Original subtitles

Narrator: A jetliner plummets to earth in the Swedish Arctic.

First Officer: Mayday, mayday, mayday!

Air Sweden 294.

Computer: Bank angle.

Captain: No! No!

Computer: Bank angle.

Narrator: A deep crater reveals an aircraft

in an astonishing descent.

Man: It's just far out of bounds

with the way we normally fly the airplane.

Narrator: Investigators are shocked by what they find.

Man: That can't be what the plane was doing.

Man: I flew the jet for 10 years

and never saw anything even remotely like this.

Narrator: As the evidence paints a terrifying picture of chaos...

Captain: Help me! Please!

First Officer: I don't know. I don't see anything!

Narrator:...and confusion. Pilot: No, no!

Man: If you get past a certain point,

that confusion can become terminal.

Man: Why did he let the captain fly the plane into the ground?

Flight Attendant: Ladies and gentlemen,

we are starting our approach.

Pilot: We lost both engines!

Flight Attendant: Put the mask over your nose.

Emergency descent.

Pilot: Mayday, mayday!

Flight Attendant: Brace for impact!

Controller: I think I lost one.

Man:...Investigation starting into this tragedy...

Man: He's gonna crash!

Narrator: 33,000 feet above the border

between Norway and Sweden,

a CRJ-200 jet cruises on autopilot

during a late-night mail run

for one of Sweden's largest cargo companies...

West Air Sweden.

First Officer: We are approaching Bodo

where the outside air temperature

is a balmy minus 61 Celsius!

Captain: Fuel?

Narrator: The 42-year-old Spanish captain

has more than 3,300 hours of flight time.

First Officer: Holding at minus 30.

We're good.

Narrator: His French first officer is 33,

with a similar number of flight hours.

Controller: Sweden 294 clear direct to Vamen.

Expect a circling approach to runway 0-1 at Tromso.

First Officer: Roger, circling approach for runway 1.

Air Sweden 294.

Narrator: The experienced flight crew took off

from Oslo, Norway, just after 11 o'clock,

for a 1 1/2-hour hop to Tromso,

high in the Norwegian Arctic.

The cargo jet is carrying about 4 1/2 tons of mail

to the remote northern community.

The CRJ-200 crosses into Swedish airspace

as it heads further and further north.

Shawn Pruchnicki is a pilot who flew the CRJ-200.

Shawn Pruchnicki: I liked the airplane

because it has all the bells and whistles.

It's just as sophisticated as any of the larger jets.

The aircraft itself is very fast.

It's a very sleek airplane, so it's, it's a lot of fun to fly.

Captain: Ready for the approach briefing?

First Officer: Let's do it.

Captain: ILS approach to runway 0-1.

Inbound heading 0-0-9.

Narrator: It's been a routine flight,

and the plane is expected to land in Tromso

in about 30 minutes.

Pilot: We need to climb and turn right.

First Officer: Acknowledged.

Captain: And according to last ATIS

we can expect light wind and zero...

Captain: What the hell?

Narrator: Suddenly, the captain sees his plane

is in a steep climb.

[Alarm Beeping]

He pushes the nose down.

First Officer: What?

Captain: What?

[Alarm Beeping]

[Alarm Beeping]

First Officer: Come up!

Computer: Terrain. Terrain. Pull up.

First Officer: Come up!

Computer: Bank angle.

Captain: Come on, help me. Computer: Bank angle.

Captain: Help me. Help me!

First Officer: Yes, I'm trying. I'm trying.

Turn left. Turn left!

Computer: Bank angle.

Narrator: The pilots can no longer make sense

of what the plane is doing.

Computer: Bank angle.

First Officer: Mayday, mayday, mayday!

Air Sweden 294.

Mayday, mayday, mayday!

Controller: 294, understood mayday.

What is the nature of your emergency, please?

Narrator: The plane loses almost 10,000 feet of altitude

and speeds towards the ground at more than 450 miles an hour.

Computer: Bank angle.

Bank angle.

[Alarm Beeping] Bank angle.

Bank angle.

Captain: We need to climb. Come on, we need to climb!

First Officer: Yes, yes, we need to climb.

