Initial design Boeing had been studying short-haul jet aircraft designs, and saw a need for a new aircraft to supplement the
727 on short and thin routes. Preliminary design work began on May 11, 1964, based on research that indicated a market for a fifty to sixty passenger airliner flying routes of . The engine chosen was the
Pratt & Whitney JT8D-1 low-bypass ratio turbofan engine, delivering of thrust. The concept design was presented in October 1964 at the
Air Transport Association maintenance and engineering conference by chief project engineer Jack Steiner, where its elaborate
high-lift devices raised concerns about
maintenance costs and dispatch reliability.
Major design developments The original 737 continued to be developed into thirteen passenger, cargo, corporate and military variants. These were later divided into what has become known as the four generations of the Boeing 737 family: • The first generation "Original" series: the 737-100 and -200, also the military T-43 and CT-43, launched February 1965. • The second generation "Classic" series: 737-300, -400 and -500, launched in 1979. • The third generation "Next Generation" series: 737-600, -700, -800 and -900, also the military C-40 and P-8, launched late 1993. • The fourth generation 737 MAX series: 737-7, -8, -9 and -10, launched August 2011.
Launch The launch decision for the $150 million (~$ in ) development was made by the board on February 1, 1965. The sales pitch was big-jet comfort on short-haul routes.
Lufthansa became the launch customer on February 19, 1965, with an order for 21 aircraft, worth $67 million (~$ in ) after the airline had been assured by Boeing that the 737 project would not be canceled. Consultation with Lufthansa over the previous winter had resulted in the seating capacity being increased to 100. On April 5, 1965, Boeing announced an order by
United Airlines for 40 737s. United wanted a slightly larger capacity than the 737-100, so the fuselage was stretched ahead of, and behind the wing. The longer version was designated the 737-200, with the original short-body aircraft becoming the 737-100. Detailed design work continued on both variants simultaneously.
Introduction on February 10, 1968|alt=Lufthansa 737-100 in flight The first -100 was rolled out on January 17, 1967, and took its maiden flight on April 9, 1967, piloted by
Brien Wygle and Lew Wallick. After several test flights the
Federal Aviation Administration (FAA) issued Type Certificate A16WE certifying the 737-100 for commercial flight on December 15, 1967. It was the first aircraft to have, as part of its initial certification, approval for
Category II approaches, which refers to a precision instrument approach and landing with a decision height between . Lufthansa received its first aircraft on December 28, 1967, and on February 10, 1968, became the first non-American airline to launch a new Boeing aircraft. Lufthansa was the only significant customer to purchase the 737-100 and only 30 aircraft were produced. The -200 was rolled out on June 29, 1967, and had its maiden flight on August 8, 1967. It was then certified by the FAA on December 21, 1967. The improved version, the 737-200 Advanced, was introduced into service by
All Nippon Airways on May 20, 1971. The 737 original model with its variants, known later as the
Boeing 737 Original, initially competed with SE 210 Caravelle and BAC-111 due to their earlier entry into service and later primarily with the
McDonnell Douglas DC-9, then its
MD-80 derivatives as the three European short-haul single aisles slowly withdrew from the competition. Sales were low in the early 1970s and, after a peak of 114 deliveries in 1969, only 22 737s were shipped in 1972 with 19 in backlog.