty on the time of the crash

I saw a bright orange flash, it looked like the plane exploded.

The controller saw a ball of fire

At his place, he presumed that the plane crashed

Some people say that it could be an explosion.

Hard evidence of sabotage requires a close examination of the wreckage.

I have to go back to the evidence,

because the evidence speaks.

The part of the plane can tell you how the accident happened.

And so far, the inexperienced team is having trouble locating the plane.

No luck, yet

Have you searched this sector here?

We looked everywhere, we looked here and here

We were able to determine where probably the aircraft would have been.

Yet, when the NAVY and the air-force started the search for the plane

they could not find it.

A NAVY ship is searching for signals from the plane's black boxes.

These begin transmitting an alert as soon as they come in contact with water

There is what we call a pinger and it emits a signal for about 30 days.

But two days in

the search hits a major hurdle.

Investigators learn

the NAVY sonar they have been using cannot home in on the signals;

it is not precise enough.

We'll never find them this way, we don't have the right equipment.

We could not sleep, we were always thinking that we need the recorders

Chaouk contacts aviation authorities in France for help.

We're hoping you can come immediately,

It is quite urgent.

They have the equipment and the expertise to find the recorders.

They are on their way

It was a learning curve for everybody the leaders or divers...

...or the NAVY people.

With the right gear,

the team should be able to search more quickly,

but valuable time has been lost,

and investigators have few leads.

This type of airplane is flying all over the world

and if there is a problem, we take whatever corrective action is needed.

The United States also sends help.

Because the 737 is American made, the NTSB's Dennis Jones

joins the team.

Welcome to Beirut

We still didn't have the crash site the flight-recorder which is always a big concern

of interest was still yet to be found

With no wreckage to study,

Jones and Chaouk turned to a record of the plane's flight path

We have the radar track of the airport

It should show us exactly what they did.

When we first got there, some of the information we had was helpful

that was the radar data and Air Traffic Control information in general

We were able to start evaluating that pretty quickly.

The radar paints a baffling picture.

It is like no one is flying

Exactly.

Almost from take off

the plane follows an unusual and erratic path.

Once you see what happened to the plane, you would wonder what is really happening.

As if there were no crew in the cockpit It is almost similar...

...of a situation where nobody is in control of the plane.

Now that they've seen the strange flightpath...

...investigators are more anxious than ever to get at the wreckage and search for answers.

What we are seeing is an external view of the radar data and ATC.

But we didn't get an idea of what actually was going on board the aircraft

We became even more eager to get the recorder

That is it!

It is exactly what we are looking for.

Finally, 8 days after the crash,

the French equipment detects the vital signals.

It was found 45 meter deep and 5 km South West of Beirut Airport

Camera's mounted on unmanned subs

capture the first images of what remains of Flight 409.

We had the Odyssey submarine that has been used for taking photos

and for the wreckage, located on the seabed

It is too expensive to bring all the wreckage to the surface,

so, investigators focus on the tail section where the 2 black boxes are stored.

They retrieve the tail, the horizontal stabilizer

the tail-part as well They are still attached together

And they found the Flight Data Recorder, located underneath it.

We were quite delighted about that

The Lebanese government immediately started making plans

on having it transported to a facility to be evaluated.

But they only find the Flight Data Recorder.

What of the Cockpit Voice Recorder?

The CVR should be nearby...

...but it is not.

So, it has got to be in this sector

While the divers continue their search

investigators study underwater video of the wreckage for clues.

OKAY, let's start mapping this out.

When a plane explodes in mid air, the debris falls in a circular pattern

but if a plane hits the water intact, the debris will fall in a linear pattern.

The underwater video allows investigators to map the position of every piece of wreckage.

Another one here, lining up nice and neat.

In this case,

we found all the pieces laying in the bed of the water

in an almost 300 meter straight line

They also search for any sign of fire damage.

You would look for a certain signature to show us

perhaps there might have been some heat damage or fire damage.

But there is no sign that the metal was ripped open by a blast

and no burn marks on any of the wreckage.