Turn left. Turn left!

Captain: No, continue right.

Computer: Bank angle.

Captain: Continue right.

First Officer: Ok, damn it!

Captain: Come on, help me. Help me, please!

First Officer: I don't know. I don't see anything!

Computer: Bank angle.

Narrator: At 8,800 feet,

flight 294 falls below radar range.

Controller: Good God.

Computer: Bank angle.

First Officer: What? What?

Computer: Bank angle.

[Groaning]

Computer: Bank angle.

Captain: No! No! No!

Narrator: West Air Sweden Flight 294...

hits the ground at almost 600 miles an hour.

The plane is obliterated.

[Helicopter Hovering]

It takes three hours before rescue helicopters arrive.

Even from the air

it's obvious the pilots could not have survived.

Nicolas Seger: The information we got from the rescue efforts

was that the aircraft was found and also that the accident

was most probably not at all survivable.

Narrator: The crash site is

in one of the most desolate places on Earth.

Seger: The accident location was in a flat valley

In mountainous area.

The site was at the time very cold,

with temperatures down towards minus 25 degrees Celsius.

Narrator: The next day, a team of investigators

from the Swedish accident investigation authority...

known as the SHK...

arrives at the crash site.

The team includes technical investigator Tony Arvidsson.

This far north, they have a very short window

to find clues as to what caused the sudden crash of flight 294.

Tony Arvidsson: We only had the daylight time

for about three hours.

Narrator: Investigators waste no time analyzing the wreckage

to pinpoint the northbound plane's orientation

as it crashed.

Arvidsson: That's the front of the plane...

so they were traveling east.

Narrator: Finding the four corners of the aircraft

confirms the theory.

Seger: The tail, the nose, the wing tips...

The aircraft had impacted the ground in an easterly direction.

Arvidsson: This is the left wing, alright.

Narrator: But it's in the wrong place for a plane flying east.

This is Arvidsson's first clue about the accident.

The left wing is found in the south end of the crater,

and the right wing is in the north end.

For a plane traveling east, it should be the other way around.

Arvidsson: If they were coming in this way

and the left wing is over there...

then they must have been upside down.

Narrator: The crash has also created a crater 20 feet deep.

[Camera Shutter Clicking]

That tells investigators the plane hit the ground

at tremendous speed.

Arvidsson: They definitely came in hard and fast.

That's not normal.

You probably don't have a lot of control over the aircraft

at that time.

Narrator: The position of the wreckage

and the size of the crater

Paints a picture of a plane hitting the ground off course,

upside down, and at a blazingly high speed.

Incredibly, both of the plane's black boxes survive the crash.

They're sent to France where the data can be downloaded.

Investigators hope the data will shed light

on why the plane was so badly out of control.

As they continue to scour the site,

blackened mail from the cargo hold

presents a grim possibility.

Arvidsson: Could we be looking at a fire?

An explosion?

[Sighs]

Narrator: A fire or explosion on board

could explain why the plane got so badly out of control

while cruising at 33,000 feet.

The team gathers as much of the cargo debris for analysis

as they can.

Arvidsson: OK, those two boxes and everything in here.

Let's get it all swabbed.

Narrator: They need to determine

Whether fire was a cause of the accident.

Arvidsson: So we sent one ton of cargo to a fire expert.

Elevator goes, along with all the control cables.

This goes, too.

Narrator: The team recovers a total

of 3 1/2 tons of wreckage.

Arvidsson: Mostly parts from the flight controls.

We tried to get as much as possible from the site.

[Speaking Swedish]

Narrator: Before fierce winter weather sets in,

investigators must abandon the site.

They can only hope the cause of this crash

lies somewhere in the pieces they're taking with them.

Swedish investigators hope

the Norwegian air traffic controller

on duty the night of the crash of flight 294

can help explain why the pilots lost control of their plane

at 33,000 feet.

Controller: How are you? Good.

OK, so, the first sign of trouble

Was a mayday call at 12:19.

First Officer: Mayday, mayday, mayday!

Air Sweden 294.

Mayday, mayday, mayday!

Controller: 294, understood mayday.

What is the nature of your emergency, please?

