The Boeing 747, sometimes nicknamed the "Jumbo Jet",45 is the first wide-body commercial airliner ever produced. Manufactured by Boeing in the United States, it is among the world's most recognizable aircraft.6 The original version of the 747 was two and a half times the size of the Boeing 707,7 one of the common large commercial aircraft of the 1960s. The aircraft is so massive that the wingspan of a 747 is longer than the length of the Wright Brother's first flight. First flown commercially in 1970, it held the passenger capacity record for 37 years.

The four-engine 747, produced by Boeing's Commercial Airplane unit, uses a double deck configuration for part of its length. The 747 is available in passenger, freighter and other versions. The 747's hump created by the upper deck allows for a front cargo door on freighter versions.

The 747-400, the latest version in service, is among the fastest airliners in service with a high-subsonic cruise speed of Mach 0.85 (567 mph or 913 km/h). It has an intercontinental range of 7,260 nautical miles (8,350 mi or 13,450 km).8 The 747-400 passenger version can accommodate 416 passengers in a typical three-class layout or 524 passengers in a typical two-class layout.

The 747 was expected to become obsolete after sales of 400 units because of the development of supersonic airliners,9 but it has outlived many of its critics' expectations, and production passed the 1,000 mark in 1993. As of December 2007, 1,396 aircraft had been built, with 125 more in various configurations on order.10 The latest version of the aircraft, the 747-8, is scheduled to enter service in 2009Development

Background and initial designThe 747 was conceived while air travel was increasing in the 1960s.12 The era of commercial jet transportation, led by the enormous popularity of the Boeing 707 and Douglas DC-8, had revolutionized long-distance travel.13 In 1965, Boeing lost the Heavy Logistics System (CX-HLS) competition for the development of a large military transport, which would eventually result in the Lockheed C-5 Galaxy. Boeing's design proposal was instead considered internally as a basis for a commercial airliner.14 Ultimately, the high-winged CX-HLS Boeing design was not used for the 747, although it may have been an influence.15 The development team did not use design concepts from the CX-HLS proposal other than those related to its high-bypass turbofan engine technology.1617 Even before it lost the CX-HLS contract to Lockheed in September 1965, Boeing was pressed by Juan Trippe, president of Pan American World Airways (Pan Am), one of its most important airline customers, to build a passenger airplane more than twice the size of the 707. During this time, airport congestion, worsened by increasing numbers of passengers carried on relatively small planes, became a problem that Trippe thought could be addressed by a large new aircraft.18

In 1965, Joseph Sutter was transferred from Boeing's 737 development team to manage the studies for a new airliner, already assigned the model number 747.19 Developing the aircraft was such a technical and financial challenge that management was said to have "bet the company" when it started the project.1 The original design included a full-length double-deck fuselage with rows of eight-across seating and two aisles on the lower deck and seven-across seating and two aisles on the upper deck.20 However, concern over evacuation routes and limited cargo-carrying capability caused this idea to be scrapped in early 1966 in favor of a wider single deck design.1 Boeing agreed to deliver the first 747 to Pan Am by the end of 1969. The delivery date left 28 months to design the aircraft, which was two-thirds the normal time.21

In April 1966, Pan Am ordered twenty-five 747-100 aircraft for US$525 million. During the ceremonial 747 contract-signing banquet in Seattle on Boeing's 50th Anniversary, Juan Trippe predicted that the 747 would be "... a great weapon for peace, competing with intercontinental missiles for mankind's destiny", according to Malcolm T. Stamper, one of the senior management for the 747 program at the time.6 As launch customer,122 and because of its early involvement before placing a formal order, Pan Am was able to influence the design and development of the 747 to an extent unmatched by a single airline before or since.23

One of the principal technologies that enabled an airplane as large as the 747 to be conceived was the high-bypass turbofan engine.16 The engine technology was thought to be capable of delivering double the power of the earlier turbojets while consuming a third less fuel. General Electric had pioneered the concept but was committed to developing the engine for the C-5 Galaxy and did not enter the commercial market until later.2425 Pratt & Whitney was also working on the same principle and, by late 1966, Boeing, Pan-Am and Pratt & Whitney agreed to develop a new engine, designated JT9D, to power the 747.25 Four of these engines were to be mounted in pods below the 747's wings.

