Europe 1954 throughout the continent there is a growing sense of optimism as the nightmare of world war 2 begins to fade former enemies forge new links there's a spirit of enterprise Civil Aviation is booming boosted by technological advances made during the conflict in just two years the number of airline passengers has nearly doubled 9:30 a.m. Sunday January 10th Rome Airport here a dozen planes come and go every hour on the tarmac stands flight 7 8 1 enroute from Singapore to London the plane is a British built two Havilland comet it's the marvel of its day and the perfect symbol of the new technological age the comet is the world's first passenger jet and it's having journey times around the world the Pride of Britain sends a message of superiority to every aircraft manufacturer in the world a dream comes true at Hatfield Airport the comet the world's first all jet airliner begun three years ago the airliner that makes every other passenger plane out of date will go into operation within 18 months the revolutionary design is based on the havens hard-won military expertise the plane is powered by four ghost jet engines and carries 42 passengers and crew and up to 800 kilometers per hour almost twice as fast as its nearest competitor to help it achieve this staggering speed efficiently it flies at a height of up to 12,000 meters where the air is thinner until now such performance with the preserve of military jet fighters 20 months after the launch there are 17 of these aircraft in service nine are owned by the British overseas Airways corporation or BOAC and among them is flight 7 8 1 9:40 a.m. BOAC engineer Gerry bull inspects the comet's undercarriage he checks for fuel leaks tire damage and marks on the airframe he pays attention to the aircraft's high-tech ultra lightweight aluminium skin it's extremely thin and vulnerable to damage be looking for this incidental damage there was none as feels like recall at that stage so my own thought at the time was walking oh we got a clean airplane today at 10 a.m. bull completes his final checks the flight crew join him the captain is Alan Gibson a31 he's one of boa c's youngest pilots captain Gibson was a man of very good ability not a person who would panic about anything he was you know confident in Rome Airport terminal members of the new Jet Set enjoy breakfast many are children returning to England for a new school term they're excited about flying on the world's first passenger jet also on the flight is renowned BBC reporter Chester Wilmot he's returning home after covering a tour of Australia by the recently crowned British Queen Chester is a devoted family man with three children he's especially close to his ten-year-old daughter Jane who was born deaf she is devoted to him unaware that he's one of Britain's best-loved broadcasters odet adores you and I knew that he'd be D and Eve's on television and he wrote books but I don't think I even quit her famous he was he took my dad 10:05 a.m. and the last pieces of luggage are stored in the hold of flight 781 the plane will be flying today with 29 passengers and six crew members on board one of the passengers is 23 year-old Bernard Butler Bernard is an electrical engineer who's been working in Bahrain to save money for his forthcoming wedding his fiancee is Pat Knight they've been engaged for two years and planned to marry in a fortnight I've made the bridesmaids dresses all the invitations have gone out and we'd already received wedding presents everything was was planned Bernhard is returning home with a surprise he's picked out a dress for Pat to wear at their wedding at 10:18 a.m. all pre-flight checks are complete captain Gibson signs to confirm that everything is in order captain Gibson seemed very relaxed also looking forward to getting home flight 781 is just one of five BOAC services from Rome to London today an older generation of slower propeller driven airliners make up the other flights at 10:19 a.m. a BOAC argument also bound for London thunders down the runway captain Johnson is up the controls at 10:30 a.m. 11 minutes after the Argonauts departure the comet taxes to the runway Gerry bull salutes goodbye a 781 champion of control drones a 71 we are clear take air traffic control granted permission for takeoff one minute later the high-tech plane takes to the air it's a sunny day and conditions for flying are perfect the journey to London will be exactly two hours and 37 minutes the gleaming jet will arrive at London Airport a staggering two hours before the propeller-driven Argonaut such speed is so far beyond anything produced by American rivals Boeing them to Douglas that comets manufacturer de havilland expect to dominate this booming market throughout Britain expectation is high from Prime Minister Winston Churchill down it was important from the British point of view to have our aircraft in the air and an aircraft which was far better than anything else so it was a booster but since the comet entered service 20 months ago they've been to accidents with the loss of 54 lives in March 1953 one crashed on takeoff in Pakistan two months later severe weather was blamed for a second disaster in India as both accidents occurred in difficult conditions reliability of the comet is not in question at 10:38 a.m. flight seven eight one climbs to an altitude of 11,000 meters twice as high as any other passenger aircraft to achieve this while allowing passengers to breathe