U.S. Air Force Tech. Sgt. Jessica Klein, 86th Operations Support Squadron Air Traffic Control Tower air traffic controller, watches a C-20H Gulfstream IV taxi on Ramstein Air Base, Germany, Aug. 1, 2017. Air traffic controllers train rigorously and undergo intense evaluation before becoming certified controllers. Because every flightline and airframe is different, they must undergo on-the-job training at each new assignment, ensuring they are fully prepared to provide air traffic safety. (U.S. Air Force photo by Senior Airman Elizabeth Baker)