Sabena from Seaboard World Airlines, using them mainly on transatlantic routes. In the same period, there were experiments with helicopter passenger service using Sikorsky S-58 aircraft from Brussels to Antwerp, Rotterdam, Eindhoven and the Paris heliport at Issy-les-Moulineaux. 1960 saw the introduction of the Boeing 707-320 intercontinental jet for trans-Atlantic flights to New York. SABENA was mainland Europe's first airline to operate a jet across the Atlantic (BOAC had been flying jet transatlantic services using the de Havilland Comet 4 since 4 October 1958). One of Sabena's aircraft became the first Boeing 707 to crash while in commercial service when Flight
Boeing 727 passengers. United Airlines requested a four-engine aircraft for its flights to high-altitude airports, especially its hub at Stapleton International Airport in Denver, Colorado. American Airlines, which was operating the four-engined Boeing 707 and Boeing 720, requested a twin-engined aircraft for efficiency. Eastern Airlines wanted a third engine for its overwater flights to the Caribbean, since at that time twin-engine commercial flights were limited by regulations to routes with 60-minute maximum flying time to an airport (see ETOPS). Eventually, the three airlines agreed on a trijet design for the new aircraft. In 1959, Lord Douglas, chairman of British European Airways (BEA),