The FAI General Aviation Commission (GAC) has implemented the use of GNSS Flight Recorders to simplify methods of gathering and certifying flight data, and to use more objective methods for measuring flight performance data.
Currently approved GNSS loggers are compulsory in Air Rally and Precision Flying Competitions.
The Requirements are documented in Annex 4 to Section 2 of the Sporting Code. The document can be found here
A software to convert logger files from GPX format to GAC format can be found hereApplication for approval of GNSS equipment must be made to Mr Ralf Grunwald, GNSS Technical Advisor .