Original subtitles

(narrator): A botched takeoff in Buenos Aires...

...stuns investigators.

- To me, that was unprecedented. - Get out of it! Get out of it!

(narrator): A shocking error...

- We're stuck in it!

(narrator): ...lies behind the deadly free-fall of American Airlines Flight 587.

(people screaming)

And when Continental Connection 3407 stalls,

the flight crew's reaction is baffling.

- Not only did they not respond correctly,

they responded in the exactly opposite way.

(narrator): Commercial pilots undergo hundreds of hours of training and testing.

Still, experienced pilots make rookie mistakes. (screaming)

- Rookie errors don't necessarily occur to just rookie pilots.

It can happen to the most experienced pilot.

- Mayday, mayday.

- It's going up!

(indistinct radio chatter)

(narrator): It's 8:30 p.m. at Jorge Newbery Airfield in Buenos Aires, Argentina.

(ATC): Wind: 020 at 5.

Altimeter: 30.10.

(narrator): A Boeing 737 flight crew prepares for takeoff.

Their plane is operated by the Argentinean airline LAPA.

- D'you make it? - No.

- Hey, Captain. - Hey.

(narrator): The captain of LAPA Flight 3142 is Gustavo Weigel.

He's an experienced pilot who's been flying for more than 20 years.

- Everything okay?

- Fine. Everything's fine.

- We're just waiting on our fuel.

(narrator): First Officer Luis Etcheverry

has logged more than 500 hours in the 737.

- Total fuel required: 8,500 kilograms to be transferred to the wings.

(narrator): Tonight's flight is a little over an hour.

Its destination: the city of Cordoba,

400 miles west of Buenos Aires.

Along with the pilots, three flight attendants and 95 passengers are on board.

- Before-start checklist. - Before-start checklist.

(narrator): The crew is making last-minute preparations for takeoff.

- Cockpit preparations? - Completed.

(in Spanish):

The relationship between the crew seemed to be very close.

It appeared that they were friends.

- You guys should come for dinner in Córdoba.

- That sounds good. What should we bring?

- You can bring the ice cream. - You know, we're seconds away.

You should probably get back there and strap in.

- Alright, guys, it's been a pleasure. See you soon.

- Cleared for takeoff, LAPA 3142.

(engines revving) - Taking off.

(narrator): Flight 3142 speeds down the runway.

As the aircraft lifts off, it's immediately apparent that something is wrong.

(in Spanish):

The plane begins to take off, but instantly it starts shaking, like it was going to fall apart.

We all knew something was going wrong.

- What the hell?

(narrator): Hurtling forward at 160 knots...

...the 737 slams violently back to the ground.

They're now headed straight for a busy highway and an industrial gas plant.

- Stop, stop, stop, stop.

(in Spanish): It was very quick.

I just looked at my friends and I braced my head.

- No, no, no, no, no! - The airplane crossed a busy highway without warning.

It killed people who were commuting at that time in their cars.

- Stop! Stop!

(narrator): Flight 3142 slams into the gas plant.

(Spanish): I could feel extreme heat all around me.

I was suffocating.

And I needed to get out, but I couldn't release my seatbelt.

(narrator): Rescuers race to the site of the crash,

but survivors on board don't have much time.

Fire threatens to consume the entire plane.

(Spanish): I felt like I was dying.

(coughing) And someone said to me, "Get out!"

(narrator): Though badly injured,

Marisa Beiro is lucky to survive.

The crash has killed 60 passengers,

three crew members, including both pilots,

and two motorists.

It's a disaster unlike anything Buenos Aires has ever seen before.

- It was a major calamity.

It involved automobiles, it involved a natural-gas regulating plant.

- It's a lot of smoke. Hard to see anything.

(narrator): Horacio Larrosa is a senior investigator

for Argentina's Accident Investigation Unit.

(in Spanish): You try to focus on the job,

and look for details that later on could be harder to find,

once the rescue teams have finished their work.

- Neither pilot survived. - Okay.

(narrator): Any hope of finding out what went wrong lies in the wreckage.

Because the 737 is American-made,

the U.S. National Transportation Safety Board joins the investigation.

- Whatever you need, we're here to help.

- There was just a tremendous amount of public concern,

and a great deal of encouragement to try to solve this definitively and quickly.

