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Coded vs Plain English Text

Updated: Nov 14, 2022

I think sometimes there's another great divide in our country 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 forecast (TAFs) and pilot weather reports (PIREPs)? They coded these reports or forecasts due to the limited bandwidth in days of teletype, 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 reason they were coded.


The primary goal of the coded form was to allow forecasters, observers or other stakeholders in the aviation industry to enter data in quickly. One could argue otherwise, but it wasn't as much about the consumers of this data or the bandwidth of the teletype connection, but more about the data entry time and the opportunity to make mistakes. Typing more characters likely means more opportunity to make a mistake.

Now that we're in the 21st Century, is there any reason to keep the coded form around? Certainly. For the same reasons as before? Not exactly. Although the code today is different than you see above, automated systems are programmed to generate the coded text. Some of the heavyweight apps and other web applications ingest that coded text and translate this into plain English. Sometimes the translation is near perfect and sometimes not. This often depends on the assumptions made by the translator - and there are hundreds of them out there. Even if the exact standard is followed by the automated system, exceptional cases pop up from time to time which may cause a poor translation...sometimes really poor.


For example, in this coded surface observation the remarks state FZRANO. From the Federal Meteorological Handbook No 1 under 12.7.2 (j) Station Status Indicators it states...


"...when automated stations are equipped with a freezing rain sensor and that sensor is not operating, the remark