Airmen from the 6th Air Refueling Squadron at Travis Air Force Base, Calif., fly a KC-10 Extender mission to support aerial refuel operations for fighter aircraft conducting patrols of the airspace surrounding Super Bowl 50 in Santa Clara, Calif., Feb. 7, 2016. The refueling operation was part of a North American Aerospace Defense Command mission in conjunction with NORAD’s air component Continental North American Aerospace Defense Command Region. NORAD ensures United States and Canadian air sovereignty through a network of alert fighter, tankers, airborne early warning aircraft, and ground based air defense assets cued by interagency and defense surveillance radars. Air Force photo by T.C. Perkins Jr.