- One of the big questions was:

How did this aircraft go off the end of the runway, especially on takeoff?

- Look here.

(narrator): The wings of the downed plane reveal the first clue for investigators.

(in Spanish): I was able to observe, with some of my colleagues,

that the aircraft's flaps were apparently not extended.

- Let's get this wing piece outta here.

(narrator): For takeoff, 737 pilots must always extend the plane's wing flaps.

The flaps increase the area of the wing and give it extra lift.

Without them, a fully loaded 737 cannot get off the ground.

Did the flaps retract during the crash,

or were they never deployed in the first place?

- When you see something that's out of place,

you begin to wonder: What has happened?

Has someone raised the flaps,

or has some electronic or hydraulic intervention made the flaps come up?

- We need to study the entire system.

(narrator): In the meantime...

- Oh, oh. Yep.

(narrator): ...the team on site retrieves the plane's black boxes.

- The importance of flight recorders in accident investigation

cannot be overemphasized.

(narrator): But they're badly damaged,

and immediately sent to Washington for repair.

- There was a good deal of pressure to get back the cockpit voice recorder

and the flight-recorder information in a timely way.

(narrator): In a nearby hangar,

investigators carefully examine every wire, gear and screw of the wing flaps.

- Actuators seem fine.

(narrator): They focus on a part that controls the flaps' movement:

the jackscrew, which acts much like a jack used to lift a car.

As it turns, it moves a nut that extends or retracts the flaps.

- That nut travels along the shaft.

It stops at various places to indicate various degrees of flap extension.

We had discovered the nuts on the screw were in the retracted position.

(narrator): The flap lever from the cockpit confirms the finding.

- The lever's pretty banged up, but it sure looks like it's in the flaps-up position.

(in Spanish):

It had left a mark with the flap lever in the up position.

So there was no chance that it had moved during the accident.

(narrator): The astonishing discovery reveals the flaps were never extended.

Flight 3142's configuration for takeoff was all wrong.

Baffled investigators wrestle with a difficult question.

- How could an attempted takeoff be made with the flaps in this position?

(passengers screaming)

(narrator): Investigators want to know how the experienced crew on board Flight 3142

took off without their flaps extended.

- No, no, no, no, no, no!

(in Spanish): You find yourself wondering:

Why did this action not take place

when it is indispensable for flight?

- Can we get the FDR data on the screen?

(narrator): The crucial black-box data finally arrives from Washington.

Investigators hope this will help explain what happened.

(sighing) - Great.

Let's go to the flap positions and engine performance.

(narrator): The flight data recorder confirms suspicions.

- With no flaps... they stall.

They get the plane back down here...

...50 metres from the end of the runway.

There's no way they could stop in time.

(narrator): It verifies the flaps were not extended, but not why.

Investigators turn to the cockpit voice recorder for clues.

(Spanish): The only possibility was in the voice recorder.

- Everything okay? - Fine. Everything's fine.

(narrator): Investigators begin by listening to what was happening just before takeoff.

- Waiting on our fuel? - So besides him,

any other guys you're interested in?

- Yes, but you don't know him.

I haven't seen him in a while.

(narrator): What they hear from the crew is astounding.

(flight attendant): The whole thing's getting complicated.

- You're breaking my heart.

(narrator): Not only unexpected, but entirely unprofessional.

- They should be running checklists. What's going on?

- They're required to have a sterile cockpit.

Once you start the engines up to 10,000 feet,

you talk only about operational procedures.

And this is to prevent distraction.

- You guys should come for dinner in Córdoba.

- That sounds good. What should we bring? - You can bring the ice cream.

- Okay. (scoffing)

- Before-start checklist.

- Before-start checklist.

- They're talking about planning a meal together,

they're talking about their romantic lives.

And this is interspersed with the checklist.

- Hey, you know I'm with you in the good times and the bad, moron.

It's a good thing I'm nothing like you.

- You're full of it. You're only with me for the good times.

- Cockpit preparations? - Completed.

- The checklists were interrupted and were performed incorrectly.

- Flaps are part of the before-takeoff checklist. Do they even do that?

- Anti-ice? - Off.

- Start levers?

- Idle stop.

- Ready to taxi, 3142.

(ATC): 3142, ready to taxi, Charlie-5 to runway 1-3.

- Charlie-5 to 1-3. - Don't smoke all of it. Give me a puff at least.

