U.S. Air Force Senior Airman Matthew Dillard, 100th Logistics Readiness Squadron cryogenic specialist from Las Vegas, secures his safety footwear prior to draining pressure on the main liquid oxygen storage tank Feb. 11, 2015, on RAF Mildenhall, England. Correct personal protective equipment is vital to Airmen working with fuel and liquid oxygen. (U.S. Air Force photo by Gina Randall/Released)