With the advent of satellite navigation equipment at an affordable price, the International Gliding Commission of FAI developed a technical specification for approved flight recorders. The IGC-approved flight recorders provide precise evidence of position for gliding competitions, world records and FAI awards and other activities. They replace earlier methods of observation that used photographic evidence or ground-based observers to record aircraft position. The IGC-approved recorders include a pressure altitude sensor and a Global Navigation Satellite System (GNSS) receiver. They also include data output in a standard ASCII-based format, the "IGC flight data format". This format is used in files with the suffix "IGC" that is specified in detail in Appendix A of the document "Technical Specification for IGC-approved GNSS Flight Recorders". It should also be mentioned that organisations outside IGC also use IGC-approved flight recorders and the IGC flight data file format.