We looked at the footage

we couldn't identify any black spots, black soot or any thing of the sort

We saw none at all.

There is no sign of any explosion.

Ethiopian 409 Beirut.

They conclude that the tower controller may have been fooled

by a trick of the light.

It was a stormy night, so throughout the night you were hearing thunderstorms, lightning,

and they do sound exactly like explosions

and they'd give you a bright light even stronger than any big explosion.

Still puzzled about the cause of the crash,

investigators turn to the newly available data from the Flight Data Recorder

Nothing, so far.

There are more than a 1000 parameters to analyze.

The FDR records essentially the instruments

another parameter from the aircraft Basically what the aircraft is doing

and that retains in this case 25 hours of information.

Almost all the data is normal

but one number stands out.

Take a look at that stabilizer setting.

It is a bit low, but still in the green.

The stabilizer is part of the tail.

Pilots adjust its angle, depending on the weight off the plane.

Move itr up, and the plane pitches up

Move it down and it forces the nose down

The fuel is good

The load is calculated

Check complete, no problems.

The FDR reveals that Flight 409's stabilizer was set further down than normal for take off

Such a small variation probably wouldn't cause the pilots to loose control of their plane,

but investigators won't know its effect

until they can test the configuration in a flight simulator.

At that point, obviously everything was on the table.

We knew we had a lot more factual finding to do.

The investigation takes a huge step forward

when the search for the missing recorder finally pays off

Aziz, we got it

I have to praise the Lebanese NAVY-diver, because with the equipment they had

they had to do real hand-search 45 m under water which is quite difficult

but they were able to recover it at the end

Investigators can only hope

that the pilots said something that will reveal why their plane went down.

Investigators sync up the conversation on the Cockpit Voice Recorder

with the known flightpath

They listen for any sign of trouble.

We want to try to get a better understanding if there might have been a mechanical problem,

based on what they were perceiving

Now, once they took off, the first part of the take off was normal

Turn right, initially heading 315

Investigators hear the controller give the pilots a new heading

but the plane goes off in a different direction.

As they approached the heading they have been assigned

they overshot the heading.

He was supposed to turn this far, but he just kept going.

Mark, they are way off course

Each time the pilots try to correct their course..

...they turn to far and banked too steeply.

It is a sure indication that the airplane has lost control.

Ethiopian 409, You are going into the mountain! Fly right now heading 270

The airplane was rolling into an ever steeper bank.

Its lift factor was decreasing, so the nose was dropping toward the sea,

ultimately leading to a spiral.

The plane was out of control.

There is nothing on the recording to suggest there was a mechanical failure.

We just could not hear anything that showed a malfunction,

which was consistent with the FDR.

It was something that we certainly did have any answers for in the beginning.

Desperate to know what brought down the 737

investigators dig in to maintenance records.

They learn that some 737s have a small but dangerous flaw

in a vital part of the tail.

Hey, Dennis, I think we need to check those trim tabs

Trim tabs are small control surfaces set into the tail of the plane.

They counteract the powerful flow of air, pushing against the tail,

making it easier for the pilot to fly the plane.

To use an analogy with cars:

it is like power-steering as compared to manual steering

If the trim tabs were damaged,

it could explain why the captain was struggling to control the aircraft.

Left heading 270?

Roger, 270

In my experience,

if I fly an airplane out of trim that can make it extremely difficult to fly

It can even go beyond the forces that the pilot can handle.

You can bring that over here.

Investigators are in luck:

the stabilizer and trim-tabs are among the few pieces of wreckage,

recovered from the sea.

The team assembled to evaluate

This aircraft hit the water close to 400 knots

so, we're expecting a lot of things to be damaged.

We wanted to evaluate to see if there is anything that was pre-existing

that might have contributed to the sequence of events.

But it is another dead end:

A close inspection of the trim tabs reveals no damage at all,

no sign of any malfunction.

They did not affect the pilots' ability to steer the plane.

Why a 737, carrying 82 passengers plunged into the sea, only minutes after take off

is still a mystery.

