engine to be more readily used. The lack of a third tail-mounted engine, as per the trijet configuration used by some competing airliners, allowed for the wings to be located further forwards and to reduce the size of the vertical stabilizer and elevator, which had the effect of increasing the aircraft's flight performance and fuel efficiency. Airbus partners had employed the latest technology, some of which having been derived from Concorde, on the A300. According to Airbus, new technologies adopted for the airliner were selected principally for increased safety, operational capability, and profitability. Upon entry into service in 1974, the A300 was a very advanced plane, which went on to influence later airliner designs. The technological highlights include advanced wings by de Havilland (later BAE Systems) with supercritical airfoil sections for economical performance and advanced aerodynamically efficient flight control surfaces. The diameter circular fuselage section allows an eight-abreast passenger seating and is wide enough for 2 LD3 cargo containers side by side. Structures are made from metal billets, reducing weight. It is the first airliner to be fitted with wind shear protection. Its advanced autopilots are capable of flying the aircraft from climb-out to landing, and it has an electrically controlled braking system. Later A300s incorporated other advanced features such as the Forward-Facing Crew Cockpit, which enabled a two-pilot flight crew to fly the aircraft alone without the need for a flight engineer, the functions of which were automated; this two-man cockpit concept was a world-first for a wide-body aircraft. Glass cockpit flight instrumentation, which used cathode ray tube (CRT) monitors to display flight, navigation, and warning information, along with fully digital dual autopilots and digital flight control computers for controlling the spoilers, flaps, and leading-edge slats, were also adopted upon later-built models. Additional composites were also made use of, such as carbon-fiber-reinforced polymer (CFRP), as well as their presence in an increasing proportion of the aircraft's components, including the spoilers, rudder, air brakes, and landing gear doors. Another feature of later aircraft was the addition of wingtip fences, which improved aerodynamic performance and thus reduced cruise fuel consumption by about 1.5% for the A300-600. In addition to passenger duties, the A300 became widely used by air freight operators; according to Airbus, it is the best selling freight aircraft of all time. Various variants of the A300 were built to meet customer demands, often for diverse roles such as aerial