- Even a puff can make you old and grey.

- Thanks. - They're actually smoking in the cockpit.

- The three were passing a cigarette, which is prohibited by the company.

They're not supposed to be smoking in the cockpit at all.

- No mention of flaps.

They're starting to taxi.

- You should probably head back there and strap in. - Alright, guys.

(narrator): The reason the crew failed to extend the flaps is now clear.

- Hurry, hurry.

(narrator): They were simply too distracted by their own careless behaviour.

(ATC): Cleared for takeoff, LAPA 3142.

(narrator): But what investigators hear next is even more shocking.

(alarm sounding) - There it is.

(narrator): It's an alarm warning the crew of their mistake.

(in Spanish): The sound of the alarm was loud.

It could be heard perfectly in the voice recorder many times.

(alarm sounding)

- I don't know what the alarm is, my friend. Everything seems fine.

- Okay, pause. How can they ignore that?

(narrator): How could a crew forget to perform

one of the most basic takeoff procedures,

and then go on to ignore the loud, persistent warning

designed to alert them to their serious mistake?

(in Spanish):

I believe they didn't understand the importance of this alarm,

which was absolutely critical for takeoff.

(narrator): Sixty-five people lost their lives

because the crew wasn't paying attention to what they were doing.

(alarm sounding)

- If the alarm went off and it warned that the flaps weren't configured,

why didn't they do something?

(narrator): In their final report,

investigators stress the need for pilots to always comply with the sterile cockpit rule.

It restricts crew conversation and helps minimize distractions during key parts of the flight.

- By not maintaining a sterile cockpit and following every checklist

and doing exactly what you're supposed to do... people die.

(narrator): But sometimes,

following strict operational discipline can still lead to catastrophe.

- Even when pilots are following the procedures correctly,

you can still have a rookie error.

- Get out of it! Get out of it!

(narrator): Just nine weeks after the 9/11 attacks,

New York's John F. Kennedy Airport is busy again.

American Airlines Flight 587 is carrying 251 passengers enroute to the Caribbean.

(groaning)

- Your leg. You check the rudders.

(narrator): The crew is preparing the plane for takeoff.

- Rudders, check. Taxi checklist is complete.

- Okay.

(narrator): Captain Ed States is a former military pilot

who joined American Airlines 16 years ago.

First Officer Sten Molin has racked up more than 4,000 hours of flying time

and is the pilot flying today.

- Winds checked.

- American 587, follow Japan Air Boeing 747 ahead.

- Follow Japan Air, American 587.

(narrator): Flight 587's flight plan takes it out over New York's Jamaica Bay

before heading south to the Dominican Republic.

- You have the airplane.

- The captain indicated the first officer would be the flying pilot on this leg.

The captain designated him to fly the flight.

That's routine. Uh, it's the captain's choice.

- American 587, Kennedy Tower. Caution:

Wake turbulence, runway 3-1 left. Taxi into position and hold.

- You happy with that distance?

- Ah, we'll be alright once we get rolling.

He's supposed to be five miles by the time we're airborne. That's the idea.

- So you're happy.

I'm on the roll.

Thank you, sir.

- V1. Rotate.

(narrator): Flight 587 lifts off at 9:14 a.m.

(banging) - American 587, heavy.

Climb and maintain 1-3,000.

(rumbling)

(narrator): Residents of Queens, New York, hear the familiar sound of jets overhead.

- Planes, you know, take off and land.

They fly right over the peninsula every 45 seconds.

It was just a normal thing.

(narrator): High above, a patch of turbulence rocks Flight 587.

- Ooh, boy. (indistinct chatter)

- Max power.

(alarm sounding) - You alright?

- Yeah. I'm fine. - Hang onto it. Hang onto it.

- Let's go for power, please!

(narrator): 2,300 feet above the ground, disaster strikes.

- Holy crap! (passengers screaming)

(narrator): The plane is losing altitude and falling out of the sky.

- What the hell are we into?

(narrator): There are more than 68,000 pounds of flammable jet fuel on board.

(screaming) - Oh, my god!

(alarm sounding) (narrator): Flight 587 plummets towards Queens, New York.

- We're stuck in it! - Get out of it! Get out of it! Get out of it!

- The house started vibrating very heavily. You know, this all happened really quick.

