Original subtitles

GIBSON: We're going over!

NARRATOR: A Boeing 727 spirals out of control over Michigan.

You're watching the world spinning outside the window.

This would be sheer stark terror.

Airspeed is 320... 350!

- Come on! Come on! - BANKS: No, no, no.

NARRATOR: Investigators track down pieces of debris...

INVESTIGATOR: Slat number 7.

Broken in two.

NARRATOR: And interview fellow pilots.

- Off the record? - Off the record.

NARRATOR: They even risk their own lives...

Okay. Test number nine.

NARRATOR: To find out what caused TWA Flight 841's uncontrollable plunge.

You feel that?

PILOT (over radio): Mayday, mayday.

AUTOMATION: Pull up.

(indistinct radio chatter)

(theme music plays)

It was insane. My hands are still shaking.

NARRATOR: 44-year-old Captain Harvey 'Hoot' Gibson has just

returned from the most harrowing flight of his life.

RONALD: Tell me what happened.

NARRATOR: A representative from the Federal Aviation Administration

takes his statement.

We were cruising over Michigan.

That sure is a strong headwind.

NARRATOR: Captain Gibson is a trained stunt pilot

who has a clean 16-year record with Trans World Airlines.

- Do a groundspeed check, will ya? - Sure thing, Hoot.

NARRATOR: First Officer Scott Kennedy has been flying with TWA for 13 years.

We're good to go up any time you want, Hoot.

NARRATOR: Flight Engineer Gary Banks is an Air Force veteran

who's been with TWA for the last 10 years.

BARRY: The crew of flight 841 had just the right

kind of experience you would want for a 727 crew.

Center, TWA 841. We'd like to try flight level 3-9-0.

CENTER (over radio): Roger, TWA 841. Climb and maintain flight level 3-9-0.

SHIBAN: They were bucking 100 knots of wind on their nose,

so he was looking for better winds up higher.

The higher you go, you essentially go faster through

the thinner air and that will hopefully get you a better groundspeed.

I can take that off your hands.

NARRATOR: 27-year-old Mark Moscicki is today's lead flight attendant.

He and three other attendants look after the 82 passengers on board.

MARK: It was an evening flight. It was leaving JFK.

It was the first time I had flown with this cockpit crew.

Everything was absolutely smooth.

NARRATOR: They're flying the narrow-body Boeing 727 aircraft.

SHIBAN: The 727 was massively over-built. It was a very sturdy airplane.

It was like driving a sports car or a fighter plane.

It was very light on the controls.

It had that feeling that you could just put it wherever you wanted it.

NARRATOR: After a 45-minute delay in New York,

the flight to Minneapolis will take about three and a half hours.

BOB: They programmed 39,000 feet and got right up there,

and sure enough, they were gaining speed.

They were probably gonna cut ten to 15 minutes off their in-route time.

I'll do another groundspeed check.

Power settings adjusted. Everything looks good.

NARRATOR: After meal service, Moscicki takes a moment to eat his own meal.

MARK: I sat in my jump seat.

Very shortly, however, there was a very abrupt buffeting of the aircraft.

It wasn't turbulence.

What the heck?

The captain noticed something was strange.

The wing had started to drop, and the autopilot was compensating for that.

I got control.

Disengaging the autopilot was the right thing

to do at that time. That's the first thing you think of.

There's something wrong with the autopilot.

BANKS: What's going on?

NARRATOR: Without any warning, the plane banks hard to the right.

BANKS: Airspeed 240.

Come on! Level up.

But if the plane still doesn't respond,

then you're thinking there's something wrong with the airplane.

The plane just kept rolling right, and it started rattling really hard too.

I would be trying the rudder, and if that's not doin' the job,

I'd start trying to fly with the engines.

But a 727, the engines are all clustered together in the back.

That probably wouldn't help you much. So this would be sheer stark terror.

Shutting the throttles.

NARRATOR: The Captain tries to slow the plane to regain control.

But the aircraft isn't responding.

(screaming)

Get 'em up! Get 'em up!

NARRATOR: Desperate to slow the plane, Gibson deploys the speed brakes.

Speed brakes are flight control surfaces

that increase drag and improve roll control.

