Airman 1st Class Christine Smith and Airman 1st Class Kaylie Cunningham, 364th Training Squadron electrical and environmental apprentice course students, remove and install an oxygen regulator on an F-15 Eagle at Sheppard Air Force Base, Texas, June 14, 2019. Oxygen is vital to pilots flying at certain altitudes where the air gets thinner. Without the regulator, the pilot would not get a steady supply of oxygen and may lose consciousness. (U.S. Air Force photo by Airman 1st Class Pedro Tenorio)