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Atis / ASOS....What Is The Difference?

Fri Apr 16, 2004 1:50 am

Hello! I work at the FBO at AEX, and I hear pilots asking for the ATIS frequency quite a bit They seem a little upset when they are told that we don't have ATIS, be we have ASOS instead. I thought that these 2 were about the same...but I guess I was wrong. Can anyone tell me what is the difference between these 2?
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RE: Atis / ASOS....What Is The Difference?

Fri Apr 16, 2004 1:58 am


The ASOS system is a collection of automated surface weather instruments that collect data. It performs surface observations in places that either do not have a human observer, or an observer 24-hours a day. The pilot is required to tune into the frequency and listen to the weather. On talking to ATC at an airfield tell them they have ASOS (also there is AWOS)

The ATIS requires a human observer looking at the weather themselves using instruments such as the barometer etc, and records the latest weather themselves talking. These are done several times a day as the human observer feels the weather has sufficiently changed that the pilot must know. Each of these recordings is given the code of Alpha, then Bravo, Charlie etc to Zulu. This goes on all day. On contact with Approach or the airfield the pilot will respond with saying "with Zulu" therefore telling the controller he has the latest weather.
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RE: Atis / ASOS....What Is The Difference?

Fri Apr 16, 2004 2:05 am

ATIS is for Automated (or Automatic, I can't recall which) Terminal Information Service, and it's a short endless loop tape recorded each hour by tower personnel that gives weather, runway in use, and NOTAM info. It's usually "cut" or recorded once an hour (when the new METAR comes out) can be updated sooner should conditions warrant. Each ATIS broadcast is given a letter, "Alpha", "Bravo", etc. so you can tell when it's been updated.

ASOS is for Automated Surface Observation System, and it's a system comprised of various sensors that actually take readings used in the hourly METAR report, stuff like wind direction/speed, cloud cover, temp/dewpoint, and baro pressure. The observations that ASOS creates are available via conventional computer access, but they are also broadcast on a VHF freq assigned to a specific ASOS, and some can even be accessed by phone. ASOS takes an observation every minute.

The main differences are that ASOS doesn't give you any runway in use info, or NOTAM info.
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RE: Atis / ASOS....What Is The Difference?

Fri Apr 16, 2004 7:01 am

ASOS- "A Shitty Observing System"- as it is know by many, is a collection of weather instruments which requires constant babysitting and amending. It requires an (overpaid) observer, certified by the NWS to take surface weather observation, to sit there and look at the OID during commercials, to push F19 twice an hour to silence the alarm, walk out side at :45 past the hour to check the sky cover, cuz even when the sky is BKN, ASOS like to show CLR, and when the instruments on the ASOS break down, the observer much go outside and take manual observation... When you call the number you get the ASOS. I got much more I could say about it, but that is the gist of it. BTW, I am the "overpaid" observer on duty right now at a major South Florida airport...

About the ATIS... ATIS is the recording done by the tower whenever I transmit an observation that is assigned a letter and contains any pertinent information about the airfield at that time. ATIS is transmitted on a airband frequency... I know one airport where the ATIS is actually broadcasted when you call the ASOS number... BTW- that airport is KHWO...
ASOS... Another Shi#y Observation Station