Air-ground communication: Two-way communication between aircraft and stations or locations on the surface of the earth.
Air-to-ground communication: One-way communication from aircraft to stations or locations on the surface of the earth.
Blind transmission: A transmission from one station to another station in circumstances where two-way communication cannot be established but where it is believed that the called station is able to receive the transmission.
Broadcast: A transmission of information relating to air navigation that is not addressed to a specific station or stations.
Duplex: A method in which telecommunication between two stations can take place in both directions simultaneously.
Ground-to-air communication: One-way communication from stations or locations on the surface of the earth to aircraft.
Interpilot air-to-air communication: Two-way communication on the designated air-to-air channel to enable aircraft
engaged in flights over remote and oceanic areas out of range of VHF ground stations to exchange necessary operational information and to facilitate the resolution of operational problems.
Non-network communications: Radiotelephony communications conducted by a station of the aeronautical mobile service, other than those conducted as part of a radiotelephony network.
Radiotelephony network: A group of radiotelephony aeronautical stations which operate on and guard frequencies from the same family and which support each other in a defined manner to ensure maximum dependability of air-ground communications and dissemination of air-ground traffic.
Readback: A procedure whereby the receiving station repeats a received message or an appropriate part thereof back to the transmitting station so as to obtain confirmation of correct reception.
Simplex: A method in which telecommunication between two stations takes place in one direction at a time.
Note.— In application to the aeronautical mobile service this method may be subdivided as follows:
a) single channel simplex;
b) double channel simplex;
c) offset frequency simplex.
Telecommunication (RR S1.3): Any transmission, emission, or reception of signs, signals, writing, images and sounds or intelligence of any nature by wire, radio, optical or other electromagnetic systems.