All language subtitles for Mayday.S21E01.WEB-DL.English-WWW.MY-SUBS.CO

WWW.MY-SUBS.CO

NARRATOR:
Staring down a thunderstorm

above the North Sea...

Take a look at that.

MAN: Oh, I don't like it.

..a modern turboprop is struck
by more than a million volts.

Oh!

After the lightning strike,

you're obviously looking to see,
"Have we been damaged?"

Damn it!
The plane's not responding.

Help me pull.

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.

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.

We'd not come across an aircraft
where there would be this difference

between the pilot input

and what the aircraft
was actually doing.

MAN: Oh, no!

We're dropping!

They were so distracted by that,

they failed to see
what was really going on.

MAN: (SHOUTING) Mayday, Mayday!

(RADIO CHATTER)

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 67-80,

requesting descent to 1-1-0.

MAN: (VIA RADIO) 67-80,
descend to 1-1-0.

The plane is more than halfway
through a 65-minute flight.

Most of the passengers
live on the Shetland Islands.

- All done?
- Yes, thank you.

I'll take that.

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.

The Captain is experienced.

He has more than 5,000 flying hours
and is the pilot flying tonight.

Passing flight level 1-5-0.

The First Officer
is monitoring the instruments

and handling all communications.

Approach, Logan 67-80.

Descending through
flight level 1-5-0,

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

She has more
than 1,000 flying hours.

The crew had good total experience.

Of course, they didn't have a lot
of experience flying the Saab 2,000,

but still it was a normal
experienced crew.

The Saab 2,000 is a twin-engine
high-speed turboprop.

It's a plane that aviation analyst
Hans-Peter Graf

knows extremely well.

The Saab 2,000 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.

They're travelling north

from Aberdeen, Scotland,

to Sumburgh on the Shetland Islands,

a remote archipelago

prone to winter squalls
and even hurricanes.

MAN: (VIA RADIO)
Logan Air 67-80,

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.

FEMALE PILOT:
OK, thanks for the update.

There's been a lot of that

so far this winter.

The ATIS, or Automatic Terminal
Information Service,

provides pilots with continuous
broadcast of essential information.

It broadcasts weather
and airport information

every 30 minutes,

on which the pilots will base
their approaches and landings.

Why don't you tune ATIS in anyway?

MAN: (VIA RADIO)
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.

The winds at Sumburgh airport
are blowing up to 47 knots,

54 miles an hour.

The crew will be facing strong gale
force winds while landing.

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.

The captain wants to be ready

for any unpredictable weather
thrown at them.

Let's brief in case
of a lightning strike.

Copy that.

OK, 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 1.5 times a year.

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

and the thing you're aware of

is that these lightning strikes
can affect the electronics

and the avionics in the aircraft.

Logan 67-80, fly heading 3-5-5.

(VIA RADIO) Latest weather
from Sumburgh,

visibility 3,300 now.

Moderate rain and snow.

Runway is wet.

3-5-5 for 67-80.
Got the weather too, thanks.

I'm gonna slow it down to 205,
before we get into the chop.

Roger that.

The crew prepares the plane
for the turbulence ahead.

Let's get them buckled in,
back there.

(BEEPING SOUND)

16 miles from Sumburgh Airport,

Flight 67-80 turns onto its final
approach to the runway.

Take a look at that.

I don't like it.

There's some bad weather developing
off the end of the runway.

Approach, Logan 67-80.

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

We might need to discontinue.

MAN: (VIA RADIO) 67-80, Roger.
Let me know.

All crews going into an airfield
in these sorts of conditions

will be wary of the thunderstorm's
activity around them.

The pilots consider their options.

How much fuel do we have left?

2,500 kilos.

Do you want to head back
to Aberdeen?

Let's circle,
make another attempt.

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 67-80,
we're gonna circle around,

turning 1-8-0 for now.

67-80, understood, maintain 2,000.

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.

As the pilots circle
for another landing attempt...

- (LIGHTENING)
- Oh! Crap!

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.

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.

After the lightning strike,

you're obviously looking to see,
"Have we been damaged?

"Are the instruments
still working correctly?"

(SIGHS) I have control.

But something's wrong.

The controls feel really heavy.

Damn it!
The plane's not responding.

There must be a degree of panic
will set in

when the controls
are just not responding.

The plane isn't responding.

Mayday, Mayday,
this is Loganair 67-80.

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.

Loganair Flight 67-80 is in distress
2,000 feet above the North Sea.

Mayday, Mayday,
this is Loganair 67-80.

Please clear the airspace.

67-80, copy.

If you can, souls on board
and fuel remaining?

33 souls on board,
2,500 kilograms of fuel.

Copy. All options are available.

Do you want to land or divert?

Without knowing what's wrong
with the plane...

(GRUNTS) It's really fighting me.

..it's too risky to attempt landing
in a storm at Sumburgh Airport.

We should divert back to Aberdeen.

- Better conditions.
- Agreed.

Aberdeen Airport is 190 miles away.

