President Ronald Regan waves from the doorway of Air Force One as he prepares to depart from the base following a stopover on his way to San Bernardino, California (CA)

Technically, Air Force One is used to describe any Air Force aircraft carrying the President — but since the middle of the 20th century, it has been standard practice to refer to specific planes that are equipped to transport the Commander-in-Chief. Today, this name refers to one of two highly customized Boeing 747-200B series aircraft, which carry the tail codes 28000 and 29000. The Air Force designation for the aircraft is VC-25A. Franklin D. Roosevelt was the first president to fly in an aircraft while in office. President Harry S. Truman replaced VC-54C in 1947 with a modified C-118 Liftmaster, calling it the Independence after his Missouri hometown. President Eisenhower introduced four propeller-driven aircraft to presidential service. This group included two Lockheed C-121 Constellations, aircraft Columbine II (VC-121A 48-610) and Columbine III (VC-121E 53-7885). They were named by First Lady Mamie Eisenhower for the columbine, official state flower of her adopted home state of Colorado. In 1959, the Air Force added the first of Boeing 707-120 jet aircraft—VC-137s, designated SAM (Special Air Missions) 970, 971 and 972. In 1962, the U.S. Air Force purchased a Boeing C-137 Stratoliner, a modified long-range Boeing 707—Special Air Mission (SAM) 26000. SAM 26000 was in service from 1962 to 1998, serving Presidents John Kennedy to Bill Clinton. During the Johnson Administration, the United States Air Force acquired a Beechcraft King Air B90 which was designated VC-6A. The aircraft was used to transport President Johnson between Bergstrom Air Force Base and his family ranch near Johnson City, Texas, and was used at least once to transport the President to Princeton, New Jersey. It was referred to as Lady Bird's airplane and later in its service life featured a basic color scheme similar to civilian aircraft. When the President was aboard, the aircraft used the call sign Air Force One. In December 1972 VC-137, Special Air Mission 27000 was added to the fleet while SAM 26000 was kept as a backup until it was finally retired. Richard Nixon was the first president to use SAM 27000; the newer aircraft served every president until it was replaced by two VC-25A aircraft (SAM 28000 and 29000) in 1990 when Reagan Administration ordered two identical 747s to replace the aging 707s he used. as of 2019, the VC-25As are to be replaced.