(sirens wailing) (people shouting)

(narrator): At impact, the fuel ignites a massive fireball,

engulfing several homes.

- The plane crashed pretty much in the backyard, in the street, uh, exploded.

(sirens wailing)

- God, it's a plane! - It looks like a war zone.

(narrator): All 260 people on board are dead,

as well as five people on the ground.

Many wonder: Was this an accident?

(sirens wailing)

- We were still heavily involved in the investigation of 9/11.

I immediately got concerned as to:

Was this another terrorist attack?

(narrator): That means the FBI and the NTSB

will be investigating this air crash together.

- This accident occurred so close to the tragedy of 9/11

that we naturally jumped to conclusions,

and we had to force ourselves to back up

and carefully study the evidence.

They came in fast and steep. Let's hope it's not what we think.

(narrator): Their mission is to answer a vital question:

Was this terrorism, or an accident?

Any evidence of a bomb would be in the debris.

- Everything else stays here for now.

- Experts would be physically examining all of the parts of the plane

to see if there was any indentations...

indicating that the explosion was inside and pushed everything out.

(narrator): But the crash site and tests for explosive residue

reveal no evidence that a bomb took down the plane.

- We learned very quickly that, in fact,

it was not a terrorist event.

(narrator): Then a discovery, three quarters of a mile from the crash,

provides investigators with a massive clue.

- We found the vertical stabilizer miles and miles away.

(narrator): The vertical stabilizer is found in Jamaica Bay,

between the airport and the crash site.

The location tells investigators it broke off while the plane was still in the air.

(beeping)

- That was a good first... first step for us.

(narrator): The vertical stabilizer is part of the tail.

Along with the horizontal stabilizer,

it's critical for stable flight.

- You can't fly without a tail. I mean, you can't.

The airplane's gonna go down. There's nothing you can do about it.

(narrator): NTSB investigators are under pressure to find out what happened to the A300,

one of the world's most popular aircraft.

- How does a vertical stabilizer just fall off?

- I'd been Investigator-in-Charge of the NTSB for, at that time,

oh, gosh, 20 years or so,

and I had never seen anything quite like this.

(narrator): Investigators turn to the plane's cockpit voice recorder,

hoping to discover what went wrong with the stabilizer.

- American 587, Kennedy Tower. Caution:

Wake turbulence, runway 3-1 left.

Taxi into position and hold.

(narrator): After the controller issues a warning about wake turbulence,

the first officer sounds concerned.

- You happy with that distance?

- Ah, we'll be okay once we get rolling.

He's supposed to be five miles by the time we're airborne.

(narrator): Wake turbulence is caused by the movement of air over and under the wing.

When the two streams of air meet at the wing tips,

they combine to create a powerful vortex that trails behind the plane.

- Max power! (alarm sounding)

- You alright? - Holy crap!

(narrator): Did the pilots get too close to the plane in front of them?

- Holy crap! (narrator): Investigators listen as First Officer Molin

wants more speed to help them fly through the turbulence.

- Hang onto it. Hang onto it.

(narrator): Moments later, catastrophe strikes. (crash)

- 15:58. That's the tail coming off.

(narrator): Was the aircraft upset by the wake of a plane taking off ahead of it?

- We knew, of course, from listening to the, uh, Air Traffic Control tapes,

that the accident aircraft took off a 1.5 minutes or two minutes after a JAL,

Japanese Airline Boeing 747.

(narrator): Radar data shows that Flight 587 was flying at a safe distance.

The wake was too weak to be dangerous.

- Not even close to what it would take to rip the tail off an Airbus.

(narrator): But another piece of data provides a vital clue:

frantic rudder movements.

(alarm sounding) (beep)

- Eleven degrees left.

Eleven degrees right.

We saw the rudder go back and forth to its maximum...

deflection several times very, very rapidly.

Could he have ripped the tail off his own plane?

(narrator): NTSB investigators wonder if extreme rudder movements on Flight 587

created an aerodynamic force strong enough to rip the vertical stabilizer off.

- We needed to determine whether that particular motion,

uh, would be violent enough to snap the vertical stabilizer off.

(narrator): Normally, pilots only move the rudder

a couple of degrees in either direction to steer the plane.

But First Officer Sten Molin was moving his plane's rudder much more than that.

- You ready?

