Boeing 707 ushering in the Jet Age. It established Boeing as one of the largest manufacturers of passenger aircraft, and led to the later series of airliners with "7x7" designations. The later 720, 727, 737, and 757 share elements of the 707's fuselage design. The 707 was developed from the Boeing 367-80, a prototype jet first flown in 1954. A larger fuselage cross-section and other modifications resulted in the initial-production 707-120, powered by Pratt & Whitney JT3C turbojet engines, which first flew on December 20, 1957. Pan American World Airways began regular 707 service on October 26, 1958. Later derivatives included the
Boeing 707 redesign to the wing and gear structures. The 707-820 was also cancelled in 1966 in favor of the 747. The militaries of the US and other countries have used the civilian 707 aircraft in a variety of roles, and under different designations. (The 707 and U.S. Air Force's KC-135 were developed in parallel from the Boeing 367–80 prototype.) The Boeing E-3 Sentry is a US military airborne warning and control system (AWACS) aircraft based on the Boeing 707 that provides all-weather surveillance, command, control, and communications. The VC-137C variant of the Stratoliner was a special-purpose design meant to serve as