Investigator: So, no explanation for the mayday call?

Controller: Uh, no, they never said.

John Nance: If it's just a mayday call like this one,

with not much specificity,

then there's not much the controller can do

other than try to discern what's happening and attempt to help.

Controller: He was descending quickly

and he started to veer east here.

Narrator: The radar data confirms

what investigators observed at the crash site.

Flight 294 was descending rapidly and veering east

just seconds before it disappeared from the screen.

Investigator: And the return never split?

Controller: Nope, just one blip all the way down.

Narrator: The radar shows only one return,

meaning it didn't break into pieces in mid-air.

Nance: If you have an airplane that came apart at altitude,

you're gonna see a lot of different radar returns.

If you have one singular return

and it doesn't advance forward very much,

maybe one more hit and then it's gone,

that indicates a dive intact.

Narrator: The investigators now know the pilots were struggling

with a serious onboard emergency...

Controller: Thanks for coming down.

Narrator:...but still don't understand

what could have caused such a catastrophic loss of control.

In Stockholm, the team inspects the 3 1/2 tons of wreckage

for signs of a fatal mechanical failure.

Arvidsson: We're looking for a failure of any control surface...

ailerons, elevators, rudder... we need to check 'em all.

Narrator: An airplane has three primary flight control surfaces:

ailerons that control roll,

elevators that control pitch

And a rudder that controls yaw.

Arvidsson: A broken flight control,

like the elevators, could cause some problems.

Narrator: But this is the worst damage Arvidsson has ever seen.

It's impossible for him to get any useful information

about flight control surfaces.

Arvidsson: This tells me nothing.

We want to make sure that the control surface

is working properly, but it was too damaged.

Narrator: Investigators try to identify the pieces of wreckage

based on serial numbers and other markings

to make sure all the control surfaces were on the plane

when it hit the ground.

Arvidsson: Left and right ailerons,

both elevators,

rudder.

We have them all.

Seger: We could find and identify

all the control surfaces,

which make it most probable that the aircraft was intact

All the way down to impact.

Narrator: They rule out a serious mechanical failure

and move on to another theory:

that an onboard fire brought down the plane.

Tests on flight 294's cargo don't offer investigators

much more insight than the control surfaces.

Arvidsson: No sign of fire or explosion.

Narrator: The cargo was destroyed at impact...

not in an onboard fire.

Searching for answers,

the investigator in charge, Nicolas Seger,

turns to the flight data,

now in from France and ready for analysis.

Seger: The FDR data for us is really important

to understand the course of events.

It also helps us to calculate the trajectory of the aircraft.

Seger: So they're cruising at 33,000 feet,

when suddenly they start to pitch way up.

Narrator: A plane normally changes pitch

by about one degree per second.

Arvidsson: But in this case you had six degrees per second,

so it was a really rapid change of pitch.

Seger: Then the plane starts pitching down

and starts rolling out of control.

Arvidsson: We could see this is not normal.

Seger: But wait a minute.

If the plane is pitching up, why is the altitude decreasing?

That can't be right.

Narrator: When a plane pitches up,

investigators would expect it to climb in altitude

and its speed to slow.

But that's not what the data from flight 294 shows.

Pruchnicki: His airspeed indicator was not changing.

The same with the altitude...

The altitude should have showed a climb

if this was good data, and it did not.

Seger: That can't be what the plane was doing.

Narrator: Investigators must get to the bottom

of the contradictory data

before they can figure out

What brought down West Air Sweden Flight 294.

Seger: We're gonna have to go back and figure out

exactly what was going on here.

Narrator: Investigators in Stockholm try to understand

discrepancies in Flight 294's flight data.

Seger: OK, so let's assume

airspeed and altitude are correct. Yes?

Narrator: The plane's pitch data doesn't make sense.

Seger: We made calculations to determine the real pitch

of the aircraft during the event.

Narrator: The calculations point to an astounding conclusion.

Seger: So... no pitch up at all?

Investigator: Not that we can tell.

Seger: The calculations indicated that the pitch

was actually going down after the start of the event.

Right here, the data shows a steep pitch up.

But the plane flies level and then pitches down.

Not up.

