Original subtitles

[Narrator] Staring down a thunderstorm

above the North Sea...

Take a look at that.

[Captain] Oh, I don't like it.

[Narrator] A modern turboprop

is struck by more than a million volts.

-[Bangs] -[Captain] Oh!

[David Miller] After the lightning strike,

you're obviously looking to see...

Have we been damaged?

Damn it! The plane's not responding! Help me pull.

[Miller] You can fly an aircraft without a compass.

You can fly an aircraft without a radio.

Mayday, Mayday! We've been struck by lightning

and are having control difficulties.

But you can't fly an aircraft without functioning controls.

[Narrator] But investigators can't figure out

how lightning could have caused the plane

to behave the way it did.

Look at that. I mean, the elevators are trying to

get the nose to pitch down instead of up.

[Julian Firth] We'd not come across an aircraft where

there would be this difference between the pilot input

and what the aircraft was actually doing.

[Captain] Oh, no!

-We're dropping! -[Grunts]

[Investigator] They were so distracted by that,

they failed to see what was really going on.

[Attendant] Ladies and entlemen, we are starting... g

[Pilot] We lost both engines!

[Attendant] ... mask over your nose. Emergency...

[Pilot] Mayday! Mayday!

[Man] It's gonna crash!

[Thunder Rumbles]

[Narrator] It's 6:45 PM.

Loganair flight 6780

cruises over the North Sea near Scotland.

Let's get lower. Request flight level 1-1-0, please.

Approach, Loganair 6780, requesting descent to 1-1-0.

[Atc] 6780, descend to 1-1-0.

[Narrator] The plane is more than halfway through

a sixty-five minute flight.

Most of the passengers live on the Shetland Islands.

[Attendant] All done?

-Yes, thank you. -I'll take that.

[Narrator] Many are returning home

from holiday shopping in Aberdeen.

Air travel is massively important

to residents in Shetland.

It's important for work meetings.

It's important for sporting events, for holidays.

It's the fastest way to travel off island,

so it's quick and convenient.

[Narrator] The Captain is experienced.

He has more than 5,000 flying hours

and is the pilot flying tonight.

[Captain] Passing flight level 1-5-0.

[Narrator] The first officer is monitoring the instruments

and handling all communications.

Approach, Logan 6780.

Descending through flight level 1-5-0,

for the I-L-S, runway 2-7.

[Narrator] She has more than one thousand flying hours.

[Hans Peter Gr The crew had good total experience.

Of course, they didn't have a lot of experience

flying the Saab 2000, but still,

it was a normal, experienced crew.

[Narrator] The Saab 2000

is a twin-engine high-speed turboprop.

It's a plane that aviation analyst

Hans Peter Graf knows extremely well.

The Saab 2000 is the most advanced turboprop

still existing and flying.

It has a jet-like performance

paired with low fuel consumption.

And it had real good performance

to fly in and out of mountainous terrain.

[narrato They're traveling north from Aberdeen, Scotland,

to Sumburgh on the Shetland Islands,

a remote archipelago

prone to winter squalls and even hurricanes.

[Ats] Logan Air 6780,

for your information, looks like the ATIS antenna

at Sumburgh has been struck by lightning,

so the system's not functioning.

I'll update conditions when I get them.

[First Officer] Okay, thanks for the update.

There's been a lot of that so far this winter. [Chuckles]

[Narrator] The ATIS,

or Automatic Terminal Information Service,

provides pilots with continuous broadcast

of essential information.

It broadcasts weather

and airport information every thirty minutes,

on which the pilots will base

their approaches and landings.

Why don't you tune ATIS in anyway.

[Atis] Sumburgh, information Tango.

Winds two-niner-zero at 3-4,

gusting 4-7. Visibility...

Guess it didn't get fried, after all.

Gusting 4-7. It's gonna get a bit rough on the way down.

[Narrator] The winds at Sumburgh airport

are blowing up to 47 knots, 54 miles an hour.

he crew will be facing strongT ale force winds while landing. g

[Sanna Aitken] I travel by air a lot. It does get windy.

We were expecting a little bit of turbulence on the way.

We knew a flight of that size, it's a small flight,

you do feel turbulence more than what you would

on a bigger plane, but it was nothing unusual.

[Narrator] The captain wants to be ready

for any unpredictable weather thrown at them.

Let's brief in case of a lightning strike.

-Copy that. -Okay, right.

