There was interest among the FlightGear users at my VA for a script to convert GPX format FlightPlans (like those on SkyVector) into FlightPlan files that FlightGear can use, so I created one.
This is only tested with GPX files downloaded from SkyVector so others may or may not work correctly.
Here is the script, it's a batch script so it's completely open-source and should work on all Windows versions, feel free to have a look at the code inside any text editor.
https://mega.nz/#!DvgHFYLL!OyFPYAkV58_r ... 3zs6hn8RFQ
Enjoy!