Liberty Airmen from the 492nd Aircraft Maintenance Unit respond to a request from the pilot to check the fuel system prior to take-off at Los Llanos Air Base, Spain, Jan. 29, 2015. The 492nd Fighter Squadron returned to their home station, Royal Air Force Lakenheath, U.K., after 11 airmen from the Greek and French air forces lost their lives following an aircraft crash at Tactical Leadership Programme 2015-1, a NATO exercise that develops leadership and interoperability amongst allies. (U.S. Air Force photo by Airman 1st Class Erin R. Babis/Released)