Instrument lights up full in case we get blinded.

Torches are here and here, on your side.

And the emergency elevator trim switch is overhead.

-Any questions? -No questions.

The statistics suggest that a particular aircraft

will probably get a lightning strike

about one and a half times a year.

You don't know when it's coming, of course,

nd the thing you're aware ofa s that these lightning strikesi

can affect the electronics and the avionics in the aircraft.

Logan 6780, fly heading 3-5-5.

Latest weather from Sumburgh, visibility 3300 now.

Moderate rain and snow. Runway is wet.

[First Officer] 3-5-5 for 6780.

Got the weather too, thanks.

I'm gonna slow it down to two-oh-five,

before we get into chop.

Roger that.

[Narrator] The crew prepares the plane

for the turbulence ahead.

Let's get them buckled in back there.

[Seatbelt Notification Bongs]

[Narrator] Sixteen miles from Sumburgh Airport,

Flight 6780 turns onto its final approach to the runway.

Take a look at that.

I don't like it.

[Narrator] There's some bad weather developing

off the end of the runway.

Approach, Logan 6780.

There's a big storm cell on radar just off the runway.

We might need to discontinue.

[Ats] 6780, Roger. Let me know.

[Miller] All crews going into an airfield

in these sorts of conditions will be wary

of the thunderstorm's activity around them.

[Narrator] The pilots consider their options.

How much fuel do we have left?

2500 kilos. You want to head back to Aberdeen?

Let's circle, make another attempt.

[Graf] They abandoned the approach

when they saw a lot of precipitation

on their weather radar just ahead of them...

Updrafts, downdrafts, wind shears,

which are not predictable.

So, you better go around and wait

or divert to another airport.

Logan 6780, we're gonna circle around,

turning 1-8-0, for now.

6780, understood, maintain 2000.

He obviously made the decision that, at that time,

he would just turn away from the airfield

and probably allow that weather to pass through

and then have another approach.

[Narrator] As the pilots circle for another landing attempt,

-[Bangs] -Oh! Crap!

[Lightening Cracks]

It sounded like a gunshot.

It was just a very short, sharp noise and a flash.

I thought, at that point, that it was something

that had happened to the engines.

[Graf] If you experience a lightning strike,

especially at night, it's a very bright light.

You can smell a burn smell, ozone smell,

and that sure is frightening

or fearsome to every crew.

Circuit breakers look fine.

[Miller] After the lightning strike,

you're obviously looking to see...

Have we been damaged?

Are the instruments still working correctly?

[Sighs] I have control.

[Narrator] But something's wrong.

The controls feel really heavy.

Damn it! The plane's not responding!

[Miller] There must be a degree of panic that will set in

when the controls are just not responding.

The plane isn't responding!

Mayday, mayday, this is Loganair 6780.

We've been struck by lightning

and are having control difficulties.

Please clear the airspace.

I knew that there was definitely something not right.

I was terrified.

[Narrator] Loganair Flight 6780 is in distress

two thousand feet above the North Sea.

[First Officer] Mayday, mayday, this is Loganair 6780.

Please clear the airspace.

6780, copy.

If you can, souls on board and fuel remaining?

[First Officer] Thirty-three souls on board,

twenty five hundred kilograms of fuel.

[Ats] Copy. All options are available.

Do you want to land or divert?

[Narrator] Without knowing what's wrong with the plane...

It's really fighting me!

[Narrator] It's too risky to attempt landing

in a storm at Sumburgh Airport.

We should divert back to Aberdeen.

-Better conditions. -Agreed.

[Narrator] Aberdeen Airport is 190 miles away.

Let's try climbing to 4,000.

6780, we're going to divert back to Aberdeen.

Something's wrong. I can't get the plane to climb.

How's your side?

It's really heavy.

[Clicking]

Trim's not doing anything, either.

If you grab on the yoke and the airplane is not responding,

they realize, hey, there's something wrong.

We need to do something.

[Narrator] Finally, the crew catches a small break.

Altitude is increasing.

[Grunts] Keep on it.

[Grunts]

[Narrator] The plane is climbing,

but not as quickly as it should be.

The elevators might be damaged.

[Narrator] In two minutes, the plane

has barely climbed two thousand feet.

The first officer worries the lightning strike

may have disabled their instruments.

Aberdeen 6780. What's our altitude?

I show you approaching 4,000 feet.

[Narrator] But the controller is getting

the exact same readings as the crew.

