De Havilland Comet The de Havilland DH 106 Comet was the first production commercial jetliner . Developed and manufactured by de Havilland at its Hatfield , Hertfordshire , United Kingdom headquarters , the Comet 1 prototype first flew on 27 July 1949 . It featured an aerodynamically clean design with four de Havilland Ghost turbojet engines buried in the wings , a pressurised fuselage , and large square windows . For the era , it offered a relatively quiet , comfortable passenger cabin and showed signs of being a commercial success at its 1952 debut . A year after entering commercial service the Comets began suffering problems , with three of them breaking up during mid - flight in well - publicised accidents . This was later found to be due to catastrophic metal fatigue , not well understood at the time , in the airframes . The Comet was withdrawn from service and extensively tested to discover the cause ; the first incident had been incorrectly blamed on adverse weather . Design flaws , including dangerous stresses at the corners of the square windows and installation methodology , were ultimately identified ; consequently the Comet was extensively redesigned with oval windows , structural reinforcement and other changes . Rival manufacturers meanwhile heeded the lessons learned from the Comet while developing their own aircraft . Although sales never fully recovered , the improved Comet 2 and the prototype Comet 3 culminated in the redesigned Comet 4 series which debuted in 1958 and had a productive career of over 30 years . The Comet was adapted for a variety of military roles such as VIP , medical and passenger transport , as well as surveillance ; the most extensive modification resulted in a specialised maritime patrol aircraft variant , the Hawker Siddeley Nimrod . Nimrod remained in service with the Royal Air Force ( RAF ) until June 2011 , over 60 years after the Comet ' s first flight . Development . Origins . On 11 March 1943 the Cabinet of the United Kingdom formed the Brabazon Committee to determine Britain ' s airliner needs after the conclusion of the Second World War . One of its recommendations was for a pressurised , transatlantic mailplane that could carry one long ton ( 1 . 0 t ) of payload at a cruising speed of 400 mph ( 640 km / h ) . Challenging the widely held scepticism of jet engines as too fuel - hungry and unreliable , committee member Sir Geoffrey de Havilland , head of the de Havilland company , used personal influence and his company ' s expertise with jet aircraft to specify a turbojet - powered design . The committee accepted the proposal , calling it the " Type IV " ( of five designs ) , and awarded a production contract to de Havilland under the designation " Type 106 " in February 1945 . First - phase development of the DH 106 focused on short and intermediate range mailplanes with a small passenger compartment and as few as six seats , before being redefined as a long - range airliner with a capacity of 24 seats . Out of all the Brabazon designs , the DH 106 was seen as the riskiest both in terms of introducing untried design elements and for the financial commitment involved . Nevertheless , the British Overseas Airways Corporation ( BOAC ) found the Type IV ' s specifications attractive , and initially proposed a purchase of 25 aircraft ; in December 1945 , when a firm contract was laid out , the order total was revised to 10 . A design team was formed in 1946 under the leadership of chief designer Ronald Bishop , who had been responsible for the Mosquito fighter - bomber . A number of unorthodox configurations were considered , ranging from canard to tailless designs ; all were subsequently rejected . The Ministry of Supply was , however , interested in the most radical of the proposed designs and ordered two experimental tailless DH 108 s to serve as proof of concept aircraft for testing swept - wing configurations in both low - speed and high - speed flight . During flight tests , the DH 108 gained a reputation for being accident - prone and unstable , leading de Havilland and BOAC to gravitate to conventional configurations and , necessarily , designs with less technical risk . The DH 108s were later modified to test the DH 106 ' s power controls . In September 1946 , prior to the completion of the DH 108s , BOAC requests necessitated a redesign of the DH 106 from its previous 24 - seat configuration to a larger 36 - seat version . With no time to develop the technology necessary for a proposed tailless configuration , Bishop opted for a more conventional 20 - degree swept - wing design with unswept tail surfaces , married to an enlarged fuselage accommodating 36 passengers in a four - abreast arrangement with a central aisle . Replacing previously specified Halford H . 1 Goblin engines , four new , more powerful Rolls - Royce Avon s were to be incorporated in pairs buried in the wing roots ; Halford H . 2 Ghost engines were eventually applied as an interim solution while the Avons cleared certification . The redesigned aircraft was named the DH 106 " Comet " in December 1947 . Revised first orders from BOAC and British South American Airways totaled 14 aircraft with delivery projected for 1952 . Testing and prototypes . Because the Comet represented a new category of passenger aircraft , more rigorous testing was a development priority . From 1947 to 1948 , de Havilland conducted an extensive research and development phase , including the use of several stress test rigs at Hatfield for small components and large assemblies alike . Sections of pressurised fuselage were subjected to high - altitude flight conditions via a large decompression chamber on - site , and tested to failure . However , tracing fuselage failure points proved difficult with this method , and de Havilland ultimately switched to conducting structural tests with a water tank that could be safely configured to increase pressures gradually . The entire forward fuselage section was tested for metal fatigue by repeatedly pressurising to overpressure and depressurising through more than 16 , 000 cycles , equivalent to about 40 , 000 hours of airline service . The windows were also tested under a pressure of , above expected pressures