Boeing 707 center section tanks. Its first flight was on January 11, 1958; 69 turbojet 707-320s were delivered through January 1963, the first passengers being carried (by Pan Am) in August 1959. The 707-420 was identical to the −320, but fitted with Rolls-Royce Conway 508 (RCo.12) turbofans (or by-pass turbojets as Rolls-Royce called them) of 18,000 lb (79 kN) thrust each. The first announced customer was Lufthansa. BOAC's controversial order was announced six months later, but the British carrier got the first service-ready aircraft off the production line. The British Air Registration Board refused to give the aircraft a certificate of airworthiness,
Boeing 707 also smaller and slower than the 707. Several major airlines committed only to the (second place in the production race) Douglas DC-8. Douglas Aircraft was the more established and preferred (by airlines and their passengers) maker of passenger aircraft at the time. Douglas had correctly decided to await the validation of a larger and more fuel efficient engine (JT4A from Pratt & Whitney), and to design a larger and longer range aircraft around this engine. To stay competitive, Boeing made a late and costly decision to redesign and enlarge the 707's wing to help increase range and payload. The new