Airmen assigned to the 51st Civil Engineer Squadron's barrier management flight raise a barrier cable in the event a fighter jet over shoots the runway or during an emergency Nov. 3, 2015, at Osan Air Base, Republic of Korea. Barrier management airmen and airfield managers from the 51st Fighter Wing ensure the flightline is operational for aircraft participating in readiness exercise Vigilant Ace 16. Vigilant Ace 16 is a large-scale exercise designed to test the combat capabilities and enhance the interoperability of the U.S. and Republic of Korea Air Forces. (U.S. Air Force photo/Staff Sgt. Benjamin Sutton)