We're really not going anywhere fast.

[Groans] Pull!

I'm almost all the way back!

[Miller] Let's face it.

You can fly an aircraft without a compass.

You can fly an aircraft without a radio.

But you can't fly an aircraft without functioning controls.

[Narrator] And then, the unthinkable happens.

Oh, no! Come on!

We're dropping!

[Narrator] Flight 6780 plunges uncontrollably

-towards the North Sea. -[Passengers Scream]

[Sanna] The flight went into that nosedive,

so we knew immediately that

something wasn't right with the plane.

[Ats] 6780... 3800 now...

600... 3400...

[Narrator] The pilots wrestle with their controls

s the plane speeds towardsa he water at 350 miles an hour. t

[Ats] You're descending.

Two thousand feet, eighteen hundred feet...

[Sanna] The dive was so fast,

you just felt like your heart was in your mouth.

I had no idea how close we were to the sea.

You couldn't see anything. It was just pitch black.

It was terrifying. It was really scary.

Fifteen hundred feet. You're descending.

Nothing's working!

Come on! Pull up!

[Narrator] The airplane is less than

ten seconds from impact.

[Miller] It must be incredibly frightening

because the pilots would be aware of their rate of descent.

They would be aware of their altitude.

And they would be aware of how much time left

they had to affect a recovery.

[Ats] 1100...

Speed. Speed!

[Narrator] In a last ditch effort to save the plane,

the captain increases engine power.

[Captain] We're climbing!

So, increasing the power may increase the amount of airflow

over the wings and give you a little bit more lift

to allow the aircraft to pull out of its descent.

[Sanna] We were traveling at such a speed

that when the plane started pulling up again,

it was a kind of a sensation of being on a roller coaster.

It was definitely a relief to start climbing

after that nose pitch.

[Narrator] The pilots have avoided near catastrophe,

ut now, they need get theirb lane back to Aberdeen, safely. p

In the moments after that,

we had a period of just terrible turbulence,

the worst turbulence I've ever experienced.

The man behind me started vomiting.

Everybody was kinda... The flight was quite quiet, though,

it was kind of eerily quiet.

Requesting flight level 2-4-0.

6780. Roger.

Climb and maintain 2-4-0.

The controls are working better now.

Ladies and gentlemen, this is the Captain...

[Sanna] It was at that point the pilot came on

and told us we'd been struck by lightning

and we were heading back to Aberdeen.

[Captain] We had some flight control issues.

Everything is under control now.

We'll be landing in Aberdeen in fifteen minutes.

And please, expect to see some emergency services

on the ground when we land.

Not to panic. It's just a standard precaution.

Thank you.

[Sanna] When you go through a moment like that, you...

[Deep Breath] Yeah, you panic until you're on the ground.

Let's fly a straight-in approach

and get this plane on the ground as soon as possible.

[Narrator] The pilots of Loganair Flight 6780

are on final approach to Aberdeen Airport.

Aberdeen, 6780, established on the localizer, runway 1-6.

[Narrator] Not knowing which instruments they can trust,

the pilots carefully configure the plane for landing.

Flaps 35.

Flaps 35.

Control feels normal.

[Narrator] Having voided disaster twice already, a

heir sole focus is to gett he plane safely on the ground. t

One-thirty. Speed looks good.

Decision height.

Runway in sight. Continue.

[Sanna] The pilot came on and told us

we'd be expecting a normal landing,

but the emergency services would be on the runway,

we weren't to be alarmed if we saw the lights.

[Wheels Touch Down]

All right. 50 knots. Coming out of reverse.

Check.

[Sanna] The landing was smooth in Aberdeen.

I was just glad that we were on the ground.

I'm happy to be on solid ground.

-Me, too. -Mm.

I burst out into tears. It was relief more probably,

than anything, a little bit of shock, probably, too.

[Narrator] It's up to investigators at

he Air Accidents Investigationt ranch, or AAIB, B

to figure out what went wrong.

David Miller is the Deputy Chief

overseeing the investigation.

I decided that this would be a full investigation

because of the closeness

this aircraft came to disaster.

We then, dispatched a small team of investigators

to the operator's base to interview the crew

and to examine the aircraft.

[Narrator] Very quickly, the flight data

nd cockpit voice recorders area ecovered from the Saab 2000. r

Great work.

Let's hope they can provide some answers.

Let's hope.

