A sign warns flight line personnel of on-going maintenance to a B-52 Stratofortress at RAF Fairford, England, Sept. 10, 2019. The signs are a necessary safety precaution, as multiple personnel from a variety of career fields may be in the area at any given time. Only those trained in adding liquid oxygen to an aircraft are allowed in the area. The maintenance was part of the on-going support for Exercise Ample Strike 19. (U.S. Air Force photo by Master Sgt. Ted Daigle)