Boeing 707 Douglas competition, Boeing soon realized this would not provide a viable payload, so it widened the fuselage to to allow five-abreast seating and use of the KC-135's tooling. Douglas Aircraft had launched its DC-8 with a fuselage width of . The airlines liked the extra space and six-abreast seating, so Boeing increased the 707's width again to compete, this time to . The first flight of the first-production 707-120 took place on December 20, 1957, and FAA certification followed on September 18, 1958. Both test pilots Joseph John "Tym" Tymczyszyn and James R. Gannett were awarded the first Iven C.
Boeing 707 the same 247,000 lb as the standard version. It was a variant for Qantas, thus had its customer number 38. The seven −138s were delivered to Qantas June–September 1959 and first carried passengers that July. The 707-120B had Pratt & Whitney JT3D-1 turbofan engines, which were quieter, more powerful, and more fuel-efficient, producing each, with the later JT3D-3 version giving . (This thrust did not require water injection, eliminating both the system and 5000–6000 lb of water.) The −120B had the wing modifications introduced on the 720 and a longer tailplane; a total of 72 were built, 31 for American