Original subtitles

A massive explosion tears a hole in the side of a 747.

What the hell was that? I don't know.

Center United 811 heavy. We had a bomb or something go on.

We are descending rapidly.

Everybody stay in your seats.

Everything that wasn't bolted down just took off out.

People are gone. The seats are gone.

There was nothing there anymore.

NTSB investigators suspect a crime.

We were quite convinced that it was probably terrorism.

But the physical evidence tells a different story.

Check this out.

I see it.

It was very perplexing to us why this had happened and how it could have

happened.

United Airlines flight 811 departs from Honolulu Airport just before 2 a.m.

Gear up.

Captain David Cronin is at the controls of tonight's flight.

It's his penultimate flight before retiring.

I flew almost 35 years with United.

LNAV, VNAV?

I've got over 30,000 hours of flight time and just about everything military

as well as civilian.

Pilot on?

Check.

First officer Al Slater is also an experienced pilot who's flown with

United for 25 years.

Climb thrust.

There's a third pilot in the cockpit.

Is set.

Second officer Randall Thomas, the flight engineer.

APU is off.

When you get to the point where you're flying an aircraft like a 747, you are

probably among the most experienced people on the airline.

And that was certainly true for this crew.

There are 337 passengers on board.

Stuart McClure, his mother and younger brother, are headed to Australia for a

family visit.

My stepfather was an executive for United Airlines, so he was over there on

business.

My mom decided to join him but didn't want to fly alone, so brought us two

boys with her.

Flight 811's next stop is Auckland, New Zealand for a stopover before flying on

to Sydney, Australia.

The Boeing 747 is a large, long-range, wide-body airliner powered by four

turbofan engines.

It's just one of the most amazing airplanes ever built.

Upwards of a million pounds of take-off weight.

can travel 7,500 miles with reserves.

The cruise speed of the airplane is Mach 0.85, which is well over 600 miles an

hour, and it will outrun pretty much any airliner available today.

I don't think we're going to top that son of a gun.

There are thunderstorms ahead.

Let's see here.

We did notice that there were thunderstorms, so I left the seatbelt

sign on.

There are 16 flight attendants on board tonight's flight.

One of them is Leonard Jenkins, who's off duty.

So we get underway.

Everything seemed pretty normal.

I really was just getting ready to take my eight-hour nap.

Okay, tell him we're going to detour over to the left.

Center, United 811 heavy. We're going to be detouring.

There's some weather.

We're going to be going left, of course.

United 811, deviation is necessary, approved.

Roger.

Airliners do not fly through thunderstorms because it would be insane

to do so.

The lightning, the wind, perhaps funnel clouds.

There are a lot of ways that a thunderstorm can kill you.

in an airplane looks like that's the end of it right there to the right

almost nine minutes into the flight just as they get past the

storm what the

hell was that i don't know i'm taking it down

Center, United 811 heavy, we have a mayday. We had a bomb or something go

on.

The engine.

We've lost number three engine.

The right inboard engine is inoperative.

And we are descending rapidly.

Coming back.

United 811, heavy, roger. Keep center advised.

We have an emergency situation.

You need to land at the nearest.

To fly the plane back to safety, Captain Cronin needs to assess the damage.

But cannot.

took off out.

So this huge cloud of smoke and I thought to myself, this is not real.

This is something in my dream I've got to wake up.

The air is escaping from the cabin.

It's difficult to breathe.

Everything just kind of went crazy.

It knocked the wind out of me and I kept thinking to myself, this is like, it

feels like I'm suffocating.

put your mask on dave okay

i'm

not getting any oxygen the explosion has damaged the plane's oxygen supply to the

crew and the passengers we're not getting oxygen either the pilots must

get the plane down to 10 000 feet quickly before they run out of

breathable air.

First things first.

Get the airplane down where everybody is safe in terms of being able to breathe

normally. Then work the other problems.

Everybody stay in your seat!

The next thing I remember, I was not in my seat anymore.

And I was standing against the bulkhead.

The whole right side of the airplane, like, the people are gone, the seats are

gone. There was nothing there anymore.

It was like a picture window.

I could see the white caps of the ocean. I could see the two engines.

Captain Cronin is having trouble turning the plane back to Honolulu.

We've got a control problem here.

With a full load of fuel on board, it's difficult to steer.

