Original subtitles

After declaring an emergency...

- Injured passengers due to severe turbulence.

...China Eastern Airlines Flight 583

seeks permission to land at a restricted

US military base in the Bering Sea.

- 300 feet.

- The Pentagon would have to take a look

at what's happening.

Is this a ruse to take a look at our radar site?

Once the plane is examined,

officials discount the possibility of espionage.

- I've never seen anything like it before.

This accident was definitely

a catastrophic event.

Two passengers died.

The flight data recorder shows

an erratic flight path.

- Wow.

Being on this airplane was like

being on a rollercoaster.

Only the cause is not what the pilots reported.

- The weather was clear.

It's unlikely there was any turbulence.

- That changes everything.

The crew of China Eastern Airlines Flight 583

is on an overnight flight from Beijing to Los Angeles.

- Approaching 39 degrees north, 1-72 degrees east.

- All good back there?

In 1993,

China Eastern Airlines was a fairly new company.

It had only been around a couple of years.

The entire China aviation market was rapidly changing.

China Eastern Airlines began operation in 1988.

It was an exciting time

with people finding that they suddenly had the ability

to start travelling overseas.

235 passengers have just finished

their meal service.

Some rest while others watch a movie.

You press this switch

and the air conditioning pops up.

The captain is a veteran pilot

with more than 8,000 flying hours.

- You try.

The captain was flying the airplane

from the right seat because he was training the person

who was in the left seat to be a new captain.

His first officer is a seasoned pilot,

but new to this plane, an MD-11.

McDonnell Douglas developed the MD-11

as a fuel-efficient option for long-haul flights.

In the early 1990s,

approximately 100 of them were in service worldwide.

The MD-11 was an upgraded version

of the DC-10.

It was more efficient flying at cruise speeds.

Although it had an automated system for flying the aircraft,

it was also changed in such a way

that it was very responsive to pilot input

if they were flying it manually.

This plane is one of five

the airline bought to grow its international service.

- Fuel check numbers look good.

- Copy that.

During the cruise portion of the flight,

things are fairly routine.

Flying at 33,000 feet,

the autopilot's on.

They've completed the first leg of the flight

from Beijing to Shanghai

and are now flying over the North Pacific,

bound for Los Angeles.

- Ladies and gentlemen.

The cabin crew is now passing out Customs Declaration Cards,

which must be completed before entering the United States.

For many passengers,

this is their first overseas flight.

The process is unfamiliar.

- We're still good at the hotel we're staying?

- Yeah.

- Something's going on with the speed indicator.

The crew has pre-programmed

a cruising speed into the computer,

which is now telling them to fly at a different speed.

The flight control computer is making numerous checks

of various systems including air temperature, airspeed,

fuel burn, etc.

And it sometimes gives suggestions to the pilots

of how they can fly more efficiently,

in this case, fly more slowly.

- Hmm.

That didn't fix it.

The Captain tries to clear

the computer's suggested speed.

It's not a big concern,

the airplane's flying fine.

But it's just odd.

And the captain tries to sort it out.

- I'm gonna try this.

- What's that?

While they're sorting out the speed issue...

the plane seems to hit some turbulence.

They start feeling this buffeting

and the airplane's shaking around.

It's definitely something that will get any pilot's attention.

Suddenly...

...one of the worst things a pilot can hear:

a stall warning alarm.

I'm taking control.

The nose of the plane is pitching up,

which shouldn't happen while cruising

at altitude with the autopilot on.

He needs to get the nose down

because if the airplane truly stalls,

it no longer has enough lift to stay flying.

It's gonna start dropping from the sky.

The captain pushes the yoke

with enough force to override the autopilot...

- Autopilot off.

...and to avoid a stall.

But now the nose pitches too far down.

The effects of the dive are felt even more severely in the cabin.

You're trying to gain control of the airplane,

trying to understand what's going on.

The adrenalin level goes dramatic real quick.

The captain uses all of his strength

to keep the plane from diving,

but the aircraft pitches up steeper than expected

exerting massive G-forces on everyone

and everything in the cabin.

- Turbulence! Seat belts everyone!

- What's going on?

In essence, this airplane was pitching up

then pitching down.

It's almost like being on a rollercoaster.

The captain attempts to level the plane,

but it goes into an even more extreme dive.

It happened so fast,

the forces are so great,

you wouldn't have time to even think of trying

to get your seat belt on.

- 8 degrees nose down...

9... 10.

The captain halts the terrifying dive,

with severe consequences for unbuckled passengers.

You're being slammed back into your seat,

and then thrown back onto whatever might be

below you at the time.