You're gonna put those out to try and slow yourself down,

because really bad things are gonna start happening soon if you keep accelerating.

Come on! Come on!

NARRATOR: But deploying the speed brakes proves useless.

8MARK: I got up from my jump seat to see if perhaps the engine was on fire.

And I never made it.

- We're going over! - AUTOMATED VOICE: Bank angle. Bank angle.

AUTOMATED VOICE: Bank angle. Bank angle.

NARRATOR: High above Saginaw, Michigan,

the Boeing 727 drops into an uncontrolled dive and spins upside down.

Something was extremely wrong. There seemed to be no control of the airplane.

People were just absolutely terrified.

I sincerely didn't think that we had wings left on the airplane.

TWA 8-4-1, this is Center.

TWA 8-4-1, Center?

Jesus.

Something is seriously wrong.

SHIBAN: You would have your hands full of airplane.

You're watching the world spinning outside the window.

You're being pressed by G-forces. It also must have been insanely noisy.

It would have been very difficult to try and troubleshoot the problem.

TWA 8-4-1, do you read me?

NARRATOR: The controllers watch helplessly as TWA 841 plummets towards the ground.

SHIBAN: Once the nose comes down on an airliner,

they want to pick up speed in a hurry if you point it at the ground.

I kept clenching my jaws and biting my teeth to keep blood in my head.

The G-forces were so extreme I felt I was going to pass out.

SHIBAN: The blood is literally being drained out of your head,

and you will first lose your vision. That's called greying out.

And then the next thing is you black out, which is where you lose consciousness

because your heart just can't pump the blood up to your brain

against all that force of gravity.

- Airspeed is 320... 350! - AUTOMATED VOICE: Bank angle. Bank angle.

- Bank angle. Bank angle. - GIBSON: I can't... I can't...

NARRATOR: TWA 841 is spiraling towards the earth

at a rate of 540 feet per second.

BARRY: To feel 6Gs, the only people that would

experience that would be military pilots.

You're gonna feel an incredible weight on you, in every part of you.

And whatever position your body is in, your head,

or your arms, they're gonna stay that way because you're not gonna be able to move.

I could see ground lights,

and I knew that we were approaching the ground very quickly.

At that point, you go from abject terror into almost acceptance.

No, no, no!

Come on, baby. Pull up!

We were falling so fast...

NARRATOR: Captain Hoot Gibson recounts his recent nightmare

piloting TWA Flight 841 over Michigan.

Airspeed is 390.

NARRATOR: But Gibson isn't giving up.

GIBSON: Come on, baby. Pull up!

NARRATOR: He has an idea.

GIBSON: Put the gear down!

If nothing else will slow you down,

the gear will slow you down, and hopefully, the plane holds together.

That's it. That's it, baby!

What saved them was putting the gear down 'cause otherwise,

they would've been a big smoking crater in a matter of seconds.

BANKS: We're pitching up 30 degrees.

Now, suddenly, we were climbing.

It was like coming out of the bottom of a rollercoaster.

SHIBAN: You would feel like you are being crushed.

The average person would feel like they weighed 900 pounds.

Scott, give me altitudes! Gary, pitch, and airspeed.

5200 feet! Jesus, which way is up?

GIBSON: Moon!

SHIBAN: It's pitch black, and you've just been spiraling down

towards the earth, and you're probably disoriented.

He sees the moon, and that's up.

You can sort the rest out later, but get away from the ground.

NARRATOR: TWA 841 has come within seconds of impact,

and now climbs back towards the night sky.

Airspeed is 160.

NARRATOR: Though the pilots are flying again,

they are not out of danger.

The steep climb is physically demanding,

and the crew struggles to maintain focus.

Uh... 10,500.11,000.

- That's it, that's it, Hoot. - Leveling 1-1-0.

This is your Captain speaking.

As you've noticed, we've had a bit of a problem,

but everything seems to be under control.

We lost system A hydraulics.

Fluids are down, pressure is down.

NARRATOR: As the crew recovers from the terrifying incident,

they assess damage to the aircraft.

We've got a flag for the lower yaw damper.

NARRATOR: A deafening rattle makes a tense situation worse.

Okay. I'm gonna fly the airplane.

You guys start running the emergencies!

BARRY: He was a good captain.