(narrator): To learn more, they create a computer simulation of an A300,

and fly it the same way as First Officer Molin,

moving the rudder 11 degrees back and forth three times.

- With each rudder deflection,

the aerodynamic loads on the tail increase.

(alarm sounding)

(alarm ringing) - There.

(alarm ringing) That would've done it.

- And it was those increasing loads that caused this.

(beeping)

- Well, he's doing it to himself!

(narrator): The discovery finally explains what happened

to American Airlines Flight 587.

But it doesn't explain why.

- So now we've eliminated several items,

and we're starting to look at the actions of the flight crew very carefully.

(narrator): Why would an experienced pilot move his rudder so violently

to fly out of the wake?

When they talk to pilots who flew with Molin,

investigators make a surprising discovery.

- Take a seat.

We began to suspect that the... first officer overreacted.

Tell me what happened.

- He had a history of responding...

very aggressively to wake turbulence.

- He did the same thing seven years ago.

- He moved the rudder pedal quickly back and forth.

The captain said he was shocked by this.

- He was overworking the rudders.

- He said, "Why did you do that? Why did you respond like that?"

And according to the statement, the first officer said,

"They taught us to respond like that in the, uh, training."

(narrator): When investigators turn their attention to American Airlines training,

they're shocked by what they learn.

Pilots are taught that minor wake turbulence can induce a sudden steep roll.

- We determined that they were actually providing...

inadvertently providing some negative training to their pilots.

That led us to the conclusion that he overreacted.

(narrator): First Officer Molin was trained to believe

that severe wake turbulence could cause a catastrophic upset.

- Max power! - You alright?

(alarm sounding) - The captain asks him: "Are you alright?"

And it's noteworthy that the captain does not add max power.

In the captain's opinion, max power is not appropriate in this situation.

The First Officer began responding with...

wheel back-and-forth and accompanied by back-and-forth rudder.

- Hang on. Hang onto it.

(alarm sounding) - The first officer overreacted on the rudders.

He didn't let the aircraft stabilize in one position or the other,

so it... it hits a stop and then whips itself back.

Back and forth, back and forth,

and this creates huge loads on the vertical part of the fin.

(narrator): The first officer's actions stress the vertical stabilizer

until it breaks under the strain.

- What the hell are we into?! (alarm sounding)

- Get out of it! Get out of it! Get out of it!

(all screaming)

(alarm sounding) (automation): Stall. Stall.

(sirens wailing) (people shouting)

(narrator): After the accident, American Airlines changes its training procedures

for wake turbulence.

- Once it became clear that some negative training was going on,

American Airlines, to their credit, uh...

revamped the program to prevent this type of activity.

(narrator): American Airlines modifies their training simulator to be more realistic.

Pilots are now taught not to use the rudder at high speed.

A new warning light is also installed in the cockpit

to help prevent pilots from deflecting the rudder too far.

- I think 587 brought an awareness to the aviation industry.

Pilots, they push that rudder in full deflection,

it could have disastrous effects.

(narrator): But despite the lessons learned from the crash

of American Airlines 587,

a rookie mistake causes disaster seven years later.

- Gear down. LOC's alive. - Gear's down.

Ah! Ah! (alarm sounding)

- Jesus Christ!

(screaming)

- It was one of the grisliest, nastiest scenes that I think I've seen.

(sirens wailing)

(narrator): Continental Connection Flight 3407,

operated by Colgan Air,

is enroute from Newark, New Jersey, to Buffalo, New York.

It's been a busy flight for Captain Marvin Renslow.

He's providing guidance to a new first officer.

- Ah...

(sneezing) Ah!

(narrator): Twenty-four-year-old Rebecca Shaw

has been with the airline for just over a year.

She must decide now if she wants to become a captain.

- I don't know what I wanna do with the upgrade.

- If you stayed on the Q, obviously you're not making the captain rate.

- Right. - But you may have a better quality of life

with regards to buying a house and having a schedule.

(narrator): Shaw trained on the plane they're flying now,

a Canadian-made Bombardier Q400.

There are 45 passengers on board.

Flight 3407 is heading northwest over Upstate New York.

The trip is only 53 minutes.

Visibility is poor,

and there's a forecast of snow and moderate winds in Buffalo.

- Folks, from the flight deck, your first officer speaking.

At this time, we're about 15 minutes outside of Buffalo.

