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Air Crash Investigation Series S24E01 Terror Over The Pacific
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00:00A massive explosion tears a hole in the side of a 747.
00:07What the hell was that?
00:09I don't know.
00:11Central United 811 Heavy, we had a bomb or something go on.
00:15We are descending rapidly.
00:17Everybody stay in your seat!
00:20Everything that wasn't bolted down just took off out.
00:25People are gone, the seats are gone, there was nothing there anymore.
00:29NTSB investigators suspect a crime.
00:35We were quite convinced that it was probably terrorism.
00:39But the physical evidence tells a different story.
00:43Check this out. I see it.
00:46It was very perplexing to us why this had happened and how it could have happened.
00:59I see it.
01:05United Airlines Flight 811 departs from Honolulu Airport just before 2 a.m.
01:09Gear up.
01:10Gear up.
01:11Gear up.
01:12Captain David Cronin is at the controls of tonight's flight.
01:18It's his penultimate flight before retiring.
01:22I flew almost 35 years with United.
01:28I've got over 30,000.
01:29I've got over 30,000 hours of flight time and just about everything military as well as civilian.
01:34How to file it on?
01:35Check.
01:36First Officer Al Slater is at the flight.
01:37I've got over 30,000 hours of flight time and just about everything military as well as civilian.
01:41How to file it on?
01:42Check.
01:43First Officer Al Slater is also an experienced pilot who's flown with United for 25 years.
01:47Climb thrust?
01:48All right, in the back of the flight.
01:49Record.
01:50I've got over 30,000 hours of flight time and just about everything.
01:53I've got over 30,000 hours of flight time and just about everything.
01:54I've got over 30,000 hours of flight time and just about everything.
01:56Military as well as civilian.
01:59I've got a pilot on.
02:00Check.
02:01First Officer Al Slater is also an experienced pilot who has flown with United for 25 years.
02:09Climb thrust.
02:11There's a third pilot in the cockpit.
02:13Is set.
02:14Second officer, Randall Thomas, the flight engineer.
02:18APU is off.
02:21When you get to the point where you're flying an aircraft like a 747,
02:26you are probably among the most experienced people on the airline.
02:31And that was certainly true for this crew.
02:33There are 337 passengers on board.
02:41Stuart McClure, his mother and younger brother, are headed to Australia for a family visit.
02:47My stepfather was an executive for United Airlines, so he was over there on business.
02:54My mom decided to join him but didn't want to fly alone, so brought us two boys with her.
03:00Flight 811's next stop is Auckland, New Zealand for a stopover, before flying on to Sydney, Australia.
03:16The Boeing 747 is a large, long-range, wide-body airliner, powered by four turbofan engines.
03:23It's just one of the most amazing airplanes ever built.
03:29Upwards of a million pounds of takeoff weight.
03:32Can travel 7,500 miles with reserves.
03:36The cruise speed of the airplane is Mach 0.85, which is well over 600 miles an hour.
03:43And it will outrun pretty much any airliner available today.
03:47I don't think we're going to top that son of a gun.
03:54There are thunderstorms ahead.
03:57Let's see here.
04:04We did notice that there were thunderstorms, so I left the seatbelt sign on.
04:09There are 16 flight attendants on board tonight's flight.
04:16One of them is Leonard Jenkins, who's off duty.
04:21So, we get underway.
04:24Everything seemed pretty normal.
04:26I really was just getting ready to take my eight-hour nap.
04:29Okay, tell them we're going to detour over to the left.
04:34Center, United 811, heavy.
04:36We're going to be detouring.
04:38There's some weather.
04:40We're going to be going left, of course.
04:42United 811, deviation is necessary, approved.
04:46Roger.
04:49Airliners do not fly through thunderstorms,
04:52because it would be insane to do so.
04:55The lightning, the wind, perhaps funnel clouds.
05:01There are a lot of ways that a thunderstorm can kill you in an airplane.
05:07Looks like that's the end of it, right there to the right.
05:13Almost nine minutes into the flight,
05:15just as they get past the storm.
05:23What the hell was that?
05:25I don't know.
05:28I'm taking it down.
05:29I'm back to Honorulu.
05:31Center, United 811, heavy.
05:33We have a mayday.