Captain: What the hell?

Narrator: It seems the captain thought

The plane was pitching up,

when it was actually flying straight and level.

[Alarm Beeping]

The discovery leads investigators

to a disturbing question.

[Beeping]

Were the pilots responding to an emergency...

Captain: Come up!

Narrator:...that didn't actually exist?

Seger: If they aren't actually pitching up,

why are they pushing the nose down?

Nance: The indication that the ADI,

the attitude deviation indicator,

on the captain's side

had suddenly shown a 30-degree pitch up

is about the only thing that even comes close to making sense

for why this crew would take a perfectly good airplane

into a dive.

Narrator: Investigators soon discover

that it's not just the pitch data that's off.

Segar: Right here, heading and roll are wonky, too.

You see that?

Investigator: Yeah. That tells us something.

Segar: Yeah.

Narrator: It's another valuable clue.

Segar: When we looked at the FDR data,

we could see four parameters

that were not consistent with the other parameters

and, uh, those were the pitch, the roll, the heading

and the ground speed.

Narrator: All four parameters come

from what's called an inertial reference unit, or IRU.

It's made up of gyroscopes

that provide information to the cockpit displays

and to the flight data recorder.

There are two IRUs... one for each pilot's display.

Segar: The FDR gets its data from the captain's side IRU.

Narrator: Investigators study the plane's manuals

and electrical drawings.

Arvidsson: We found that the IRU 1

was sending the attitude signal to flight data recorder

and the primary flight display number one.

Narrator: It's an important discovery.

The captain's display and the flight data recorder

both get their pitch data from the same source.

Seger: Now, this is what the captain was seeing.

Narrator: Investigators are coming

to a troubling conclusion:

The captain's instrument was telling him

the plane was pitching up

when it was still flying level,

and that it was rolling to the right

when it was actually rolling left.

Pruchnicki: The automation is telling him point the nose down,

and he's trying to follow this.

Unfortunately it's erroneous information,

and that eventually leads

to a loss of control of the aircraft.

I flew the jet for 10 years

and never saw anything even remotely like this.

Captain: What the hell?

Narrator: It's now clear the pilot was receiving

bad information from a faulty IRU.

[Alarm Beeping]

Is it possible the first officer was, too?

Seger: The FO's instrument has its own gyro.

Narrator: Investigators learn that IRU 1

was only feeding the captain's instrument.

A second IRU feeds the first officer's display

and is not recorded by the flight data recorder.

Seger: So is it possible that both sides could have failed?

Narrator: If the first officer's instrument was correct,

he should have seen that the plane was flying

straight and level.

So why did he allow the captain

to push the plane into a high speed dive?

To find out, the team recreates the flight in a simulation

based on the data from IRU 1.

Seger: OK, start the animation.

Narrator: It paints an almost incomprehensible picture.

Seger: Three seconds after his instrument shows a pitch up,

He pushes the nose down.

Arvidsson: The pilots tried to solve the problem

by pushing the elevators to nose down.

Narrator: When the captain pushes the nose down,

his ADI continues to show a pitch up,

so he keeps pushing the plane into a steeper and steeper dive.

Seger: Then they begin to roll to the left.

Narrator: The plane continues to roll until it's on its back.

Seger: Eventually they do reach a speed of 508 knots.

Nance: It is pretty much incredible

that the aircraft did not start breaking up

because of the aerodynamic forces.

But any control movement at all is gonna rip the tail off

or gonna rip the control surfaces off.

Narrator: Flight 294 hits the ground inverted

at a speed of almost 600 miles an hour.

Nance: The speed with which this airplane went from stable flight

to a smoking hole, a crater, literally,

uh, is just astounding,

Because it involves a descent rate, at one point,

of over 20,000 feet per minute.

That's a straight vertical dive at almost speed of sound.

Uh, it means that whatever happened

happened extremely rapidly.

Narrator: Investigators can now see what happened,

but they still don't understand

why the failure of a single instrument

led to such a sudden and catastrophic crash.

Seger: How do you go from level flight at 33,000 feet

to a 1,000-kilometers-per-hour impact in what, uh...

one minute, 20 seconds?