comfortably the engineer operates a pressurization system from the cockpit as the comet rises the air pressure inside the cabin is maintained at the equivalent altitude of two and a half thousand metres a level easily tolerated by the human body but for some passengers adapting to this new sensation is difficult soon though they acclimatize and settle back into their seats for the flight what they cannot know is that they will never make it to London 1954 and the state-of-the-art comet jet airliner has taken off from Rome enroute to London on board a 29 passengers and six crew as flight 7/8 one climbs captain Gibson receives a message from captain Johnson in the slower Argonaut that took off a few minutes earlier each pilot uses the plane's callsign how jig for the Argonaut yoke Peter for the comet at 10:42 a.m. captain Gibson contacts air traffic entry the plane will find Northwest over the Italian coastline high above the Mediterranean Sea [Music] like at 10:51 a.m. captain Gibbs and again radios the message ends mid-sentence and captain Johnson gets no response he contacts Rome Airport at 10:56 a.m. the airport controller tries to contact the comet without success they fear something is terribly wrong 200 kilometers northwest on the island of elba a group of Italian fishermen are repairing their nets among them is 33 year old Luigi puppy as they work something extraordinary happens a break in the air and then there was a bang and I heard a sound like thunder but it was not like any thunder I'd ever heard before [Music] they watch in amazement as flaming wreckage falls from the sky at 11:15 a.m. air traffic control receives word that a plane has crashed into the sea of the island of elba it confirms their worst fears Gerry bull is the news the senior engineer says got some bad news sherry and I look at him and he sent the comet stone it's an emptiness you can't really describe it it's just this numbness you get and the next reaction of course is is this something I didn't do 12 p.m. Greenwich Mean Time Chester Wilmots family arrived at Heathrow Airport in West London to welcome the BBC reporter home a day with sparkling we've added the airport my turbulent the third flight at night arrives with a friend after a four-hour journey from Natyam she's looking forward to seeing Bernhard again there was 11 months since I've seen donut and I was very excited that he was coming home and I was going to see him 1200 kilometers away a small for tiller of fishing boats heads off the coast of Elbert towards the crash site at first we saw nothing then we saw a flock of seagulls which were pecking at something so we headed straight for the seagulls and that was where the plane had crashed it's a harrowing scene bodies and debris float in the water among the carnage is a white wedding dress [Music] 1:30 p.m. flight 7 8 1 is now over an hour late airport staff mark the plane has delayed Jane Wilmot keeps a close eye on the arrivals board hello I wanted to keep me be the first she's standing off-key bakken custom plane delay plane delayed Jane suddenly notices that all referenced of light 781 has been removed she decides to ask at the BOAC desk and our question / the gun we can't tell you you go and get your mother I'll be happy to speak with your mother Edith Wilmot is taken to a side room her children wait outside they still believe their father's plane is delayed out if I were the you things happen minutes later Edith returns visibly shocked and close to tears [Music] she tells her children the Chester is dead Jane will never see her beloved father again but I can believe it happening but I've a except that I need coming home from our birthday but I kept on saying to myself the button teeth [ __ ] he doesn't the pilot the grim task of informing friends and relatives continues Patricia night can scarcely believe what she hears were tortured Condell they didn't know whether there were bodies found an art and there was nothing we could do in an instant Pat's hopes for the future are destroyed in Italy the fishermen begin the gruesome task of recovering bodies as a young India it was a big shock every time we went near a corpse we would shout come over here come over here because they seemed still alive their eyes were open when we got near you could see they were dead in total 35 passengers and crew died on board comet flight 7 8 115 bodies are recovered there are no survivors [Music] the dere des carried to a small chapel in port at Euro [Music] local people say prayers children bring flowers [Music] [Applause] the horrific crash is headline news around the world the question on everybody's lips is how could the most advanced airliner in aviation history just fall out of the sky was it a tragic accident or something more sinister in 1954 the mysterious crash of the comet dominates the thoughts of the British nation [Music] what could have possibly caused the most advanced passenger plane in history to disintegrate in midair within hours of the crash a team of experts working for BOAC begin a technical examination of the comet fleet they must discover if there's a flaw in the design or a manufacturing fault Britain's position as the world leader in passenger jet travel depends upon it the enquiry that follows will turn into one of the most complex and important in aviation history now by going deep into the investigation we can reveal the critical chain of events that caused the downing of flight 781 Paul