05:34We had a bomb or something go on.
05:38The engine.
05:40We've lost number three engine.
05:42The right inboard engine is inoperative.
05:46And we are descending rapidly.
05:49Coming back.
05:50United 811, heavy, roger.
05:51Keep center advised.
05:53We have an emergency situation.
05:55You need to land at the nearest suitable airport.
06:03And that would be Honolulu, right behind them.
06:06Call flight attendants.
06:08Copy.
06:08To fly the plane back to safety, Captain Cronin needs to assess the damage.
06:17But cannot.
06:18A huge explosion seemed to rock the whole plane, just a huge pop, and everything that wasn't bolted down just took off out.
06:33So 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.
06:46The air is escaping from the cabin.
06:49It's difficult to breathe.
06:52Everything just kind of went crazy.
06:54It knocked the wind out of me, and I kept thinking to myself, this is like, it feels like I'm suffocating.
07:01Put your mask on, Dave.
07:04Okay.
07:16I'm not getting any oxygen.
07:19The explosion has damaged the plane's oxygen supply to the crew and the passengers.
07:24We're not getting oxygen either.
07:29The pilots must get the plane down to 10,000 feet quickly, before they run out of breathable air.
07:40First things first.
07:42Get the airplane down where everybody is safe in terms of being able to breathe normally.
07:47Then work the other problems.
07:49Everybody's seeing your seat!
07:51The next thing I remember, I was not in my seat anymore.
08:00And I was standing against the bulkhead.
08:03Stay in your seat!
08:07The whole right side of the airplane, like, the people are gone, the seats are gone.
08:13There was nothing there anymore.
08:16It was like a picture window.
08:17I could see the white caps of the ocean.
08:23I could see the two engines.
08:32Captain Cronin is having trouble turning the plane back to Honolulu.
08:37We've got a control problem here.
08:38With a full load of fuel on board, it's difficult to steer.
08:45Start dumping the fuel.
08:47I'm dumping.
08:49United 811 heavy.
08:51When able, for the soles on board and fuel a landing.
08:55Okay, stand by.
08:57We'll give you the information as quickly as possible.
08:59United 811 heavy, roger.
09:00And their troubles keep increasing.
09:05We've got a problem with number four engine.
09:08The right outboard engine is overheating.
09:12Can you maintain 240?
09:15Yes, just barely.
09:18You've got all this fuel because you're going to Auckland.
09:22And now you've lost two engines.
09:24And you've descended rapidly.
09:25The crew is facing a very serious situation.
09:31We're losing altitude.
09:33I know it.
09:37With that kind of weight, two engines are not going to keep you in the air.
09:43You're going to come down.
09:49You're helpless.
09:50You have no control over what's about to happen to you.
09:52At that point, I realized, okay, this is where we die.
10:06Watch your heading.
10:08Watch your heading.
10:09You want to go direct to, we're going direct to Honolulu.
10:13Yeah.
10:15Eight minutes after an explosion on board United Flight 811,
10:19the pilots struggle to keep their aircraft from plunging into the Pacific Ocean.
10:24Okay, I'm going downstairs to see what the hell is going on.
10:32You've got a fire up there.
10:34There's a fire out there?
10:35There was an engine on fire.
10:47With fuel, there was like a stream of fire.
10:53You just see flames just streaming out the back of the engines.
10:58Looks like it's engine number four.
11:00Go through the procedure to shut the engine down.
11:01Second officer, Randall Thomas, reaches one of the flight attendants.
11:20Please get us down!
11:22The right side is gone.
11:34We're about the first row right back.
11:36It's just open.
11:38You're just looking outside.
11:39What do you mean?
11:40Looks like a bomb.
11:42The fuselage is just open.
11:45I mean, the whole right side is gone.
11:47From about row one right back to, uh...
11:50Is anybody...
11:52Some people have probably gone.
11:55I don't know.
12:02You know, it's a terrible thing when you're a captain of an airplane and you lose passengers.
12:06Not only have the pilots lost thrust in the two right engines, now the instruments aren't providing direction to the airport.
12:18They'll need the controller to guide them in.
12:21Center United 811 heavy.
12:23We need a vector now.
12:25We're losing VOR.
12:26We're down to 6,500.