Narrator: Investigators are stumped.

Seger: The failure of one single instrument

in a triple-redundant system

should allow the crew or the operations

to actually cope with this situation.

Narrator: To better understand how the pilots

were interpreting flight data,

investigators now turn

To the cockpit voice recording of flight 294.

Seger: Let's hear what was happening up there.

Captain: Ready for the approach briefing?

First Officer: Let's do it.

Narrator: Investigators hear no signs of trouble

in the minutes leading to the accident...

until...

Captain: According to last ATIS, we can expect...

Seger: Ok, now this is where the trouble starts.

Captain: What the hell?

[Alarm Beeping]

First Officer: What?

[Alarm Beeping]

Captain: What?

[Rattling] [Alarm Beeping]

[Groaning]

[Rattling] [Alarm Beeping]

Seger: They're barely talking to each other.

Arvidsson: We were a little bit surprised

that there were no communication for the first 10 to 12 seconds

After the problems started.

Computer: Bank angle.

First Officer: Come up!

Narrator: For some reason the two pilots

never discuss the unusual pitch...

Captain: Come on, help me. Help me.

Computer: Bank angle. Captain: Help me!

First Officer: Yes, I'm trying. I'm trying.

Turn left. Turn left!

Narrator:...or how to troubleshoot the issue.

Captain: No!

Computer: Bank angle.

Seger: Wait a minute, stop.

Computer: Bank angle.

Seger: Bank angle. Bank angle.

When did this start?

Arvidsson: 13 seconds after the trouble started.

Seger: 40 degrees, exactly when it should come up.

Narrator: The warning is programmed to sound

when the plane's bank angle gets to 40 degrees,

Which is precisely when it sounded on Flight 294.

In a CRJ-200, the bank angle display and warning

get data from the IRU designated to the first officer's side.

Hearing the bank angle callouts

gives the investigation some vital information.

Arvidsson: Inertial reference unit number 2

was working as it should be.

Seger: The first officer was getting good information.

Narrator: The discovery confirms the first officer

should have known the plane

was never pitching up in the first place.

Seger: So why did he let the captain

fly the plane into the ground?

First Officer: We need to climb and turn right.

Captain: Acknowledged.

Narrator: Investigators have a new mystery to solve.

Captain: And according to last ATIS,

we can expect light wind and zero...

What the hell?

Narrator: When the captain of Flight 294

Plunges into a deadly dive...

[Alarm Beeping]

Why didn't the first officer intervene?

As investigators look at the FDR data,

they make an important discovery.

The pilots both received what's called a miscompare warning.

The warning is shown on both displays

when there's a mismatched reading between them,

in this case, P-I-T for pitch.

Investigators now know

that while the captain saw a sudden 30-degree pitch up

and the co-pilot saw a perfectly level aircraft,

both saw the pitch discrepancy warning.

It's a puzzling find,

because pilots are trained how to react to the warning.

[Alarm Beeping]

Captain: Come up!

[Groaning]

Pruchnicki: You would hope that communication-wise

you'd be able to verbalize,

"I have what appears to be an extreme pitch up.

What are you showing on your side?"

Captain: I'm showing a pitch up.

Narrator: In the event of a discrepancy,

pilots should check a third standby instrument

to determine which side is wrong

and switch the faulty instrument to the working IRU.

Captain: It looks like my side's bad.

Switching to IR 2 now.

Pruchnicki: Ideally, what we refer to

as the standby attitude indicator

could have kind of broken the tie.

In other words we have three sources of information,

and the best 2 out of 3 is what you're trained to go with.

Seger: Alright, let's see what they say next.

Narrator: But when investigators listen to the CVR...

Captain: We need to climb. Come on, we need to climb.

First Officer: Yes, yes, we need to climb.

Turn left. Turn left!

Narrator:...they don't hear that kind of conversation.

Computer: Bank angle. Captain: Continue right.

First Officer: Ok, damn it!

Narrator: Instead, they hear the sound of a crew

that can't figure out what's happening to their plane

or how to correct the problem.

Captain: Come on, help me. Help me, please!

First Officer: I don't know. I don't see anything!

Computer: Bank angle.

