The 633rd Aerospace Medicine Squadron's reduced oxygen breathing device illuminates during a training exercise at the Physiological Training Center at Langley Air Force Base, Va., Feb. 14, 2012. The training objective of the ROBD is to allow aviators experience and recognize the signs and symptoms of hypoxia, or oxygen deprivation, while executing aircraft specific emergency procedures to correct the problem. (U.S. Air Force photo by Senior Airman John D. Strong II/Released)