Staff Sgt. David Atteberry, left, an aircraft hydraulic systems technician assigned to the 92nd Aircraft Maintenance Squadron, Fairchild Air Force Base, Wash., signals to a fellow maintainer while working on the wing of a KC-135 Stratotanker during Red Flag 15-4 at Nellis AFB, Nev., Aug. 25, 2015. Red Flag provides realistic combat training in a contested, degraded and operationally-limited environment, which provides aircrews with real-time war scenarios and helps ground crews test and improve their operational readiness. (U.S. Air Force photo by Staff Sgt. Siuta B. Ika)