The 737 was designed as a logical short- range airplane to complement larger 707 and 727 jetliners. The first flight of the 737-100 occurred April 9, 1967, and it was certified by the U.S. Federal Aviation Administration in December 1967 after more than 1,300 hours of flight testing by a six-airplane fleet. For the first time, certification included approval for automatic approaches in bad weather under Category II conditions -- defined as 100-foot ceilings and 1,200-foot forward visibility. Boeing delivered 30 737-100s.