12:29We evidently had a bomb or something.
12:31Uh, big section of the right side of the airplane is missing.
12:38United 811 heavy.
12:39Do you have the airport in sight clear for visual approach?
12:43The controller gives the pilots permission to conduct a visual approach instead.
12:48But they're still too far out to see the airport.
12:51Uh, we're still 45 DME, so you watch us.
12:55United 811.
12:56I have you on radar.
13:01We've got to get down and wait here.
13:04I say we land overweight.
13:06We're at 652,000 pounds right now.
13:10Even though Flight 811 has been dumping fuel, it's still 90,000 pounds over the safe landing weight.
13:17We've got 45 miles to go.
13:22United 811, uh...
13:23You're missing the right side of the cabin or the right wing, sir?
13:27That's affirmative.
13:28We're missing a section of the right side of the airplane.
13:30Part of the fuselage is missing.
13:34We need all medical equipment we can get and all equipment standing by.
13:38United 811 heavy, roger.
13:43Okay, put your harnesses on.
13:45We plan for evacuation.
13:47Tell them.
13:48Oh, you bet.
13:49Honolulu, United 811 heavy.
13:51We do plan to evacuate on the runway.
13:55United 811 heavy, roger.
13:56Okay, let me try to talk to the flight attendant.
14:08In the cabin, the crew is preparing the passengers for ditching.
14:12It was loud.
14:19We ran around getting lifeless on people.
14:24It's a feeling of like, I'm not sure this is really going to matter at this point when we hit the water.
14:29I can't reach him down there.
14:39I say we land with 10 degrees.
14:42Ten miles from the airport, the pilots make the final preparations for landing.
14:48We're higher than hell.
14:48But the airport still isn't anywhere in sight.
14:55United 811, turn right, heading 070.
15:01It's right there.
15:02Down to your right.
15:05Okay.
15:08The pilots must now make a right turn with no right side engines.
15:13You've got all of the thrust coming out of these two turbofan engines on the left-hand side.
15:22And you've got two of them that aren't developing any thrust.
15:27It's a dangerous maneuver.
15:30If done incorrectly, the thrust from the left engines could put the plane into a steep roll.
15:35We're either going to land on the airport, in the water, or drastically change the topography of downtown Honolulu.
15:46With a massive hole in the fuselage, more than 45,000 pounds overweight, two dead engines, and unknown damage to the control surfaces,
15:57the pilots of United 811 managed to line up with the runway in Honolulu.
16:01United 811 is cleared to land 8 left.
16:07Equipment is standing by.
16:09Wind 05012.
16:13Cleared to land 8 left.
16:14United 811 heavy.
16:17Okay, well, let's try the gear.
16:31Head down!
16:48I see light!
16:50Freeze!
16:51Freeze!
16:55That's where it really became very, very real for us.
16:58We knew that whatever was going to happen to us, we were going to do it together.
17:05I'm coming off on the power.
17:08Moments from touchdown, the pilots slow the plane to make it easier to stop the overweight aircraft.
17:1550 feet.
17:24Watch your trim.
17:2630.
17:26Center the trim.
17:27Center the trim.
17:2910.
17:30It was unbelievable how fast we were going.
17:43Go to reverse number two only, because we're still at 170.
17:47The pilots hope reverse engine power will stop the plane before the runway ends.
18:08Prepare to evacuate.
18:10Probably the best landing I've ever made.
18:23Shut them down.
18:26Shut down the engines.
18:2725 minutes after the explosion, Flight 811 has returned to Honolulu Airport.
18:48Nine of the 337 passengers were blown out of the airplane over the Pacific.
19:06The search for them and the wreckage begins immediately.
19:10It was a huge area and very difficult for us to pinpoint where, over the water, it actually occurred.
19:21Ron Schleid from the National Transportation Safety Board, or NTSB, leads the investigation.
19:29We flew out of Washington and went into Honolulu.
19:34An FBI agent went with us, the bomb expert.
19:40They have jurisdiction to investigate for criminal activity.
19:48That hole's got to be at least 10 feet wide by 15 feet high.
19:54Forward cargo door is missing, too.
19:57The Boeing 747 has two cargo doors on the right side.
20:02The aft and the forward cargo doors.