As the plane is tossed up and down,

the crew avoids a stall by keeping the nose

from pitching up too much.

But the nose downs are a problem.

- The pitch downs were more extreme than the pitch ups

and the aircraft was losing altitude.

On the next oscillation,

the plane pitches down an astonishing 24 degrees.

The captain battles to stop the plane from diving,

while passengers struggle for their lives.

A lot's going on.

It's a dark night. He's using his instruments.

Forces are nothing like he's ever seen before

and so it takes several of these cycles of this porpoising

until finally he is able to get the airplane back to level.

30 seconds in,

the oscillations lessen

and the plane begins to stabilize.

- Level at 0 degrees.

To the crew, the event probably felt

like it lasted, you know, an hour.

In reality, it lasted a little less than a minute.

What just happened?

- No idea.

Even with the autopilot on,

there's no time to relax.

There's no guarantee that what happened won't happen again.

They're flying over the vast Pacific Ocean,

nowhere near an airport.

And several passengers are seriously wounded.

We have many injuries.

- We need to get this plane on the ground.

Airlines Flight 583): Chn

is back at 33,000 feet.

Now it needs a place to land.

- 235 passengers on board, unknown number injured.

- Call it in now.

- Flight 583, requesting the nearest airport,

this is an emergency.

- Airspeed?

298 knots.

- Angle of attack.

- 0.

For now, everything seems to be working.

All they know at the moment is the airplane's

flying what appears to be fine

but, then again,

until we land and get out and look at it, we don't know.

With injured passengers on board,

the captain can't take the risk of flying 37,000 miles

to their destination: Los Angeles.

- We're 39 degrees North, 1-76 East.

Copy. Please stand by.

The crew considers where they might land.

- Are we closer to Russia or to the US?

This far out over the Pacific,

mainland Russia is 22,000 miles to the northwest.

Anchorage, Alaska is the same distance to the northeast.

They're in one of the few places in the world

where there's nothing really close by.

- Ladies and gentlemen.

The plane encountered severe turbulence

and the damage is being assessed.

Please cooperate and be patient.

We are planning for an emergency landing.

Flight 583 is overseen

by air traffic control in Honolulu,

2,000 miles away.

What is your emergency?

- Injured passengers due to severe turbulence.

Stand by please.

It's an unusual situation:

A civilian Chinese airplane

in international airspace in urgent need of an airport.

Looks like it's either Anchorage or Shemya.

Waiting for clearance.

Shemya, a tiny island on the western tip

of Alaska's Aleutian Island chain,

is about 1,000 miles away.

Anchorage is twice as far.

Because it's an Air Force base,

Shemya has medical staff and equipment

to treat injured passengers.

Shemya is basically an island

in the middle of nowhere,

operated by the US Air Force.

It's strictly for military operation.

There are no commercial flights.

The decision to allow

the China Eastern Airlines Flight to land

is taken to the highest levels.

The Pentagon would have to take a look

at what's happening here.

Is this a real emergency, or is this a ruse

to take a look at our big radar site we have there?

I imagine there was a lot of discussion going on

from a security point of view.

Cleared to divert to Shemya.

- We're cleared to divert to Shemya.

The captain had a choice to make:

Do I go to the closest available runway,

which was Shemya, or do I go further on to Anchorage,

which might be catastrophic

had there been damage to the aircraft.

- Okay, we're going to Shemya.

We have received permission to land at Shemya Air Force Base.

Damage to our aircraft is unknown.

Can we get a weather report?

The crew prepares for a difficult night landing

on an airstrip they've never seen before

with unknown damage to their airplane.

Shemya has extreme weather,

heavy cloud cover, fog and high winds is the norm.

After a nerve-wracking two hours in the air,

the plane is now only 40 miles from the air base.

- Altimeters. - Set.

They really don't know

what's gonna happen when they slow up.

Did the elevators get damaged?

Will the landing gear come down?

There's a lot of things they've gotta be concerned about.

As they get closer, the weather intensifies.

- ILS armed.

Runway 28.

The crew connects to an Instrument Landing System

that uses radio signals to guide them in.

- 3,000 feet.

- The crew at this point is going to be under a good amount of stress

and pressure to make sure that they do it right the first time,

wanting to get the people to help as quickly as possible.

- Autopilot off.

Taking control.

They're now only 6 miles from the runway.

- Gear down.

Landing gear is down.

500 feet.

400 feet.

300 feet.

The ILS gets the plane as far

as 200 feet above the ground.

Then the captain has to fly by sight.

- We have touchdown.

The emergency is over.

The plane is safely on the ground.

Medical teams immediately assess passengers.

The findings are grim.

