Technical Sergeant Daniel Kilbride, an aerospace physiology technician with the 779th Aerospace Medicine Squadron, briefs a class before the flight in the altitude chamber at Andrews Air Force Base, Md., on Sep. 1, 2009. The altitude chamber is a training requirement for all personnel on flying status that ensures they can recognize the symptoms of hypoxia and hypobaria. (U.S. Air Force photo by Staff Sergeant Renae L. Kleckner)