Witte is an aviation metallurgist for six years he studied the comet investigation and is an expert on this turning point in aviation safety with he knows that with no established protocol for air crash investigation it was an epic task the difficulties they faced as an investigation team was to develop a whole new series of techniques for looking into a major air crash and they had to really invent tests invent methods of doing things as they went along but witty needs to be sure that this landmark case actually did get to the truth now for the first time in half a century he will re-examine the vital evidence if he discovers their findings are wrong it will rewrite the history of air crash investigation from the beginning the inquiry team are faced with an enormous challenge in 1954 the investigation team had no black boxes they had no flight data recorders they had no way of understanding what was going on in the plane at the time of the accident their best clue the aircraft itself lies at the bottom of the Mediterranean Sea without the remains of the plane the team know they must unravel the mystery with the flimsiest of evidence with little to go on the press speculate that sabotage might be the cause of the crash these are the early years of the Cold War and there are fears that subversive communists may be responsible Obama and that were came up fairly rapidly you know it was it has to be how did it happen a bomb could have been hidden on board while the plane was taking on extra baggage it's only a theory but if true it would at least eliminate doubts about the safety of the comet itself with the pride and prosperity of a nation riding on the Comets success a closed eyes kept on the investigation from the very top Winston Churchill himself if saboteurs are responsible the investigators know they must come up with hard evidence they know that flight 781 would have been flying at around eleven thousand meters when something caused it to break up a fall from the sky the Italian fishermen provide a few clues I saw a huge ball of fire rotating plunging into the sea he left a huge huge cloud of smoke captain Johnson pilot of the Argonaut deepens her mystery the radio went dead in mid-sentence everything just cut out instantly but it's the victims themselves that provide the biggest mystery within hours of the crash Italian pathologist dr. antonia fawn re-examines the bodies despite finales considerable experience he finds a pattern of injuries he has never seen before the victim suffered broken limbs and damaged ribs injuries sustained after death but what confuses Furnari is that many of the bodies have fractured skulls wounds he discovers that were sustained before death he finds another puzzling clue the lungs of almost all the victims are extensively damaged many have ruptured like an exploding balloon to top it all Fionn re-enlist it's a strange perplexing picture and he's baffled with so little evidence the investigation hits a dead end [Music] concerned Prime Minister Churchill summons his advisers and takes an unprecedented step Churchill commands the Royal Navy to retrieve the wreckage of flight 781 from the seabed his orders are simple endeavor to locate and solve comet the task however is anything but simple there has never been a salvage operation like it before the wreckage lies at the depth of 120 meters and no one knows exactly where today if an aircraft crashed in similar circumstances that black box recorders that have transponders and would lead the investigators and then the recovery teams to the spot where the aircraft was the Navy didn't have that information HMS Wrangler an anti-submarine frigate searches an area of 260 square kilometers three salvage vessels are on hand to help they're equipped with the most up-to-date technology including an underwater camera and a deep seat observation chamber but progress is delayed by bad weather then on February 12th 33 days after the crash Navy experts identify the first piece of the comet wreckage on the underwater camera divers descend to the seafloor over the next few weeks small bits of debris are sent back to England for examination then comes a major find a large section of the rear fuselage is located and brought to the surface [Music] meanwhile in London the comet fleet sits idle BOAC hemorrhages cash at the rate of fifty thousand pounds per week with so much invested in the aircraft pressure builds to get the planes back into the air on March 23rd ten weeks after the disaster the British government give the airline the go-ahead to resume service at London Airport a comet and I now about to leave for Johannesburg was taking out extra crew members press and television attends the relaunch manages everybody was in the highest minutes at the resumption of coming he o AC chairman Sir miles Thomas gives the comet a public vote of confidence we obviously wouldn't be flying the comet with pastors in it on service where we not wholly satisfied that the conditions are acceptable for carrying passengers anywhere in the world wreckage from flight 7-8 one arrives in England piece by piece investigators identify and mark every fragment in a hangar carpenters build a wooden frame of the comet aircraft as the wreckage of cumulates they wire each piece onto this skeleton now with the entire comet fleet back in service it's more important than ever to find the cause of the crash the lives of hundreds of passengers depend on it