149 people are injured.

Dozens of passengers and crew are taken to hospital.

One passenger is dead,

another is fatally wounded.

- This accident was definitely a catastrophic event.

Many, many passengers and flight attendants

were seriously injured.

Passengers who are well enough to travel

are flown to Anchorage International Airport

and transferred to hospital for treatment there.

- At that time, I think I would die.

Of course, surely I would die.

A team of investigators

from the National Transportation Safety Board,

or NTSB, flies in from Washington.

Greg Feith leads the investigation.

You'd never know anything was wrong with it from here.

They did land on US territory

and so we were gonna conduct the investigation.

And because it was an MD-11,

it was a relatively new airplane.

I'll go check inside.

We needed to find out what really happened.

As soon as investigators arrive at Shemya,

they inspect the aircraft for signs of damage.

- I'll go check out the cockpit.

We didn't have a lot of information.

We knew that there had been an emergency landing,

that the airplane had encountered severe turbulence.

With that kind of information, you can build

a lot of different storylines.

The cockpit looked normal.

But as soon as you looked down the aisle,

it looked like a bomb had gone off.

- I've never seen anything like it before.

- Row 15, bin down on seats B and C.

Seat 23B, signs of impact damage.

The cabin gives them a glimpse into the tragedy

that unfolded during the flight.

There was a lot of baggage

that had come out of the overheads.

Broken glasses, broken dishes,

they are basically lethal weapons

if they are flying through the air.

- Hey. Check out those marks.

- Likely scuff marks from shoes.

That was really disturbing because passengers,

they had to have been floating not only in space

but they had to have rotated

so that their feet were above their head.

- It seems like there was a sudden pitch down.

- The damage is worse in the aft section.

Someone got badly hurt here.

People in the back are more likely to get injured.

That tail of the airplane tends to get whipped about

almost like a fishtail.

- Let's see if we can find some passengers

that are well enough to talk to us.

We really needed statements from passengers

and flight attendants who had experienced the violence.

They were gonna give us a first-hand account

of what really took place.

Thanks for coming in today.

Okay.

When the incident happened,

what's the first thing you remember?

- The plane started to shake.

Then it went up and down like this.

The shaking could be the result of turbulence.

- How quickly did this happen?

- So fast.

I think I'm lucky to be alive.

- When the plane started shaking,

did the crew give a turbulence warning?

- One of the common causes of turbulence

tends to be bad weather such as rain or hailstorms.

If the turbulence is unforeseen,

passengers who don't have their seat belts on

are at much greater risk for injury.

- Did you see out a window?

Was there any bad weather?

- Not that I could see.

- Thank you.

They described that the flight was actually relatively smooth.

They didn't notice any kind of turbulence.

There was nothing unusual about the flight

leading up to the main event.

Investigators turn to the weather reports

from the day of the incident.

- This isn't what I expected.

The weather was clear.

It's unlikely there was any turbulence.

- That changes everything.

- What about the elevators?

- Definitely worth a look.

A damaged elevator could have led to a loss of control.

We had to determine whether or not there was a problem.

Elevators are hinged flaps

on the trailing edge of the horizontal stabilizer.

When the pilot pushes or pulls on the control column,

the elevators respond by rising or lowering,

creating pitch.

Investigators look for any exterior signs

of elevator damage.

Everything looks good on the outside.

I'll check for internal damage.

We use what's called the tap test.

And it's a very simple test

and in fact, it's done with a quarter.

It should sound solid.

If you hear a hollow type of sound,

that's a very good indication that there is a delamination

in one or multiple layers of that composite material.

I'm hearing nothing out of the ordinary.

After we cleared the elevators,

we still had to understand what may have caused

this airframe buffet.

No substructure failures or anomalies were found.

Nothing wrong with the elevators.

- Then what else?

- What did the captain have to say?

- I'll check the status of his interview.

We wanted to know

what he was doing as far as his duties

and responsibilities leading up to the upset.

- I'm taking control.

- Hey. You're not gonna believe this.

Page 22.

NTSB investigators turn to the captain's account

of China Eastern Airlines Flight 583's high-altitude incident.

- He mentions turbulence before the onset of the incident.

We knew there wasn't any. - That's not all. Keep reading.

- He noticed the slats were extended?

- Yup.

The MD-11 has eight slats

on the leading edge of each wing.

When extended, they change the curvature of the wing,

creating more surface area.

Used in tandem with the flaps,

they provide extra lift during takeoff.

- That's weird.

Why would the slats be extended during cruise?

Investigators now have a very promising lead.

There's no reason to place slats at 33,000 feet.

