Controllers and their calculated checks
U.S. Air Force Master Sgt. Earl Schaad, 31st Operation Support Squadron chief air traffic controller, verifies flight information, Aug. 5, 2015, at Aviano Air Base, Italy. Airmen coordinate with Italian air force air traffic controllers daily to ensure all flights are certified to arrive and depart from Aviano. (U.S. Air Force photo by Airman 1st Class Cary Smith/Released)