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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]
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Key Takeaways:

  • The coded format of aviation weather reports (e.g., METARs, TAFs) was originally created to allow forecasters to input data quickly and accurately, not primarily due to limited bandwidth.
  • Despite modern automation, the coded format remains valuable because automated plain English translations often introduce significant errors, potentially leading to misinterpretations of critical weather information.
  • While a global shift to generating weather data in plain English from the source is possible, it would be an immense and costly undertaking, and the author advocates for preserving the reliable coded version.
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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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