background image

AIM

10/12/17

4−1−7

Services Available to Pilots

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.

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.

EXAMPLE−

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

broadcast.