AIM 8/15/19  TBL 4 − 1 − 3 Other Frequency Usage Designated by FCC Use Frequency Air-to-air communication  (private fixed wing aircraft). 122.750 Air-to-air communications (general aviation helicopters). 123.025 Aviation instruction, Glider, Hot Air Balloon  (not to be used for advisory service) . 123.300 123.500 4 − 1 − 12. Use of UNICOM for ATC Purposes UNICOM service may be used for ATC purposes, only under the following circumstances: a. Revision to proposed departure time. b. Takeoff, arrival, or flight plan cancellation time. c. ATC clearance, provided arrangements are made between the ATC facility and the UNICOM licensee to handle such messages. 4 − 1 − 13. Automatic Terminal Information Service (ATIS) a. ATIS is the continuous broadcast of recorded noncontrol information in selected high activity terminal areas. Its purpose is to improve controller effectiveness and to relieve frequency congestion by automating the repetitive transmission of essential but routine information. The information is continu- ously broadcast over a discrete VHF radio frequency or the voice portion of a local NAVAID. Arrival ATIS transmissions on a discrete VHF radio frequency are engineered according to the individual facility requirements, which would normally be a protected service volume of 20 NM to 60 NM from the ATIS site and a maximum altitude of 25,000 feet AGL. In the case of a departure ATIS, the protected service volume cannot exceed 5 NM and 100 feet AGL. At most locations, ATIS signals may be received on the surface of the airport, but local conditions may limit the maximum ATIS reception distance and/or altitude. Pilots are urged to cooperate in the ATIS program as it relieves frequency congestion on approach control, ground control, and local control frequencies. The Chart Supplement U.S. indicates airports for which ATIS is provided. d. Pilots should notify controllers on initial contact that they have received the ATIS broadcast by repeating the alphabetical code word appended to the broadcast. c. Pilots should listen to ATIS broadcasts whenever ATIS is in operation. Dulles International information Sierra. One four zero zero zulu. Wind three five zero at eight. Visibility one zero. Ceiling four thousand five hundred broken. Temperature three four. Dew point two eight. Altimeter three zero one zero. ILS runway one right approach in use. Departing runway three zero. Advise on initial contact you have information sierra. b. ATIS information includes: 1. Airport/facility name 2. Phonetic letter code 3. Time of the latest weather sequence (UTC) 4. Weather information consisting of: (a) Wind direction and velocity (b) Visibility (c) Obstructions to vision (d) Present weather consisting of: sky condi- tion, temperature, dew point, altimeter, a density altitude advisory when appropriate, and other pertinent remarks included in the official weather observation 5. Instrument approach and runway in use. The ceiling/sky condition, visibility, and obstructions to vision may be omitted from the ATIS broadcast if the ceiling is above 5,000 feet and the visibility is more than 5 miles. The departure runway will only be given if different from the landing runway except at locations having a separate ATIS for departure. The broadcast may include the appropriate frequency and instructions for VFR arrivals to make initial contact with approach control. Pilots of aircraft arriving or departing the terminal area can receive the continuous ATIS broadcast at times when cockpit duties are least pressing and listen to as many repeats as desired. ATIS broadcast must be updated upon the receipt of any official hourly and special weather. A new recording will also be made when there is a change in other pertinent data such as runway change, instrument approach in use, etc. 4 − 1 − 7 Services Available to Pilots EXAMPLE −