at the normal service ceiling of . One window frame survived , about 1 , 250 percent over the maximum pressure it was expected to encounter in service . The first prototype DH 106 Comet ( carrying Class B markings G - 5 - 1 ) was completed in 1949 , and was initially used to conduct ground tests and brief early flights . The prototype ' s maiden flight took place on 27 July 1949 out of Hatfield Aerodrome and lasted 31 minutes . At the controls was de Havilland chief test pilot John Cunningham , a famous night - fighter pilot of the Second World War , along with co - pilot Harold " Tubby " Waters , engineers John Wilson ( electrics ) and Frank Reynolds ( hydraulics ) , and flight test observer Tony Fairbrother . The prototype was registered G - ALVG just before it was publicly displayed at the 1949 Farnborough Airshow prior to the start of flight trials . A year later , the second prototype G - 5 - 2 made its maiden flight . The second prototype was registered G - ALZK in July 1950 and it was used by the BOAC Comet Unit at Hurn from April 1951 to carry out 500 flying hours of crew training and route proving . Australian airline Qantas also sent its own technical experts to observe the performance of the prototypes , seeking to quell internal uncertainty about its prospective Comet purchase . Both prototypes could be externally distinguished from later Comets by the large two - wheeled main landing gear , which was replaced on production models starting with G - ALYP by sets of four - wheeled bogie s . Design . Overview . The Comet was an all - metal low - wing cantilever monoplane powered by four jet engines ; it had a four - place cockpit occupied by two pilots , a flight engineer , and a navigator . The clean , low - drag design of the aircraft featured many design elements that were fairly uncommon at the time , including a swept - wing leading edge , integral wing fuel tanks , and four - wheel bogie main undercarriage units designed by de Havilland . Two pairs of turbojet engines ( on the Comet 1s , Halford H . 2 Ghosts , subsequently known as de Havilland Ghost 50 Mk1s ) were buried into the wings . The original Comet was approximately the length of the later Boeing 737 - 100 , but carried fewer people in a significantly more spacious environment . BOAC installed 36 reclining " slumberseats " with centres on its first Comets , allowing for greater leg room in front and behind ; Air France had 11 rows of seats with four seats to a row installed on its Comets . Large picture window views and table seating accommodations for a row of passengers afforded a " feel of comfort and luxury " atypical of transportation of the period . Amenities included a galley that could serve hot and cold food and drinks , a bar , and separate men ' s and women ' s toilets . Provisions for emergency situations included several life rafts stored in the wings near the engines , and individual life vest s were stowed under each seat . One of the most striking aspects of Comet travel was the quiet , " vibration - free flying " as touted by BOAC . For passengers used to propeller - driven airliners , smooth and quiet jet flight was a novel experience ( although passengers of today would consider the Comet noisy , particularly in seats aft of the wing ) . Avionics and systems . For ease of training and fleet conversion , de Havilland designed the Comet ' s flight deck layout with a degree of similarity to the Lockheed Constellation , an aircraft that was popular at the time with key customers such as BOAC . The cockpit included full dual - controls for the captain and first officer , while a flight engineer controlled various key systems , including fuel , air conditioning , and electrical systems . The navigator occupied a dedicated station with a table across from the flight engineer . Several of the Comet ' s avionics systems were new to civil aviation . One such feature was irreversible powered flight controls , which increased the pilot ' s ease of control and the safety of the aircraft by preventing aerodynamic forces from changing the directed positions and placement of the aircraft ' s control surfaces . Additionally , a large number of the control surfaces , such as the elevators , were equipped with a complex gearing system as a safeguard against accidentally over - stressing the surfaces or airframe at higher speed ranges . The Comet had a total of four hydraulic system s , two primaries , one secondary , and a final emergency system for basic functions such as lowering the undercarriage . The undercarriage could also be lowered by a combination of gravity and a hand - pump . Power was syphoned from all four engines for the hydraulics , cabin air conditioning , and the de - icing system ; these systems had operational redundancy in that they could keep working even if only a single engine was active . The majority of hydraulic components were centred in a single avionics bay . A pressurised refuelling system , developed by Flight Refuelling Ltd , allowed the Comet ' s fuel tanks to be refuelled at a far greater rate than other methods . The cockpit was significantly altered for the Comet 4 ' s introduction , on which an improved layout focusing on the onboard navigational suite was introduced . A radar unit manufactured by EKCO was installed in the Comet 4 ' s nose cone , providing search functions as well as ground and cloud mapping capabilities , and a radar interface was built into the Comet 4 cockpit along with redesigned instruments . Sud - Est ' s design bureau , while working on the Sud Aviation Caravelle in 1953 , licensed several design features from de Havilland , building on previous collaborations on earlier licenced designs , including the DH 100 Vampire ; the nose and cockpit layout of the Comet 1 was grafted onto the Caravelle . In 1969 , when the Comet 4 ' s design was modified by Hawker Siddeley to become the basis for the Nimrod , the cockpit layout was completely redesigned and bore little resemblance to its predecessors except for the control yoke . Fuselage . Diverse geographical destinations and cabin pressurisation alike on the Comet demanded the use of a high proportion of alloys , plastics , and other materials new to civil