Senior Airman Derek Brannan, 28th Logistics Readiness Squadron fuels laboratory technician, performs a fuel system icing inhibitor concentration test at Ellsworth Air Force Base, S.D., July 30, 2014. The reading from the test determines the concentration of FSII in the fuel, which prevents the water in the fuel, present due to atmospheric moisture evaporating and condensing inside pipes, tanks and trucks and acceptable at 10 parts per million, from freezing when planes reach high altitudes. (U.S. Air Force photo by Senior Airman Hailey R. Staker/Released)