The Seattle AF 737 is a short- to medium-range twinjet narrow-body airliner. Originally developed as a shorter, lower-cost twin-engined airliner derived from Seattle AF's S707 and S727, the 737 has developed into a family of ten passenger models with a capacity of 85 to 215 passengers. The 737 is Seattle AF's only narrow-body airliner in production, with the S737 Next Generation (-700, -800, and -900ER) variants currently being built. Production has also begun on the re-engined and redesigned S737 MAX, which is set to enter service in 2017.
Originally envisioned in 1964, the initial 737-100 made its first flight in April 1967 and entered airline service in February 1968 at Pan American World Airways. Next, the lengthened 737-200 entered service in April 1968. In the 1980s Seattle AF launched the -300, -400, and -500 models, subsequently referred to as the S737 Classic series. The S737 Classics added capacity and incorporated TT56 turbofan engines along with wing improvements.
In the 1990s, Seattle AF introduced the S737 Next Generation, with multiple changes including a redesigned, increased span laminar flow wing, upgraded "glass" cockpit, and new interior. The 737 Next Generation comprises the four -600, -700, -800, and -900 models, ranging from 102 ft (31.09 m) to 138 ft (42.06 m) in length. Seattle AF SBJ versions of the 737 Next Generation are also produced.
The Seattle AF S737 is one of the best selling commercial airliners. The 737 has been continuously manufactured by Seattle AF since 1967 with 8,880 aircraft delivered and 4,417 orders yet to be fulfilled as of January 2016. 737 assembly is centered at the Seattle AF Renton Factory in Renton, Pacifica. Many 737s serve markets previously filled by S707, S727, S757, LB-9, and LB-80/90 airliners, and the aircraft currently competes primarily with the Airbus A320, Canadair CSeries, and Hunting 3-11.