Safety was a high priority on a large passenger airplane such as the 747. It was designed with a new methodology called fault tree analysis, which allowed the effects of a failure of a single part to be studied to determine its impact on other systems.1 To address concerns about safety and flyability, the 747's design included structural redundancy, redundant hydraulic systems, quadruple main landing gear and split control surfaces.26

The prototype 747, City of Everett, at the Museum of Flight in Seattle, WashingtonAt the time, it was widely thought that the 747 would eventually be superseded by supersonic transport aircraft.27 Boeing designed the 747 so that it could be adapted easily to carry freight and remain in production even if sales of the passenger version declined. The cockpit was, therefore, placed on a shortened upper deck so that a freight-loading door could be included in the nose cone; this design feature produced the 747's distinctive "bulge".12 However, the predicted obsolescence of the 747 by supersonic transports (SST), such as the Concorde, Tupolev Tu-144 and the canceled Boeing 2707, never occurred; SSTs were not widely adopted because of high fuel consumption, noise, and sonic boom restrictions.2829

Production plantBecause Boeing did not have a plant large enough to assemble the giant airliner, it chose to build a new one. The company considered locations in about 50 cities,30 and eventually decided to build the new plant some 30 miles (48 km) north of Seattle on a site adjoining a military base at Paine Field near Everett, Washington.31 It bought the 780 acre (316 hectare) site in June 1966.32

Developing the 747 had been a major challenge, and building its assembly plant was also a huge undertaking. Boeing president William M. Allen asked Malcolm T. Stamper, then head of the company's turbine division, to oversee construction of the Everett factory and to start production of the 747.33 To level the site, more than 4 million cubic yards (3.1 million m³) of earth had to be moved.34 Time was so short that the 747's full-scale mock-up was built before the factory roof above it was finished.35 Boeing had promised to deliver the 747 to Pan Am by 1969, which gave it less than four years to develop, build and certify. Work progressed so quickly that the plane's developers became known as "The Incredibles".17 The plant is the largest building by volume ever built.1731

Development and testingBefore the first 747 was fully assembled, testing began on many components and systems. One important test involved evacuation of 560 volunteers from a cabin mock-up via the plane's emergency chutes. The first full-scale evacuation took two and a half minutes instead of the maximum of 90 seconds mandated by the Federal Aviation Administration, and several volunteers were injured. Subsequent test evacuations achieved the 90-second goal but caused more injuries. Most problematic was evacuation from the airplane's upper deck; volunteer passengers, instead of using a conventional slide, escaped by using a harness attached to a reel.36

Boeing built an unusual training device known as "Waddell's Wagon" (named for a 747 test pilot, Jack Waddell) that consisted of a mock-up cockpit mounted on the roof of a truck. While the first 747s were still being built, the device allowed pilots to practice taxi maneuvers from a high upper-deck position.17

Uniformed flight attendants representing each of the 747's initial 26 airline customers during rollout ceremonyOn 30 September 1968, the first 747 was rolled out of the Everett assembly building before the world's press and representatives of the 26 airlines that had ordered the plane.37

Over the following months, preparations were made for the first flight, which took place on 9 February 1969, with test pilots Jack Waddell and Brien Wygle at the controls3839 and Jess Wallick at the flight engineer's station. Despite a minor problem with one of the flaps, the flight confirmed that the 747 handled extremely well. The plane was found to be largely immune to "Dutch roll", a phenomenon that had been a major hazard to the early swept-wing jets.40

During later stages of the flight test program, flutter testing showed that the wings suffered oscillation under certain conditions. This difficulty was partly solved by reducing the stiffness of some wing components. However, a particularly severe high-speed flutter problem was solved only by inserting depleted uranium counterweights as ballast in the outboard engine nacelles of the early 747s.41 This measure caused anxiety when these aircraft crashed, as did China Airlines Flight 358 at Wanli in 1991 and El Al Flight 1862 at Amsterdam in 1992.4243

The flight test program was hampered by problems with the plane's JT9D engines. Difficulties included engine stalls caused by rapid movements of the throttles and distortion of the turbine casings after a short period of service.44 The problems delayed 747 deliveries for several months and stranded up to 20 planes at the Everett plant while they awaited engine installation.45 The program was further delayed when the one of five test aircraft suffered serious damage during a landing attempt at Renton Municipal Airport, site of Boeing's Renton plant. The test aircraft was being taken to have its test equipment removed and a cabin installed when pilot Ralph C. Cokely undershot the short runway and sheared off the 747's landing gear.46 However, these difficulties did not prevent Boeing from taking one of the test aircraft to the 28th Paris Air Show in mid-1969, where it was displayed to the general public for the first time.47 The 747 achieved its FAA airworthiness certificate in December 1969, making it ready for introduction into service.48

