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 Commercial Airplanes 61, would step down immediately and be replaced. Kevin G. McAllister was named president and CEO of Boeing Commercial Airplanes (BCA). For all models sold beginning with the Boeing 707 in 1957, except the 720, Boeing's naming system for commercial airliners has taken the form of 7X7 (X representing a number). All model designations from 707 through 787 have been assigned, leaving 797 as the only 7X7 model name not assigned to a product. For model numbers in the 707 to 777 range, the model number consists of an airplane's model number, for example 707 or 747, followed by a