20:05We could see from the ground cargo, baggage, and we could see the remains of seats and the cabin area.
20:19Looking at the airframe itself becomes important, the direction of failures.
20:24Whether you have damage from inside the aircraft to outside, or the damages from outside in.
20:32The floor is buckled.
20:37Some of the seats are missing.
20:39The decompression likely broke the cabin floor beams.
20:43We were quite convinced that it was probably terrorism.
20:47There's damage on the leading edge and on the engines.
20:51The damage to the wing and engines is likely caused by debris that came off the plane.
20:55There's no sign of pitting.
21:06Upon closer examination, investigators find no obvious signs of a bomb.
21:13The NTSB guys generally have an idea of what they're looking for.
21:18A peddling of the metal.
21:21They saw no evidence of that.
21:23No signs of fatigue or corrosion either.
21:27Once the FBI took the swabs for chemical residue and tested them, they reported they were all negative.
21:35And that was pretty conclusive evidence that there was not a bomb.
21:40The team now considers whether there was some kind of structural failure to the aircraft.
21:45All of the fractures appeared to be fresh overstress damage, not any pre-existing damage.
21:55This made us consider that there was a problem with the door itself.
22:03We have some wiring from the door here.
22:06NTSB investigators turn their attention to what remains of the cargo door system.
22:11Okay, what else we got?
22:12Instead of using a plug door, which is stowed inside the cargo hold and gets jammed into the frame as the plane pressurizes,
22:23Boeing designed the 747 with an outward opening door to create more space for cargo in the hold.
22:30Looks like we at least have the pins.
22:32Investigators find a key component of the locking mechanism, the latch pins for the cargo door.
22:43The new 747 cargo door design uses a three-stage locking system.
22:52An exterior switch electrically powers the door to a near-closed position.
22:57C-shaped latches, or cams, then rotate around pins.
23:01A handle on the exterior of the door lowers metal sectors, which secure the latches in place.
23:10There's some wear in the pins, but hard to tell for sure what it means.
23:13There was transfer of metal and discoloration.
23:19We 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.
23:29There's some wear for sure, but it's likely from the latches rotating around the pins as the door closes.
23:35Makes sense.
23:36Hang on.
23:43Have a look.
23:46Investigators find evidence of heat tinting on the surface of the pin.
23:51I see it.
23:53Heat tinting occurs when the surface oxide layer of stainless steel changes colour due to heating.
24:01There's also some metal transfer from the latches on the pins.
24:04You're right.
24:07The presence of latch material on the pins suggests the separation of the cargo door was extremely fast and violent.
24:18The amount of force to cause a transfer of metal from the latches to the pins had to be enormous.
24:26There's metal from the latch in the same place on every pin.
24:32The location of the latch metal on the pins gives investigators their first big break.
24:39The latches were open and the door came off.
24:42The locking mechanism of the cargo door was designed to be fail-safe.
24:49So it's very perplexing to us why this had happened and how it could have happened.
24:54I'm checking the FAA records.
25:01I'll go through the Boeing ones.
25:03The locking system on the 747 cargo door failed before.
