radio communications

Communication is of paramount importance in aviation. If a communication is misunderstood, incorrect, or garbled, even the simplest message can lead to a lapse in safety. The goal of all communications is to provide unambiguous, correct, and current information and clearances to aircrews and controllers.

Communication is a process of sending information from a transmitter to a receiver using some means of transmission. In aviation we usually think of two-way communication by voice using radio as the means of transmission. This could be a pilot to a controller or a controller to a pilot. Other possibilities exist. An airline flight crew could be communicating with their "company" or specifically their airline's operations department for information or feedback. A private or corporate pilot could talk with "UNICOM," a fixed base operation (FBO), at an airport to obtain the current weather data, or verify runway operations or to arrange ground transportation or fuelling.

Both air traffic controller and pilot/co-pilot act as a sender and receiver of communication.

All civil aircraft radio communications transmit and receive on the aircraft band of frequencies 118.000 MHz to 135.975 MHz. "MHz" is the abbreviation for megahertz. The radio works using the "simplex" system, meaning only one person can talk at a time. The microphone is keyed and the person talks. Upon completing that communication, he/she releases the switch and listens. The person receiving the message then keys his/her microphone and talks. Both cannot talk at the same time as their simultaneous transmissions will block out each other's signal.

Emergencies are broadcast using the international distress frequencies of 121.5 or 243 MHz. Broadcasting on 121.5 MHz gets attention quickly.

Some radio transmissions are recorded and broadcast for flight crews to access at any time. Automated Terminal Information Service (ATIS) with current local airport information is available by radio or telephone at towered airports. Computer-generated automated weather reports are available at many towered and un-towered airports by radio or telephone. Learning how to speak in aviation language via the radio is crucial to maintaining safety in the skies.