Air National Guard Staff Sgt. Michael Hoffman, 176th Aircraft Maintenance Squadron crew chief, Joint Base Elmendorf-Richardson, Alaska, wipes away residual oil from an HC-130 Combat King II cargo aircraft during a Vigilant Ace 16 aeromedical evacuation mission Nov. 5, 2015, at Osan Air Base, Republic of Korea. Vigilant Ace 16 is a peninsula-wide exercise designed to enhance combat capabilities and interoperability of the U.S. and Republic of Korea Air Forces. (U.S. Air Force photo/Staff Sgt. Benjamin Sutton)