In common parlance the term refers to those Air Force aircraft specifically designed, built, and used for the purpose of transporting the president. The Presidential aircraft is a prominent symbol of the American presidency and its power.
The idea of designating specific military aircraft to transport the President arose in 1943, when officials of the United States Army Air Forces – the predecessor to the U.S. Air Force – became concerned with relying on commercial airlines to transport the President.
A C-87 Liberator Express was reconfigured for use as a presidential transport; however, it was rejected by the Secret Service amid concerns over the aircraft's safety record.
A C-54 Skymaster was then converted for presidential use; this aircraft, dubbed the Sacred Cow, transported President Franklin D. Roosevelt to the Yalta Conference in February 1945, and was subsequently used for another two years by President Harry S. Truman.
The “Air Force One” call sign was created after a 1953 incident during which a flight carrying President Dwight D. Eisenhower entered the same airspace as a commercial airline flight using the same call sign.
Several aircraft have been used as Air Force One since the creation of the presidential fleet, including two Boeing 707s introduced in the 1960s and 1970s, respectively; since 1990, the presidential fleet has consisted of two Boeing VC-25As – specifically configured, highly customized Boeing 747-200B series aircraft.
Capable of refueling midair, Air Force One has unlimited range and can carry the President wherever he needs to travel.
The onboard electronics are hardened to protect against an electromagnetic pulse, and Air Force One is equipped with advanced secure communications equipment, allowing the aircraft to function as a mobile command center in the event of an attack on the United States.
Inside, the President and his travel companions enjoy 4,000 square feet of floor space on three levels, including an extensive suite for the President that features a large office, lavatory, and conference room.
Air Force One includes a medical suite that can function as an operating room, and a doctor is permanently on board. The planes two food preparation galleys can feed 100 people at a time.
Air Force One also has quarters for those who accompany the President, including senior advisors, Secret Service officers, traveling press, and other guests.
Several cargo planes typically fly ahead of Air Force One to provide the President with services needed in remote locations.
The Air Force is looking into replacing the two VC-25 aircraft with three replacement aircraft beginning in 2017.
