Air Force One

Air Force One is the official call sign for a United States Air Force aircraft carrying the President of the United States, and is commonly used to denote the primary presidential aircraft, currently the Boeing VC-25A. The concept of designating a specific aircraft for presidential travel originated during World War II, when a C-54 Skymaster was converted for presidential use and dubbed the Sacred Cow. The "Air Force One" call sign was created in 1954, and since then, various aircraft have been designated as Air Force One, including Lockheed Constellations, Boeing 707s, and the current Boeing VC-25As.learn more on wikipedia