Radio technicians fix the frequency
U.S. Air Force Senior Airman Alex Lollar, 606th Air Control Squadron radio frequency transmission technician from Pensacola, Fla., assembles a GRC-171 radio transceiver at Spangdahlem Air Base, Germany, June 30, 2014. In working condition, the transceiver, designed for reliable air traffic control communications, can transmit a signal to aircraft approximately 250 nautical miles away. (U.S. Air Force photo by Senior Airman Gustavo Castillo/Released)