[Rattling]

Computer: Bank angle.

Pruchnicki: And what that tells us

is that the crew members were both very mentally consumed

with looking at their primary flight display,

trying to figure out actually what is going on.

What is the real position of the aircraft in space?

Narrator: It's a troubling revelation.

Captain: What the hell?

Narrator: Seger decides they need to see

exactly what the pilots experienced

when the instruments began to fail.

They book time in a CRJ simulator.

Seger: OK, so let's start the error on the left side, please.

Narrator: They fly the same route as Flight 294

and program a fault into the left side IRU.

Seger: In the simulator we could observe

the two primary flying displays,

and we could also see that everything was working

according to design.

There it is.

Freeze it there, please.

Narrator: When the captain's ADI shows a sudden climb,

the miscompare warning comes on,

telling the captain and first officer

they're seeing different pitch readings.

Seger: OK.

Alright, let's pick it up here.

Narrator: Then they make a new discovery.

Seger: And now we've got the declutter mode kicking in.

Freeze it there, please.

[Camera Shutter Clicking]

Alright.

Narrator: When a pilot's ADI

reaches extreme pitch or roll values,

it goes into what's called declutter mode.

All non-essential information disappears,

and red arrows tell the pilots which direction to fly.

Arvidsson: The declutter mode is to help the pilot

focusing on the most important things.

[Alarm Beeping]

Narrator: But that's not the only insight

the flight simulator provides the investigation.

[Alarm Beeping]

Seger: And guess what disappears in declutter mode?

Narrator: Investigators learn that in declutter mode

the P-I-T discrepancy warning

alerting the pilots of mismatched displays

also disappears.

Seger: Four seconds after that warning appeared,

it disappears for good.

Narrator: It's not enough time for the captain

To register the problem.

Captain: What the hell?

Narrator: And as a result,

he instinctively pushes the nose down,

not realizing he's putting the plane into a dive.

Soon the first officer's gauge also enters declutter mode...

but in almost the opposite configuration

of the captain's display.

[Groaning]

[Alarm Beeping]

First Officer: Come up!

[Alarm Beeping]

Seger: Now neither one of them has a discrepancy warning.

Pruchnicki: This is potentially problematic

because the crew is still trying to figure out what's going on,

in addition to following the erroneous automation commands.

So this box, what was telling them what the problem was,

actually disappears

when the situation becomes even more dire.

Computer: Bank angle.

Narrator: As the pilots were struggling

to regain control of their plane...

Captain: Help me!

First Officer: Yes, I'm trying. I'm trying.

Turn left. Turn left!

Narrator:...both were missing a vital piece of the puzzle...

that their displays were showing different pitch angles.

Pruchnicki: That's one bit of information

that really should not have been removed

when it goes to a decluttering function.

That was the only cue that they really had

that there was potentially a problem

between both primary flight displays.

Narrator: Investigators now have a picture

of what happened in the cockpit.

Captain: We need to climb! Computer: Bank angle.

Captain: Come on, we need to climb!

First Officer: Yes, yes, we need to climb.

Turn left. Turn left!

Captain: No, continue right.

First Officer: Ok, damn it!

Narrator: But to figure out why the pilots couldn't tell

if they were climbing or diving...

Captain: Come on, help me! Help me, please!

First Officer: I don't know. I don't see anything!

Narrator:...investigators will need to take to the skies.

Narrator: Investigators fly an identical plane

on the same route under the same moonless conditions

to find out what the pilots of flight 294

could and couldn't see on the night of the accident.

Seger: I can see lights.

Maybe Ritssem?

And I can just see the horizon, over there.

First Officer: We are approaching Bodo.

Pruchnicki: Even when flying at nighttime,

there can still be visual cues that can help you understand

the orientation of your aircraft...

Things like you can still see a visible horizon sometimes

when there are a lot of city lights.

Narrator: The test seems to be in vain,

Revealing nothing out of the ordinary.

Seger: Ok, let's start the descent into Tromso.

[Click]

Now I can't see anything out there.

It was very, very difficult to discern the horizon

during this flight when you had the cockpit illumination on.

[Click]

Narrator: Investigators have made a major discovery.