Start dumping the fuel.

I'm dumping.

9-8-11 heavy.

When able, forward the souls on board and fuel a landing.

Okay, stand by. We'll give you the information as quickly as possible.

9-8-11 heavy, roger.

And the troubles keep increasing.

We've got a problem with number 4 engine.

The right outboard engine is overheating.

Can you maintain 240?

Yes, just barely.

You've got all this fuel because you're going to Auckland, and now you've lost

two engines, and you've descended rapidly.

The crew is facing a very serious situation.

We're losing altitude.

I know it.

With that kind of weight, two engines are not going to keep you in the air.

You're going to come down.

You're helpless. You have no control over what's about to happen to you.

At that point, I realized, okay, this is where we die.

Watch your heading.

Watch your heading. You want to go direct to, we're going direct to

Honolulu.

Yeah.

Eight minutes after an explosion on board United Flight 811, the pilots

struggle to keep their aircraft from plunging into the Pacific Ocean.

Okay, I'm going downstairs to see what the hell is going on.

You got a fire out there.

There's a fire out there?

There was an engine on fire.

With fuel, there was like a stream of fire.

You just see flames just streaming out the back of the engines.

Looks like it's engine number four.

Go through the procedure to shut the engine down.

Second Officer Randall Thomas reaches one of the flight attendants.

Please get it down!

The right side is gone.

We're about the first row right back.

It's just open.

You're just looking outside.

What do you mean?

Looks like a bomb.

The fuselage just opened.

I mean, the whole right side is gone from about row one right back to, uh...

Has anybody... Some people have probably gone. I don't know.

You know, it's a terrible thing when you're a captain of an airplane and you

lose passengers.

We got a real problem here.

Not only have the pilots lost thrust in the two right engines, now the

instruments aren't providing direction to the airport.

They'll need the controller to guide them in.

Center, United 811 Heavy, we need a vector now. We're losing VOR, we're down

to 6500.

We evidently had a bomb or something.

A big section of the right side of the airplane is missing.

United 811 Heavy, do you have the airport in sight clear for visual

approach?

The controller gives the pilots permission to conduct a visual approach

instead, but they're still too far out to see the airport.

We're still 45 DME, so you watch us.

United 811, I have you on radar.

We gotta get down and wait here.

I say we land overweight.

We're at 652,000 pounds right now.

Even though Flight 811 has been dumping fuel, it's still 90,000 pounds over the

safe landing weight.

We've got 45 miles to go.

United 811, you're missing the right side of the cabin or the right wing,

sir? That's affirmative. We're missing a section of the right side of the

airplane. Part of the fuselage is missing.

We need all medical equipment we can get and all equipment standing by.

United 811, heavy roger.

Okay, put your harnesses on.

Plan for evacuation.

Tell them.

Oh, you bet.

Honolulu, United 811 Heavy, we do plan to evacuate on the runway.

United 811 Heavy, roger.

Okay, let me try to talk to the flight attendant.

In the cabin, the crew is preparing the passengers for ditching.

It was loud.

We ran around getting life vests on people.

It's a feeling of like, I'm not sure this is really going to matter at this

point when we hit the water.

I can't reach him down there.

I say we land with 10 degrees.

10 miles from the airport, the pilots make the final preparations for landing.

We're higher than hell.

But the airport still isn't anywhere in sight.

United 811, turn right heading 070.

It's right there, down to your right.

Okay.

The pilots must now make a right turn with no right side engines.

You've got all of the thrust coming out of these two turbofan engines on the

left-hand side.

And you've got two of them that aren't developing any thrust.

It's a dangerous maneuver.

If done incorrectly, the thrust from the left engines could put the plane into a

steep roll.

We're either going to land on the airport, in the water, or drastically

change the topography of downtown Honolulu.

With a massive hole in the fuselage, more than 45,000 pounds overweight, two

dead engines, and unknown damage to the control surfaces, the pilots of United

811 managed to line up with the runway in Honolulu.

United 811 is clear to land 8L. Equipment is standing by.

Wind 05012.

Cleared to land 8L. United 811 Heavy.

Okay, well let's try the gear.

That's where it really became very, very real for us.

We knew that whatever was going to happen to us, we were going to do it

together.

I'm coming up on the power.

