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The Boeing 777, commonly referred to as the Triple Seven, is an American long-range wide-body airliner developed and manufactured by Boeing Commercial Airplanes. The 777 is the world's largest twinjet and the most-built wide-body airliner.

The jetliner was designed to bridge the gap between Boeing's other wide body airplanes, the twin-engined 767 and quad-engined 747, and to replace aging DC-10 and L-1011 trijets. Developed in consultation with eight major airlines, the 777 program was launched in October 1990, with an order from United Airlines. The prototype was rolled out in April 1994, and first flew in June. The 777 entered service with the launch operator United Airlines in June 1995. Longer-range variants were launched in 2000, and first delivered in 2004.

The 777 can accommodate a ten–abreast seating layout and has a typical 3-class capacity of 301 to 368 passengers, with a range of 5240 to 8555 nmi. The jetliner is recognizable for its large-diameter turbofan engines, six wheels on each main landing gear, fully circular fuselage cross-section, and a blade-shaped tail cone. The 777 became the first Boeing airliner to use fly-by-wire controls and to apply a carbon composite structure in the tailplanes.

The original 777 with a maximum takeoff weight (MTOW) of 545,000-660,000 lb was produced in two fuselage lengths: the initial 777-200 was followed by the extended-range -200ER in 1997; and the 33.25 ft longer 777-300 in 1998. These 777 Classics were powered by 77,200-98000 lbf General Electric GE90, Pratt & Whitney PW4000, or Rolls-Royce Trent 800 engines. The extended-range 777-300ER, with a MTOW of 700,000-775,000 lb, entered service in 2004, the longer-range 777-200LR in 2006, and the 777F freighter in 2009. These longer-haul variants use 110,000–115,300 lbf GE90 engines and have extended raked wingtips. In November 2013, Boeing announced the 777X development with the -8 and -9 variants, both featuring composite wings with folding wingtips and General Electric GE9X engines.

, Emirates was the largest operator with a fleet of 163 aircraft. , more than 60 customers have placed orders for 2,268 Triple Sevens across all variants, of which 1,727 have been delivered. This makes the 777 the best-selling wide-body airliner, while its best-selling variant is the 777-300ER with 837 aircraft ordered and 832 delivered. The airliner initially competed with the Airbus A340 and McDonnell Douglas MD-11; since 2015 it has mainly competed with the Airbus A350 and later also with the A330-900. , the 777 has been involved in 30 aviation accidents and incidents, including five hull loss accidents out of eight total hull losses with fatalities including one ground casualty.

Background


In the early 1970s, the Boeing 747, McDonnell Douglas DC-10, and the Lockheed L-1011 TriStar became the first generation of wide-body passenger airliners to enter service. In 1978, Boeing unveiled three new models: the twin-engine or twinjet Boeing 757 to replace its 727, the twinjet 767 to challenge the Airbus A300, and a trijet 777 concept to compete with the DC-10 and L-1011. The mid-size 757 and 767 launched to market success, due in part to 1980s' extended-range twin-engine operational performance standards (ETOPS) regulations governing transoceanic twinjet operations. These regulations allowed twin-engine airliners to make ocean crossings at up to three hours' distance from emergency diversionary airports. Under ETOPS rules, airlines began operating the 767 on long-distance overseas routes that did not require the capacity of larger airliners. The trijet 777 was later dropped, following marketing studies that favored the 757 and 767 variants. Boeing was left with a size and range gap in its product line between the 767-300ER and the 747-400.

By the late 1980s, DC-10 and L-1011 models were approaching retirement age, prompting manufacturers to develop replacement designs. McDonnell Douglas was working on the MD-11, a stretched successor of the DC-10, while Airbus was developing its A330 and A340 series. In 1986, Boeing unveiled proposals for an enlarged 767, tentatively named 767-X, to target the replacement market for first-generation wide-bodies such as the DC-10, and to complement existing 767 and 747 models in the company lineup. The initial proposal featured a longer fuselage and larger wings than the existing 767, along with winglets. Later plans expanded the fuselage cross-section but retained the existing 767 flight deck, nose, and other elements. However, airline customers were uninterested in the 767-X proposals, and instead wanted an even wider fuselage cross-section, fully flexible interior configurations, short- to intercontinental-range capability, and an operating cost lower than that of any 767 stretch.

Airline planners' requirements for larger aircraft had become increasingly specific, adding to the heightened competition among aircraft manufacturers. By 1988, Boeing realized that the only answer was a clean-sheet design, which became the twinjet 777. The company opted for the twin-engine configuration given past design successes, projected engine developments, and reduced-cost benefits. On December 8, 1989, Boeing began issuing offers to airlines for the 777.

Design effort


Alan Mulally served as the Boeing 777 program's director of engineering, and then was promoted in September 1992 to lead it as vice-president and general manager. The design phase of the all-new twinjet was different from Boeing's previous jetliners, in which eight major airlines (All Nippon Airways, American Airlines, British Airways, Cathay Pacific, Delta Air Lines, Japan Airlines, Qantas, and United Airlines) played a role in the development. This was a departure from industry practice, where manufacturers typically designed aircraft with minimal customer input. The eight airlines that contributed to the design process became known within Boeing as the "Working Together" group. At the group's first meeting in January 1990, a 23-page questionnaire was distributed to the airlines, asking what each wanted in the design. By March 1990, the group had decided upon a baseline configuration: a cabin cross-section close to the 747's, capacity up to 325 passengers, flexible interiors, a glass cockpit, fly-by-wire controls, and 10 percent better seat-mile costs than the A330 and MD-11.

The development phase of the 777 coincided with United Airlines's replacement program for its aging DC-10s. On October 14, 1990, United became the launch customer with an order for 34 Pratt & Whitney-powered 777s valued at US$11 billion (~$ in ) and options for 34 more. The airline required that the new aircraft be capable of flying three different routes: Chicago to Hawaii, Chicago to Europe, and non-stop from Denver, a hot and high airport, to Hawaii. ETOPS certification was also a priority for United, given the overwater portion of United's Hawaii routes. In late 1991, Boeing selected its Everett factory in Washington, home of 747 production, as the 777's final assembly line (FAL). In January 1993, a team of United developers joined other airline teams and Boeing designers at the Everett factory. The 240 design teams, with up to 40 members each, addressed almost 1,500 design issues with individual aircraft components. The fuselage diameter was increased to suit Cathay Pacific, the baseline model grew longer for All Nippon Airways, and British Airways' input led to added built-in testing and interior flexibility, along with higher operating weight options.