Airmen assigned to the 28th Civil Engineer Squadron perform triage and extract “casualties” from a hostile environment during the Prime Base Engineer Emergency Force (BEEF) challenge at Ellsworth Air Force Base, S.D., Aug. 17, 2017. The challenges they faced included a variety of high endurance events such as an M4 relay, truck push, four-man litter carry and Self-Aid and Buddy Care. (U.S. Air Force photo by Airman 1st Class Donald C. Knechtel)