The huge cost of developing the 747 and building the Everett factory meant that Boeing had to borrow heavily from a banking syndicate. During the final months before delivery of the first airplane, the company had to repeatedly request additional funding to complete the project. Had this been refused, Boeing's survival would have been threatened.4922 Ultimately, the gamble succeeded, and Boeing held a monopoly in very large passenger aircraft production for many years.50

Entry into serviceOn 15 January 1970, First Lady of the United States Patricia Nixon christened Pan Am's first 747 at Dulles International Airport (later renamed Washington Dulles International Airport) in the presence of Pan Am chairman Najeeb Halaby. Instead of champagne, red, white and blue water was sprayed on the plane. The 747 entered service on 22 January 1970, on Pan Am's New York–London route;51 the flight had been planned for the evening of 21 January, but engine overheating made the original airplane unusable. Finding a substitute delayed the flight by more than six hours to the following day.52

The 747 enjoyed a fairly smooth introduction into service, overcoming concerns that some airports would not be able to accommodate an airplane that large.53 Though technical problems occurred, they were relatively minor and quickly solved.54 After the aircraft's introduction with Pan Am, other airlines that had bought the 747 in order to stay competitive began to put their own planes into service.5556 Boeing estimated that half of the early 747 sales were to airlines requiring the airplane's long range rather than its payload capacity.57 But though the 747 had the lowest potential operating cost per seat, this could only be achieved when the aircraft was fully loaded; costs per seat increased rapidly as occupancy declined. Fuel consumption for a moderately loaded 747, one with only 70 percent of its seats occupied, used more than 95 percent of the fuel needed by a fully occupied 747. High costs resulted when the large aircraft carried few passengers.58

When economic problems in the United States and other countries after the 1973 oil crisis led to reduced passenger traffic, several airlines found they did not have enough passengers to fly the 747 economically, and they replaced them with the recently introduced and smaller McDonnell Douglas DC-10 and Lockheed L-1011 trijet wide bodies59 (and later the twinjet 767 and A300). Having tried replacing coach seats on its 747s with piano bars in an attempt to attract more customers, American Airlines eventually relegated its 747s to cargo service and in 1983 exchanged them with Pan Am for smaller aircraft;60 Delta Airlines also removed its 747s from service after several years.61

International flights that bypassed traditional hub airports and landed at smaller cities became more common throughout the 1980s, and this eroded the 747's original market.62 However, many international carriers continued to use the 747 on Pacific routes.63 In Japan, 747s on domestic routes are configured to carry close to the maximum passenger capacity.64

The 747 rapidly achieved iconic status, appearing in various film productions such as the Airport series of disaster films, Air Force One and Executive Decision.6566

Further developmentsAfter the initial 747-100 model, Boeing developed the higher Maximum Takeoff Weight -100B variant and higher passenger capacity -100SR (Short Range) variant.67 Increased maximum takeoff weight, or MTOW, can allow an aircraft to carry more fuel and have longer range.68 The -200 model followed, entering service in 1971. It featured more powerful engines and higher takeoff weight. Passenger, freighter and combination passenger-freighter versions were produced.67 The shortened 747SP (special performance) with a longer range was also developed in the mid-1970s.69

Flight deck of 747-200The 747 line was further developed with the launching of the 747-300 in 1980. The -300 resulted from Boeing studies to increase the seating capacity of the 747. Solutions such as fuselage plugs and extending the upper deck over the entire length of the fuselage were rejected. The early designation of the -300 was 747SUD for "stretched upper deck" then 747-200 SUD,70 followed by 747EUD, before the 747-300 designation was used.71 The 300 model was first produced in 1983. It included a stretched upper deck (SUD), increased cruise speed and increased seating capacity. Passenger, short range and combination freighter-passenger versions were produced.67

In 1985, development of the longer range 747-400 was begun.72 The new variant had a new glass cockpit, which allowed for a cockpit crew of two instead of three.73 Development cost soared, and production delays occurred as new technologies were incorporated at the request of airlines. Insufficient workforce experience and reliance on overtime contributed to early production problems on the 747-400.1 The -400 entered service in 1989.74

