The automatic provision of current, routine information to arriving and departing aircraft throughout 24 hrs or a specified portion thereof:
Data link-automatic terminal information service (D-ATIS). The provision of ATIS via data link.
Voice-automatic terminal information service (Voice-ATIS). The provision of ATIS by means of continued and repetetive voice broadcasts.
Use of ATIS
An important element of an ATIS broadcast is the designator (identifying code), which is a letter of the ICAO spelling alphabet. Designators assigned to consecutive ATIS are in alphabetical order. The pilot listens to the ATIS just prior initial contact and notes the code letter; on check-in, the pilot reports the code letter of the ATIS copied. This enables the controller to confirm that the pilot has copied the current ATIS. Normal practice is for the controller to up-date the pilot if the ATIS or any element of it subsequently changes materially.
In some cases, Operator procedures predicated on R/T communications safety require that both pilots in multi-crew aircraft remain on the principal ATC frequency once the aircraft is below FL100/10,000ft. This means that ATC must pass any significant changes to the reported ATIS.