The airliner was launched as the 7X7 project on July 14, 1978, the prototype first flew on September 26, 1981, and it was certified on July 30, 1982. The original 767-200 entered service on September 8 with United Airlines, and the extended-range 767-200ER in 1984. It was stretched into the 767-300 in October 1986, followed by the 767-300ER in 1988, the most popular variant. The 767-300F, a production freighter version, debuted in October 1995. It was stretched again into the 767-400ER from September 2000. To complement the larger 747, it has a seven abreast cross-section, accommodating smaller LD2 ULD cargo containers. The 767 is Boeing's first wide-body twinjet, powered by General Electric CF6, Rolls-Royce RB211, or Pratt & Whitney JT9D turbofans. JT9D engines were eventually replaced by PW4000 engines. The aircraft has a conventional tail and a supercritical wing for reduced aerodynamic drag. Its two-crew glass cockpit, a first for a Boeing airliner, was developed jointly for the 757 − a narrow-body aircraft, allowing a common pilot type rating. Studies for a higher-capacity 767 in 1986 led Boeing to develop the larger 777 twinjet, introduced in June 1995. For more details of the design, development, deliveries,history and variants, click here. Specifications below are for the most popular 767-300ER.