Investigators travel to Seattle, Washington

to Boeing state of the art flight simulator

OKAY, we are going to run the Ethiopian 409

We are going to set the trim to match their's

The flight data has shown that 409's stabilizer was set to a shallower take off angle

They now need to know if that somehow affected the pilot's ability

to handle the plane.

You get a front row seat of what the flight crew were seeing at the time

and how the aircraft was handling.

OKAY, let's see how this thing is going to fly.

The low angle of the nose makes the plane difficult to handle at first.

It is definitively not happy

The trim was mis-set for take off

by a small margin, but nevertheless

by enough to create an undesirable pressure for the pilot on the controls.

So, the pilot was always fighting the airplane to one degree or another.

But in the simulator, the pilot has no difficulty correcting the problem

OKAY, we try it with no trim at all

Every single time we tried to recover this aircraft

we were able to recover it.

They should have been able to recover.

They conclude that the low stabilizer setting did not cause this crash.

Something else made the 737 spiral into the sea.

Officials from Ethiopian Airlines still believe terrorism is to blame.

They insist that an on-board bomb cannot be ruled out

until more of the wreckage is recovered from the Mediterranean.

The investigators don't agree

We told them it is quite a small possibility that there was something put on-board that plane

but when the plane explodes with a bomb on board,

it doesn't go up and left, and right, and up and down and then

something explode on the plane.

But stamping out rumours is never easy

Investigators are under growing pressure to explain what happened

If it wasn't a bomb then what did bring down Flight 409?

An aircraft accident investigation

often the best approach is the Sherlock Holmes approach

You eliminate everything you know didn't happen...

...what is left, is probably what did happen.

The controllers did their job,

the ground base navigational systems were working

the airplane was functioning properly.

So what we have left is the crew.

Investigators return to the Cockpit Voice Recorder

They hope the crew's conversation can shed light on why two qualified pilots

lost control of a mechanically sound airplane.

Check complete, no problems

They notice something odd

The mood, even the speed of the voice or even the tone

They did not reflect on what is actually happening

during the take off roll, the captain saw something because he tells

'Did you see that?'

But then, there was no reaction from the First Officer

The First Officer is uncharacteristically quiet

OKAY, engage the AUTOPILOT

Even worse, he is not following his captain's commands.

The advantage of engaging the AUTOPILOT in that situation

is that the pilot can then let the AUTOPILOT worry about the attitude

while he sits back and takes the big picture:

Maintain situational awareness.

The AUTOPILOT can adjust the throttles to maintain a safe airspeed

and can keep the plane on the right heading

but investigators learn it was impossible for the AUTOPILOT to engage on Flight 409.

There's no way it can come ON

OKAY, engage the AUTOPILOT

It is designed not to switch ON if one of the pilots is pulling on the control column

as the captain was.

For some reason,

the First Officer didn't give his captain a crucial piece of information

that the AUTOPILOT did not come ON.

Had the AUTOPILOT be engaged,

when the captain ordered the First Officer to engage it

would have saved the whole flight.

The interaction between the crew-members were not what we would expect

from professional crew at that time

The crew's behaviour is baffling.

It forces investigators to consider an unlikely explanation for what went wrong.

Something called subtle incapacitation.

It is very difficult to recognize a subtle incapacitation

If the pilot had the control, has a stroke, and slams over the control wheel

there is no question that you have got a person who is incapacitated

Confirm heading 210

Negative, sir

to proceed direct CHEKKA, turn left now heading 270

Left heading 270?

Roger, left heading 270

However, if the pilot at the controls...

...starts to loose the picture...

...and does so silently...

...and starts to misapply controls, push the wrong buttons...

...it may take a while before the other crew-members pick up on that failure.

That sequence is called subtle incapacitation.

It is a controversial idea that goes beyond the usual definition of pilot error.

Subtle incapacitation can come from physiological reasons

psychological reasons

or a combination of both

It could be something minor,

medications could cause it, stress,

fatigue could cause it

Because commercial aviation demands such high levels of performance

drugs and alcohol, used by pilots is closely scrutinized.