With the cockpit lights turned on,

it would have been impossible for the pilots

to see the lights below or the horizon.

The pilots of 294 would likely have depended entirely

on their instruments for guidance...

instruments that showed contradictory information.

Computer: Bank angle.

Captain: We need to climb! Come on, we need to climb!

First Officer: Yes, yes, we need to climb.

Turn left. Turn left!

Captain: No, continue right! Continue right!

Nance: When we can't see outside,

We trust our instruments.

But if your instrument is telling you something

that is completely separate from what your body is telling you,

it's not a matter of ignoring one or the other,

it's a matter of verifying what the situation is.

Narrator: The discovery reveals a critical piece of the puzzle.

Captain: Ready for the approach briefing?

First Officer: Let's do it.

Narrator: After the captain of flight 294

switches on the cockpit lights...

Captain: And according to last ATIS we can expect...

Narrator:...his display begins to indicate

a substantial pitch upwards.

Captain: What the hell?

Narrator: But the glare inside the cockpit

means the pilots can't see the horizon below.

[Alarm Beeping]

The captain can't tell if his plane

is actually climbing or not.

Pruchnicki: Had this happened earlier

When they might have had some form of a visible horizon,

it could have had an entirely different outcome,

and probably would have.

Seger: He sees this, so his first reaction

is to push his nose down.

Narrator: Seger thinks the captain's response...

Captain: Help me. Help me!

First Officer: Yes, I'm trying. I'm trying.

Narrator:...made it impossible for either pilot

to make sense of the plane's movements.

First Officer: Turn left. Computer: Bank angle.

Nance: One of the adages that we have kind of instilled

in commercial aviation and in military aviation

is, in an emergency, order a cup of coffee first

before you decide to do something.

There are very few things in aviation

that need an instantaneous physical response.

Narrator: In less than 30 seconds,

the plane is upside down and diving.

Computer: Bank angle.

Narrator: Extreme negative G forces

make the pilots feel weightless,

so they can't tell if they're climbing or descending.

Pruchnicki: When faced with a negative-G environment,

it's disorienting for many reasons,

one of which is that it actually affects your cognitive ability,

so your ability to understand the situation that you're in.

Seger: In just five seconds his autopilot disconnects.

He's faced with a 30-degree pitch up,

and his instrument display changes.

Computer: Bank angle.

First Officer: Mayday, mayday, mayday!

Air Sweden 294!

Mayday, mayday, mayday!

Narrator: Investigators believe that rapid-fire chain of events

triggers what's known as the startle or surprise effect

in both pilots.

Seger: That surprised effect,

uh, together with the lack of communication

between the pilots,

Can explain the difficulties there were to solve the problem.

Computer: Bank angle. Bank angle.

Pruchnicki: This is basically the environment

that they found themselves in,

going from extremely normal operations

to extremely abnormal operations basically within a split second.

First Officer: Turn left. Turn left!

Captain: No, continue right.

Computer: Bank angle. Captain: Continue right.

First Officer: Ok, damn it! Captain: Help me.

Pruchnicki: In a lot of ways, this accident

is kind of a perfect storm scenario:

the fact that both crew members

were looking away from their instruments

as they were required to do briefing the approach;

the fact that the autopilot disconnected so quickly;

the fact that the indication of pitch was so extreme.

Computer: Bank angle.

Captain: Come on, help me. Help me, please!

First Officer: I don't know. I don't see anything!

Narrator: Investigators now believe

they have pieced together

what went so horribly wrong on flight 294.

Captain: No! No! No!

Narrator: But they still have one final question to answer.

Captain: Ready for the approach briefing?

First Officer: Let's do it.

Narrator: The final minutes of flight 294

are now clear to investigators.

Captain: ILS approach to runway 0-1, inbound heading 0-0-9.

Narrator: The approach briefing is interrupted

when the captain notices a sudden climb.

Captain: Light wind and zero...

What the hell?

Seger: The start of the event was a runaway

on the left side pilot flying display,

showing an increasing pitch.

Narrator: But he has no idea what he's seeing

is from a faulty inertial reference unit.