Since the arrival of the 747-400, several stretching schemes for the 747 have been proposed. Boeing announced the larger 747-500X and -600X designs in 1996.75 The new variants would have cost more than $5 billion to develop,75 and interest was not sufficient to launch the program.76 Boeing offered the more modest 747X and 747X stretch derivatives in 2000 as alternatives to the Airbus A3XX. However, the 747X family was unable to attract enough interest to enter production. Boeing switched from the 747X studies to pursue the Sonic Cruiser in 200177 and, after the Sonic Cruiser program was put on hold, the 787.78 Some of the ideas developed for the 747X were used on the 747-400ER.79 After several variants were proposed but later abandoned, some industry observers became skeptical of new aircraft proposals from Boeing.80 However, in early 2004, Boeing announced tentative plans for the 747 Advanced that were eventually adopted. Similar in nature to the 747-X, the stretched 747 Advanced used technology from the 787 to modernize the design and its systems.

A size comparison of four large aircraft: the Spruce Goose, an Antonov An-225, an Airbus A380, and a 747-8On 14 November 2005, Boeing announced it was launching the 747 Advanced as the Boeing 747-8.81 Long delays in production of the Airbus A380 helped the 747-8 order book. Two Airbus customers signed additional 747-8 orders;8283 two customers cancelled their A380 orders, and several launch customers deferred delivery or considered switching to the 747-8 and 777F aircraft.8485

The 747 remained the largest passenger airliner in service until the Airbus A380 began airline service in 2007.86 In 1991, a record-breaking 1,087 passengers were airlifted aboard a 747 to Israel as part of Operation Solomon.87 The 747 was the heaviest airliner in regular service until the use of the Antonov An-124 Ruslan in 1982. The 747-400ER model regained that distinction in 2000. The Antonov An-225 cargo transport remains the world's largest aircraft by several measures (including the most accepted measures of maximum gross takeoff weight and length). The Hughes H-4 Hercules is the largest aircraft by wingspan, but it only flew once.88 Only two An-225 aircraft have been produced, and only one is still flying as of 2007, while the 747 and A380 are made for serial mass production.

Some 747 aircraft have been converted for special uses. A 747-100 owned by General Electric is used as a testbed for their engines8990 such as General Electric GEnx.91 A firefighting prototype has been constructed by Evergreen International.92 Eventually, the 747 may be replaced by a new design dubbed "Y3".

DesignThe Boeing 747 is a large, wide-body (two-aisle) airliner with four wing-mounted engines. The wings have a high sweep angle of 37.5 degrees for a fast, efficient cruise93 of Mach 0.84 to 0.88, depending on the variant. The sweep also allows the 747 to use existing hangars.194 Seating capacity is more than 366 with a 3-4-3 seat arrangement (a cross section of 3 seats, an aisle, 4 seats, another aisle, and 3 seats) in economy class and a 2-3-2 arrangement in first class on the main deck. The upper deck has a 3-3 seat arrangement in economy class and a 2-2 arrangement in first class.95

Cargolux 747-400F with the nose loading door openRaised above the main deck, the cockpit creates a hump. The raised cockpit is to allow front loading of cargo on freight variants.93 The upper deck behind the cockpit provides space for a lounge or extra seating. The "stretched upper deck" became available as an option on the 747-100B variant and later as standard on the 747-300.

The 747's maximum takeoff weight ranges from 735,000 pounds (333,400 kg) for the -100 to 970,000 lb (439,985 kg) for the -8. Its range has increased from 5,300 nautical miles (6,100 mi, 9,800 km) on the -100 to 8,000 nmi (9,200 mi, 14,815 km) on the -8I.9697

The 747 has multiple structural redundancy including four redundant hydraulic systems and four main landing gears with 16 wheels, which provide a good spread of support on the ground and safety in case of tire blow-outs. The redundant main gear allows for landing on two opposing landing gears if the others do not function properly.98 In addition, the 747 has split control surfaces and sophisticated triple-slotted flaps that minimize landing speeds and allow the plane to use standard-length runways.99 For transportation of spare engines, early 747s could accommodate a non-functioning fifth-pod engine under the port wing of the aircraft between the nearest functioning engine and the fuselage.100101

VariantsThe 747-100 was the original variant launched in 1966. The 747-200 soon followed, with an order in 1968. The 747-300 was launched in 1980 and was followed in 1985 by the 747-400. Lastly, the 747-8 was announced in 2005. Several versions of each variant have been produced. Many of the early variants were in production simultaneously.