As soon as you would see that the slats had extended

at that altitude in cruise,

that would be an alarm bell.

- If the slats were out,

that would explain the pitch up described by the passengers.

- They're controlled by this handle here.

- We should check the entire slat system.

We had to determine whether one or more of the components

in that slat system had either malfunctioned or failed.

The first look is clean.

No obvious signs of damage.

We had to access all the mechanical linkages.

There's hydraulic valves, electrical mechanical systems,

so we had to make the determination

whether or not they were functioning as designed.

Okay, let's test them.

Extend the slats.

There's one handle in the cockpit

that controls both the slats and the flaps.

Typically, the slats are deployed first

so when you pull it back to the first notch,

the slats get deployed.

You pull it back further; the flaps get deployed.

- It all seems to be working fine.

I'm not seeing any mechanical issues at all.

They examined the whole system

and they extended normally, they retracted normally.

There was no obvious damage to the aircraft.

- I still think the slats are part of the problem.

- Maybe it wasn't mechanical?

- Good thought.

Maybe it wasn't.

Everything showed that the airplane

was perfectly fine to fly.

And so the investigation would focus

to what the pilots did or did not do

that caused the upset.

Did the pilots somehow deploy the slats

at high altitude?

- Now we had to determine whether or not

those slats had been deployed inadvertently.

You got all the reports?

- Yup.

Have any pilots accidentally

deployed the slat handle in an MD-11?

They review old incident reports.

We do what's called "a look back,"

so we're looking at whether or not this is an isolated event

or a systemic problem.

- Hey, look at this.

- What have you got?

- 10 incidents in two years.

- Clipboard fell on the handle.

First officer rested his arm on the handle.

"Slats extended in cruise flight."

There had been other events with this particular system,

either an uncommanded

or inadvertent deployment of the slats.

50% were due to some sort

of pilot contact with the slat handle.

If the pilot didn't know he knocked the handle,

he probably didn't hit it that hard.

- So it could've moved

to the slats only position.

- And deploying the slats at high speed

would trigger the buffeting,

which was likely misconstrued as turbulence.

What was happening in the cockpit

right before the buffeting started?

- The captain said he was using

the control keypad, here.

- They are really close together.

Investigators have a new theory;

a simple movement could have triggered

the entire chain of events.

- We've gotta see how easy it is

to knock this handle out of place.

Investigators test whether the crew

of China Eastern Airlines Flight 583

could have inadvertently knocked the slat handle

out of position during flight.

- Ready? - Ready.

It moved.

- Now the first officer was sitting in the left seat

so he could have knocked it.

But the captain said he was playing with the keypad.

- They tried different techniques about, okay,

if you hit the handle from the right side back,

you hit the handle from the front side back,

what would it take to jar

the handle out of position?

- Hang on, let me try something.

Bingo. That's what the captain was doing

when the buffeting started.

- It didn't take much force either.

It's a major breakthrough.

Proof that the handle could have been accidentally moved

while the captain reached for the keypad.

- It was real easy during normal movement

using the keypad on the centre pedestal

to inadvertently strike the handle

and cause an uncommanded slat deployment.

Investigators have uncovered

a dangerous design flaw in the MD-11.

- So the handle probably moved in flight.

And then the captain retracted the slats.

The captain said that he saw that the slat handle

had been out of position at about the same time

the stall warning system triggered.

He immediately moved the slat handle

back into the retract position.

The slats were fully extended for just seconds.

- Now, that explains the initial pitch up.

But... there has to be more to it than that.

I mean, the plane went up and down several times.

The slats wouldn't have caused that.

Investigators still don't understand

why Flight 583 experienced

so many extreme oscillations.

- The cockpit voice recorder would record for 30 minutes

and overwrite itself,

so we didn't have that information.

However, with the flight data recorder,

we could see control positions,

we could gain other information.

Okay, first up, let's look at pitch.

So we have five big oscillations in roughly 20 seconds.

The biggest pitch up is here,

oscillation 1, 9.5 degrees.

The biggest pitch down happens here,

-24 degrees, oscillation #4.

For the first time, they can see the severity

of the oscillations passengers described.

- And it starts to stabilize... here.

The team launches into a second-by-second analysis

of the first pitch up.

- The slats were extended here,

during the beginning of the first pitch up.

- It's gradual at first.

Is the autopilot on?

So it's on for the first few seconds.

And it would have been fighting to bring the nose down.

When the slats deploy, the airplane will have

a natural nose or pitch up tendency.

With the autopilot engaged,

it will actually correct for that pitch up

and return the airplane to a level attitude.

But the autopilot is losing the battle.

The pitch keeps increasing.