He had them diagnose the problem while he flew the airplane,

knowing that you can't do both effectively.

Turn pump emergency switches to depressurize and check quantity.

The fluid is zero. It's all gone.

NARRATOR: With a damaged hydraulic system, the aircraft is severely impaired.

Okay. We gotta land. Detroit is our best option.

KENNEDY: Okay, uh... We're 60 miles out.

BOB: When they decided to divert,

they selected Detroit with reasonable weather, long runways.

It was a developed airport with Crash, Fire, Rescue.

Center, 8-4-1.

Go ahead, TWA 8-4-1.

Okay, listen, we had a problem. We lost about 20,000 feet.

- We need vectors to Detroit. - 45 miles from Detroit now.

If you'd like to come left, heading 1-6-0 vectors to Detroit.

Okay, turn left 160, TWA 8-4-1.

Remove your glasses, earrings, and anything else that might be sharp.

Place anything soft in your lap to cushion the impact.

NARRATOR: 30 miles from the airport,

flight attendants prepare the cabin for an emergency landing.

The passengers were amazingly quiet.

I mean they looked at us for complete direction.

15 miles from Detroit now.

Nice and easy, give me flaps 15.

NARRATOR: Unaware of the extent of the damage,

Gibson tests the aircraft's controllability.

KENNEDY: Flaps 15.

Whoa, whoa, whoa. Retract the flaps.

Extending the flaps causes the plane to roll sharply to the left.

You are going to land without flaps,

at this point, which means you're going to go very fast,

much faster than you would ever land this airplane.

Go in fast. There's no other way.

This is gonna be our only approach.

NARRATOR: With ruptured hydraulics and a compromised plane,

the pilots of TWA 841 have only one shot at landing at Detroit Airport.

KENNEDY: Landing checklist complete. Coming through... 200 feet.

I was pretty convinced that we'd probably be scraping

down the runway, lots of sparks and flames.

50... 40... 30...

Brace!

220 knots in this case.

Just an insane rate of speed for a landing.

Reverse thrust. Come on. Come on. Stop.

(tense music)

(tense music stops)

Let's get these passengers off the plane.

He's just put this badly damaged airplane down at

about 90 knots faster than a normal landing speed.

This guy was good. He was really good.

Hoot, that's unbelievable.

I mean, what the heck went so wrong with that plane?

I haven't the faintest idea.

NARRATOR: Investigators from the National Transportation Safety Board

arrive in Detroit to determine what went wrong with TWA Flight 841.

They look in good shape. Let's get the data on these.

NARRATOR: The flight data recorder and cockpit voice recorder

are removed from the aircraft and sent for analysis.

LES: Let's check that out.

Slat Number 7 is missing.

NARRATOR: Slats and flaps are control surfaces

on the leading and trailing edges of the wings.

They are always extended in tandem.

Both devices increase lift at low speeds during takeoff and landing.

It's pretty banged up.

NARRATOR: Investigators wonder why the slat came off.

- The hydraulics lines are ruptured too. - A logical outcome for a slat tearing off.

It looks like the actuator for the slat is damaged.

NARRATOR: The actuator is part of the mechanism

that pushes a piston to unlock the slat, allowing it to either deploy or retract.

Let's get the actuator off the wing, so we can get a better look at it.

One of the interesting remnants of this inspection

was the number 7 slat actuator.

Look at how it's broken.

/There are no scrape marks inside either.

NARRATOR: Investigators uncover an important clue.

The slat came off in an extended position.

BOB: Number 7 slat actuator had broken.

The piston inside it was gone, and they could recognize

from looking at the opening of the fracture

that the piston had been in the deployed position.

NARRATOR: A slat should never deploy at cruising speed.

Maybe this slat extended by accident.

The only way to know for sure is to test the hydraulic system.

For the slat to have been deployed un-commanded required a failure

of the hydraulic system and a failure of the locking mechanism.

I'll start with flaps 2.

Flaps 15.

Flaps 15.

Looks good. Next, flaps 20.

Flaps 20.

NARRATOR: Investigators run through every flap setting possible.

All right, let's wrap it up. Everything's working fine.

BARRY: The functional tests demonstrated that the hydraulic system worked.

