A U.S. Navy MH-60S Knighthawk helicopter is being prepared on the flightline for a field training exercise at Davis-Monthan Air Force Base Sept. 17, 2013. The MH-60S traveled from the Helicopter Sea Combat Squadron 23, Naval Air Station North Island, Calif. to participate in joint training with the A-10 Thunderbolt squadrons and Combat Search and Rescue units of D-M. (U.S. Air Force photo by Airman 1st Class Chris Massey/Released)