25:10i've got something two years ago there was an incident on another 747 look at that march 1987
25:23pan-american flight 125 was en route from london to new york when there was a pressurization
25:30problem the door was open an inch and a half
25:35the pan-am agent used a wrench to close the door manually and once he got it closed
25:44he inadvertently backed the wrench up and opened the door slightly
25:51the pan-am latches were manually turned to the open position and the lock sectors were broken
25:59how can the force of a socket wrench break the sectors well look get this
26:05the lock sectors they were made of a weak material
26:13the locking sectors were made of aluminum so they would bend and break
26:20what action was taken after the pan-am incident the faa issued an airworthiness directive
26:28requiring that each lock sector be reinforced with a steel doubler
26:32see united airlines they had 18 to 24 months to do it maybe they hadn't got the work done yet
26:41i'll check united's maintenance records
26:45did flight 811 have weak lock sectors
26:48looks like the lock sectors hadn't been replaced yet
26:56at the time of the accident the accident airplane still had the aluminum sectors
27:01because it wasn't scheduled to be replaced for two months
27:06did you have any issues closing the door
27:08not at all closed fine investigators consider how the door was closed and if the latches were over
27:15rotated like the ones on pan-am 125 did you close the door electrically or manually i closed it electrically
27:25i wouldn't have closed it manually it takes too much effort what do you mean you have to crank the wrench 95
27:31the ramp agent on 811 did not use a power tool as was used on pan-am
27:40this left us without any explanation for what happened
27:49what'd you find out well the ramp agent closed the door electrically properly using the switch
27:54and the dispatch mechanic said he did a circle check of the plane prior to departure
28:03he checked the forward cargo door with a flashlight
28:07and it was flushed to the aircraft
28:14what about the cargo door indicator light in the cockpit
28:17the second officer said that the light went out
28:26investigators confirmed that the second officer saw the cargo door light in the cockpit go off
28:32indicating that the door was closed
28:38while ntsb investigators consider other reasons why the cargo door opened they get an update on recovery
28:45efforts
28:50they mapped the currents and narrowed the debris field to 12 square miles
28:56finding the lost cargo door might be the key to the investigation
29:02but take a look at the depth 14 000 feet
29:07recovery teams aren't able to search for wreckage at a depth of 14 000 feet
29:12at that point the deepest we had ever searched and recovered wreckage was 6 000 feet under the water
29:22if the door was properly closed then maybe it subsequently opened due to an electrical problem
29:33did the electrical system accidentally open the door in flight
29:37according to the manual when the plane lifts off the ground all power to the door is disconnected
29:47electrical operation of the door to open it in flight was impossible
29:53if not in the air then
29:56maybe on the ground
30:06we considered that there possibly could have been a short in the electrical system that caused the door
30:13to unlatch on the ground
30:15it's everything
30:18almost
30:21you have all the electrical switches except one
30:24investigators perform continuity testing on the cargo door switches and relays recovered from the aircraft
30:32this one's good
30:36as is this one
30:37check this out
30:47that's a burn mark
30:51they also notice that some of the wiring insulation has stripped off
30:55that switch is a closed circuit there's nothing to do with opening the door
31:07the exposed wire on the switch could not have caused the cargo door to open
31:14we had ruled out most electrical system failures as the cause of the accident so that had us look at other options
31:25here you go
31:32the team now considers whether a mechanical failure caused the cargo door to open
31:40maybe there's something here
31:42investigators review the operations of the cargo door on four united 747s at honolulu airport
31:49this is strange
31:53says here that one of the ramp agents kicked on a cargo door to get it open
31:59they discover an instance of a cargo door opening only with the use of force
32:07when we heard that the ramp agents had to kick the door
32:10we figured that there was some type of misalignment
32:14misrigging of the cargo door and its locking mechanisms
32:19maybe the door kicking was just an isolated case
32:24investigators turned to the maintenance report of the flight 811 aircraft
32:29to determine if there was ever a fit issue with the forward cargo door
32:34no fit or alignment issues were ever reported
32:37right but check out when the plane was inspected
32:44when it was empty
32:49a 747 fully loaded with people fuel and cargo can add upwards of 300 000 pounds to the aircraft
32:59causing the fuselage to bend and distort
33:04get this
33:06in december 1988
33:08there were eight write-ups about door misalignment
33:12two months before the accident the forward cargo door failed to close fully under electrical operation
33:19and they were not able to drive the latches fully closed
33:26and they were not able to drive the latches fully closed
33:31did united fix the problem
33:38investigators learned that an electrical switch on united flight 811
33:42couldn't properly close the misaligned cargo door
33:46but was it ever repaired the maintenance was deferred
33:51because they would close the door manually
33:56if there was a fit issue and they would close it manually
34:00that would explain the wear marks we found on the pins
34:02the wear on the door indicated a long history of manual operation and uh miss rigging of the door
