Air Force One arrives at Andrews Air Force Base, Md., on Sept. 11, 2001, with President George W. Bush on board. The president was in Florida when the terrorist attacks on the Pentagon, the World Trade Center in New York City, and in Pennsylvania too place. According to the Air Mobility Command History Office, tankers refueled fighters providing cover for Air Force One as the president moved from Florida. By Sept. 12, tankers also flew air refueling missions for the E-4B National Airborne Operations Center, the president's airborne command and control center. (U.S. Air Force Photo)