Let's try climbing to 4,000.

67-80, 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.

Trim's not doing anything either.

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

they realised,
"Hey, there's something wrong.

"We need to do something."

Finally, the crew catches
a small break.

Altitude is increasing.

Keep on it.

The plane is climbing,
but not as quickly as it should be.

The elevators might be damaged.

In two minutes, the plane
has barely climbed 2,000 feet.

The first officer worries

the lightning strike may have
disabled their instruments.

Aberdeen 67-80.
What's our altitude?

I show you approaching 4,000 feet.

But the controller is getting
the exact same readings as the crew.

We're really not going
anywhere fast.

- Pull!
- I'm almost all the way back.

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.

And then, the unthinkable happens.

Oh, no! Come on!

We're dropping!

Flight 67-80 plunges uncontrollably
towards the North Sea.

(SCREAMING)

The flight went into that nosedive,

so we knew immediately that,

that something wasn't right
with the plane.

(SCREAMING)

MAN: (VIA RADIO)
67-80... 3,800 now.

600. 3,400.

The pilots wrestle
with their controls

as the plane speeds towards
the water at 350 miles an hour.

You're descending.

2,000 feet, 1,800 feet.

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.

1,500 feet. You're descending.

Nothing's working!

Come on!

Pull up!

The airplane is less
than ten seconds from impact.

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.

MAN: (VIA RADIO) 1,100.

Speed. Speed!

In a last-ditch effort
to save the plane,

the captain increases engine power.

MALE PILOT: 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.

We were travelling 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.

The pilots have avoided
near catastrophe,

but now they need get their plane
back to Aberdeen safely.

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 kind of...

The flight was quite quiet though.
It was kind of eerily quiet.

Requesting fight level 2-4-0.

67-80. Roger.

Climb and maintain 2-4-0.

The controls are working better now.

MALE PILOT: Ladies and gentlemen,
this is the captain...

It was at that point
the pilot came on

and told us we'd been struck
by lightning

and we were,
we were heading back to Aberdeen.

We had some flight control issues.

Everything is under control now.

We'll be landing in Aberdeen
in 15 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.

When you go through a moment
like that, you...

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.

The pilots of Loganair Flight 67-80

are on final approach
to Aberdeen Airport.

Aberdeen, 67-80,

established on the localiser,
runway 1-6.

Not knowing which instruments
they can trust,

the pilots carefully configure
the plane for landing.

Flaps 35.

Flaps 35.

Control feels normal.

Having avoided disaster
twice already,

their sole focus is to get the plane
safely on the ground.

130. Speed looks good.
Decision height.

Runway in sight. Continue.

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.

Alright, 50 knots.

- Coming out of reverse.
- Check.

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.
- Mmm...

I burst out into tears.

It was relief
more probably than anything,

a little bit of shock
probably too.

It's up to investigators

at the Air Accidents
Investigation Branch, or AAIB,

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.

Very quickly, the flight data
and cockpit voice recorders

are recovered from the Saab 2,000.

Great work.

Let's hope they can provide
some answers.

Let's hope.

The normal process for investigation

is 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.

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.

Right.

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

Mm-hmm.

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.

Investigators see signs
of a lightning strike

on the nose of the aircraft.

It looks like some surface
damage as well.

- Yeah?
- Yeah.

The point of strike
will often leave scarring,

localised burning,
sometimes a small hole.

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

Elevators look fine.

Hang on.

Have a look at that exhaust cone.

Oh, yeah.

That's where the lightning exited.
Look at it.

Parts of it are completely melted.

And there was a little bit
of burning damage

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.

Oh! Crap!

The team now knows
how the lightning struck the plane.

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?

OK, you ready?

The AAIB tests
the plane's flight controls

o see if they're working.

MAN: (VIA RADIO)
OK. Check the rudder.

Looks good.
How about the elevators?

Yeah, elevators are working too.
Everything checks out.

Investigators are perplexed.

If the plane was functioning
properly,

why did it become
so difficult to control

after the lightning strike?

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.

AAIB investigators interview
the pilots of Flight 67-80.

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.

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.

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.

Trim's not doing anything either.

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

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.

Really?

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?

Puzzled by the crew's account

of the incident
on board flight 67-80,

investigators turn to the cockpit
voice recorder for answers.

It will answer many questions

as to why things were happening
the way they were

and how the crew
were working together

and interacting together.

WOMAN: (VIA RECORDING)
Aberdeen ground,

67-80 taxiing on Whiskey
for parking stand seven.

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?

WOMAN: (VIA RECORDING)
Aberdeen ground,

67-80 taxiing on Whiskey for parking
stand seven.

That's all there is.

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

The CVR has recorded over
the critical moments of the flight.

It's a major setback
for the investigation.

We discovered
that the cockpit voice recorder,

which only lasts for 30 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.

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.
- Hmm.

Will the data recorder
provide the answers they need

to solve this case?

Flight data recorders
often add a level of detail

that simply can't be gained from,
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 2.5 minutes,

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

And then they are
in a very steep nosedive

for 20 seconds towards
the North Sea.