[Miller] The normal rocess for an investigation isp

the investigators take the recorders,

the cockpit voice recorder and the flight data recorder,

bring them back to the laboratories

and recover the data.

It looks to be in pretty good shape.

Unusually so, yeah.

[Narrator] Investigators need to confirm the crew's report

of a lightning strike, as well as

the flight attendant's account

of seeing an orb of light pass through the cabin.

Ball lightning is a rare and little understood phenomenon

known to precede lightning strikes inside airplanes.

[Lightening Cracks]

All right.

Well, there's no damage on the wing tip.

Mm-hmm.

[Miller] Lightning can strike, more or less, anywhere

on an aircraft, but it tends to strike

on the leading edge of the wings

or the radome at the front of the aircraft.

There's soot marks on the radome.

Lightening it is.

[Narrator] Investigators see signs

of a lightning strike on the nose of the aircraft.

It looks like some surface damage, as well.

-Yeah? -Yeah.

[Miller] The point of strike will often leave scarring,

localized burning, sometimes a small hole.

Right. Let's see where it exited the aircraft, then.

The elevators look fine.

Hang on.

Have a look at that exhaust cone.

[2nd Investigator] Oh, yeah.

That's where the lightning exited.

Look at it. Parts of it are completely melted.

[Julian Firth] There was little bit of burning damage, a

both to the front of the aircraft

and the exit point of the lightning strike,

which was at the very tail of the aircraft

where the auxiliary power unit exhaust was placed.

[Captain] Oh! Crap!

[Narrator] The team now knows how

he lightning struck the plane. t

The controls feel really heavy.

So, one of the first things to go and have a look at...

What was the effect of the lightning strike?

Were the systems damaged? Were there malfunctions?

Okay, you ready?

[Narrator] The AAIB tests the plane's flight controls

to see if they're working.

[Lead Investigator Over Radio] Okay, check the rudder.

Looks good. How about the elevators?

Yeah, elevators are working, too. Everything checks out.

[Narrator] Investigators are perplexed.

If the plane was functioning properly,

why did it become so difficult to control

after the lightning strike?

[Firth] There were no abnormalities,

no system defects that we could find,

either structurally or within the avionics

Beyond that, it looked like

a completely normal, serviceable aircraft.

[Narrator] AAIB investigators

interview the pilots of Flight 6780.

[Firth] When we're fortunate enough,

as in these circumstances, to have a surviving flight crew,

then their recollections are really important for us

to understand exactly how the event progressed

from their perspective.

So, what happened after the lightning struck the plane?

After the lightning struck, the autopilot disconnected.

I have control.

[Firth] The crew of the aircraft

became aware, fairly shortly after the lightning strike,

that the aircraft wasn't responding as they expected

to their flight control inputs.

And then, what happened?

Well, we had control issues.

The plane wouldn't climb.

We tried everything and the plane wasn't responding.

[Firth] The pilot flying was finding

that he was having to put an increasingly strong

backward effort on the control column

to raise the nose of the aircraft.

I can't get the plane to climb. How's your side?

-It's really heavy. -[Captain Straining]

Trim's not doing anything, either.

The aircraft wasn't responding the way that he expected.

[Lead Investigator] And then?

And then we entered a steep nosedive.

And the control issues continued.

Nothing's working!

Come on!

Pull up!

Speed. Speed!

It wasn't until after we'd increased power

that we were able to get the aircraft under control.

Oh, really?

[Miller] Why did the crew believe that

they had control restrictions and control problems

when, in fact, testing of the aircraft

showed there were no faults?

-Let's have a listen, shall we? -Ah.

[Narrator] Puzzled by the crew's account

of the incident onboard flight 6780,

investigators turn to the cockpit voice recorder

for answers.

[Miller] It will answer many questions

s to why things were happeninga he way they weret

and how the crew were working together

and interacting together.

[First Officer Recording] Aberdeen ground, 6780

taxiing on Whiskey for parking stand seven.

[Narrator] But something's not right.

Aberdeen?

No, this is from when they landed back at Aberdeen.

Right. Can you stop it and go back to the top

and play it again, please?

[Recorder Clicks]

[First Officer Recording] Aberdeen ground, 6780

taxiing on Whiskey for parking stand seven.

That's all there is.

Well, that's not gonna help us very much now, is it?

[Narrator] The CVR has recorded over

the critical moments of the flight.

It's a major setback for the investigation.

