Boeing 707 lb (57.8 kN) with water injection. Maximum takeoff weight was 247,000 lb and first flight was on December 20, 1957. Major orders were the launch order for 20 707-121 aircraft by Pan Am and an American Airlines order for 30 707-123 aircraft. The first revenue flight was on October 26, 1958; 56 were built, plus seven short-bodied −138s; the last −120 was delivered to Western in May 1960. The 707-138 was a −120 with a fuselage 10 ft shorter than the others, with 5 ft (three frames) removed ahead and behind the wing, giving increased range. Maximum takeoff weight was
Boeing but the design experience was used in the development of the Model 314 that followed a year later. Overlapping with the period of the YB-15 development, an agreement with Pan American World Airways (Pan Am) was reached, to develop and build a commercial flying boat able to carry passengers on transoceanic routes. The first flight of the Boeing 314 Clipper was in June 1938. It was the largest civil aircraft of its time, with a capacity of 90 passengers on day flights, and of 40 passengers on night flights. One year later, the first regular passenger service from the U.S.