U.S. Air Force Staff Sgt. Jacob Wade, 52nd Operations Support Squadron non-commissioned officer in charge of aircrew flight equipment quality assurance, far left, teaches a member of the Czechian air force about the joint combined aircrew system tester training system at 21st tactical air base in April 2021. Each aircrew member must undergo an oxygen mask fitting to receive their appropriate oxygen levels by the JCAST system. (Courtesy Photo)