Oxygen Mask Breathing Units-5/P are stored on hooks when not being used by students undergoing altitude training at the 779th Aerospace Medical Squadron chamber facility at Joint Base Andrews, Md. Students are typically military or civilian personnel who perform their jobs in flying aircraft, like pilots, flight engineers, boom operators, load masters, flight attendants and aerial photographers. (U.S. Air Force photo by Staff Sgt. Joe Yanik)
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