After experiencing difficulties with the C-87 , the USAAF arranged with Douglas Aircraft to construct a new transport aircraft specifically for presidential use . Nicknamed the " Sacred Cow " , this modified C-54 Skymaster ( VC-54C ) , which included a vertical lift in the lower fuselage for the President and his wheelchair , became the first military aircraft to transport a U.S. president when President Roosevelt took it to the Soviet Union for the Yalta Conference in February 1945 . President Roosevelt used the Sacred Cow only once before his death in April 1945 ; however , the Sacred Cow remained in presidential service during the first 27 months of the Truman Administration . On 26 July 1947 , President Truman signed the National Security Act of 1947 while on board the Sacred Cow . This act established the U.S. Air Force as an independent service , making the Sacred Cow the " birthplace " of the USAF
Yalta Conference
Yalta Conference
Special Air Mission