'' For the history of Special Air Missions after 1966 see 89th Airlift Wing '' In 1944 Air Transport Command ( ATC ) organized the ' '' 503d AAF Base Unit ' '' at Washington National Airport , Virginia and assigned it to its '' ' North Atlantic Division ' '' . The unit replaced the ' '' 26th Transport Group ' '' and the '' ' Washington National Airport Staff Squadron ' '' . Because of its frequent transport of high-ranking passengers , the unit was referred to as the " Brass Hat Squadron . " The 503d operated the first airplane designated as a presidential plane , the Douglas VC-54C known as the " Sacred Cow . " This aircraft was used by Presidents Roosevelt and Truman . It took President Roosevelt to the Yalta Conference in 1945 . On 26 July 1947 , President Truman signed the National Security Act of 1947 while on board this plane . This act established the Air Force as an independent service , making the Sacred Cow the " birthplace " of the USAF . In 1947 the unit began to operate the Douglas VC-118 named " Independence " after President Truman 's home town as the primary presidential airplane
Yalta Conference
Yalta Conference
1254th Air Transport Wing