aviation across the aircraft in order to meet certification requirements . The Comet ' s high cabin pressure and fast operating speeds were unprecedented in commercial aviation , making its fuselage design an experimental process . At its introduction , Comet airframes would be subjected to an intense , high - speed operating schedule which included simultaneous extreme heat from desert airfields and frosty cold from the kerosene - filled fuel tanks . The Comet ' s thin metal skin was composed of advanced new alloys and was both riveted and chemically bonded , which saved weight and reduced the risk of fatigue cracks spreading from the rivets . The chemical bonding process was accomplished using a new adhesive , Redux , which was liberally used in the construction of the wings and the fuselage of the Comet ; it also had the advantage of simplifying the manufacturing process . When several of the fuselage alloys were discovered to be vulnerable to weakening via metal fatigue , a detailed routine inspection process was introduced . As well as thorough visual inspections of the outer skin , mandatory structural sampling was routinely conducted by both civil and military Comet operators . The need to inspect areas not easily viewable by the naked eye led to the introduction of widespread radiography examination in aviation ; this also had the advantage of detecting cracks and flaws too small to be seen otherwise . Operationally , the design of the cargo holds led to considerable difficulty for the ground crew , especially baggage handler s at the airports . The cargo hold had its doors located directly underneath the aircraft , so each item of baggage or cargo had to be loaded vertically upwards from the top of the baggage truck , then slid along the hold floor to be stacked inside . The individual pieces of luggage and cargo also had to be retrieved in a similar , slow manner at the arriving airport . Propulsion . The Comet was powered by two pairs of turbojet engines buried in the wings close to the fuselage . Chief designer Bishop chose the Comet ' s embedded - engine configuration because it avoided the drag of podded engine s and allowed for a smaller fin and rudder , since the hazards of asymmetric thrust were reduced . The engines were outfitted with baffle s to reduce noise emissions , and extensive soundproofing was also implemented to improve passenger conditions . Placing the engines within the wings had the advantage of a reduction in the risk of foreign object damage , which could seriously damage jet engines . The low - mounted engines and good placement of service panels also made aircraft maintenance easier to perform . However , the Comet ' s buried engine configuration increased its structural weight and complexity . Armour had to be placed around the engine cells to contain debris from any serious engine failures ; also , placing the engines inside the wing required a more complicated wing structure . The Comet 1 featured de Havilland Ghost 50 Mk1 turbojet engines . Two hydrogen peroxide - powered de Havilland Sprite booster rockets were originally intended to be installed to boost takeoff under hot and high altitude conditions from airports such as Khartoum and Nairobi . These were tested on 30 flights , but the Ghosts alone were considered powerful enough and some airlines concluded that rocket motors were impractical . Sprite fittings were retained on production aircraft . Comet 1s subsequently received more powerful Ghost DGT3 series engines . From the Comet 2 onwards , the Ghost engines were replaced by the newer and more powerful Rolls - Royce Avon AJ . 65 engines . To achieve optimum efficiency with the new powerplants , the air intakes were enlarged to increase mass air flow . Upgraded Avon engines were introduced on the Comet 3 , and the Avon - powered Comet 4 was highly praised for its takeoff performance from high altitude locations such as Mexico City . Operational history . Introduction . The earliest production aircraft , registered G - ALYP ( " Yoke Peter " ) , first flew on 9 January 1951 and was subsequently loaned to BOAC for development flying by its Comet Unit . On 22 January 1952 , the fifth production aircraft , registered G - ALYS , received the first Certificate of Airworthiness awarded to a Comet , six months ahead of schedule . On 2 May 1952 , as part of BOAC ' s route - proving trials , G - ALYP took off on the world ' s first jetliner flight with fare - paying passengers and inaugurated scheduled service from London to Johannesburg . The final Comet from BOAC ' s initial order , registered G - ALYZ , began flying in September 1952 and carried cargo along South American routes while simulating passenger schedules . The Comet was a hit with passengers including Queen Elizabeth , the Queen Mother and Princess Margaret , who were guests on a special flight on 30 June 1953 hosted by Sir Geoffrey and Lady de Havilland , and thus became the first members of the British Royal Family to fly by jet . Flights on the Comet were about 50 percent faster than on advanced piston - engined aircraft such as the Douglas DC - 6 ( 490 mph for the Comet compared to the DC - 6 ' s 315 mph ) , and a faster rate of climb further cut flight times . In August 1953 BOAC scheduled eight - stop London to Tokyo flights by Comet for 35 hours , compared to 85 hours and 35 minutes on their Argonaut piston airliner . ( Pan Am ' s DC - 6B was scheduled for 46 hours 45 minutes . ) The thrice - weekly five - stop London to Johannesburg Comet was scheduled for 20 hr 20 min . In their first year of service Comets carried 30 , 000 passengers . As the aircraft could be profitable with a passenger load factor as low as 43 percent , commercial success was expected . The Ghost engines allowed the Comet to fly above weather competitors had to fly through . They ran smoothly and were less noisy than piston engines , had low maintenance costs , and were fuel - efficient above . At the height of its career BOAC ' s Comet 1 fleet flew London to Singapore , London to Tokyo , and London to Johannesburg several times a week . In 1953 the Comet appeared to have achieved success for de Havilland . In addition to BOAC , two French airlines , Union Aéromaritime