It did not cause an un-commanded slat deployment.

Here's what we got from Boeing.

NARRATOR: Did the locking mechanism on the 727's wing

somehow fail, releasing the slat?

For a slat to unlock accidentally,

the pin inside the actuator must be subjected to more than 70 Gs of force.

70 Gs?

There's no way the locking mechanism experienced that level of stress.

BARRY: A 70 G pull-through by an aircraft just doesn't happen.

The investigators were faced with a serious challenge of

where to go next.

Take a look.

NARRATOR: Investigators get a break when debris from Flight 841

is recovered seven miles north of Saginaw, Michigan.

INVESTIGATOR: Slat Number 7.

Broken in two.

Look at this.

Here's the Number 7 slat's T-bolt.

NARRATOR: T-bolts are part of the slat track assemblies.

The number 7 slat T-bolt was attached to the inboard side

of the slat, which deploys and retracts inside the wing.

Let's send this to the lab.

NARRATOR: They hope metallurgical analysis will offer some clues.

But an important question remains: why did the slat extend?

There's only one other way a slat could extend. Through pilot action.

BOB: This was something that had been probably commanded in the cockpit.

And, uh, it was distressing to everybody.

NARRATOR: Why would a pilot do something as dangerous

as extending the slats at cruising speed?

LES: I can't find anything in the captain's statements

about slats and flaps.

NARRATOR: Investigators review the crew's statements.

They look for any mention that flaps and slats were deployed mid-flight.

There's nothing from the other crew members either.

I have an idea.

Thanks for meeting with me.

NARRATOR: The NTSB consults with pilots to learn

why they might extend a flap or a slat mid-flight.

- Off the record? - Off the record.

- INSTRUCTOR: Flaps, yes. Slats, no. - Flaps?

NARRATOR: Investigators learn of an unauthorized procedure

used by some pilots that could save fuel and potentially time.

I thought that wasn't possible.

It is, if you pop the breaker.

NARRATOR: The procedure involves deploying trailing edge flaps by two degrees.

By pulling the circuit breaker for slats,

the flaps can be extended while preventing the slats

from automatically deploying at the same time.

SHIBAN: It's one of those things everybody knows about,

but I've never heard anyone ever admit to it.

INVESTIGATOR: Ready?

NARRATOR: Investigators turn to the Cockpit Voice Recorder

for evidence that TWA 841's pilots used the unauthorized procedure.

GIBSON (over tape): Let's get these passengers off the plane.

Hang on. Did you start the tape at the beginning?

- Yes. It's fully rewound. - Play it again, just to be sure.

GIBSON: Let's get these passengers off the plane.

The plane's already on the ground.

NARRATOR: This can only point to one thing.

The pilots erased the tape.

The CVR contained no information whatsoever,

uh, which was unfortunate, to say the least.

We have to talk to Gibson.

NARRATOR: The team flies to California to question Captain Gibson in person.

The Safety Board conducts public hearings.

They question the flight crew.

I told him I thought it was... I said...

I said, "The airplane is gonna roll," and, uh...

NARRATOR: The Captain admits to routinely

erasing the Cockpit Voice Recorder after every flight,

even though that isn't a step on any checklist.

PANELIST: Do you usually erase the recording?

I usually do. Yes.

BARRY: It's just not credible that after the crew had been through what they did,

where they came within seconds of dying,

that the captain would erase the CVR as a, as a matter of habit or routine.

Something's wrong here.

NARRATOR: Captain Gibson's vague explanation

doesn't sit well with investigators.

Given what happened, they suspect the flight crew

attempted the unsanctioned procedure, and then tried cover up their actions.

BARRY: The only reason he would erase the CVR

was to keep information from what he knew would be an investigation.

Investigators believed he had something to hide.

Maybe the FDR data can tell us more.

NARRATOR: The team studies TWA 841's flight data to uncover

any evidence that the crew attempted a mid-flight flap extension.

LES: Wow, it sure picks up speed.

In 44 seconds, the plane goes from 229 knots to over 400 knots.

That's incredible.

Look at this.

NARRATOR: Close inspection of the data gives the team an important clue.

INVESTIGATOR: That's odd. Are those oscillations?

Yeah. In the G-trace.

