Many of the tower controlled airports provide Automatic Terminal Information Service (ATIS), which broadcasts on a specially assigned radio frequency a continuous recording of essential but routine noncontrol information such as current weather, communication requirements, and the runways and types of approaches in use.
There are three distinct advantages of this service: First, extensive use of ATIS by pilots greatly reduces the congestion on the regular tower and ground control radio frequencies, and reduces the routine workload on the controllers. This allows the controllers to devote more time to the specific control of arriving and departing aircraft; second, the ATIS broadcast provides more information than is contained in the normal tower or ground control instructions for taxi, takeoff, landing, weather, NOTAMs, etc. and third, the pilot can receive this information when cockpit duties are least pressing and can listen to as many repeats as desired.
The ATIS broadcast should be monitored prior to requesting taxi clearance or prior to requesting landing clearance. Arriving pilots should monitor the broadcast well in advance of entering the Airport Traffic Area. Each ATIS broadcast carries an identifying phonetic alphabet code word (Alpha, Bravo, Charlie, etc.). This code word is important. After receiving the ATIS broadcast, the pilot, on initial contact with ground control, tower, or approach control, should state that the information has been received and repeat the specific code word. Example "...TULSA GROUND CONTROL, THIS IS CESSCRAFT SEVEN FOUR SIX FOUR CHARLIE, ON TERMINAL RAMP, READY TO TAXI. I HAVE INFORMATION ECHO. OVER..."
When notified by the pilot that ATIS has been received, the control tower operator, in giving takeoff or landing instructions, will not repeat certain information contained in the ATIS broadcast. Monitoring the published ATIS radio frequency and using this information will assist the pilot in planning the flight into the airport traffic area with regard to runway, weather conditions, and the approach and departure routes of other air traffic. Airports at which this service is available are indicated on aeronautical charts and in the Airman's Information Manual.