And that would trigger the stall warning.

Yup, the stall warning turns on here.

A few seconds later, the autopilot disengages.

And now the nose dives down sharply.

- I'm taking control.

Autopilot... off.

- So the captain's at the controls

when this big drop happens.

Show me the elevator data.

Wow.

So the captain made some elevator inputs

starting right here.

- That is a huge nose down command.

- It's an overcorrection. And I think I know why.

- I'm taking control.

Autopilots are designed

so they won't just let go easily.

You don't want somebody just accidentally bumping

against the controls to suddenly knock the autopilot off.

He felt a resistance

and pushed against that resistance

of the autopilot, disengaging it.

Unfortunately, that led to an excessive amount

of nose down elevator command.

He started a chain reaction of pushing

and pulling too hard on the yoke.

At high altitude,

the pitch forces are very light on the yoke.

So when he pulls back to get the nose up...

...he's putting in too much up force.

It goes up too high...

he pitches down, it goes down too low...

...and he puts in several cycles on the control yoke

trying to get back to normal.

It's called a "pilot-induced oscillation,"

or PIO.

The pilot overcorrects,

and the plane responds,

creating increasingly uncontrollable movements.

Once you get into the oscillations, it's hard to stop.

Everything is happening fast.

We were able to calculate

that the occupants of the airplane experienced

1.24 negative Gs

and 2 positive Gs.

No wonder there were so many injuries,

including two fatalities.

He did get the plane back under control.

It just took a while.

Pilot-induced oscillations

can cause extreme stresses on the aircraft.

Usually, the best course of action

is to put in less control force.

Once that happens, you can have a nice, stable flight.

- So why would an experienced captain struggle so long

to get a plane back under control?

Long day ahead.

You're gonna need this.

- I pulled the captain's files.

Investigators turn their attention to the captain

of Flight 583's training

to determine why he repeatedly overcorrected

with his control column.

- He had over 13,000 hours on the MD-11.

That should be plenty.

He flew other passenger jets too.

The captain had flown Ilyushins,

he had flown Airbus 300s.

He had experience on big aircraft,

he had experience with high-altitude flight.

Everything would indicate that he was well qualified

to fly the airplane.

- No complaints,

no prior accidents.

He's clean as a whistle.

The captain passed all

of his MD-11 training without incident.

- Even took a refresher course a few weeks

before the accident flight.

- Hmm.

Let me see the training manual.

Investigators take a closer look

at the training the captain received.

- A critical aspect of accident investigation

when you're looking at an event like this

is pilot training.

The captain did go through a very comprehensive textbook

or classroom training.

- Find anything?

Actually...

it's what I didn't find that interests me.

No simulator training.

- None? - Nope.

Not for an inadvertent slat deployment during cruise

or an upset at high altitude.

- Hmm.

Just giving them something to read

is sort of like trying to learn to ride a bicycle

if you've only read a manual.

- What's going on?

With simulator training,

you get some hands-on training

and you have a good idea of what to expect.

He did not have that training.

So in fact, he was really a test pilot

trying to get this airplane back under control

after this uncommanded slat deployment.

Was there something about the design

of the aircraft that made it difficult to regain control?

- This is the Airbus A300 here, and the DC-10.

Here is our MD-11.

When compared to other large passenger jets,

one design feature stands out.

- Look at the centre of gravity.

It's so far aft.

Most planes have their centre of gravity

further forward, in the midsection.

- That would make the MD-11

less stable.

The MD-11 was designed

to increase fuel efficiency.

And to do that, you move the centre of gravity

back fairly far aft.

The airplane becomes more pitch sensitive.

I found the airplane

to be very maneuverable.

But some people would get a little bit behind it

and you could end up in cases

where the airplane would overshoot

what you were expecting.

Investigators conclude that the captain

could have stabilized the oscillations sooner

with faster, less forceful control inputs.

But the design of the aircraft m

made that difficult to do.

In their final report,

NTSB investigators found that an unintended movement

of the slat handle likely caused the slats

to extend and the airplane to pitch up.

The probable cause, as determined by the NTSB,

did not place any kind of blame,

or even talk about the flight crew

actually causing this event.

This was a strict design issue that,

unfortunately, the crew became a victim of.

The report also notes that many

of the severely injured passengers either had

their seat belts unfastened

or were standing in the aisle.

The flight attendants had made

an announcement about seat belts,

but as is often the case,

passengers may have ignored that announcement.

And that left many passengers vulnerable.

When you are in an airplane,

not just for takeoff, not just for landing,

it is critical that you keep your seat belt on.

You never know what can happen in flight.

Subtitling: difuze