That's 9,500 feet per minute.

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 1,100 feet.

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.

What were the pilots doing
to recover from the dive?

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.

The controls feel really heavy.

Look at the line.

I mean, they're having
a very difficult time

getting that plane to climb.

We know from the data

that the aircraft 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.

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

The FDR data confirms the pilots
were tackling a control problem.

But why?

The Captain said they were also
applying pitch trim.

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.

Investigators make
a puzzling discovery.

Look at that.

The elevators are trying to get
the nose to pitch down

instead of up.

After the lightning strike,

some unknown force
was fighting the pilots' inputs

to both the control column
and the pitch trim.

It's very difficult to imagine what,

let's say, an 80-pound force
feels like.

Normal control pressures
are much, much lower

that, in the order
of sort of ten to 20 pounds.

So, an 80 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.

Trim's not doing anything either.

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.

Right.

Could we take a look
at the autopilot data, please?

Finally, the team zeros in
on the answer.

The autopilot was on
almost the entire time.

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 2,000 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.

Investigators discover
that after the lightning strike,

the pilots were in a tug of war
with the plane.

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

FEMALE PILOT: It's really heavy.

So, we then had to look
at why did the crew misunderstand

the status of the aircraft?

The AAIB contacts the Captain
of flight 67-80

to better understand why he thought
the autopilot disconnected

when, in fact, it hadn't.

The Saab 340? OK. Thanks.

He said he assumed the lightning
would disable the autopilot.

The team learns the pilot trained
for lightning strikes

on another airplane,
the Saab 340.

To change from Saab 340
to the Saab 2,000,

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.

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.

I have control.

So, when the lightning strike
happened for real,

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

The controls feel really heavy.

"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?

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.

One way of thinking about this

is to imagine you're driving down
the highway

in a car on cruise control

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.

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".

In the Saab 2,000,

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.

The team is surprised to discover

there is no force override
for the autopilot in the Saab 2,000.

Something's wrong.

I can't get the plane to climb.

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.

MALE PILOT: How's your side?

It's really heavy.

Trim's not doing anything either.

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.

Investigators soon discover
that the Saab 2,000 is unique.

Look at that.

There.

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 2,000.

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.

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.

When the autopilot is connected,
that will be a green AP.

Well, what does the control panel
look like

when the autopilot goes off?

Like this.

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.

One could argue
whether that visual clue

is enough to warn the crew
of the status of the autopilot.

I have control.

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!

But all we have here is a colour
change between green and white.

And that sometimes
is very difficult to perceive

when you're in
a high-stress situation.

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".

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?

MAN: (VIA RADIO) 67-80, 3,800 now.

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.

(ALARM GOING OFF)

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!

Come on.

So, why did the pilots
of Flight 67-80

ignore all warnings telling them
that the autopilot was in control?

AAIB investigators have learned
that after a lightning strike,

the crew of Loganair Flight 67-80

didn't recall hearing
audible warnings

that the autopilot was engaged
and set to maintain 2,000 feet.

Lightning struck the plane

and for 2.5 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?

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.

And I have control.

(ALARM GOING OFF)

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 tunnelling,"

and one aspect of that
is an intentional deafness

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

(ALARM GOING OFF)

It's very difficult for a crew

to break the vicious circle
of cognitive tunnelling

where they're concentrating
on one event

and not looking
at the bigger picture.

The controls feel really heavy.

But if the pilots were suffering
from cognitive tunnelling,

how were they able to regain
control of the plane?

MAN: OK. Look at this.

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.

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.

Had the autopilot disconnected
more than seven seconds later,

the airplane would have gone
into the ocean,

in a dive at over 300 knots.

This wasn't a fatal accident
by pure luck.

Investigators believe
they finally understand

what caused the terrifying incident
on board Loganair Flight 67-80.

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

Roger that.

We'll wait until the storm's over.

..the crew is startled
and disoriented

by a lightning strike.

(SCREAMING)

In a moment of high stress,

the captain believes
the autopilot has disengaged...

I have control.

..when it hasn't.

(ALARM GOING OFF)

The autopilot remained engaged

and they didn't realise
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.

Engaged in a tug of war
with the aircraft,

cognitive tunnelling takes over.

(ALARM GOING OFF)

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

How's your side?

The highly stressed pilots
don't register the audible warnings

telling them that the autopilot
is still engaged.

It's really heavy.

The trim's not doing
anything either.

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!

If it wasn't for a split-second
fluke error in the computer system

and the relentless efforts
of the crew...

Speed. Speed!

..Flight 67-80 would have slammed
into the North Sea

at 380 miles per hour.

I would say I was a nervous flier
for a couple years.

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

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

The final report recommends
several safety changes

to the autopilot system.

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.

For investigators,

the lessons of Loganair 67-80
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 recognise
that they will behave instinctively,

particularly when under stress.

That's the real challenge
for the future of automated systems.

Captioned by Ai-Media
ai-media.tv