747-100 Pan Am 747-100 illustrating the original size of the upper deck design and window layoutThe first 747-100s were built with six upper-deck windows (three per side) to accommodate upstairs lounge areas. Later, as airlines began to use the upper-deck for premium passenger seating instead of lounge space, Boeing offered a 10-window upper deck as an option. Some -100s were retrofitted with the new configuration.102

A 747-100B version, which has a stronger airframe and undercarriage design as well as an increased maximum takeoff weight (MTOW) of 750,000 pounds (340,000 kg) was offered. The 747-100B was delivered only to Iran Air and Saudia (now Saudi Arabian Airlines).103 Optional engine models were offered by Rolls-Royce (RB211) and GE (CF6), but only Saudia ordered the Rolls-Royce option.104

No freighter version of this model was developed by Boeing. However, 747-100s have been converted to freighters.105 A total of 250 -100s (all versions, including the 747SP) were produced; the last one was delivered in 1986.106 Of these, 167 were 747-100, 45 were SP, 29 were SR, and 9 were 100B.107

747-100SR A Shuttle Carrier Aircraft, a modified 747-100SRResponding to requests from Japanese airlines, Boeing developed the 747-100SR as a "short range" variant of the 747-100. The SR has a lower fuel capacity but can carry more passengers, up to 498 in early versions and more than 550 in later models,67 because of increased economy class seating. The 747SR has a modified body structure to accommodate the added stress accumulated from a greater number of takeoffs and landings.108 The -100SR entered service with Japan Airlines (then Japan Air Lines) on 7 October 1973.32 Later, short range versions of the -100B and the -300 were also developed. The SR airplanes are used primarily on domestic flights in Japan.109

Two 747-100B/SRs were delivered to Japan Airlines (JAL) with a stretched upper deck to accommodate more passengers. This modification is known as the "SUD" (stretched upper deck).110111

All Nippon Airways (ANA) operated 747SRs on domestic Japanese routes with 455 or 456 seats but retired the last aircraft on 10 March 2006.112 JAL operated the 747-100B/SR/SUD variant with 563 seats on domestic routes, and retired these planes in the third quarter of 2006. JAL and JALways have operated the -300SRs on domestic leisure routes and to other parts of Asia.

747SPMain article: Boeing 747SP Bahrain Royal Flight Boeing 747SP climbing. The undercarriages have not yet fully retracted.The 747SP is 48 feet and four inches shorter than the 747-100. Apart from the planned 747-8, the SP is the only 747 with a fuselage of modified length. Fuselage sections were eliminated fore and aft of the wing, and the center section of the fuselage was redesigned. Single-slotted flaps replaced the complex triple-slotted Fowler flaps of the 100 series.113 The under-wing "canoes", which housed the flap mechanisms on full-size 747s, were eliminated entirely on the SP.114 The 747SP, compared to earlier variants, had a tapering of the aft upper fuselage into the empennage, a double hinged rudder, and longer vertical and horizontal stabilizers.115

The Boeing 747SP was granted a supplemental certificate on 4 February 1976 and entered service with Pan American World Airways, the launch customer, that same year.114

A total of forty-five 747SPs were built.116 The 44th 747SP was delivered on 30 August 1982. Boeing re-opened the 747SP production line to build one last 747SP five years later in 1987 for an order by the United Arab Emirates government.114

As of August 2007, 17 Boeing 747SP aircraft were in service with Iran Air (3), Saudi Arabian Airlines (1), Syrian Arab Airlines (2) and as executive versions. NASA's Dryden Flight Research Center has one modified for the SOFIA experiment.117

747-200The 747-200 has more powerful engines, higher takeoff weights (MTOW), and range than the -100. A few early -200s retained the three-window configuration of the -100 on the upper deck, but most were built with a 10-window configuration on each side.118

Air France 747-200 in landing configurationSeveral versions in addition to the -200 were produced. The 747-200B is an improved version of the 747-200, with increased fuel capacity and more powerful engines; it first entered service in February 1971.119 The -200B aircraft has a full load range of about 6,857 nmi (12,700 km). The 747-200F is the freighter version of the -200 model. It could be fitted with or without a side cargo door.119 It has a capacity of 105 tons (95.3 tonnes) and a MTOW of up to 833,000 lb (378,000 kg). It entered first service in 1972 with Lufthansa.120 The 747-200C Convertible is a version that can be converted between a passenger and a freighter or used in mixed configurations.67 The seats are removable, and the model has a nose cargo door.119 The -200C could be fitted with an optional side cargo door on the main deck.121

