U.S. Air Force Staff Sgt. Dylan Crump, 1st Operations Group aerospace and operational physiology technician, test fits a mask onto Lt Col Samuel Mcintyre, NATO Allied Command Transformation deputy chief of staff military assistant, at 1st OG AOP, Joint Base Langley-Eustis, Va., Dec. 5, 2017. The department trains individuals to understand and recognize the symptoms they may receive while becoming hypoxic. (U.S. Air Force photo by Airman 1st Class Tristan Biese)