Senior Airmen Jonathon Simmons, 25th Aircraft Maintenance Unit load master, reviews system operational guidelineswith his crew during the first night of Vigilant Ace 16 at Osan Air Base, Republic of Korea, Nov. 2, 2015. Vigilant Ace 16 is a peninsula-wide readiness exercise geared toward strengthing the interoperability of the ROK/U.S. alliance. (U.S. Air Force photo/Staff Sgt. Amber Grimm)