[Alarm Beeping]

The pitch warning disappears,

the autopilot disconnects,

and the captain pushes the nose down

following instructions on his ADI.

As the plane begins to dive,

the pilots don't know their displays no longer match.

First Officer: What?

Captain: What?

Narrator: And as they can't see the natural horizon outside,

neither pilot can verify their actual attitude.

As the plunging jet rapidly gains speed,

negative G-forces make the pilots feel weightless.

Flight 294 rolls to the left until it banks upside down.

Computer: Bank angle.

Pruchnicki: It's possible that this occurred

because now the first officer had grabbed the yoke

to steady himself

or to possibly try to contribute to solving the problem.

Narrator: Upside down and hurtling to earth,

the first officer's display shows the plane in a nosedive

And banking left.

First Officer: Come up!

Computer: Bank angle.

Narrator: But the captain sees the opposite:

A plane climbing and rolling right.

First Officer: Come up!

Narrator: His first officer's suggestions make no sense,

and the inverted G-forces make it almost impossible to think.

Captain: Come on, help me.

Help me. Help me!

First Officer: Yes, I'm trying. I'm trying.

Turn left. Turn left!

Computer: Bank angle. Captain: No.

Nance: When you get sucked into a reality

in the middle of the night like this,

that is not commensurate with what's actually happening...

in other words, it's an induced reality...

then it begins to get confusing,

and if you get past a certain point,

that confusion can become terminal.

Narrator: The plane is in a steep dive, nearly inverted,

and traveling at speeds approaching 600 miles an hour.

Nance: Once you get to that point,

the mind pretty much checks out

in terms of giving you good guidance

on how to fly the airplane.

And after that point, uh, there's just no recovering.

Captain: We need to climb. Come on, we need to climb.

First Officer: Yes, yes, we need to climb.

Turn left. Turn left!

Captain: No, continue right.

Computer: Bank angle. Pull up.

Captain: Continue right!

First Officer: Ok, damn it!

Captain: Come on, help me! Help me, please!

First Officer: I don't know. I don't see anything!

Computer: Bank angle. First Officer: What... what?

Computer: Bank angle.

[Groaning]

Computer: Bank angle.

Captain: No! No! No!

Narrator: 80 seconds from the first sign of trouble,

the plane slams into the ground.

Pruchnicki: There's no training that's typically provided

to understand how to effectively recover

from a situation such as this.

Narrator: The final question for investigators

will be the most difficult to answer.

Why did the inertial reference unit fail in the first place?

With more than 9,000 identical units

in service around the world,

the answer is vitally important.

The IRUs have been recovered from the crash site,

but they're very badly damaged.

Arvidsson: The physical IRU was damaged beyond recognition.

And, uh, we couldn't find out what caused the problem.

Nothing.

Narrator: Without the device's memory cards,

investigators are unable to determine

the cause of the failure.

Arvidsson: We tried in every possible way,

but we didn't have enough evidence to understand it.

Captain: What the hell?

Narrator: Regardless of what caused it,

the IRU's failure should not have caused an accident.

There are backup instruments on board for precisely that reason.

Nance: Redundancy is one of the keys to aviation safety,

because not only do we need redundant pilots,

uh, because human beings can fail,

but we need redundant instruments.

We don't want to ever get in a situation

where a single-point failure

is going to cause you to not be able to fly the airplane safely.

Narrator: In their final report,

investigators list the pilots' failure to communicate properly;

the lack of information provided by the flight instruments

about the failure;

and the effect of negative G-loads on the crew

as the main factors causing the accident.

Arvidsson: It's important to communicate really early

When you've got a problem,

so the other pilot can understand what's going on.

Narrator: The investigators recommend that airlines

adopt standard callouts for pilots to use

in similar emergency situations

and that manufacturers improve the design

of primary flight displays

so that important error messages aren't removed

in declutter modes.

Nance: If you've got more than one crew member,

and in almost all instances in airline flights you do,

you need a procedure

for immediately checking with each other

and having standard callouts

so that you're coordinating your actions

and coordinating your brains.

Here we had one carbon-based brain

making decisions that were incorrect

and starting a slide into an accident sequence

because there was no coordination with the other one.