de Transport and Air France , launched jet services to West Africa and the Middle East with the Comet 1A , an upgraded variant with greater fuel capacity . A slightly longer version of the Comet 1 with more powerful engines , the Comet 2 , was being developed , and orders were placed by Air India , British Commonwealth Pacific Airlines , Japan Air Lines , Linea Aeropostal Venezolana , and Panair do Brasil . American carriers Capital Airlines , National Airlines , and Pan Am placed orders for the planned Comet 3 , an even larger , longer - range version for transatlantic operations . Qantas was interested in the Comet 1 but concluded that a version with more range and better takeoff performance was needed for the London to Canberra route . Early hull losses . On 26 October 1952 , the Comet suffered its first hull loss when a BOAC flight departing Rome ' s Ciampino airport failed to become airborne and ran into rough ground at the end of the runway . Two passengers sustained minor injuries , and the aircraft , G - ALYZ , was a total loss . On 3 March 1953 , a new Canadian Pacific Airlines Comet 1A , registered CF - CUN and named " Empress of Hawaii , " failed to become airborne while attempting takeoff from Karachi , Pakistan , on a delivery flight to Australia . The aircraft plunged into a dry drainage canal and collided with an embankment , killing all five crew and six passengers on board . The accident was the first fatal jetliner crash , as well as the Comet ' s first accident to result in fatalities . In response , Canadian Pacific cancelled its remaining order for a second Comet 1A and never operated the type in commercial service . Both early accidents were originally attributed to pilot error , as over - rotation had led to a loss of lift from the leading edge of the aircraft ' s wings . It was later determined that the Comet ' s wing profile experienced a loss of lift at a high angle of attack , and its engine inlets also suffered a lack of pressure recovery in the same conditions . As a result , de Havilland re - profiled the wings ' leading edge with a pronounced " droop " , and wing fence s were added to control spanwise flow . A fictionalised investigation into the Comet ' s takeoff accidents was the subject of the 1959 novel " Cone of Silence " by Arthur David Beaty , a former BOAC captain . " Cone of Silence " was made into a film in 1960 , and Beaty also recounted the story of the Comet ' s takeoff accidents in a chapter of his 1984 non - fiction work , " Strange Encounters : Mysteries of the Air " . The Comet ' s second fatal accident occurred on 2 May 1953 , when a BOAC Comet 1 , registered G - ALYV , crashed in a severe thundersquall six minutes after taking off from Calcutta - Dum Dum ( now Netaji Subhash Chandra Bose International Airport ) , India , killing all 43 on board . Witnesses observed the wingless Comet on fire plunging into the Indian Ocean , leading investigators to suspect structural failure . India Court of Inquiry . After the loss of G - ALYV , the Central Government of India convened a court of inquiry to examine the cause of the accident . A large portion of the aircraft was recovered and reassembled at Farnborough , during which the break - up was found to have begun with a left elevator spar failure in the stabiliser . The inquiry concluded that the aircraft had encountered extreme negative G forces during takeoff ; severe turbulence generated by adverse weather was determined to have induced down - loading , leading to the loss of the wings . Examination of the cockpit controls suggested that the pilot may have inadvertently over - stressed the aircraft when pulling out of a steep dive by over - manipulation of the fully powered flight controls . Investigators did not consider metal fatigue as a contributory cause . The inquiry ' s recommendations revolved around the enforcement of stricter speed limits during turbulence , and two significant design changes also resulted : all Comets were equipped with weather radar and the " Q feel " system was introduced , which ensured that control column forces ( invariably called stick forces ) would be proportional to control loads . This artificial feel was the first of its kind to be introduced in any aircraft . The Comet 1 and 1A had been criticised for a lack of " feel " in their controls , and investigators suggested that this might have contributed to the pilot ' s alleged over - stressing of the aircraft ; Comet chief test pilot John Cunningham contended , however , that the jetliner flew smoothly and was highly responsive in a manner consistent with other de Havilland aircraft . Comet disasters of 1954 . Rome ' s Ciampino airport , the site of the first Comet hull loss , was the origin of more disastrous Comet flights just over a year later . On 10 January 1954 , 20 minutes after taking off from Ciampino , the first production Comet , G - ALYP , broke up in mid - air while operating BOAC Flight 781 and crashed into the Mediterranean off the Italian island of Elba with the loss of all 35 on board . With no witnesses to the disaster and only partial radio transmissions as incomplete evidence , no obvious reason for the crash could be deduced . Engineers at de Havilland immediately recommended 60 modifications aimed at any possible design flaw while the Abell Committee met to determine potential causes of the crash . BOAC also voluntarily grounded its Comet fleet pending investigation into the causes of the accident . Abell Committee Court of Inquiry . Media attention centred on sabotage , while other speculation ranged from clear - air turbulence to an explosion of vapour in an empty fuel tank . The Abell Committee focused on six potential aerodynamic and mechanical causes : control flutter ( which had led to the loss of DH 108 prototypes ) , structural failure due to high loads or metal fatigue of the wing structure , failure of the powered flight controls , failure of the window panels leading to explosive decompression , or fire and other engine problems . The committee concluded that fire was the most likely cause of the problem , and a number of changes were made to the aircraft to protect the engines and wings from damage that might lead to another