April 1954 while investigators urgently look for clues into the crash of Comet flight seven eight one the British government give BOAC the go-ahead to relaunch their comet fleet it's a terrible mistake at 6:32 p.m. on April 8 16 days after the resumption of flying a comic takes off from Rome bound for Egypt 14 passengers and seven crew members are on board 33 minutes into the flight the pilot reports that he's on course flying at 11,000 meters it's his final message a further 21 people are dead the news sends shockwaves around the world barely a fortnight after reassuring the public the comet is safe to fly boa C's chairman publicly admits that he was wrong obviously we cannot continue to carry the public in comets until this disaster is fully explained similarities between the two accidents are uncanny both planes were refueled and checked at Rome by the same engineers including Gerry bull you just can't accept that an airplane likeness again it's gone Dover same where and you've lost his people in it both aircraft were flying at an altitude of around 10,000 meters both crashed into the Seas shortly afterwards it seems there must be a floor in the aircraft itself [Music] again the British Navy looks for evidence they recover five bodies along with a few personal effects Churchill acts decisively he appoints the Royal aircraft establishment Britain's leading aeronautical research center to investigate petting the inquiry will be sir Arnold Hall Hall has an impressive reputation he's a Cambridge scholar and one of the outstanding scientists of his generation sir Arnold Hall is a brilliant scientist and he was one of those people who would let the facts speak for themselves and would make judgments based on fact not on pinyin Churchill instructs hall the cost of solving the comet mystery must be reckoned neither in money nor in manpower but even for a man as qualified as Hall it's going to be a tall order the second plane to crash rests under a thousand metres of water and is impossible to retrieve the hope is that if they can establish the cause of flight 7/8 one's crash it would explain why the second aircraft went down over the next four months seven eight ones wreckage is methodically pieced together at sir Arnold halls headquarters in Farnborough it's groundbreaking work never before on that scale has an aircraft been reassembled by anyone and the investigation team had to learn how to do it and develop the techniques and tools to reassemble a very badly damaged aircraft as they examine each piece of debris they find intriguing clues bits of carpet pills from the first-aid cabinet a corner of a mirror from the toilet and scraps of passengers luggage are all found wedged into the rear end of the fuselage under the root of the tail fin it suggests an explosion at the front of the cabin that blasted personal belongings to the rear of the plane the question is how and where did the explosion start as the wreckage begins to provide some clues so - to the victims four of the bodies retrieved from the second crash are flown to Britain for postmortem the pathologist finds identical injuries to those of flight 781 fractured skulls and ruptured lungs Paul has a hunch could the entire plane have burst like a balloon after all the pressurized cabin designed to keep passengers comfortable would mean that the aluminium skin of the comet is highly stressed any structural failure and it might simply explode of its own accord such a violent decompression as it's called has never happened on a passenger plane before but Hall and his team believe this could explain the terrible injuries to test the theory they staged a pioneering experiment the team built a perspex model of the fuselage 1/10 the actual size the cabin includes 28 miniature seats with six dummies the model is housed inside a pressure chamber when the pressure in the fuselage is increased to eight and a quarter pounds the equivalent of flying at 12,000 meters the team deliberately ruptured the model a high-speed camera captures the results the rapidly escaping air causes a tremendous release of energy seats tear apart and fly through the air the dummies catapult vertically and smash their heads on the cabin roof it's a graphic demonstration of a phenomenon experts like Paul witty understand only too well the pressure cabin exploding is the same as a 500-pound bomb coming off inside the cabin the experiment appears to explain how the victims of both flights sustained such horrifying head injuries not only that the sudden change in pressure would cause the air inside the victims to expand rapidly rupturing their lungs instantly [Applause] if explosive decompression can explain what happened to both planes the team must discover exactly what caused the weakness in the structure of the fuselage but a failure in the aluminium skin seems implausible the manufacturers own tests show the natural life expectancy of the fuselage is over 10,000 flights many more than the number flown by the two crashed planes nevertheless sir Arnold is not a man to leave any stone unturned he decides to put the entire airframe to the test sir Arnold Hall decided that failure of the pressure cabin could be one of the possible causes and because he wanted to make sure that everything was looked at this was just one of the tests that was performed before testing begins the team look closely at the comet design they discover that to withstand the stress caused by