Airmen assigned to the 28th Civil Engineer Squadron push a six-passenger vehicle during the Prime Base Engineer Emergency Force (BEEF) challenge at Ellsworth Air Force Base, S.D., Aug. 17, 2017. In this obstacle, engineers were required to push the vehicle for 100 yards to put their endurance to the test. (U.S. Air Force photo by Airman 1st Class Donald C. Knechtel)