A 100th Civil Engineer Squadron firefighter extinguishes a fire inside a mock aircraft, as part of annual proficiency skill training at a burn pit at RAF Mildenhall, England, March 21, 2018. All firefighters are required to conduct live-fire training at least twice a year to stay proficient and keep their qualifications current. (U.S. Air Force photo by Tech. Sgt. Emerson Nuñez)