repeated pressurization the skin of the aircraft must be immensely strong but it must also be extremely light in order to achieve this de havilland developed a lightweight aluminium alloy skin just over half a millimeter thick the comet's skin thickness was as thin as the designers dared go to withstand the cabin pressurization and it was fixed while how little they thought they could get awakened sir Arnold devises a test to assess the strength of the plane's fuselage the experiment is on a completely different scale to anything they have attempted before it requires the construction of a massive water tank measuring 34 metres long by 7 metres wide and 5 metres deep [Applause] working non-stop it takes a team of engineers and six weeks to complete the team at the Royal aircraft establishment are working really hard they're working 24 hours a day they work in shifts they're sleeping on-site they are a very dedicated team by May 29th it's ready the engines and cabin upholstery of a comet are stripped out the empty plane is gently maneuvered into the water tank with the wings protruding on either side hydraulic rams move the wings up and down to simulate flight conditions engineers fill the tank in the plane with water when they are both full they force more water into the plane pressurizing it as if people were flying after five minutes engineers reduce the pressure each test puts the same amount of strain into the aircraft as a single flight at 12,000 meters sir Arnold plans to test the fuselage to destruction it could take up to five months the experiment runs 24/7 using 1950s technology it's a grueling task today we wouldn't do a water tank test we'd actually use computer modeling and computer simulation to understand how the aircraft would behave as the tests continue there are other lines of inquiry in mid-june five months after the crash of flight 781 the team assembled two-thirds of the fuselage onto the wooden frame half a wing lies on the floor it's now clear from the tears in the metal that the aircraft has indeed decompressed violently and blown apart at the seams by following the fractures back to where they started they think the initial failure was probably at the front of the fuselage somewhere between the cabin and the cockpit it seems as if the tail and rear fuselage then came away from the main cabin the rear wing structure followed and then the outer wing tips the cockpit broke away as the plane plummeted to earth and finally fuel from the wings set the debris ablaze but the exact cause of this tragedy is still a mystery then on June 24th sir Arnold Hall gets a call that changes everything the team running the water tank tests has had a major breakthrough [Music] less than a month after testing began after the equivalent of just three thousand flights the comet fuselage ruptures engineers immediately drain the tank and sir Arnold Hall inspects the damage there is a massive tear in the aircraft's skin two meters long and one meter deep the tear follows the line of the planes windows and doors it's a shocking but vital turning point they have uncovered a major weakness in the structure of the comet the entire fleet seems to be fatally flawed I think everybody was thunderstruck de havilland certainly with thunder stroke because they didn't expect a comet airframe to fell so soon in its life but what triggered such a dramatic failure there's one prime suspect a phenomenon known as metal fatigue it's something Paul with Eno's well this is a piece of aluminum sheets similar to that which was used on the comics skin but much thinner one cycle of load isn't going to fail it at all but if I repeatedly load it like this fatigue is caused when a metal is repeatedly flexed one way and then the other there you can just see us about three or four millimeters across the sheets after a while my newt cracks start to fall cracks bring further and further across the site the crack steadily increase in size and eventually the part fails but there are two problems with this explanation metal fatigue leaves a telltale microscopic pattern on the surface of the metal although in the 1950s the technology for detecting this pattern is in its infancy none of the parts reclaimed from the sea seemed to show any sign of it secondly before the comet went into service the manufacturers did extensive fatigue tests to find out how the fuselage would behave under repeated pressurization it passed with flying colors Sahara look knows he must come up with hard evidence to prove the theory he must find a part of flight 7-8 one that shows signs of the fatigue the piece of evidence that sir Arnold needed above all other was that source of fatigue crack growth that he knew was there in the airframe somewhere a single piece of wreckage is all that's needed to validate the entire investigation but this crucial evidence still lies at the bottom of the Mediterranean Sea it's 1954 an investigator sir Arnold Hall believes that the cause of the two comet crashes is a rupture in the plane's lightweight skin after a unique pressure test on the Comets cabin the team examined the two meters split that has ripped along the side of the fuselage they make some frightening discoveries by tracing the tear back they find it starts at the forward escape hatch this is not surprising stress to the aircraft should be evenly spread throughout the fuselage but when a door or window is cut into the plane it weakens the structure from