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 farm or something. Go on. We are
descending rapidly. Everybody's staying
your feet. Everything that wasn't bolted
down just took off out.
People are gone. The seats are gone.
There was Nothing here anymore.
NTSB investigators susp.. 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 2:00am you're
up.
GE 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 El Nav Veav.
I've got over 30,000 hours of flight time
and just about everything, military as
well as civilian. How to pilot on check.
First Officer Al Sladeider 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 exp varian 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 bodydy airliner. Powered by four
turbofan engines. It's just
one of the most amazing airplanes ever
been. Upwards of a million pounds of
takeoff 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'some weather. We're going
to be going left of course. United 811
deviation is necessary approved.
Roger.
Aliners 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 take it down back to Honolulu Center.
United 811 heavy, we have a mayday. We had
a farmmb or something go on the
engines. We've lost number three engine.
The right inboard engine is inoperative
and we are descending rapidly. Coming back
nine eight eleven heavy Roger. Keep center
advised an emergency situation.
You need to land at the nearest suitable
airport and that would be Honolulu right
behind them. Col flight attend stop
to fly the plane back to safety. Captain
Cronin needs to assess the damage but
cannot.
A huge explosion seemed to rock the whole
plane. Just a huge pop and
everything that wasn't bolted down just
took off out.
I saw this huge cloud of smoke and
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. With your mask on dav 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 10,000ft
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's stay your
face.
The next thing I remember I was not in my
seat anymore.
I was standing against the bulkhead.
Stand in your seat.
The whole right side of the airplane,
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 got a
control problem here. With a full
load of fuel on board, it's difficult to
steer. Start dumbing the fuel. I'm dumping
eight heavy when able for the souls on
board and fuel a landing. Okay,
stand by. We'll give you the information
as quickly as possible. Not eight. Eleven
heavy. Roger. And their troubles keep
increasing. We got a problem with them 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 out. 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 struggled 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 up 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 a ATT to
number four. Go through the procedure to
shut the engine down.
Second Officer Randall Thomas reaches one
of the flight attendants.
Please get us down.
The right side is gone. We're about the
first row. Right back is just open.
You're just looking outside. What do you
mean? Looks like a bomb? The fuselage is
just open. I mean, the whole right side is
gone. From about row one right back to U.
Is anybody.
Some people are 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. Big section of
the right side of the airplane is missing.
United811 heavy, do you have the airport
and sight clear for a visual approach.
The controller gives the pilot permission
to conduct a visual approach instead. But
they're still too far out to see the
airport. We're still 45PME, so you watch
us'not 8 11, I have you on radar.
We got to get down and wait here. I'd say
we land overweight. We're 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 11, 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. UN United eight
eleven heavy, roger.
Okay, put your harnesses on. Plan for
evacuation. Tell him. Oh you bet.
Honolulu, United 811 heavy, we do plan to
evacuate on the Runway. 811 heavy,
roger.
Okay, let me try to talk to the flight
attendant.
In the cabin. The crew is preparing the
passenger challenges for ditching.
It was loud. We ran around getting life
us on people.
It's a feeling of like I'm not sure this
is really going toa 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. 8 11,
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 role. 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 United811 managed to line up
with the Runway in Honolulu.
United 811 is clear to land. 8 left.
Equipment is standing by. Win 05012
cleared to land. 8 left. 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.
50ft. What you trim 30 center
the trim center. The trim 10 is
unbeliev with how fast they're going.
Go reverse number two. Only because
they're still at 170. The pilots hope
reverse engine power will stop the plane
before the Runway endsac
probably the best landing ive 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 Schled 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 has got
to be at least 10ft wide by 15ft 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'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'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 pedding 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 pree 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 turned 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 hole 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 holde. 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 somewhere 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 lates rotating around the
pins as the door closes. Makes sense.
Hang on. Have a look.
Investigators find evidence of heat
tinting on the surface of the pin. I see
it. Heat tinting occurs when the surface
oxide layer of stainless steel changes
color due to heating. 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 vient.
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. Latches were open when the door
came. The locking mechanism of the cargo
door was designed to be fail safe. So
it'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 in
invertently 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, get 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 sections hadn'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. Close.
Fine. Investigators consider how the door
was closed and if the latches were over
rotated like the ones on Pan Am125.
Did you close the door electrically or
manually? I closed it electrically.
I wouldn't have closed it manually. 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 mechanics 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?
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 mapped 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. 14,000ft.
Recovery teams aren't able to search for
wreckage at a depth of 14,000ft. At that
point, the deepest we had ever searched
and recovered wreckage was 6,000ft under
the water.
If the door was properly closed, then
maybe it's 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 powers 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 as short in the electrical system
that caused the door to unlatch on the
ground.
This everything? Almost. We 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 s
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 a 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.
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 mis rigging of
the cargo door and its locking mechanisms.
Maybe the door kicking was just an
isolated case.
Investigators 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
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.
An 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 m
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.
Hello. Three months after the NTSB
publishes its report on United Flight 811,
the US Navy offers to assist the recovery
efforts. Site scan sonar U
huh? 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 sealooor to create an image
of the seabed and any debris that might be
lying on it.
14,000ft. 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 Hildrop is on
board the vessel searching for the cargo
door. I felt a lot of
pressure. This accident represented one
of the deepest recoverage 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 the hurricane, with
equipment failure. So there's a lot of
stops and starts se cliff to
chew.
After two months of searching,
we have the door. 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
downolulu.
With the complete locking system
recovered, investigators tried to confirm
their theory that A misaligned cargo door
caused the lock sectors to break, just
like we thought. The latshes 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 toress either. One of
the things you can do is look inside the
switches and see their cond 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 23,000ft,
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.
Hello. 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.