Drug testing is part of any transportation employee

from baggage handlers all the way up to the cockpit.

It is typically done on a random basis.

But there is no formal test for fatigue.

Other accidents, but the same kind of sequence of events taken place.

The best known example is ColganAir Flight 3407

In 2009,

two overtired pilots failed to react properly to a warning that their plane was about to stall.

All 49 people on board were killed.

This room doesn't make you sleepy?

Investigators continue to analyze the cockpit recording

What are these guys doing?

They listen to what the pilots were saying, just before take off

This room doesn't make you sleepy?

the recorder say: Sleep

Immediately, our attention stuck up

What are they doing up there?

Was there weed in it?

Did you feel dizzy?

Al right, I couldn't sleep

Well, me too

Investigators are shocked to hear the pilots joking about being tired

and the reference to weed.

Subtle incapacitation may not be such an unlikely cause after all.

Trying to explain the behaviour of the pilots on that particular airline

was really the most difficult part of this investigation

This is why we considered every single issue starting from the food they had,

the type of rest they had.

Piecing together the pilots' movements in the hours leading up to the crash

is now the top priority

In the case of this accident

the pilots' bodies weren't recovered,

so there was no way they could do post mortal examinations.

We immediately called the hotel to check the garbage,

if there was any bottle of alcohol, any drugs.

Did they see a crew out, having drinks or something

They study security footage for any signs that the pilots were impaired.

We also looked at the footage of the crew, coming in to the airport

They were walking normally everybody who spoke to, said they were normal

Investigators travel to Ethiopia

to interview family members about the crew's habits

Thank you for taking the time to see me I am very sorry for your lost

I just want to ask you a few questions about your brother

Did he ever drink?

No

There is no evidence to suggest either pilot abused alcohol or drugs.

The captain didn't drink at all, so he was a sport-guy

concentrating on his sports.

Subtle incapacitation is difficult to prove.

In the crash of Flight 409, the evidence so far is mixed.

but what investigators discover next, could tip the balance.

Employment records detailing the pilots' flight hours

reveal critical information about the captain.

He'd been working almost none stop for nearly 2 months

In 51 days, he probably flew something like 45 days

Daily, daily, daily flying just taking the minimum rest

It is legal, but it is quite a lot of work.

Work, work, work

The crew's last chance to rest was a scheduled stop over

after flying into Beirut.

I could use some food that didn't come from an airplane

Yeah, a good meal would be good

Alright, let's do it

Prior to the flight, they had a heavy lunch and they were not able to rest properly

so they were commenting on not being able to rest properly prior to the flight

Did you feel dizzy?

I couldn't sleep

Investigators suspect that the heavy meal affected their sleep.

Indigestion and the fatigue, definitively affected the pilot's behaviour

throughout the flight process

The storm conditions likely added to the pilots' stress.

The weather could be a factor and I think pressure on the pilots

Fatigued and under increasing stress, they lost track of where they were

and what they were doing.

This flight was in jeopardy from the outset

It seems that the crew was never fully on top of what was happening.

Investigators conclude

that the accident was caused by a crew that was simply too tired

or too confused to recover from the first wrong turn.

It is a textbook example of subtle incapacitation

We could prove that the symptoms that we saw are similar to the symptoms

of somebody who has a subtle incapacitation.

The accident exposes a risk to aviation that no amount of engineering...

...can overcome.

After the crash of Flight 409, investigators suggest

Ethiopian Airlines introduce much more rigorous rules regarding crew rest.

It is one thing to have the experience, expertise to do the work

but you have to be in good condition in order to perform.

As long as airplanes are operated by humans

fatigue, distraction, and other human weaknesses can only be managed

never erased.

I'm not sure that we can prevent subtle incapacitation,

but we should at least try to eliminate all the possibilities that are human factor

because human factors are still the majority of most of the accidents.

Narrator Jonathan Aris

Subtitles Rein Croonen