[Miller] We discovered that the cockpit voice recorder,

which only lasts for thirty minutes,

has been overwritten by subsequent events,

so there was no record of the crew conversation

and how they interacted with each other.

And so you have to look elsewhere for the information.

[Lead Investigator] Right. This is what we know, so far.

The lightning struck, the autopilot disconnected,

they had control problems.

Then, the plane did a nosedive.

Well, let's review the data.

[Lead Investigator] Hmm.

[Narrator] Will the data recorder

provide the answers they need to solve this case?

[Firth] light data recorders often addF

a level of detail that simply can't be gained

from the witnesses themselves, and crucially,

quite often, the information that's gathered

from a recording device

offers a slightly different perspective

to what we might get from personal recollections.

Stop.

This is where the lightning struck at 2,000 feet.

Right. And then, for the next two and a half minutes

there's a slow, uneven climb to 4,000 feet.

And then, they are in a very steep nosedive

for twenty seconds towards the North Sea.

That's 9500 feet per minute.

[Narrator] Investigators are struck by

how close the flight came to total disaster.

It was seven seconds from plunging into the sea

before they finally managed to pull out at 1100 feet.

[Firth] The aircraft had a very high rate of descent

in the moments before it reached that height.

And so, we were really very close

to a very serious accident.

[Narrator] What were the pilots oing to recover from the dive? d

Look at the control column data.

Right after the lightning struck,

the crew pulled back on the control column

to pitch the nose up.

I have control. [Grunts]

The controls feel really heavy.

[2nd Investigator] Look at the line.

I mean, they're having a very difficult time

getting that plane to climb.

[Firth] We know rom the data that the aircraftf

climbed to around about 4,000 feet.

The pilot was finding that he was having to put

an increasingly strong backward effort on the control column

to raise the nose of the aircraft.

The aircraft wasn't responding the way that he expected.

[Narrator] The FDR data confirms the pilots

were tackling a control problem.

But why?

The Captain said they were also applying pitch trim.

[Narrator] Pitch trim moves the tail elevators

up and down to maintain the pitch of the aircraft.

Could we take a look at the pitch trim data, please?

Right.

[Narrator] Investigators make a puzzling discovery.

Look at that!

The elevators are trying to get the nose

to pitch down instead of up.

[Narrator] After the lightning strike,

some unknown force was fighting the pilots' inputs

to both the control column and the pitch trim.

[Miller] It's very difficult to imagine what,

let's say, an eighty pound force feels like.

Normal control pressures are much, much lower than that,

in the order of, sort of, ten to twenty pounds.

So, an eighty pound pull is really extraordinary

and very difficult to maintain.

Something's wrong. I can't get the plane to climb.

How's your side?

-It's really heavy. -[Captain Straining]

Trim's not doing anything, either.

[Firth] We found that, although the pilots were applying

a significant nose up pitch control input

by pulling the stick back towards them,

the aircraft was actually trimmed nose down.

Whatever was trimming the pitch control system

was effectively overcoming the effort of the pilots.

The crew said the lightning struck,

the autopilot disconnected,

and then they had control problems.

[2nd Investigator] Right.

[Lead Investigator] Could we take a look at

the autopilot data, please?

[Narrator] Finally, the team zeros in on the answer.

[2nd Investigator] The autopilot was on

almost the entire time.

[Firth] The pilots themselves were very clear

in their recollection that it had disengaged.

All of the evidence we had indicated

the autopilot had, in fact, remained engaged.

It's no wonder the pilot had control problems.

The autopilot was set to keep the plane at 2000 feet.

Right. And whenever the pilots

tried to get the plane to climb,

the autopilot would engage and bring the plane back down.

Back to its assigned altitude.

[Narrator] Investigators discover that

after the lightning strike,

he pilots were in a tug of wart ith the plane. w

I can't get the plane to climb. How's your side?

[First Officer] It's really heavy.

[Miller] So, we then had to look at

why did the crew misunderstand

the status of the aircraft?

[Narrator] The AAIB contacts the Captain of flight 6780

to better understand why he thought

the autopilot disconnected when, in fact,

-Uh-huh. -[Narrator] it hadn't

The Saab 340?

Okay. Thanks.

He said he assumed the lightning

would disable the autopilot.

[Narrator] The team learns

the pilot trained for lightning strikes

on another airplane, the Saab 340.

To change from Saab 340 to the Saab 2000,

you can say it's like changing from a motorbike to a bus.