The 747-200M is a combination version that has a side cargo door on the main deck and can carry freight in the rear section of the main deck. A removable partition on the main deck separates the cargo area at the rear from the passengers at the front. This model can carry up to 238 passengers in a 3-class configuration if cargo is carried on the main deck. The model is also known as the 747-200 Combi.119 As on the -100, a stretched upper deck (SUD) modification was later offered. A total of 10 converted 747-200s were operated by KLM.119 UTA French Airlines also had two of these aircraft converted.122123

A total of 393 of the -200 versions had been built when production ended in 1991.124 Of these, 225 were 747-200s, 73 were 747-200F, 13 were 747-200C, 78 were 747-200M, and 4 were military.125

747-300 Pakistan International Airlines (PIA) 747-300 on final approach to London Heathrow AirportThe differences between the -300 and the -200 include a lengthened upper deck with two new emergency exit doors and an optional flight-crew rest area immediately aft of the flight deck. Compared to the -200, the upper deck is 23 feet 4 inches longer (7.11 m) than the -200.126 A new straight stairway to the upper deck instead of a spiral staircase is another difference between the -300 and earlier variants.67 The staircase creates room below and above for more seats. With minor aerodynamic changes, Boeing increased the cruise speed of the -300 to Mach 0.85 from Mach 0.84 on the -100/-200.126 The -300 features the same takeoff weight. Two of the three engine choices from the -200 were unchanged in the -300, but the General Electric CF6-80C2B1 was offered instead of the CF6-50E2 offered on the -200.67

The 747-300 name, which was proposed for a variant that was never launched, was revived for this new version, which was introduced in 1980. Swissair ordered the first 747-300 on 11 June 1980.127 The 747-300 first flew on 5 October 1982. Swissair was the first customer to accept delivery on 23 March 1983.32

In addition to the passenger version, other versions were available. The 747-300M has cargo capacity in the rear portion of the main deck similar to the -200M, but with the stretched upper deck it can carry more passengers.128 The 747-300SR is a short range version to meet the need for a high-capacity domestic model. Japan Airlines operated such aircraft with more than 600 seats on the Okinawa–Tokyo route and elsewhere. Boeing never launched a newly built freighter version of the 747-300, but it modified used passenger -300 models into freighters starting in 2000.129

A total of 81 aircraft were ordered, 56 for passenger use, 21 -300M and 4 -300SR versions.130 The 747-300 was soon superseded by the launch of the more advanced 747-400 in 1985, just two years after the -300 entered service.131 The last 747-300 was delivered in September 1990 to Sabena.67132

747-400Main article: Boeing 747-400 An Air India Boeing 747-400. The winglet is a noticeable difference between most 400s and other variantsThe 747-400 is an improved model with increased range. It has wing-tip extensions of 6 feet (1.8 m), winglets of 6 feet (1.8 m), and a new glass cockpit designed for a flight crew of two instead of three. The use of electronics reduced the number of dials, gauges, and knobs from 971 to 365. It has tail fuel tanks, revised engines, and a new interior. The longer range was used by some airlines to bypass traditional fuel stops, such as Anchorage.133 The -400 was offered in passenger (400), freighter (400F), combi (400C), domestic (400D), extended range passenger (400ER) and extended range freighter (400ERF) versions. The freighter version does not have an extended upper deck.134 The 747-400D was built for short range operations and does not include winglets, but these can be retrofitted.135

The passenger version first entered service in February 1989 with Northwest Airlines on the Minneapolis to Phoenix route.74 The combi version entered service in September 1989 with KLM. The freighter version entered service in November 1993 with Cargolux. The 747-400ERF entered service in October 2002, and the 747-400ER entered service the following month with Qantas,136 the only airline ever to order the passenger version.

The last passenger version of the 747-400 was delivered in April 2005. Boeing announced in March 2007 that it had no plans to produce further passenger versions of the -400.137 However, orders for 36 -400F and -400ERF freighters were already in place at the time of the announcement.137

In October 2007, a total of 670 of the 747-400 series aircraft had been delivered.138 At various times, the largest 747-400 operator has been Singapore Airlines,139 Japan Airlines,139 and British Airways.140