34:14even worse with repeated manual opening and closing of a misaligned door
34:19the lock sectors could easily have been damaged if the latches were being over rotated
34:31with the latches and lock sectors still at the bottom of the sea
34:35the ntsb is forced to conclude that the cargo door was sufficiently misaligned
34:40to prevent it from closing properly
34:44when we write the final report of an accident we present the evidence that we have and make our best
34:51conclusions based on that evidence we knew there was mechanical damage to the door
34:58we suspected that was the cause and that's the way we wrote the report
35:03in april of 1990 the ntsb published its findings the report recommends the faa issue a directive
35:14requiring the installation of a device to prevent the latches from over rotating
35:22but we wanted to get the door we really wanted to find the door to prove our theory
35:27oh three months after the ntsb publishes its report on united flight 811 the u.s navy
35:44offers to assist the recovery efforts side scan sonar
35:47uh-huh the navy came to me and said we've got a system that we're testing
35:59it was experimental a new sonar system and it was at the time classified
36:09a side scan sonar device towed from a ship emits high frequency sound pulses that bounce off the sea floor
36:17to create an image of the sea bed and any debris that might be lying on it
36:2414 000 feet really with the ability to scan deeper than previously possible
36:30the navy offers to test the device in the pacific ocean all right let's do it
36:36they said we would like to try and test it on that door and they would do it for no cost to us
36:42we said sure
36:57nothing in this sector
37:00ntsb investigator frank hill drop is on board the vessel searching for the cargo door
37:06i felt a lot of pressure this accident represented one of the deepest recoveries that was going to be
37:15attempted they search an area of 12 square miles divided into 57 sectors
37:22hang on
37:31i think we got something the team finds evidence of a debris field
37:38there was pretty high confidence that they were in the right area and the experts can tell
37:43roughly what they're looking at is it metallic in nature is it a good return
37:47a three-person submersible vehicle called the sea cliff is deployed the expedition confirms the
37:56debris is from flight 811 but finding the cargo door proves difficult
38:01we had some problems with weather with the hurricane with equipment failure so there was a lot of
38:08stops and starts
38:19after two months of searching
38:23we have the door the missing piece is found
38:27the door was in two pieces on the bottom of the ocean we had to recover both pieces
38:36get them on the ship and take them to honolulu
38:42with the complete locking system recovered investigators try to confirm their theory
38:47that a misaligned cargo door caused the lock sectors to break
38:51just like we thought
38:54the latches were in the open position
38:57check this out but then they discover something unexpected and critical
39:04these sectors aren't broken
39:06they're just bent
39:09the lock sectors were largely intact they weren't damaged like we expected them to be
39:16so that led us in a little bit more of another direction
39:21no visible evidence of any burning or arcing
39:25investigators now reconsider a theory they previously rejected
39:30that there was an electrical issue with the door
39:33no signs of heat distress either
39:37one of the things you can do is look inside the switches and see their condition
39:43we always examine the wiring we look for nicks or cuts when the wires are bundled together
39:49check this out investigators find a crucial piece of evidence
39:57there's chafing on some of the wires in this bundle
40:00it's proof that the conditions for a short circuit existed
40:06all it takes for a short circuit to happen is for that conductor that's inside that insulation
40:11to touch another wire or touch a piece of metal so we're always concerned about wiring in airplanes
40:18all set
40:19can a short circuit open a locked door on a 747 looks good give it a try
40:35well there you have it we determined that probably the short circuit could have caused the uh the the motors to engage the latch cams and uh open the door
40:54so we know there's no power to the door once the wheels lift off the ground
40:59and the door was closed and locked here
41:03so
41:03the short happened somewhere here
41:09during taxi
41:10the short circuit causes the latch to partially open when the plane is still on the ground
41:17then when the plane approaches 23 000 feet
41:22the significant pressure differential between the inside and the outside
41:27forces the door open and causes a massive decompression on board
41:31nine people are lost
41:49so
41:56nine months after recovering the cargo door investigators get disturbing news
42:02it happened again another United 747 cargo door opened while on the tarmac in New York
42:22despite these incidents the fleet is never grounded I felt anger you know rage my heart
42:39just goes out to the to the victims two years after the accident the NTSB publishes a second
42:49report updating the cause opening of a cargo door on a large aircraft is a catastrophic event it's
42:59unacceptable event it's like a wing falling off the FAA and Boeing took more than two years to
43:10require changes I remember it like it was yesterday it just doesn't hurt so much and you don't think
43:23about it 24-7 the experience in the event that night it told me I needed to make my life matter
43:33whether it be with the people that I share it with every single day or with what I put my energy
43:42towards every single day the nine that didn't make it would expect that of us and of me
Recommended
44:24
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