3. The ASOS/AWOS data outlets include:
(a) Those necessary for on-site airport users.
(b) National communications networks.
(c) Computer-generated voice (available
through FAA radio broadcast to pilots, and dial-in
telephone line).
NOTE-
Wind direction broadcast over FAA radios is in reference
to magnetic north.

4. An ASOS/AWOS report without human
intervention will contain only that weather data
capable of being reported automatically. The
modifier for this METAR report is "AUTO." When

7-1-28

an observer augments or backs-up an ASOS/AWOS
site, the "AUTO" modifier disappears.
5. There are two types of automated stations,
AO1 for automated weather reporting stations
without a precipitation discriminator, and AO2 for
automated stations with a precipitation discriminator.
As appropriate, "AO1" and "AO2" must appear in
remarks. (A precipitation discriminator can determine the difference between liquid and
frozen/freezing precipitation).
NOTE-
To decode an ASOS/AWOS report, refer to FIG 7-1-7 and
FIG 7-1-8.
REFERENCE-
A complete explanation of METAR terminology is located in AIM,
Paragraph 7-1-30 , Key to Aerodrome Forecast (TAF) and Aviation
Routine Weather Report (METAR).

Meteorology