747 LCF Dreamlifter Boeing 747 Large Cargo Freighter, also called Dreamlifter, is modified from 747s previously in airline use. The aircraft in the photo is shown before painting.Main article: Boeing 747 Large Cargo FreighterThe 747-400 Large Cargo Freighter or Dreamlifter141 (originally called the 747 Large Cargo Freighter or LCF)142 is a Boeing-designed modification of existing 747-400s to a larger configuration to ferry Boeing 787 sub-assemblies to the Boeing plant in Everett, Washington, for final assembly. Evergreen Aviation Technologies Corporation is completing modifications of 747-400s into Dreamlifters in Taiwan. The aircraft flew for the first time on 9 September 2006.143 The Dreamlifter's only intended purpose is to transport sub-assemblies for the Boeing 787.144 The aircraft is certified to carry only essential crew and not passengers.145 Two aircraft have been built, and two more are on order.142

747-8Main article: Boeing 747-8Boeing announced a new 747 variant, the 747-8 (referred to as the 747 Advanced prior to launch) on November 14, 2005, which will use same engine and cockpit technology as the 787 (It was decided to call it the 747-8 because of the technology it will share with the 787 Dreamliner.) Plans call for the new design to be quieter, more economical and more environmentally friendly. The 747-8 is stretched to add more payload capacity. This involves lengthening from 232 to 251 feet (70.8 to 76.4 m), surpassing the Airbus A340-600 to become the world's longest airliner.146

Artist's impression of a Boeing 747-8 Intercontinental in the colors of Lufthansa, the launch customerThe passenger version, dubbed 747-8 Intercontinental or 747-8I, will be able to carry up to 467 passengers in a 3-class configuration and fly more than 8,000 nmi to (14,815 km) at Mach 0.855. As a derivative of the already common 747-400, the 747-8 has the economic benefit of similar training and interchangeable parts.147 The 747-8I is scheduled to enter service in 2010.148

Also offered is the 747-8 Freighter or 747-8F, which derives from the 747-400ERF. The 747-8F is 251 feet (76.4 m) long and can accommodate 154 tons (140 tonnes) of cargo. To aid loading and unloading, it features an overhead nose-door. It has 16 percent more payload capacity than the 747-400F and can hold seven additional standard air cargo containers. The 747-8F is scheduled to enter service in 2009.149

As of December 2007, there were 78 firm orders for the Boeing 747-8F, from Cathay Pacific (10), Atlas Air (12), Nippon Cargo Airlines (14), Cargolux (13), Emirates SkyCargo (10), Volga-Dnepr (5), Guggenheim Aviation Partners (4) and Korean Air (5). A total of 25 firm orders had been placed for the Boeing 747-8I; of these, 5 were from Boeing Business Jet and 20 from Lufthansa.150

Government and military variants 20-1101 Japanese Air Force One, one of the two customized Boeing 747-400s that have been part of the Japan Air Self-Defense Force since 1993 VC-25A 29000, one of the two customized Boeing 747-200Bs that have been part of the U.S. presidential fleet since 1990C-19 – The U.S. Air Force gave this designation to the 747-100s used by some U.S. airlines and modified for use in the Civil Reserve Airlift Fleet.151 VC-25 – This aircraft is the U.S. Air Force Very Important Person (VIP) version of the 747-200B. The U.S. Air Force operates two of them in VIP configuration as the VC-25A. Tail numbers 28000 and 29000 are popularly known as Air Force One, which is technically the air-traffic call sign for any United States Air Force aircraft carrying the U.S. President. Although based on the 747-200B design, they contain many of the innovations introduced on the 747-400, such as an updated flight deck and engines. Partially completed aircraft from Everett, Washington, were flown to Wichita, Kansas, for final assembly, in contrast with civilian aircraft, which are completed in Everett. E-4B – Formerly known as the National Emergency Airborne Command Post (referred to colloquially as "Kneecap"), this aircraft is now referred to as the National Airborne Operations Center (NAOC). YAL-1 – This is the experimental Airborne Laser, a component of the National Missile Defense plan. Shuttle Carrier Aircraft – Two 747s were modified to carry the Space Shuttle. One is a 747-100 (N905NA), acquired in 1974 from American Airlines; the other is a 747-100SR (N911NA), acquired from Japan Airlines in 1988. It first carried a shuttle in 1991. A number of other governments also use the 747 as a VIP transport, including Bahrain, Brunei, India, Iran, Japan, Kuwait, Oman, Pakistan, Qatar, Saudi Arabia and United Arab Emirates. Several new Boeing 747-8s have been ordered by Boeing Business Jet for conversion to VIP transport for several unidentified customers.152 C-33 – This aircraft was a proposed U.S. military version of the 747-400 intended to augment the C-17 fleet. The plan was canceled in favor of additional C-17 military transports. KC-33A – A proposed 747 was also adapted as an aerial refueling tanker and was bid against the DC-10-30 during the 1970s Advanced Cargo Transport Aircraft (ACTA) program that produced the KC-10A Extender. Before the Khomeini-led revolution, Iran bought four 747-100 aircraft with air-refueling boom conversions to support a fleet of F-4 Phantoms.153154 It is unknown whether these aircraft remain usable as tankers. Since then, other proposals have emerged for adaptation of later 747-400 aircraft for this role.153 747 CMCA – This variant was considered by the U.S. Air Force as a Cruise Missile Carrier Aircraft during the development of the B-1 Lancer strategic bomber. It would have been equipped with 50 to 100 AGM-86 ALCM cruise missiles on rotary launchers. This plan was abandoned in favor of more conventional strategic bombers.155