NARRATOR: The G-trace shows the level of G-forces

being put on the plane throughout the flight.

Let's get this section blown up.

BARRY: The G-trace showed the G forces in the airplane

were sort of increasing and then decreasing in a certain rhythmic pattern.

Very, very unusual.

The oscillations start at 39,000 feet. Just before the upset.

They show up 1, 2, 3... 13 seconds before the roll starts.

Wow. It looks like the plane was really bouncing around.

What the heck?

NARRATOR: The data tells investigators

that the plane was moving erratically for 13 seconds before the first roll.

Here's a thought.

What if there's a flap and slat configuration

that could cause the vibration?

Let's find out.

We've reached 39,000 feet.

NARRATOR: NTSB investigators take an unprecedented risk

in an attempt to replicate the oscillations recorded

on TWA 841's G-trace.

Okay. We've got more than a dozen configurations and maneuvers.

NARRATOR: They run a test flight to determine

if these anomalies resulted from a mid-flight slat extension.

Conducting a flight test would enable them

to perform maneuvers that could be compared

to what the flight data recorder recorded on 841.

229 knots.

LES: Okay. Test Number One. Let's start by popping the breaker.

Okay. Slats are retracted.

Ready? Flaps 2.

TEST PILOT: Flaps 2.

NARRATOR: Investigators try to match the unusual oscillations

by testing different flap and slat configurations.

Test Number 2. Flaps 5, slats remain retracted.

BARRY: NTSB investigators, they'll do anything. They love that stuff.

But I would have been pretty scared.

Okay. Test Number Nine. Flaps 2, slats 2, 3, 6 and 7.

TEST PILOT: Flaps 2. Ready?

You feel that?

NARRATOR: The flight test gives investigators a tantalizing new lead.

Investigators are very careful with flight tests

to take the same aircraft, to record parameters carefully.

All those things have to factor into a flight test

in order to be of any use to the investigation.

LES: Here's the data from the tests. Scenario number 9 should match up.

NARRATOR: To confirm their results,

investigators compare the data with the FDR's G-trace.

INVESTIGATOR: It's a perfect match.

BARRY: The flight test showed that extending the flaps and slats

would create in the airplane oscillations found on 841.

INVESTIGATOR: So this was the test when the plane was shaking the most?

This is the one.

Flaps 2, slats 2, 3, 6 and 7 deploy...

and are retracted 13 seconds later.

NARRATOR: They now have evidence that TWA 841's crew

enacted the unauthorized procedure of pulling

a slat circuit breaker and then deploying the flaps independently.

But if that's what the crew did,

why did the slats deploy and nearly bring down the plane?

What the heck?

SHIBAN: Those slats are gonna shake,

because you're going faster than the limiting airspeed.

So I would expect it to get very noisy and probably to buffet quite a bit.

NARRATOR: The test flight indicates the slat circuit breaker was reset,

which caused the slats to deploy.

So we know the pilots popped the breaker

to enact the procedure, but why did they push it back in?

And why did it take the crew 13 seconds

to realize the problem and then retract the slats?

NARRATOR: Investigators search for answers in all of the crew's statements.

The lead flight attendant remembered that the flight engineer

was out of the cockpit before the vibrations began.

Let me see that.

I'm gonna take a bathroom break. I'll get rid of these trays.

I noticed the cockpit door open,

and I saw the flight engineer coming out with the meal trays.

I didn't want him to think I was shirking my responsibilities.

I immediately met him.

- Oh, let me get those for you. - Thank you.

MARK: I was kind of surprised.

I had never had a cockpit member actually bring those trays back to the cabin.

They waited for us.

Well, that's it. The Flight Engineer was out of the cockpit.

And out of the loop.

NARRATOR: Investigators now have a theory

about what happened in the cockpit on the night of April the 4th.

The Flight Engineer leaves the cockpit to return the trays.

With Banks out of the cockpit, Gibson launches the unauthorized procedure.

The pilots deploy the flaps.

What do you say we get to Minneapolis a little quicker?

- Okay. How are we gonna do that? - Watch this.

GIBSON: Flaps 2.

Fancy trick. Heard about it, but I've never tried it.

Works like a charm.

BARRY: I could see the junior crew member saying, "He's the boss. Let's do it."

