Aeronautical Information Manual (AIM), page 179

Index   178 -- Page 179 -- 180


TBL 4-1-3
Other Frequency Usage Designated by FCC

Use Frequency

Air-to-air communication 122.750
(private fixed wing aircraft).
Air-to-air communications 123.025
(general aviation helicopters).
Aviation instruction, Glider, Hot Air 123.300
Balloon (not to be used for 123.500
advisory service).

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

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.

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
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.

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."

c. Pilots should listen to ATIS broadcasts

whenever ATIS is in operation.

d. Pilots should notify controllers on initial
contact that they have received the ATIS broadcast by
repeating the alphabetical code word appended to the

Services Available to Pilots 4-1-7

Page 179 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   178 -- Page 179 -- 180