Senior Airman Max Todd, 33rd Aircraft Maintenance Squadron crew chief, signals a successful hook-up during the hot pit refueling of an F-35A Lightning II at Eglin Air Force Base, Fla., May 13, 2016. The engines are left running during this type of refueling so pilots are able to return to the air quickly. It can take as little as 20 minutes for a crew chief to fill the nearly 17,000 pound fuel tank. (U.S. Air Force photo/Senior Airman Andrea Posey)