If he says it's okay, it's okay. Today, that would be unthinkable.

The flight engineer returns and notices a breaker is popped.

LES: What would any good flight engineer do?

He pushes it back in.

NARRATOR: Flight Engineer Banks returns

and notices the slat circuit breaker is pulled.

He returns the breaker to the normal position,

unaware that the captain had pulled it deliberately

to prevent the slats from extending along with the flaps.

Exactly. Normal operations resume.

With flaps set for 2, the slats extend automatically.

The cockpit begins to vibrate.

What the heck? What did you just do?

- What do you mean? - Just now! What did you just do?

The breaker was out. I pushed it back where it should be.

- Jesus. Flaps up. Flaps up, Scott! - Flaps up.

GIBSON: We're going over!

They bungled the maneuver.

NARRATOR: Investigators have figured out how TWA 841's crew

might have lost control of a Boeing 727.

But they're still missing a key piece of the puzzle.

How come Slat Number 7 never retracted along with the rest of the slats?

The metallurgical report is in.

NARRATOR: Investigators turn to results from a metallurgical analysis

of the T-bolt from the number 7 slat on TWA flight 841.

They found some shearing.

Pre-existing metal fatigue.

NARRATOR: The team discovers a fracture in the T-bolt,

which would have caused the slat to sag on the inside when extended.

BARRY: The slat is kept in the forward part of the wing,

which gets all of the air forces, as the airplane progresses.

At .8 times the speed of sound,

that's gonna be enormous, enormous air pressure.

LES: So all that air pressure twists the sagging slat.

NARRATOR: Slat Number 7 can no longer retract.

Under the extreme air loads of a diving plane, it finally rips off.

Investigators finally understand how TWA 841

went into a horrifying dive above Saginaw, Michigan,

on the night of April the 4th, 1979.

I'm gonna take a bathroom break. I'll grab these trays.

NARRATOR: Unaware the captain was conducting an unsanctioned procedure,

disengaging the slat circuit breaker to deploy only the flaps,

the flight engineer resets the popped breaker.

- What did you just do? - What do you mean?

NARRATOR: Precious seconds pass as the captain tries

to figure out what's happened.

Meanwhile, the aircraft flies at a high speed with its flaps

and slats extended perilously.

The captain, the passengers,

and flight attendants talked about feeling the vibrations

in the airplane caused by extension of the slats

and flaps at 39,000 feet.

Flaps up. Flaps up, Scott.

- Flaps up. - GIBSON: I have control.

NARRATOR: The flaps and slats retract,

except for the damaged number 7 slat on the right wing.

BARRY: The number 7 slat, if it's extended,

you're gonna have more drag on the right side

than on the left wing, and that's gonna cause that wing to descend.

In other words, it's gonna put the airplane in a right turn,

which is exactly what happened.

Come on. Level up.

NARRATOR: But it's too late.

Little does the crew know, slat number 7 is still extended,

keeping the plane in a roll.

We're going over.

NARRATOR: TWA 841's flight crew is unable to regain control of the aircraft.

Then, in a stroke of incredible good luck,

slat number 7 rips off the plane just 8,000 feet above the ground.

The departure of the slat allowed the return of controllability to the aircraft.

NARRATOR: With the wing symmetry partially restored

and the landing gear deployed, it's just enough to slow the

to slow the plane and allow the crew to regain control

and ultimately land the battered 727 at Detroit.

Reverse thrust!

NARRATOR: The NTSB recommends additional warnings to flight crews

about the dangers of high-speed deployment of flaps and slats.

No punitive action is taken against the crew.

BOB: NTSB conclusions are not a criminal thing,

they're not a blame thing, they're trying to prevent

the next accident by offering up a probable cause

that needs to be corrected.

NARRATOR: The pilots maintained their innocence,

claiming they did not deliberately extend the flaps mid-flight.

Captain Gibson took it to his grave with him, in 2015.

The other two guys aren't talking.

NARRATOR: Following this accident,

newer planes now come equipped with flight computers

that prevent the deployment of flaps and slats above certain altitudes.

There was speculation over manipulation of controls, all that sort of thing.

I've given it a great deal of thought over the past 41 years

and have come to the conclusion that I'll never know what happened.