Moments from touchdown, the pilots slow the plane to make it easier to stop the

overweight aircraft.

50 feet.

Aren't you trim?

30. Center the trim. Center the trim.

10.

It's unbelievable how fast we were going.

Go to reverse.

Number two only because we're still at 170.

The pilots hope reverse engine power will stop the plane before the runway

ends.

Probably the best landing I've ever made.

Shut him down.

Shut down the engines.

25 minutes after the explosion.

flight 811 has returned to honolulu airport

nine

of the 337 passengers were blown out of the airplane over the pacific the search

for them and the wreckage begins immediately it was a huge area

and very difficult for us to pinpoint where over the water it actually

occurred.

Ron Schleed from the National Transportation Safety Board, or NTSB,

leads the investigation.

We flew out of Washington and went into Honolulu.

An FBI agent went with us, the bomb expert.

They have jurisdiction to...

investigate for criminal activity.

That hole's got to be at least 10 feet wide by 15 feet high.

Forward cargo door is missing too.

The Boeing 747 has two cargo doors on the right side, the aft and the forward

cargo doors.

We could see from the ground cargo and baggage and we could see the remains

of seats and the cabin area.

Looking at the airframe itself becomes important, the direction of failures,

whether you have damage from inside the aircraft to outside or the damages from

outside in.

The floor is buckled. Some of the seats are missing.

The decompression likely broke the cabin floor beams.

We were quite convinced that it was probably terrorism.

There's damage on the leading edge and on the engines.

The damage to the wing and engines is likely caused by debris that came off

the plane.

There's no sign of pitting.

Upon closer examination, investigators find no obvious signs of a bomb.

The NTSB guys generally have an idea what they're looking for.

A peddling of the metal.

They saw no evidence of that.

No signs of fatigue or corrosion either?

Once the FBI took the swabs for chemical residue and tested them, they reported

they were all negative.

And that was pretty conclusive evidence that there was not a bomb.

The team now considers whether there was some kind of structural failure to the

aircraft.

All of the fractures appeared to be fresh overstress damage, not any pre

-existing damage.

This made us consider that there was a problem with the door itself.

We have some wiring from the door here.

NTSB investigators turn their attention to what remains of the cargo door

system. Okay, what else we got?

Instead of using a plug door, which is stowed inside the cargo hold and gets

jammed into the frame as the plane pressurizes, Boeing designed the 747

with an outward opening door to create more space for cargo in the hole.

Looks like we at least have the pins.

Investigators find a key component of the locking mechanism.

The latch pins for the cargo door.

The new 747 cargo door design uses a three-stage locking system.

An exterior switch electrically powers the door to a near closed position.

C-shaped latches or cams then rotate around pins.

A handle on the exterior of the door lowers metal sectors which secure the

latches in place.

There's some wear in the pins, but hard to tell for sure what it means.

There was transfer of metal and discoloration.

We couldn't tell for sure what the damage was, so we had to remove the pins

and take them to a laboratory for further analysis.

There's some wear for sure, but it's likely from the latches rotating around

the pins as the door closes.

Makes sense.

Hang on.

Have a look.

I see it.

There's also some metal transfer from the latches on the pins.

You're right.

The presence of latch material on the pins suggests the separation of the

cargo door was extremely fast and violent The amount

of force to cause a transfer of metal from the latches to the pins had to be

enormous There's metal from the latch in the same place on

every pin

The location of the latch metal on the pins gives investigators their first big

break. The latches were open when the door came off.

The locking mechanism of the cargo door was designed to be fail-safe. So it's

very perplexing to us why this had happened and how it could have happened.

I'm checking the FAA records.

I'll go through the Boeing ones.

Has the locking system on the 747 cargo door failed before?

I've got something.

Two years ago, there was an incident on another 747.

Look at that, March 1987.

Pan American flight 125 was en route from London to New York when there was a

pressurization problem.

The door was open an inch and a half.

The Pan Am agent used a wrench to close the door manually, and once he got it

closed, he inadvertently backed the wrench up and opened the door slightly.

The Pan Am latches were manually turned to the open position, and the lock

sectors were broken.

How can the force of a socket wrench break the sectors?

Well, look at this.

The lock sectors.

They were made of a weak material.

The locking sectors were made of aluminum so they would bend and break.

