Members of the Arnold Engineering Development Complex workforce bow their heads as a prayer is said during a memorial held in remembrance of John Hill and Alvin Overman who died 50 years ago working at Arnold Air Force Base, Tenn., Dec. 9, 2021. The two men were working in an offline furnace and became asphyxiated by argon that had settled in their location. They did not have the O2 meters that have since become available to warn them of dangerous air conditions. (U.S. Air Force photo by Jill Pickett)