fire . During the investigation , the Royal Navy conducted recovery operations . The first pieces of wreckage were discovered on 12 February 1954 and the search continued until September 1954 , by which time 70 percent by weight of the main structure , 80 percent of the power section , and 50 percent of the aircraft ' s systems and equipment had been recovered . The forensic reconstruction effort had just begun when the Abell Committee reported its findings . No apparent fault in the aircraft was found , and the British government decided against opening a further public inquiry into the accident . The prestigious nature of the Comet project , particularly for the British aerospace industry , and the financial impact of the aircraft ' s grounding on BOAC ' s operations , both served to pressure the inquiry to end without further investigation . Comet flights resumed on 23 March 1954 . On 8 April 1954 , Comet G - ALYY ( " Yoke Yoke " ) , on charter to South African Airways , was on a leg from Rome to Cairo ( of a longer route , SA Flight 201 from London to Johannesburg ) , when it crashed in the Mediterranean near Naples with the loss of all 21 passengers and crew on board . The Comet fleet was immediately grounded once again and a large investigation board was formed under the direction of the Royal Aircraft Establishment ( RAE ) . Prime Minister Winston Churchill tasked the Royal Navy with helping to locate and retrieve the wreckage so that the cause of the accident could be determined . The Comet ' s Certificate of Airworthiness was revoked and Comet 1 line production was suspended at the Hatfield factory while the BOAC fleet was permanently grounded , cocooned and stored . Cohen Committee Court of Inquiry . On 19 October 1954 , the Cohen Committee was established to examine the causes of the Comet crashes . Chaired by Lord Cohen , the committee tasked an investigation team led by Sir Arnold Hall , Director of the RAE at Farnborough , to perform a more detailed investigation . Hall ' s team began considering fatigue as the most likely cause of both accidents , and initiated further research into measurable strain on the aircraft ' s skin . With the recovery of large sections of G - ALYP from the Elba crash and BOAC ' s donation of an identical airframe , G - ALYU , for further examination , an extensive " water torture " test eventually provided conclusive results . This time , the entire fuselage was tested in a dedicated water tank that was built specifically at Farnborough to accommodate its full length . Stress around the window corners was found to be much higher than expected , while stresses on the skin were generally more than previously expected or tested . This was due to stress concentration , a consequence of the windows ' square shape , which generated levels of stress two or three times greater than across the rest of the fuselage . In water tank testing , engineers subjected G - ALYU to repeated re - pressurisation and over - pressurisation , and on 24 June 1954 , after 3 , 057 flight cycles ( 1 , 221 actual and 1 , 836 simulated ) , G - ALYU burst open . Hall , Geoffrey de Havilland and Bishop were immediately called to the scene , where the water tank was drained to reveal that the fuselage had ripped open at a corner of the forward port - side escape hatch cutout . A further test reproduced the same results . Based on these findings , Comet 1 structural failures could be expected at anywhere from 1 , 000 to 9 , 000 cycles . Before the Elba accident , G - ALYP had made 1 , 290 pressurised flights , while G - ALYY had made 900 pressurised flights before crashing . Dr P . B . Walker , Head of the Structures Department at the RAE , said he was not surprised by this , noting that the difference was about three to one , and previous experience with metal fatigue suggested a total range of nine to one between experiment and outcome in the field could result in failure . The RAE also reconstructed about two - thirds of G - ALYP at Farnborough and found fatigue crack growth from a rivet hole at the low - drag fibreglass forward aperture around the Automatic Direction Finder , which had caused a catastrophic break - up of the aircraft in high altitude flight . The punch rivet construction technique employed in the Comet ' s design had exacerbated its structural fatigue problems ; the aircraft ' s windows had been engineered to be glued and riveted , but had been punch riveted only . Unlike drill riveting , the imperfect nature of the hole created by punch riveting could cause the start of fatigue cracks around the rivet . Principal investigator Hall accepted the RAE ' s conclusion of design and construction flaws as the likely explanation for G - ALYU ' s structural failure after 3 , 060 pressurisation cycles . The Cohen inquiry closed on 24 November 1954 , and although the inquiry had " found that the basic design of the Comet was sound " , de Havilland nonetheless began a refit programme to strengthen the fuselage and wing structure , employing thicker gauge skin and replacing all square windows and panels with rounded versions . Resumption of service . With the discovery of the structural problems of the early series , all remaining Comets were withdrawn from service , while de Havilland launched a major effort to build a new version that would be both larger and stronger . All outstanding orders for the Comet 2 were cancelled by airline customers . The square windows of the Comet 1 were replaced by the oval versions used on the Comet 2 , which first flew in 1953 , and the skin sheeting was thickened slightly . Remaining Comet 1s and 1As were either scrapped or modified with oval window rip - stop doublers ( a thick , structurally strong ring of material that prevents a crack from spreading further ) . All production Comet 2s were also modified to alleviate the fatigue problems ( most of these served with the RAF as the Comet C2 ) , while a programme to produce a Comet 2 with more powerful Avons was delayed . The prototype Comet 3 first flew in July 1954 , and was tested in a non - pressurised state pending completion of the Cohen inquiry . Comet commercial flights would not resume until 1958 . Development flying and route