U.S. Air Force Master Sgt. Travis Shaw, the pararescue medical program manager at Air Combat Command, explains the required run time for the Physical Aptitude Stamina Test (PAST) to Senior Airman D’Vonte Washburn, an aircraft maintenance scheduler with the 1st Maintenance Group, at Langley Air Force Base, Va., March 3, 2016. The PAST has different time and repetition requirements for the special operations career field the Airman is pursuing such as combat control or pararescue. Each exercise in the PAST is pass or fail, ensuring the candidates are meeting the minimum requirements for the desired career field. (U.S. Air Force photo by Airman 1st Class Derek Seifert)