Undeveloped variantsBoeing has studied a number of 747 variants that have not gone beyond the concept stage.

747-300 TrijetDuring the 1970s, Boeing studied the development of a shorter body, three-engined 747 to compete with the smaller Lockheed L-1011 TriStar and McDonnell Douglas DC-10, which had lower trip costs than the 747SP. The 747-300 Trijet would have had more payload, range and passenger capacity. The center engine would have been fitted in the tail with an S-duct intake similar to the L-1011's. However, engineering studies showed that a time-consuming and costly redesign of the 747 wing would be necessary.156

747-500X, -600X and -700XBoeing announced the 747-500X and -600X at the 1996 Farnborough Air Show.75 The proposed models would have combined the 747's fuselage with a new 251 ft (77 m) span wing derived from the 777. Other changes included adding more powerful engines and increasing the number of tires from two to four on the nose landing gear and from 16 to 20 on the main landing gear.157

The 747-500X concept featured an 18 ft (5.5 m) stretch to 250 ft (76.2 m) long, and the aircraft was to carry 462 passengers over a range up to 8,700 nautical miles (10,000 mi, 16,100 km), with a gross weight of over 1.0 Mlb (450 Mg).157 The 747-600X concept featured a greater stretch to 279 ft (85 m) with seating for 548 passengers, a range of up to 7,700 nmi (8,900 mi, 14,300 km), and a gross weight of 1.2 Mlb (540 Mg).157 A third study concept, the 747-700X, would have combined the wing of the 747-600X with a widened fuselage, allowing it to carry 650 passengers over the same range as a 747-400.75 The cost of the changes from previous 747 models, in particular the new wing for the 747-500X and -600X, was estimated to be more than $5 billion.75 Boeing was not able to attract enough interest to launch the aircraft.76

747X and 747X StretchAs Airbus progressed with its A3XX study, Boeing in 2000 offered the market a 747 derivative as an alternative. This was a more modest proposal than the previous -500X and -600X that would retain the 747's overall wing design and add a segment at the root, increasing the span to 229 ft (70 m).158 Power would have been supplied by either the Engine Alliance GP7172 or the Rolls-Royce Trent 600, which were also proposed for the 767-400ERX.159 A new flight deck based on the 777's would be used. The 747X aircraft was to carry 430 passengers over ranges of up to 8,700 nmi (10,000 mi, 16,100 km). The 747X Stretch would be extended to 263 ft (80.2 m) long, allowing it to carry 500 passengers over ranges of up to 9,000 miles (7,800 nmi, 14,500 km).158 Both would feature an interior based on the 777's signature architecture.160 Freighter versions of the 747X and 747X Stretch were also studied.161

Like its predecessor, the 747X family was unable to garner enough interest to justify production, and it was shelved along with the 767-400ERX in March 2001, when Boeing announced the Sonic Cruiser concept.77 Though the 747X design was less costly than the 747-500X and -600X, it was criticized for not offering a sufficient advance from the existing 747-400. The 747X did not make it beyond the drawing board, but the 747-400X being developed concurrently moved into production to become the 747-400ER.162

747-400XQLRAfter the end of the 747X program, Boeing continued to study improvements that could be made to the 747. The 747-400XQLR (Quiet Long Range) was meant to have an increased range of 7,980 nmi (9,200 mi, 14,800 km), with improvements to improve efficiency and reduce noise.163 Improvements studied included raked wingtips similar to those used on the 767-400ER and a sawtooth engine nacelle for noise reduction.164 Although the 747-400XQLR did not move to production, many of its features were used for the 747 Advanced, which has now been launched as the 747-8..