In the 1950s, with its four-engine DC-4, DC-6, and DC-7, McDonnell Douglas became the leading manufacturer of airliners. The "Douglas Commercials" were the epitome of modern airplane manufacturing. As the first airplane of this Douglas series, the DC-6, possessed a pressurized cabin and, besides its greater travel comfort, distinguished itself for its efficiency and reliability. Although its grand career ended abruptly with the beginning of the jet age, some of it are still in operation fifty years after production was discontinued.
Cubana, the airline of the socialist island state of Cuba, was founded by the US American North American Aviation in 1929, and belonged to Juan Trippe's Pan Am empire from 1932 until 1954. With Fidel Castro's Cuban revolution in 1959, however, the American co-production was over. In fact, the airline has suffered heavily from an economic embargo imposed by the USA, making the operation of desperately needed modern airplanes almost impossible.