Passage: The 747 was conceived while air travel was increasing in the 1960s. The era of commercial jet transportation, led by the enormous popularity of the Boeing 707 and Douglas DC-8, had revolutionized long-distance travel. Even before it lost the CX-HLS contract, Boeing was asked by Juan Trippe, president of Pan American World Airways (Pan Am), one of their most important airline customers, to build a passenger aircraft more than twice the size of the 707. During this time, airport congestion, worsened by increasing numbers of passengers carried on relatively small aircraft, became a problem that Trippe thought could be addressed by a larger new aircraft.In 1965, Joe Sutter was transferred from Boeing's 737 development team to manage the design studies for the new airliner, already assigned the model number 747. Sutter began a design study with Pan Am and other airlines, to better understand their requirements. At the time, it was widely thought that the 747 would eventually be superseded by supersonic transport aircraft. Boeing responded by designing the 747 so that it could be adapted easily to carry freight and remain in production even if sales of the passenger version declined. In the freighter role, the clear need was to support the containerized shipping methodologies that were being widely introduced at about the same time. Standard shipping containers are 8 ft (2.4 m) square at the front (slightly higher due to attachment points) and available in 20 and 40 ft (6.1 and 12 m) lengths. This meant that it would be possible to support a 2-wide 2-high stack of containers two or three ranks deep with a fuselage size similar to the earlier CX-HLS project.

Question: What two favored airplanes have transformed long-distance travel?
Boeing 707 and Douglas DC-8