Senior Airman Jonell Sanchez, an air traffic controller assigned to the 28th Operations Support Squadron, transfers beacon codes during a training simulation at Ellsworth Air Force Base, S.D., Jan. 25, 2017. Air traffic controllers maintain a safe environment for pilots by providing safety alerts and managing the flow of aircraft in and out of airspace. (U.S. Air Force photo illustration by Airman 1st Class Donald C. Knechtel)