It is highly reccomended to purchase a NAVIGRAPH subscription and download their level d FMSDATA / waypoint / navaid data! If you do not wish to do that, there is older data linked below. But it won't have most of the newer procedures, and is only for a limited number of airports, as naturally it is not possible to distribute commercial data. If runway numbering changed, it is quite possible that it will not work due to FlightGear limitations in the routing code.
To install navdata, create a folder FMSDATA, and add it to your additional scenery folders, at the top of the list. Inside that folder, place all the XXXX.procedures.xml files, in the format FMSDATA/X/X/X/XXXX.procedures.xml. For instance, FMSDATA/Airports/E/G/K/EGKK.procedures.xml.
If you want to run the MCDU on a phone or tablet for better realism and easier input, put mcdu.html into the FGDATA/Phi folder, run FlightGear with enabled HTTP server (i.e. command line --httpd=8080) and open http://your-flightgear-computer:8080/mcdu.html in the browser on your phone or tablet.
Some external tools you might want to checkout and use with this Model.
NOTE: These are external tools so make sure to check their terms of use
* [Trim Calculator (for FSLabs, but will work for us)](https://forums.flightsimlabs.com/index.php?/files/file/675-a320x-trim-calculation-tool/)
* [Take off performance calculator (excel)](https://forums.flightsimlabs.com/index.php?/files/file/763-a320-takeoff-and-landing-performance-calculator/)
* [Take off performance calculator (.exe -- different to above) ](http://www.avsimrus.com/f/for-pilots-19/popular-calculator-to-calculate-takeoff-parameters-in-from-airbus-type-36340.html)
* [Take off performance calculator (online)](http://wabpro.cz/A320/)