A RQ-4 Global Hawk taxies on the flightline as a U-2 Dragon Lady makes its final approach Sept. 17, 2013, at Beale Air Force Base, Calif. The RQ-4 and U-2 are the Air Force’s primary high-altitude intelligence, surveillance and reconnaissance aircraft. (U.S. Air Force photo by Airman 1st Class Bobby Cummings/Released)