Definition
A continuous broadcast of recorded non-control information at busier airports, transmitted on a dedicated radio frequency or VOR voice channel. It carries current routine details such as the active runway, wind, visibility, ceiling, temperature, dew point, altimeter setting, approach in use, and any notices to airmen relevant to the airport. Each broadcast is identified by a phonetic alphabet letter (Information Alpha, Bravo, Charlie, and so on) that changes whenever the information is updated.
Plain English
A looped recording you tune in before you call the tower or ground. It tells you everything routine about the airport right now -- which runway is in use, the weather, the altimeter setting -- so the controllers don't have to repeat it to every aircraft.
Context Anchor
You encounter it before departure, before arrival, and during flight planning when checking the latest information for a controlled airport.
Derivation
Automatic because it plays on a loop without a controller speaking live. Terminal because it covers the airport area (the terminal environment, where flights begin and end), not the en route portion of flight. Information Service describes what it provides.
Why Pilots Care
Reduces frequency congestion by letting pilots receive routine information independently, allowing controllers to focus on traffic management.
Analogy
It is like a recorded front-desk message for the airport: listen first, get the basics, then talk to the right person with fewer questions.
Intuition Check
Do not read “terminal” as the airport passenger building. Here it means the airport operating area where aircraft are arriving, departing, and being controlled.
Example Sentence 1
Ten miles out, the pilot tuned the ATIS frequency, copied the active runway and altimeter setting, and then called Approach with 'Information Delta.'
Example Sentence 2
After the Automatic Terminal Information Service updated with new visibility numbers, the pilot adjusted the approach briefing accordingly.