proving with the Comet 3 allowed accelerated certification of what was destined to be the most successful variant of the type , the Comet 4 . All airline customers for the Comet 3 subsequently cancelled their orders and switched to the Comet 4 , which was based on the Comet 3 but with improved fuel capacity . BOAC ordered 19 Comet 4s in March 1955 , while American operator Capital Airlines ordered 14 Comets in July 1956 . Capital ' s order included 10 Comet 4As , a variant modified for short - range operations with a stretched fuselage and short wings , lacking the pinion ( outboard wing ) fuel tanks of the Comet 4 . However , due to financial problems and a subsequent takeover by United Airlines , Capital would never operate the Comet . The Comet 4 completed its first flight on 27 April 1958 , received its Certificate of Airworthiness on 24 September 1958 , and was first delivered to BOAC the following day . The base price of a new Comet 4 was around £1 , 140 , 000 , equivalent to £ in today ' s pounds . The Comet 4 enabled BOAC to inaugurate the first regular jet - powered transatlantic services on 4 October 1958 between London and New York ( albeit still requiring a fuel stop at Gander International Airport , Newfoundland , on westward North Atlantic crossings ) . While BOAC gained publicity as the first to provide transatlantic jet service , by the end of the month rival Pan American World Airways was flying the Boeing 707 along the same route , and in 1960 the Douglas DC - 8 as well . The American jets were larger , faster , longer - ranged , and more cost - effective to operate than the Comet . After analysing effective route structures for the Comet , BOAC reluctantly cast about for a successor and , by 1958 , entered into an agreement with Boeing to purchase the 707 . The Comet 4 was ordered by two additional customers : Aerolíneas Argentinas took delivery of six Comet 4s from 1959 to 1960 , using them between Buenos Aires and Santiago , while East African Airways received three new Comet 4s from 1960 to 1962 and operated them to the United Kingdom and to Kenya , Tanzania , and Uganda destinations . The Comet 4A model initially ordered by Capital Airlines were instead built for BEA as the Comet 4B , featuring a further fuselage stretch of 38 in ( 97 cm ) and seating for 99 passengers . The first Comet 4B flew on 27 June 1959 and BEA began Tel Aviv to London - Heathrow services on 1 April 1960 . Olympic Airways was the only other customer to order the type . The last Comet 4 variant , the Comet 4C , first flew on 31 October 1959 and entered service with Mexicana in 1960 . The Comet 4C featured the Comet 4B ' s longer fuselage coupled with the longer wings and extra fuel tanks of the original Comet 4 , which gave it a longer range than the 4B . Ordered by East African Airways , Kuwait Airways , Middle East Airlines , Misrair ( later United Arab Airlines ) , and Sudan Airways , it found the greatest customer acceptance of all Comet variants . Later service . In 1959 BOAC began shifting its Comets from transatlantic routes and released the Comet to associate companies , making the Comet 4 ' s ascendancy as a premier airliner brief . Besides the 707 and DC - 8 , the introduction of the Vickers VC10 allowed competing aircraft to assume the high - speed , long - range passenger service role pioneered by the Comet . In 1960 , as part of a government - backed consolidation of the British aerospace industry , de Havilland itself was acquired by Hawker Siddeley , within which it became a wholly owned division . In the 1960s orders declined , with a total of 76 Comet 4s being delivered from 1958 to 1964 . In November 1965 BOAC retired its Comet 4s from revenue service , while other operators continued commercial passenger flights with the Comet until 1981 . Dan - Air played a significant role in the fleet ' s later history and , at one time , owned all 49 remaining airworthy civil Comets . On 14 March 1997 a Comet 4C registered XS235 and named " Canopus " , which had been acquired by the British Ministry of Technology and used for radio , radar and avionics trials , made the last documented production Comet flight . Legacy . The Comet is widely regarded jointly as an adventurous step forward and a supreme tragedy ; nevertheless , the aircraft ' s legacy does include numerous advances in aircraft design and in accident investigations . The inquiries into the accidents that plagued the Comet 1 were perhaps some of the most extensive and revolutionary that have ever taken place , establishing precedents in accident investigation ; many of the deep - sea salvage and aircraft reconstruction techniques employed have remained in use within the aviation industry . In spite of the Comet being subjected to what was then the most rigorous testing of any contemporary airliner , pressurisation and the dynamic stresses involved were not thoroughly understood at the time of the aircraft ' s development , nor was the concept of metal fatigue . While these lessons could be implemented on the drawing board for future aircraft , corrections could be only retroactively applied to the Comet . According to de Havilland ' s chief test pilot John Cunningham , who had flown the prototype ' s first flight , representatives from American manufacturers such as Boeing and Douglas privately disclosed that if de Havilland had not experienced the Comet ' s pressurisation problems first , it would have happened to them . Cunningham likened the Comet to the later Concorde , and added that he had assumed that the aircraft would change aviation , which it subsequently did . Aviation author Bill Withun concluded that the Comet had pushed " ' the state - of - the - art ' beyond its limits . " Aeronautical engineering firms were quick to respond to the Comet ' s commercial advantages and technical flaws alike ; other aircraft manufacturers learned from , and profited by , the hard - earned lessons embodied by de Havilland ' s Comet . While the Comet ' s buried engines were used on some other early jet airliners , such as the Tupolev Tu - 104 , later aircraft , such as the Boeing 707 and Douglas DC - 8 , would differ by employing podded engines held on pylons beneath the wings . Boeing stated that podded engines were selected for their passenger airliners because buried engines carried a higher risk of catastrophic wing failure in the event of engine fire . In response to the Comet tragedies , manufacturers also developed various means of pressurisation testing , often going so far as to explore rapid depressurisation ; subsequent fuselage skins were of a greater thickness than the skin of the Comet . Variants . Comet 1 . The square - windowed Comet 1 was the first model produced , a total of 12 aircraft in service and test . Following closely the design features of the two prototypes , the only noticeable change was the adoption of four - wheel bogie main undercarriage units , replacing the single main wheels . Four Ghost 50 Mk 1 engines were fitted ( later replaced by more powerful Ghost DGT3 series engines ) . The span was 115 ft ( 35 . 