Weather in Buffalo is pretty foggy.

Snowing a bit there. I'd like to make sure

everyone remains in their seat so the flight attendants can prepare the cabin for arrival.

(narrator): As the flight makes its approach,

the pilots prepare the aircraft for landing.

- Gear down. LOC's alive. - Gear's down.

- Alright. Flaps, 15.

(narrator): Extending the flaps provides more lift,

allowing the plane to slow to its final-approach speed.

(alarm sounding) - Uh...

Oh! Ah!

(alarm sounding)

(narrator): Suddenly, the Q400 slips out of control.

Captain Renslow struggles to contain his aircraft.

(alarm sounding) - Ah!

(Renslow groaning) - Mother... (exclamations)

(panting)

(narrator): But it seems to have a mind of its own.

(all screaming)

- Mother bear!

- Should the gear be up?! - Gear... up! (narrator): It's too late.

The plane is now in a stall, and Renslow can't recover.

- Ah, we're down.

(screaming)

(all screaming)

(narrator): The plane crashes into a suburban home in Clarence Center,

a town five miles short of Buffalo Airport.

All 49 passengers and crew are killed on impact.

One person on the ground also dies.

The devastated house and downed plane are a blazing inferno.

(sirens wailing)

- The height of it was just unbelievable. (siren wailing)

Obviously because of the fuel that was probably added to it, and, uh,

and the debris area was very large.

It was a horrific sight.

(narrator): Firefighters work tirelessly through the night.

The scene in the morning is one of utter devastation.

- Clint Crookshanks from the NTSB. Can I start poking around?

(narrator): Clint Crookshanks is one of the first investigators on the case.

- When we arrived on scene, there was a fire still burning.

Turns out it was from a gas line that had been broken in the house.

The firemen would put the fire out and it would reignite every couple of minutes.

(narrator): Investigators hope the flight's black boxes will provide answers.

- We were able to cut a hole in the side of the fuselage.

Once we took the recorders out of the airplane,

we put them on the jet and they were flown back to Washington, DC,

to our headquarters.

(narrator): At the NTSB labs in Washington,

Systems Investigator Scott Warren analyzes

the aircraft's cockpit voice recorder, or CVR,

to determine if there are any indications of a problem in the cockpit.

- Is that ice on the windshield?

(narrator): He discovers that six minutes before the crash,

the crew of Flight 3407 notices a build-up of ice on the aircraft.

(Renslow): I got it on my side.

You don't have yours?

- Oh, yeah. Oh, it's lots of ice.

(narrator): Ice can be a deadly threat to any airplane.

- If an aircraft has ice on it, it will have more drag on it,

so it will require more power to maintain a given airspeed.

- When ice accretes on a wing, it adds weight to the airplane,

but most importantly, it changes the shape of the wing.

And it's the curved shape of the wing that actually creates the lift.

So by changing the lift characteristics of the airplane,

it makes it less able to fly.

- Flaps, 15 before...

(narrator): The CVR reveals that only minutes after the crew detects ice,

a device called the stick shaker goes off.

(Shaw): Ah! (beeping)

(narrator): It's a warning to pilots that the plane is losing airspeed.

If they don't go faster, the plane will stall and fall out of the sky.

(Shaw screaming)

Scott Warren knows the Q400 has a sophisticated de-icing system.

To prevent ice accumulating, the plane has rubber bladders along the front of the wings

called de-icing boots.

A series of valves uses air from the engines

to inflate the boots and crack the ice off the wing.

Studying the flight data recorder, or FDR,

will reveal whether the de-icing system was switched on.

(Warren): We know from the FDR data that the de-icing system

had been selected on by the crew,

and it was on during the majority of the flight.

(narrator): The pilots had switched the de-icing mechanisms on.

But were they working properly? To answer that question,

investigators sift through piles of charred wreckage

until they find the de-icing valves.

- We took those valves and, as far as we could tell,

all those valves were working properly.

(narrator): If ice didn't bring down Flight 3407...

...what else caused the plane to stall,

crash, and kill 50 people?

(narrator): Investigators know icing conditions were not bad enough

to take down Continental Connection Flight 3407.

Something else must've caused it to suddenly lose airspeed.

NTSB investigator Scott Warren knows the plane was flying at 131 knots

when the stick shaker went off,

more than enough speed to stay airborne.

