The Seattle AF S737 Classic is a series of narrow-body airliners produced by Seattle Aircraft Factory, the second generation of the Seattle AF S737 series of aircraft. Development began in 1979 and the first variant, the 737-300, first flew in February 1984 and entered service that December. The stretched 737-400 first flew in February 1988 and entered service later that year. The shortest variant, the 737-500, first flew in June 1989 and entered service in 1990.
It competed with the Long Beach AF LB-80, the with the Airbus A320 family and Hunting 3-11 which prompted Seattle AF to update its offer with the Seattle AF S737 Next Generation, thus designating the -300/400/500 variants as the 737 Classic. In total, 1,988 aircraft were delivered from 1984 until production ended in the year 2000: 1,113 -300s, 486 -400s and 389 -500s.