Weather Reporting Systems Examined: ATIS, AWOS, and ASOS
As a pilot, it's essential to keep a close eye on the weather for a safe and smooth flight. Fortunately, we've got three trustworthy weather reporting systems to help us stay informed:
- Automatic Terminal Information Service (ATIS)
- Automated Weather Observing System (AWOS)
- Automated Surface Observing System (ASOS)
Navigating through these acronyms can be tricky, and their similarities might confuse you. But we're here to make sense of it all.
The Differences between ATIS, AWOS, and ASOS
ATIS, AWOS, and ASOS all provide vital weather updates, but there's a clear distinction.
ATIS broadcasts essential weather and airport information at controlled airports.
On the other hand, ASOS and AWOS only report weather conditions and don't deliver airport information like the ATIS. AWOS stations send weather data every minute and are run by the Federal Aviation Administration (FAA). ASOS stations are more advanced and are typically run by the National Weather Service (NWS).
In simpler terms (with some exceptions that we'll explore later), ATIS reports both weather and airport information at controlled airports, while ASOS represents a more advanced version of AWOS that automatically provides weather data at both controlled and uncontrolled airports.
Here's a summary table to visualize the differences:
AWOS
| | | ||--------------|--------------|---------------|| Update Frequency | Hourly | Every minute || Comprehensiveness | Most comprehensive | Least comprehensive || Availability | Towered airports only | Towered and non-towered airports |
Automated Terminal Information Service (ATIS) Explained
ASOS
The Automated Terminal Information Service (ATIS) is like your personal airport news channel when you're approaching an airport. It delivers essential details you need to know, including:
- Current weather
- Active runways
- Available approaches
- Notable conditions or changes
ATIS
But remember, ATIS isn't real-time; broadcasts usually update every hour unless there's a significant weather or operation change. To make sure you have the latest information, always double-check the ATIS code (usually a letter) to ensure you're tuned into the latest recording.
ATIS vs. AWOS and ASOS
Unlike AWOS and ASOS, the Automated Terminal Information Service (ATIS) doesn't just provide weather info; it also offers airport-specific details.
In contrast, AWOS and ASOS are focused solely on weather conditions, reporting meteorological data automatically. And while humans can be involved in broadcasting ATIS messages, an automated ATIS system records and plays the messages when the control tower is open.
Update Frequency
Here's the takeaway: At airports with a control tower, ATIS gives you an overview, including the weather. AWOS and ASOS provide weather data but not additional airport-specific information, updating automatically and more frequently than ATIS.
What Information Can You Get from an ATIS?
Every minute
An ATIS broadcast typically includes the following information:
- The ATIS information identifier (a letter from the phonetic alphabet)
- The current wind direction and speed
- Visibility
- The temperature and dew point
- The altimeter setting
- Active runways
- Instrument approaches
- NOTAMs
- Special instructions or airport advisories, such as taxiway closures or construction areas
Every minute
Here's an example of a typical ATIS broadcast:
"Danbury Tower ATIS information India, one-two-five-three Zulu,Wind two-four-zero at five,Visibility ten,Scattered clouds one-zero thousand,Temperature two-one dewpoint one-zero,Altimeter three-zero zero-niner,Runway two-six in use for arrivals and departures,Arriving aircraft, expect the visual approach,Use caution for bird activity in the vicinity,For further information, contact flight service frequencies,Advise on contact that you have ATIS information India."
Every hour
Automatic ATIS
Automated ATIS systems make the process more efficient by reducing the workload of Air Traffic Controllers. The most common form of automatic ATIS uses a synthetic voice to read the ATIS messages, saving controllers from recording the messages every hour.
Some ATIS frequencies are labeled "D-ATIS" or "digital-ATIS." These modern systems deliver essential airport information digitally, right into the cockpit. This helps pilots receive readable information and reduces the chance of misheard instructions from manual broadcasts.
Automated Weather Observing System (AWOS) Explained
Comprehensiveness
AWOS is all about weather, providing information instantly. It's like having a personal weather station at your fingertips!
Table 1 shows the types of information AWOS provides, depending on the level of the station.
Least comprehensive
| Level/Type | Information Provided ||-------------------------|------------------------------------------|| | Barometric pressure, altimeter setting. || | Altimeter setting and visibility. || | Wind speed and gusts, wind direction, variable wind direction, temperature and dew point, altimeter setting, density altitude. || | What provides + visibility. || | What's provided in + sky condition, cloud ceiling height, liquid precipitation accumulation. || | What's provided in + precipitation type identification (rain, snow, drizzle). || | What's provided in + thunderstorm detection. || | What's provided in + precipitation type identification, thunderstorm detection. || | What's provided in + precipitation type identification, freezing rain detection (previously known as ). || | What's provided in + freezing rain detection + runway surface condition. || | All the information in + runway surface condition. |
As you can see, AWOS stations range from basic to highly advanced, reporting various weather elements automatically, 24/7.
More comprehensive
Automated Surface Observing System (ASOS) Explained
ASOS functions similarly to AWOS but offers even more features, delivering real-time weather data and contributing significantly to the National Weather Service's (NWS) climatological database.
Most comprehensive
ASOS stations are operated by the NWS, unlike AWOS units, which are handled by the FAA. The NWS uses ASOS data to support public, aviation, and marine forecasts, as well as severe weather warnings and many other weather-related operations.
Finding ATIS, ASOS, or AWOS Frequencies
Wondering how to locate ATIS, ASOS, or AWOS frequencies at airports? Here are three simple methods:
Airport Diagrams
Availability
Look for a dedicated airport diagram for large airports, where you'll find the relevant frequencies listed.
Sectional Charts
Towered and non-towered airports
Think of sectional charts as treasure maps. They'll give you lots of valuable information—including ATIS, ASOS, or AWOS frequencies by locating your airport on the chart.
Approach Plates
Towered and non-towered airports
For airport approach plates, you'll find relevant ATIS, ASOS, or AWOS frequencies listed alongside other essential information.
If an airport lacks these stations, you might find the nearest one's frequency listed on the approach plate.
Only towered airports
FAA Directory
The FAA's airport directory helps you search for any ASOS or AWOS station, including their levels and operating agencies. Phone numbers are also usually included for remote access to weather data from AWOS stations.
But be cautious, as we've found that many of the listed phone numbers no longer work, especially for smaller airports.
ATIS, ASOS, or AWOS vs. METAR
Now you might be wondering about METARs and where they fit into the picture. The primary difference between METARs and ATIS/ASOS/AWOS lies in how and when you receive the information.
Typically, you'll receive ATIS, ASOS, or AWOS information from a dedicated radio frequency or data link, while you'll obtain METAR information during pre-flight briefings or from the airport database.
Here's a quick comparison of what we covered:
- ATIS: Comprehensive airport and weather information (issued when the control tower is open).
- AWOS: Basic weather updates from automated stations (24/7, updated every few minutes).
- ASOS: The most comprehensive (and advanced) automated weather data from stations operated by the NWS (updated every minute).
- METAR: A coded weather report from the closest airport, provided every hour with detailed current and recent weather conditions.
The Automated Terminal Information Service (ATIS) differs from Automated Weather Observing System (AWOS) and Automated Surface Observing System (ASOS) as it delivers not only weather updates but also essential airport information at controlled airports. Meanwhile, ASOS and AWOS, although automated, only provide weather conditions with ASOS being a more advanced version, typically operated by the National Weather Service (NWS). In the realm of finance and technology, navigating through these acronyms can be likened to understanding the complexities in managing stock market data or technological advancements in weather forecasting systems.
