Background Information.

In the early 1970s, the Boeing 747, McDonnell Douglas DC-10 and the Lockheed 1011 Tristar were the first generation of wide-body passenger airliners to  enter service. In 1978, Boeing unveiled three new models: the twin-engine Boeing 757 to replace its Boeing 727, the twin-engine Boeing 767 that was intended to challenge the Airbus A300, and a tri-jet 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 an emergency diversionary airport. Under these  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 favoured the 757 and 767 variants. Boeing was left with a size and range gap in its product line between the Boeing 767-300 and the Boeing 747-400.

By the late 1980s, the Douglas DC-10s and Lockheed 1011 Tristars were approaching retirement age, prompting manufacturers to develop replacement designs. McDonnell Douglas was working on the MD-11, which was a stretched and upgraded successor of the DC-10. On the other side of the Atlantic Ocean Airbus was developing its A330 and A340 series aircraft. 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 Douglas 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 added winglets. Later plans expanded the fuselage cross-section but retained the existing 767 flight deck, nose, and other elements.

Airline customers were uninterested in the 767-X proposal. The consensus was that they wanted an even wider fuselage cross-section, with a flexible interior configuration with both short and intercontinental-range capability. It was also important that the operating costs of this new airliner would be 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 new clean-sheet design, which became the 777 twin-jet. The company opted for the twin-engine configuration given past design successes and the projected engine developments being touted, and reduced-cost benefits. On December 08, 1989, Boeing began issuing offers to airlines for their Boeing 777 next generation airliner.

United Airlines became the 777's launch customer on October 14, 1990, when it placed an order for 34 Pratt & Whitney-powered aircraft valued at US$11 billion with options on an additional 34 airframes. The development phase coincided with United's replacement program for its aging DC-10s. United 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 the airline’s Hawaii routes. 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.

The  Boeing 777 was the first commercial aircraft designed entirely by computer . Each design drawing was created on a three-dimensional CAD software system known as CATIA, sourced from Dassault Systems and IBM. This permitted engineers to assemble a virtual aircraft, in simulation, to check for interference and verify that the thousands of parts would fit properly, thus reducing costly rework. Boeing developed its high-performance visualization system, FlyThru, later called IVT (Integrated Visualization Tool) to support large-scale collaborative engineering design reviews, production illustrations, and other uses of the CAD data outside of engineering. Boeing was initially not convinced of CATIA’s abilities and built a physical mock-up of the nose section to verify its results. The test was so successful that additional mock-ups were cancelled. The 777 ‘was completed with such precision that it was the first Boeing jet that didn’t need its kinks worked out on an expensive physical mock-up plane’, which contrasted sharply with the development of Boeing's next new airliner, the Boeing 787.

On April 09, 1994, the first 777, number WA001, was rolled out in a series of 15 ceremonies held during the day to accommodate the invited guests. The first flight took place on June 12, 1994, under the command of chief test pilot John E. Cashman. This marked the start of an 11-month flight test program that was more extensive than testing for any previous Boeing model. Nine aircraft fitted with General Electric, Pratt & Whitney, and Rolls-Royce engines were flight tested at locations ranging from the desert airfield at Edwards Air Force Base in California to frigid conditions in Alaska, mainly at Fairbanks International Airport. To satisfy ETOPS requirements, eight 180-minute single-engine test flights were performed. The first aircraft built was used in Boeing's non-destructive testing campaign from 1994 to 1996, and provided data for the -200ER and -300 programs. At the successful conclusion of flight testing, the Boeing 777 was awarded simultaneous airworthiness certification by the U.S. Federal Aviation Administration  (FAA) and the European Joint Aviation Authorities (JAA) on April 19, 1995.