English: Staff Sgt. Spencer Stone, 60th Medical Operations Squadron medical technician, listens as the responsibilities of non-commissioned offers are read during a promotion ceremony at Travis Air Force Base, California, Oct. 30, 2015. Following his promotion to senior airman minutes earlier, Stone was promoted to the rank of staff sergeant by order of Air Force Chief of Staff Gen. Mark A. Welsh III. According to Air Force Instruction 36-502, the chief of staff of the Air Force has the authority to promote any enlisted member to the next higher grade. Stone became the recipient of the rare honor following his heroic actions in August when he and two friends thwarted a potential terrorist attack on a train traveling to Paris. (U.S. Air Force photo by Ken Wright/FOUO)