Automatic Terminal Information Service, or ATIS, is a continuous broadcast of recorded noncontrol information in busier terminal (i.e. airport) areas. ATIS broadcasts contain essential information, such as weather information, which runways are active, available approaches, and any other information required by the pilots, such as NOTAMs. Pilots usually listen to an available ATIS broadcast before contacting the local control tower, in order to reduce the controllers' workload and relieve frequency congestion.

The recording is updated when there is a significant change in the information, like a change in the active runway. It is given a letter designation (e.g. bravo), from the Phonetic Alphabet. The letter progresses down the alphabet and starts at Alpha each day. When contacting the control tower or ground station, a pilot will indicate he/she has "information" and the ATIS identification letter to let the controller know that the pilot is up to date with all current information.