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Decoding the Weather

The goal of the coded form was to allow forecasters and observers to key in data quickly.

Even in the 21st century, pilots must decode the cryptic language of surface observations, terminal aerodrome forecasts, and pilot weather reports. [Credit: iStock]
Gemini Sparkle

Key Takeaways:

  • The coded format for aviation weather (METARs, TAFs) was originally designed for rapid, error-free data entry by forecasters, not primarily due to limited bandwidth.
  • Although modern apps can translate these codes, current automated translations into plain English are frequently inaccurate or misleading due to flawed assumptions or software design, potentially causing critical misinterpretations.
  • Switching all global automated weather systems to generate plain English directly would be a costly and complex undertaking, requiring extensive modifications to both data generation and consumption applications.
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QUESTION: Let’s face it, technology has advanced in the last decade or two, so why do we have to know how to read all that goofy textual weather?

Answer: There’s a great divide in our aviation community that’s been going on for decades with no end in sight. That is, why are we in the 21st century and still decoding the cryptic language of surface observations, terminal aerodrome forecasts (TAFs), and pilot weather reports (PIREPs), just to name a few? After all, they coded these reports or forecasts more than a half-century ago because of the limited bandwidth in the days of 1,200 baud rates, right? Well, yes and no. There’s no harm blaming this on these data limitations, especially if it makes you feel better, but that’s not the real reason they were coded in the first place. And no, the coded form wasn’t preserved over the years as a hazing ritual for student pilots.

The primary goal of the coded form was to allow forecasters, observers, or other stakeholders in the aviation or weather industry to key in observations and forecasts quickly. One could argue otherwise, but it wasn’t as much about the consumers of this data or the bandwidth of the teletype connection used as it was about the data entry time and opportunity to make mistakes. 

Scott Dennstaedt, Ph.D

Scott resides in Charlotte, North Carolina, and flies regularly throughout the Mid-Atlantic and Southeast U.S. He is a CFI and former NWS meteorologist. Scott is the author of "The Skew-T log (p) and Me: A Primer for Pilots" and the founder of EZWxBrief.

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