A U.S. Air Force KC-135 Stratotanker aircraft assigned to the 927th Air Refueling Wing flies overhead after refueling a C-17 Globemaster III aircraft over the United States July 1, 2014.
C-17s rely on aerial refueling to complete long-distance missions. (DoD photo by Airman 1st Class Clayton Cupit, U.S. Air Force/Released). Original public domain image from Flickr