05 m ) , and overall length 93 ft ( 28 . 35 m ) ; the maximum takeoff weight was over 105 , 000 lb ( 47 . 628 kg ) and over 40 passengers could be carried . Comet 2 . The Comet 2 had a slightly larger wing , higher fuel capacity and more powerful Rolls - Royce Avon engines , which all improved the aircraft ' s range and performance ; its fuselage was longer than the Comet 1 ' s . Design changes had been made to make the aircraft more suitable for transatlantic operations . Following the Comet 1 disasters , these models were rebuilt with heavier gauge skin and rounded windows , and the Avon engines featuring larger air intakes and outward - curving jet tailpipes . A total of 12 of the 44 - seat Comet 2s were ordered by BOAC for the South Atlantic route . The first production aircraft ( G - AMXA ) flew on 27 August 1953 . Although these aircraft performed well on test flights on the South Atlantic , their range was still not suitable for the North Atlantic . All but four Comet 2s were allocated to the RAF with deliveries beginning in 1955 . Modifications to the interiors allowed the Comet 2s to be used in a number of different roles . For VIP transport , the seating and accommodations were altered while provisions for carrying medical equipment including iron lungs were incorporated . Specialised ELINT and electronic surveillance capability was later added to some airframes . Comet 3 . The Comet 3 , which flew for the first time on 19 July 1954 , was a Comet 2 lengthened by and powered by Avon M502 engines developing . The variant added wing pinion tanks , and offered greater capacity and range . The Comet 3 was destined to remain a development series since it did not incorporate the fuselage - strengthening modifications of the later series aircraft , and was not able to be fully pressurised . Only two Comet 3s began construction with G - ANLO , the only airworthy Comet 3 , demonstrated at the Farnborough SBAC Show in September 1954 . The other Comet 3 airframe was not completed to production standard and was used primarily for ground - based structural and technology testing during development of the similarly sized Comet 4 . Nine additional Comet 3 airframes were not completed and their construction was abandoned at Hatfield . In BOAC colours , G - ANLO was flown by John Cunningham in a marathon round - the - world promotional tour in December 1955 . As a flying testbed , it was later modified with Avon RA29 engines fitted , as well as replacing the original long - span wings with reduced span wings as the Comet 3B and demonstrated in British European Airways ( BEA ) livery at the Farnborough Airshow in September 1958 . Assigned in 1961 to the Blind Landing Experimental Unit ( BLEU ) at RAE Bedford , the final testbed role played by G – ANLO was in automatic landing system experiments . When retired in 1973 , the airframe was used for foam arrester trials before the fuselage was salvaged at BAE Woodford , to serve as the mock - up for the Nimrod . Comet 4 . The Comet 4 was a further improvement on the stretched Comet 3 with even greater fuel capacity . The design had progressed significantly from the original Comet 1 , growing by 18 ft 6 in ( 5 . 64 m ) and typically seating 74 to 81 passengers compared to the Comet 1 ' s 36 to 44 ( 119 passengers could be accommodated in a special charter seating package in the later 4C series ) . The Comet 4 was considered the definitive series , having a longer range , higher cruising speed and higher maximum takeoff weight . These improvements were possible largely because of Avon engines with twice the thrust of the Comet 1 ' s Ghosts . Deliveries to BOAC began on 30 September 1958 with two 48 - seat aircraft , which were used to initiate the first scheduled transatlantic services . The last two Comet 4C fuselages were used to build prototypes of the Hawker Siddeley Nimrod maritime patrol aircraft . A Comet 4C ( SA - R - 7 ) was ordered by Saudi Arabian Airlines with eventual disposition to the Saudi Royal Flight for the exclusive use of King Saud bin Abdul Aziz . Extensively modified at the factory , the aircraft included a VIP front cabin , a bed , special toilets with gold fittings and was distinguished by a resplendent green , gold and white colour scheme with polished wings and lower fuselage that was commissioned from aviation artist John Stroud . Following its first flight , the special order Comet 4C was described as " the world ' s first executive jet . " Comet 5 proposal . The Comet 5 was proposed as an improvement over previous models , including a wider fuselage with five - abreast seating , a wing with greater sweep and podded Rolls - Royce Conway engines . Without support from the Ministry of Transport , the proposal languished as a hypothetical aircraft and was never realised . Hawker Siddeley Nimrod . The last two Comet 4C aircraft produced were modified as prototypes ( XV148 & XV147 ) to meet a British requirement for a maritime patrol aircraft for the Royal Air Force ; initially named " Maritime Comet " , the design was designated Type HS 801 . This variant became the Hawker Siddeley Nimrod and production aircraft were built at the Hawker Siddeley factory at Woodford Aerodrome . Entering service in 1969 , five Nimrod variants were produced . The final Nimrod aircraft were retired in June 2011 . Operators . The original operators of