All systems are different. Performance is different.

You're flying a totally different airplane.

[Miller] During the training on the Saab 340,

the commander had experienced

a simulated lightning strike to that aircraft,

which caused both generators to fail,

and in doing so, would cause the autopilot to disconnect.

[Sighs] I have control.

[Miller] So, when the lightning strike happened for real,

his first thoughts were, "the autopilot has failed."

The controls feel really heavy.

[Miller] "I must control the aircraft myself."

And in fact, the lightning strike

had had minimal effect on the aircraft.

Would you pull up the control data column again, please?

[Narrator] If the lightning didn't

disconnect the autopilot,

investigators wonder why it remained engaged

for more than two minutes

as the pilots struggled with the controls?

Wouldn't the force applied to the control column

and the pitch trim have overridden the autopilot?

Now, in most aircraft, if the pilot intervenes

on the controls and tries to apply a force

against the autopilot,

the autopilot is designed to disengage.

[Firth] One way of thinking about this is to imagine

ou're driving down the highwayy n a car on cruise control, I

and you're getting close to a car in front of you,

so you press the brake. And what you expect to happen

is for the car to slow down.

You don't expect the cruise control to oppose the brake

and add more power to maintain 65 miles an hour,

but that's essentially what was happening in this case.

[Narrator] The autopilot was attempting to keep the plane

at 2,000 feet, despite all attempts by the crew to climb.

It says here, applying an override force to the column

will not cause the autopilot to disengage.

[Graf] In the Saab 2000, the autopilot would

not disconnect when you exert force on the control columns.

There's more. "Pressing the main pitch trim switches

also has no effect to cause the autopilot to disengage."

[Narrator] The team is surprised to discover

here is no force override fort he autopilot in the Saab 2000. t

Something's wrong.

I can't get the plane to climb.

[Miller] One thing the pilot would have done

is as he pulled back

and feeling the force on the control column,

he would have used the switches on the control column

to apply trim in the appropriate way.

[Captain] How's your side?

It's really heavy.

Trim's not doing anything, either.

[Miller] But when the autopilot's engaged,

in this model of aircraft,

the trim switches are inhibited.

So, no matter how much they selected those trim switches,

they were having absolutely no effect.

[Narrator] Investigators soon discover

that the Saab 2000 is unique.

Look at that. There.

[Narrator] It's one of the few planes in existence

that doesn't have an autopilot override.

Every plane has an autopilot override function,

except for the Saab 2000.

[Firth] It just had a different design

to all the other aircraft we were aware of.

And really, to discover that the autopilot

had greater authority than the human pilots

was a bit of a revelation for us.

[Narrator] It still doesn't explain why the crew

didn't know the autopilot was on almost the entire time.

Wouldn't there be some sort of indicator in the cockpit?

Yeah. I'll show you. Look over here.

[Firth] When the autopilot is connected,

that will be a green AP.

Well, what does the control panel look like

when the autopilot goes off?

[2nd Investigator] Like this.

[Firth] When that autopilot pilot is not connected,

it will be a white AP, but the letters AP remain.

-That's it? -That's it.

It just goes from green to white.

[Miller] One could argue whether that visual clue

is enough to warn the crew

of the status of the autopilot.

I have control.

[Miller] It's not as if the AP disappears

when it's not engaged and appears when it is engaged.

Oh, no! Come on!

We're dropping!

[Miller] But all we have here is a color change

between green and white,

And that sometimes, is very difficult to perceive

when you're in a high-stress situation.

[Narrator] Investigators believe

that the autopilot visual indication

might have been too small for the pilots to see

as they struggled to control their plane.

Surely there would have been aural warnings?

Yes, right here. It says, the plane's computer

would have sounded a caution chime.

[Narrator] Even if the pilots missed the visual indications

for the autopilot, caution chimes would have

alerted them when they adjusted the pitch trim.

The Captain never said anything about hearing any chimes.

Right. So, what's going on then?

[Ats] 6780, 3800 now.

[Miller] If they are trimming against the autopilot

for more than ten seconds, a chime will announce

to say that there is a pitch mis-trim situation.

[Alert Chiming]

[Firth] We see from the data

that it's highly likely that the alerts would have occurred,

but the crew don't recall having heard them.

-Nothing's working! -[Alter Chiming]

Come on!

[Narrator] So, why did the pilots of Flight 6780

ignore all warnings telling them that

the autopilot was in control?

