Air Force One is the term used to describe any United States Air Force aircraft carrying the President of the United States. The designation was officially adopted in 1954 following an incident involving a converted Lockheed Constellation that shared a flight number with a commercial airline while carrying President Dwight D. Eisenhower. Since then, several aircraft have been modified to serve as Air Force One, each equipped with advanced technology and security features.
The Douglas C-54 Skymaster was one of the first aircraft designated for presidential use. President Franklin D. Roosevelt flew on this plane, known as the Sacred Cow, to attend the Yalta Conference in February 1945. The Skymaster included special modifications such as a sleeping area and a battery-powered elevator for Roosevelt's wheelchair.
Following Roosevelt, President Harry S. Truman utilized the Douglas VC-118A Liftmaster until 1953. Nicknamed Independence after Truman's hometown, this aircraft featured unique interior designs and was notable for being used when Truman signed the National Security Act of 1947 onboard.