- Alright. Flaps, 15.

- When the stick shaker went off... - Uh...

Oh! (alarm sounding)

- ...they were not necessarily at the edge of a stall.

They were still 20 knots or so away from the stall.

(narrator): This new revelation deepens the mystery of Flight 3407.

The stall warning was triggered when the plane was in no danger of slowing to a stall speed.

Investigators work with the plane's manufacturer to learn more about the aircraft.

They discover the Bombardier Q400 has a unique safety feature

known as a Reference Speed Switch.

The switch changes the airspeed at which the plane's stall warning is activated.

- - Some kind of variable Ref Speed?

(narrator): Captain Renslow should have activated the switch

before flying through the icy weather.

- When you are in icing conditions,

and ice does accrue on the wing,

it can cause the stall speed to go up,

and so this Ref Speed Switch correspondingly causes

the warning to come on sooner or at a higher speed.

- What that switch does, is it basically, uh,

changes the trigger settings for the stick shaker.

(narrator): If ice was slowing the plane,

Captain Renslow would be alerted sooner than usual to pick up speed

and avoid a stall situation.

Investigators eventually find the Reference Speed Switch panel

buried in layers of crash debris.

- Bingo.

(narrator): And it's in the activated position.

- And we'll probably be picking up some ice.

(narrator): If Renslow and Shaw remembered to configure the plane properly

by turning on the Reference Speed Switch,

why didn't they notice their airspeed was too slow for the icy conditions?

- Obviously you're not making the captain rate. - Right.

(narrator): The CVR reveals a chilling answer.

The flight crew had been talking throughout the flight,

continuing into the landing approach,

a violation of the "sterile cockpit rule."

(Shaw): Yeah, and that's another thing.

And he said, "Yeah, you're gonna be upgraded in six months."

Blah, blah, blah. (Renslow laughing)

(narrator): When the stick shaker goes off,

the distracted crew is caught off-guard. (exclamations)

- Once the stick shaker activated, they could have, uh,

turned the switch off, or put the nose down and increased their airspeed.

(narrator): Using data from the flight recorders,

investigators create a computer simulation

to give them a better understanding of the crash.

- Watch what happens just after the stick shaker goes off.

(narrator): It illustrates that just after the stick shaker was triggered,

the plane suddenly pulled up.

This action dramatically slowed the aircraft.

And at this point, it did stall.

- Essentially, the airplane entered an aerodynamic stall from which it did not recover.

It pitched over and hit the ground.

(narrator): Investigators are dumbfounded.

Both pilots should have known how to respond

to one of flight's most basic tasks.

The crew's every action during the critical seconds after the stall warning sounded

now demand careful scrutiny.

- We wanted to see if the way they flew the airplane was the way they were trained.

(narrator): Investigators dig deeper into the FDR data

to examine how the pilot manoeuvred the plane after the stick shaker was triggered.

They focus in on the control column.

What Scott Warren finds is stunning.

In response to the stick shaker, Captain Renslow should have pushed the column forward

to bring the nose down and gain speed.

But the distracted captain did the exact opposite.

- Ah! - We found that the crew, instead of pushing forward,

which is the normal response to a stick shaker triggering,

the crew was actually pulling back on the control.

(narrator): This had the effect of pulling the nose up,

causing the airspeed to drop and tipping the aircraft into an actual stall.

Captain Renslow apparently mishandled

one of the most elemental piloting manoeuvres:

How to recover from a stall. (Shaw exclaiming)

- Had the first officer simply called out, "You're stalled, advance the power,

push the nose over," the airplane would've been able to recover.

- From a human point of view, it's sad to recognize that those sorts of things happened,

and the tragedy that came from that.

(narrator): It's concluded that Captain Renslow's failure to properly respond

to the stall warning is the primary cause of the crash of Flight 3407.

He reacted in the worst possible way

and sealed the fate of the plane.

- You get a stall warning and you have to take corrective action,

and you know the altitude is very low,

you don't have a lot of options;

you just have to be able to react.

(screaming) - No, no, no, no, no! Ah!

(narrator): At the heart of some of the worst airline accidents

lie mistakes of staggering simplicity.

- What the hell are we into?!

- Rookie errors don't necessarily occur to just rookie pilots.

It can happen to the most experienced pilot.

(sirens wailing)

Subtitling: difuze