the stress concentrates around the weakened air is to investigate further they rigged another aircraft with strain gauges designed to measure stress in the airframe the results are shocking during flight the stress to the skin around the planes windows and doors reaches 70 percent of its total strength four times greater than the rest of the aircraft's skin this is dangerously high and twice what the designers intended then the team discover an even more worrying detail the supports around the windows are riveted not glued as designed the problem is the rivets have punched into the metal not drilled this technique creates tiny manufacturing defects which would repeat it flying can turn into fatigue cracks the presence of manufacturing cracks in a highly stressed area meant that you are highly likely to suffer from fatigue failure sir Arnold and his team know they're getting close but they have not yet conclusively sold the mystery they found no trace of metal fatigue on any of the wreckage from flight 781 it was vital that he found that piece of evidence from the seabed that would tie the crash to the accident investigation in an unequivocal man then on August 12th seven months after flight 781 crashed an Italian trawler snags a large piece of wreckage [Music] it turns out to be a section of the roof from 7-8 ones fuselage the piece includes two small windows built for sending and receiving radio signals sir Arnold Hall and his team inspect the wreckage at Farnborough and immediately find what they're looking for a rivet hole in the corner of one of the windows shows a tiny crack when they put the piece together with the rest of the wreckage they find that all the cracks run back to this point they have their missing clue the future of the comet the world's first passenger jet airliner hangs upon the outcome of a court of inquiry being held at church on Tuesday October 19th after six months of grueling work sir Arnold Hall presents his findings to a court of inquiry but one detail fascinates Witte in 1954 the techniques for analyzing metal fatigue were crude the final piece of wreckage was examined with an ordinary microscope and the team relied on experience to make their conclusion today London Science Museum safeguards the crucial piece of wreckage Paul with he goes to see the historic item for himself no one has ever used modern methods to re-examine the evidence using 21st century no how will he wants to look again at the wreckage and check that sir Arnold got it right in order to preserve the damaged section it has been mounted onto a plate running from a rivet hole is the crack which it's believed started the catastrophe to examine the damage in more detail Witte makes an impression of the crucial area using a silicon-based putty then at Imperial College London where he uses an electron microscope to examine the sample [Music] magnifying the crack about 200 times witty shows what sir armed would have seen this is the fatigue crack we saw on the Comets skin and Surin old homeless team could see that using their techniques of the day but zooming in further to 800 times where he can see detail that sir Arnold never could he finds a tiny manufacturing defect probably formed when the rivet was punched into the metal and it was that manufacturing defect that caused this forty crack to grow and it's this image here that shows that sir Arnold Holness team were right it vindicates them seeing that it was a fatigue crack whose name grew to failure 52 years after the most groundbreaking and innovative investigation in aviation history Paul Witte has conclusive proof that sir Arnold Hall's results are absolutely right now by rewinding the events leading up to that fateful crash and by following the evidence uncovered during the investigation we can reveal how flight 7 8 1 was down 10:31 a.m. January 10th 1954 26 minutes to disaster flight 7 8 1 takes off from Rome Airport the plane is designed with an exceptionally thin aluminium skin rivets punched into the aircraft during construction create microscopic manufacturing defects on each flight the pressurization system puts enormous strain on the fuselage causing stress to the skin especially around the windows and doors repeated pressurization turn the manufacturing defects into fatigue cracks but get bigger with every flight 19 minutes to disaster flight 7-8 one climbs to 11,000 meters as it ascends the pressure increases and the aircraft's skin becomes more stressed at 10:51 a.m. the Comets pilot captain Gibson sends a radio message five seconds to disaster a fatigue crack which is two centimeters in length and the aircraft skin rips apart at 10:57 a.m. the shattered pieces of flight 781 fall from the sky 35 people are dead [Music] on the island of elba lies a memorial to those who lost their lives over fifty years ago the pain of the tragedy will never be forgotten but the scientific understanding gained during the investigation is comfort to some I know gave my mother a good deal of comfort for the tests they did on the following the comic craft they save people a greater four years after the crash the comet did fly again but it never achieved the commercial success it once promised in the interim American company Boeing developed their own passenger jet and became the dominant force in the world of aviation the de Havilland Aircraft Company went into decline and were eventually taken over passenger air travel had changed forever you
