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Howto:Fetch live aloft data

9 bytes removed, 09:19, 30 May 2009
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== Introduction ==This [[:Category:Howto|HOWTO ]] describes how to setup live setting of wind aloft. This is the wind speed, direction and temperature for different altitudes. [[FlightGear]]'s feature of setting current weather by using the <tt>--enable-real-weather-fetch </tt> uses [[METAR ]] which only reports ground weather.
The aloft feature currently only works if you have a source distribution of FlightGear or the [[CVS ]] version since you have to apply a tiny patch to the sourcecode (just a single line). It only works if you have '''bash''', '''awk''', '''wget''' and '''netcat''' on your machine. This is usually the case if you are running linux and should be no sweat for OS/X but might require some setup if you have some less feature rich operating system.
== General description ==
The wind aloft data is brought to you by the nice people of Jeppesen(R). Under [[http://www.jeppesen.com/weather http://www.jeppesen.com/weather]] a Text Weather service is provided free of charge. We use this service to fetch the aloft forcast and use these data as input for FlightGear.
When enabling the <tt>--real-weather-fetch </tt> option, FlightGear searches for the nearest airport to your present position that has a METAR service. If it finds one, it propagates the environmental settings and the station id of the airport the METAR was fetched for. A tiny add-on sends this station-id to a listening daemon program called aloftd.
The aloftd waits for input from FlightGear and interprets it as station ids. If the station id changes, it retrieves the aloft forcast from Jeppesen(R), parses the data, connects to the FlightGear telnet server and sets the aloft data in the property tree.
so it reads
// fgSetupWind(dir_from, dir_to, speed, gust);
in the file src/Environment/environment_ctrl.cxx. It should be around line 620. Perform a make for FlightGear.<br/> 
'''EDIT:''' This is no longer needed if you use FlightGear CVS. Just set the property
/environment/params/metar-updates-winds-aloft

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