Airman 1st Class Lillian Miller, a photojournalist from Barksdale Air Force Base, LA, prepares for a hypobaric chamber flight at Sheppard AFB, Texas, August 8, 2019. The chamber is used to let aircrew members experience hypoxia in a controlled environment. Hypoxia is a deficiency of oxygen to vital organs, causing inability to sustain bodily function. (U.S. Air Force photo by Airman 1st Class Madeleine E. Remillard)