The origins of this type lie with a US Army requirement for a c-54 Skymaster successor providing the advantages of a greater payload, higher performance, and very importantly, full pressurization so that the plane could climb above adverse weather. The new transport first flew in February 1946 as the XC-112A but the US Army Air Force had lost interest with the end of the Second World War. The type therefore became the civil DC-6 airliner, soon developed into improved DC-6A and DC-6B models With the Lockheed Constellation series these civil models were largely instrumental in developing long range air transport. In 1947 the USAAF bought a single DC-6 as the C-118 presidential transport, which was named The Independence after President Harry S. Truman"s home town in Missouri. This plane paved the way for larger military orders. The USAAF has become the USAF by this time, and ordered 101 examples of the DC-6A as a personnel and logistic transport under the designation C-118A. The Navy had already ordered 65 similar aircraft for logistic transport with the designation R6D-1. When the current tri-service designation system was introduced in 1962, the designation C-118B was allocated to the remaining navy aircraft; the R6D-1ZVIP and staff transport sub variant became the VC-118B.