Capital Airlines Lockheed Constellations. In 1955 they became the first U.S. operator of the British manufactured, four engine Vickers Viscount, the first passenger turboprop airliner. The Viscount propjets were deployed on the flagship Washington-Chicago route and the airline had planned to fly them on expanded service; however, Capital was mostly stymied by the federal Civil Aeronautics Board (CAB). The CAB also refused Capital a requested subsidy. Still, Capital's passenger-miles in 1957 were 88% more than 1955. On November 14, 1956 a Capital pilot reported seeing a blue-white ball in the sky. The pilot, Captain William J. Hull, was a senior captain who
Turboprop civil aircraft, such as the Lockheed L-188 Electra and the Tupolev Tu-95, have also used turboprop power. The Airbus A400M is powered by four Europrop TP400 engines, which are the third most powerful turboprop engines ever produced, after the eleven megawatt-output Kuznetsov NK-12 and 10.4 MW-output Progress D-27. In 2017, The most widespread turboprop airliners in service were the ATR 42/72 (950 aircraft), Bombardier Q400 (506) and Dash 8-100/200/300 (374), Beechcraft 1900 (328), de Havilland Canada DHC-6 Twin Otter (270), Saab 340 (225). Less widespread and older airliners include the BAe Jetstream 31, Embraer EMB 120 Brasilia, Fairchild Swearingen Metroliner,