U.S. Air Force Airman 1st Class David Velke, 1st Operations Support Squadron air traffic controller, coordinates aircraft taxi movement at Langley Air Force Base, Va., Dec. 18, 2013. Air traffic controllers offer emergency assistance to aircraft and are responsible for notifying and coordinating with emergency personnel. Velke hails from (U.S. Air Force photo by Airman 1st Class Victoria H. Taylor/ Released)