AIB investigators have learnedA hat after a lightning strike, t

the crew of Loganair Flight 6780

didn't recall hearing audible warnings

hat the autopilot was engagedt nd set to maintain 2,000 feet. a

Lightning struck the plane, and for two and a half minutes

the crew struggled with the controls

to get the plane to climb.

Right. They were so distracted by that,

they failed to see what was really going on.

Could the stress have affected

their perception of the situation?

[Miller] We have to bear in mind, of course,

this was at night, in turbulent, poor weather,

heavy rain,

and the lightning strike would have been really quite bright,

and the noise would have been alarming.

So, it's, sort of, understandable

that their performance was degraded

because of the stress situation.

I have control.

[Alert Chiming]

[Firth] A couple of things happen when we get stressed.

We tend to focus on fewer and fewer things,

and we tend to not notice the other things,

and that can be either visual cues or auditory cues.

So, we get what's called cognitive tunneling,

and one aspect of that is an intentional deafness,

so an alert might occur, but we might not hear it.

[Alert Chiming]

[Miller] It's very difficult for a crew

to break the vicious circle of cognitive tunneling,

where they're concentrating on one event

and not looking at the bigger picture.

The controls feel really heavy.

[Narrator] But if the pilots were suffering

from cognitive tunneling,

how were they able to regain control of the plane?

[2nd Investigator] Okay, look at this.

[Narrator] The AAIB makes one last horrifying discovery.

The only reason the autopilot ever disengaged

was because of a random glitch in the plane's computer system.

[Firth] The reason for the disconnection was that

there was a momentary loss of data to the air data computer.

And we know that's one of the conditions

that would cause the autopilot to disconnect.

And that's what caused it to disconnect, in this case.

[Graf] Had the autopilot disconnected

more than seven seconds later,

the airplane would have gone into the ocean

in a dive at over three hundred knots.

This wasn't a fatal accident, by pure luck.

[Narrator] Investigators elieve they finally understandb

what caused the terrifying incident

onboard Loganair Flight 6780.

While circling away from a bad storm at Sumburgh Airport...

Roger that. We'll wait until the storm's over.

[Bangs]

[Narrator] the crew is startled and disoriented

by a lightning strike.

[Passengers Scream]

[Narrator] In a moment of high stress,

he captain believest he autopilot has disengaged... t

I have control.

[Narrator] when it hasn't.

[Alert Chiming]

The autopilot remained engaged and they didn't realize

that was the case, so effectively,

from that point until it disengaged,

they were fighting the autopilot.

They wanted to climb. It wanted to descend.

And because of the way the flight controls

were configured, the autopilot was going to win.

[Narrator] Engaged in tug of war with the aircraft, a

ognitive tunneling takes over. c

-[Captain] Something's wrong. -[Alert Chiming]

I can't get the plane to climb. How's your side?

[Narrator] The highly stressed pilots don't register

the audible warnings telling them that

he autopilot is still engaged. t

It's really heavy.

The trim's not doing anything, either.

[Narrator] The final blow

is a one-of-a-kind autopilot system

without a force override.

I have every sympathy for crews being startled

when something unusual happens,

whether there's an explosive engine failure,

or a lightning strike, in this case.

But the training must kick in and the crew must revert to,

in effect, as I say, sit on your hands for a few moments,

make an assessment of what's happened, what's gone wrong,

what's working, what's not working,

and then deal with the situation from there.

Oh, no! Come on!

We're dropping!

[Narrator] If it wasn't for a split-second fluke error

in the computer system

and the relentless efforts of the crew...

Speed. Speed!

[Narrator] Flight 6780 would have slammed into

the North Sea at 380 miles per hour.

[Sanna] I would say I was a nervous flier

for a couple years.

So, I've just kind of gone through the motions of

building myself up to knowing that it's gonna be fine.

[Narrator] The final report recommends

several safety changes to the autopilot system.

[Firth] We then made recommendations,

looking at how aircraft could be certified in future

to make sure that no future design could be certified

where neither operation of the control column,

nor operation of the pitch control switches,

would result in disconnection of the autopilot.

[Narrator] For investigators, the lessons of Loganair 6780

go beyond this one near tragedy.

We can only go so far in educating human operators

in how a system works.

Ultimately, we have to recognize

that they will behave instinctively,

articularly when under stress. p

That's the real challenge

for the future of automated systems.