What action was taken after the Pan Am incident?

The FAA issued an airworthiness directive requiring that each

lock sector be reinforced with a steel doubler.

See, United Airlines, they had 18 to 24 months to do it.

Maybe they hadn't got the work done yet.

I'll check United's maintenance records.

Did Flight 811 have weak lock sectors?

Looks like the lock sectors haven't been replaced yet.

At the time of the accident, the accident airplane still had the aluminum

sectors because it wasn't scheduled to be replaced for two months.

Did you have any issues closing the door?

Not at all. It closed fine.

Investigators consider how the door was closed and if the latches were over

-rotated, like the ones on Pan Am 125.

Did you close the door electrically or manually?

I closed it electrically.

I wouldn't have closed it manually.

It takes too much effort.

What do you mean?

You have to crank the wrench 95 times.

The ramp agent on 811 did not use a power tool as was used on Pan Am.

This left us without any explanation for what happened.

What did you find out?

Well, the ramp agent closed the door electrically, properly using the switch.

And the dispatch mechanic said he did a circle check of the plane prior to

departure.

He checked the forward cargo door with a flashlight, and it was flushed to the

aircraft.

What about the cargo door indicator light in the cockpit?

The second officer said that the light went out.

Investigators confirmed that the second officer saw the cargo door light in the

cockpit go off, indicating that the door was closed.

While NTSB investigators consider other reasons why the cargo door opened.

they get an update on recovery efforts they map the currents and

narrowed the debris field to 12 square miles finding the lost cargo door

might be the key to the investigation let's take a look at the depth 14 000

feet recovery teams aren't able to search for wreckage at a depth of 14 000

feet at that point The deepest we had ever searched and recovered wreckage was

6000 feet under the water.

If the door was properly closed, then maybe it subsequently opened due to an

electrical problem.

Did the electrical system accidentally open the door in flight?

According to the manual, when the plane lifts off the ground, all power to the

door is disconnected.

Electrical operation of the door to open it in flight was impossible.

If not in the air, then

maybe on the ground.

We considered that there possibly could have been a short in the electrical

system that caused the door to unlatch on the ground.

Is this everything?

Almost.

You have all the electrical switches except one.

Investigators perform continuity testing on the cargo door switches and relays

recovered from the aircraft.

This one's good.

As is this one.

Check this out.

That's a burn mark.

They also noticed that some of the wiring insulation has stripped off.

That switch is a closed circuit.

It has nothing to do with opening the door.

The exposed wire on the switch could not have caused the cargo door to open.

We had ruled out most electrical system failures.

as the cause of the accident so that had us look at other options

here you go

the team now considers whether a mechanical failure

caused the cargo door to open maybe there's something here

Investigators review the operations of the cargo door on four United 747s at

Honolulu Airport.

This is strange.

It says here that one of the ramp agents kicked on a cargo door to get it open.

They discover an instance of a cargo door opening only with the use of force.

When we heard that the ramp agents had to kick the door We figured that there

was some type of misalignment, misrigging of the cargo door and its

locking mechanisms.

Maybe the door kicking was just an isolated case.

Investigators turned to the maintenance report of the Flight 811 aircraft to

determine if there was ever a fit issue with the forward cargo door.

No fit or alignment issues were ever reported.

Right, but check out when the plane was inspected.

when it was empty.

A 747 fully loaded with people, fuel, and cargo can add upwards of 300

,000 pounds to the aircraft, causing the fuselage to bend and distort.

Get this. In December 1988, there were eight write-ups about door

misalignment.

Two months before the accident, the forward cargo door failed to close fully

under electrical operation.

A ill-fitting door could cause the latching motors to not drive the

latches fully closed.

Did United fix the problem?

Investigators learned that an electrical switch on United Flight 811 couldn't

properly close the misaligned cargo door.

But was it ever repaired?

The maintenance was deferred because they would close the door manually.

If there was a fit issue and they would close it manually, that would explain

the wear marks we found on the pins.

The wear on the door indicated a long history of manual operation and mis

-rigging of the door.

Even worse, with repeated manual opening and closing of a misaligned door, the

lock sectors could easily have been damaged if the latches were being over

-rotated.

With the latches and lock sectors still at the bottom of the sea, the NTSB is

forced to conclude that the cargo door was sufficiently misaligned.

to prevent it from closing properly.

