U.S. Air Force Staff Sgt. Daniel Rivera, 1st Maintenance Group maintenance training instructor, instructs a class on “hot pit” refueling procedures at Joint Base Langley-Eustis, Va., Sept. 13, 2016. Hot pit refueling systems allow aircraft to land and refuel while the engines are still running. (U.S. Air Force photo by Staff Sgt. Teresa J. Cleveland)