Extra EA-500/Smooth weather

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Smooth Weather

General

The Extra500 features a special weather mode designed to prevent strong jumps in pressure, temperature and wind while flying. It can be activated in the EXTRA 500 menu --> Toggle Smooth Weather.

It works on top of 'Basic Weather' and uses the 6-10 closest METAR-s to create a 'local' METAR for the position of the aircraft. Especially pressure and temperature have an additional filter to make the transition as smooth as possible.

It does not work with 'Advanced Weather', in fact it will switch it off. If you want to return to an other weather sort, toggle smooth weather off and use the normal weather dialog.

Also, there is a penalty in performance. Once a minute, the METAR stations are updated and this might result in a noticeable lag. This lag is very pronounced when first activated, so it is advised to activate while on the ground. The scan range for the (valid) METAR stations is variable and keeps the number of stations used in between 6 and 10.

Obviously if you are in an area with limited METAR coverage, smooth weather will not work as intended. It needs at least 3 or 4 METAR-s to be effective and in large areas on our planet the METAR coverage is somewhat scarce. It works much better in Europe than in Africa or even the North-American continent.

Finally, the current implementation is a proof of concept and the code a bit rough on the edges. Nevertheless it works pretty well under the circumstances it is designed to work.

Technicalities

The average METAR is displayed in the Environment - Weather dialog. Two things you will notice:

• it still features an airport (the nearest airport actually) and this airport might not even have a weather station. This airport is only used to get the correct altitude which is used for calculations. The METAR itself is however always for the aircraft position.
• Some METAR parts are not displayed. These are directly written to the property tree, so no need to worry.

If you want to know what the smooth weather system is doing, the properties can be found in the property tree under /extra500/weather. If you change the 'debug' property to true, it will dump some values on the terminal.