When we write the final report of an accident, we present the evidence that

we have and make our best conclusions based on that evidence.

We knew there was mechanical damage to the door. We suspected that was the

cause and that's the way we wrote the report.

In April of 1990, the NTSB published its findings.

The report recommends the FAA issue a directive requiring the installation of

a device to prevent the latches from over-rotating.

But we wanted to get the door. We really wanted to find the door to prove our

theory. Yeah. That's amazing.

Hello?

Three months after the NTSB publishes its report on United Flight 811, the US

Navy offers to assist the recovery efforts.

Sidescan sonar.

The Navy came to me and said, we've got a system that we're testing.

It was experimental, a new sonar system, and it was at the time classified.

A side-scan sonar device towed from a ship emits high-frequency sound pulses

that bounce off the sea floor to create an image of the seabed and any debris

that might be lying on it.

14,000 feet, really.

With the ability to scan deeper than previously possible, the Navy offers to

test the device in the Pacific Ocean.

All right, let's do it.

They said, we would like to try and test it on that door.

And they would do it for no cost to us.

We said, sure.

Nothing in this sector.

NTSB investigator Frank Hildrup is on board the vessel searching for the cargo

door.

I felt a lot of pressure.

This accident represented one of the deepest recoveries that was going to be

attempted.

They search an area of 12 square miles, divided into 57 sectors.

Hang on.

I think we got something.

The team finds evidence of a debris field.

There was pretty high confidence that they were in the right area.

and the experts can tell roughly what they're looking at. Is it metallic in

nature? Is it a good return?

A three-person submersible vehicle called the Sea Cliff is deployed.

The expedition confirms the debris is from Flight 811, but finding the cargo

door proves difficult.

We had some problems with weather, with a hurricane, with equipment failure, so

there was a lot of stops and starts.

After two months of searching, the missing piece is

found.

The door was in two pieces on the bottom of the ocean. We had to recover both

pieces, get them on the ship and take them to Honolulu.

With the complete locking system recovered, Investigators try to confirm

their theory that a misaligned cargo door caused the lock sectors to break.

Just like we thought.

The latches were in the open position.

Check this out.

But then they discover something unexpected and critical.

These sectors aren't broken.

They're just bent.

The lock sectors were largely intact.

They weren't damaged like we expected them to be.

So that led us in a little bit more of another direction.

No visible evidence of any burning or arcing.

Investigators now reconsider a theory they previously rejected, that there was

an electrical issue with the door.

No signs of heat distress either.

One of the things you can do is look inside the switches and see their

condition.

We always examine the wiring.

We look for nicks or cuts when the wires are bundled together.

Check this out.

Investigators find a crucial piece of evidence.

There's chafing on some of the wires in this bundle.

It's proof that the conditions for a short circuit existed.

All it takes for a short circuit to happen is for that conductor that's

inside that insulation to touch another wire or touch a piece of metal.

So we're always concerned about wiring in airplanes.

All set.

Can a short circuit open a locked door on a 747?

Looks good.

Give it a try.

Well, there you have it.

We determined that probably the short circuit could have caused the motors to

engage the latch cams and open the door.

So we know there's no power to the door once the wheels lift off the ground.

And the door was closed and locked here.

So the short happened somewhere here during taxi.

The short circuit causes the latch to partially open when the plane is still

on the ground then when the plane approaches 23,000 feet The

significant pressure differential between the inside and the outside

Forces the door open and causes a massive decompression on board

Nine people are lost

Nine months after recovering the cargo door investigators get disturbing news.

Thank you.

It happened again.

Another United 747 cargo door opened while on the tarmac in New York.

Despite these incidents, the fleet is never grounded.

I felt anger, you know, rage.

My heart just goes out to the victims.

Two years after the accident, the NTSB publishes a second report updating the

cause.

Opening of a cargo door.

on a large aircraft is a catastrophic event it's unacceptable event it's like

a wing falling off the faa and boeing took more

than two years to require changes i remember

it like it was yesterday it just doesn't hurt so much and you don't think about

it 24 7.

The experience and the event that night, it told me I needed to make my life

matter.

Whether it be with the people that I share it with every single day or with

what I put my energy towards every single day, the nine that didn't make it

would expect that of us and of me.