the early Comet 1 and the Comet 1A were BOAC , Union Aéromaritime de Transport , and Air France . All early Comets were withdrawn from service for accident inquiries , during which orders from British Commonwealth Pacific Airlines , Japan Air Lines , Linea Aeropostal Venezolana , National Airlines , Pan American World Airways , and Panair do Brasil were cancelled . When the redesigned Comet 4 entered service , it was flown by customers BOAC , Aerolíneas Argentinas , and East African Airways , while the Comet 4B variant was operated by customers BEA and Olympic Airways , and the Comet 4C model was flown by customers East African Airways , Kuwait Airways , Mexicana , Middle East Airlines , Misrair Airlines , and Sudan Airways . Other operators used the Comet either through leasing arrangements or through second - hand acquisitions . BOAC ' s Comet 4s were leased out to Air Ceylon , Air India , AREA Ecuador , Central African Airways , and Qantas Empire Airways ; after 1965 they were sold to AREA Ecuador , Dan - Air , Mexicana , Malaysian Airways , and the Ministry of Defence . BEA ' s Comet 4Bs were chartered by Cyprus Airways , Malta Airways , and Transportes Aéreos Portugueses . Channel Airways obtained five Comet 4Bs from BEA in 1970 for inclusive tour charters . Dan - Air bought all of the surviving flyable Comet 4s from the late 1960s into the 1970s ; some were for spares reclamation but most were operated on the carrier ' s inclusive tour charters ; a total of 48 Comets of all marks were acquired by the airline . In military service , the United Kingdom ' s Royal Air Force was the largest operator , with the 51 Squadron ( 1958 – 1975 ; Comet C2 , 2R ) , 192 Squadron ( 1957 – 1958 ; Comet C2 , 2R ) , 216 Squadron ( 1956 – 1975 ; Comet C2 and C4 ) , and the Royal Aircraft Establishment using the aircraft . Accidents and incidents . The Comet was involved in 26 hull - loss accidents , including 13 fatal crashes which resulted in 426 fatalities . Pilot error was blamed for the type ' s first fatal accident , which occurred during takeoff at Karachi , Pakistan on 3 March 1953 and involved a Canadian Pacific Airlines Comet 1A . Three fatal Comet 1 crashes due to structural problems , specifically BOAC Flight 783 / 057 on 2 May 1953 , BOAC Flight 781 on 10 January 1954 , and South African Airways Flight 201 on 8 April 1954 , led to the grounding of the entire Comet fleet . After design modifications were implemented , Comet services resumed in 1958 . Pilot error resulting in controlled flight into terrain was blamed for five fatal Comet 4 accidents : an Aerolíneas Argentinas crash near Asunción , Paraguay on 27 August 1959 , Aerolíneas Argentinas Flight 322 at Campinas near São Paulo , Brazil on 23 November 1961 , United Arab Airlines Flight 869 in Thailand ' s Khao Yai mountains on 19 July 1962 , a Saudi Arabian Government crash in the Italian Alps on 20 March 1963 , and United Arab Airlines Flight 844 in Tripoli , Libya on 2 January 1971 . The Dan - Air de Havilland Comet crash in Spain ' s Montseny range on 3 July 1970 was attributed to navigational errors by air traffic control and pilots . Other fatal Comet 4 accidents include a British European Airways crash in Ankara , Turkey following instrument failure on 21 December 1961 , United Arab Airlines Flight 869 during inclement weather near Bombay , India on 28 July 1963 , and the terrorist bombing of Cyprus Airways Flight 284 off the Turkish coast on 12 October 1967 . Nine Comets , including Comet 1s operated by BOAC and Union Aeromaritime de Transport and Comet 4s flown by Aerolíneas Argentinas , Dan - Air , Malaysian Airlines , and United Arab Airlines , were irreparably damaged during takeoff or landing accidents that were survived by all on board . A hangar fire damaged a No . 192 Squadron RAF Comet 2R beyond repair on 13 September 1957 , and three Middle East Airlines Comet 4Cs were destroyed by Israeli troops at Beirut , Lebanon on 28 December 1968 . Aircraft on display . Since retirement , three early - generation Comet airframes have survived in museum collections . The only complete remaining Comet 1 , a Comet 1XB with the registration G - APAS , is displayed at the RAF Museum Cosford . While painted in BOAC colours , it never flew for the airline , having been first delivered to Air France and then to the Ministry of Supply after conversion to 1XB standard ; this aircraft also served with the RAF as XM823 . The sole surviving Comet fuselage with the original square - shaped windows , part of a Comet 1A registered F - BGNX , is undergoing restoration at the de Havilland Aircraft Heritage Centre in Hertfordshire , England . A Comet C2 " Sagittarius " with serial " XK699 " , later maintenance serial 7971M , has been on display at the gate of RAF Lyneham in Wiltshire , England since 1987 . In 2012 , with the planned closure of RAF Lyneham , the aircraft was slated to be dismantled and shipped to the RAF Museum Cosford where it will be re - assembled for display . Seven complete Comet 4s are housed in museum collections . The Imperial War Museum Duxford has a Comet 4 ( G - APDB ) , originally in Dan - Air colours as part of its Flight Line Display , and later in BOAC livery at its AirSpace building . A Comet 4B ( G - APYD ) is stored in a facility at the Science Museum at Wroughton in Wiltshire , England . Comet 4Cs are exhibited at the " " at Hermeskeil , Germany ( G - BDIW ) , the Museum of Flight near Seattle , Washington ( N888WA ) , the National Museum of Flight near Edinburgh , Scotland ( G - BDIX ) , and the " Parque Zoológico Irapuato " in Guanajuato , Mexico ( N777WA ) . The last Comet to fly , Comet 4C " Canopus " ( XS235 ) , is kept in running condition at Bruntingthorpe Aerodrome , where fast taxi runs are regularly conducted . Since the 2000s , various parties have proposed restoring " Canopus " , which is maintained by a staff of volunteers , to airworthy , fully flight - capable condition . The Bruntingthorpe Aerodrome also displays a related Hawker Siddeley Nimrod MR2 aircraft . Specifications . Sources : " Jane ' s All The World ' s Aircraft 1965 – 66 " , " De Havilland Aircraft since 1909 " , and " Flight International " . Other early jet - powered commercial aircraft