ATNS and some African States developed GPS approach procedures, also known as the RNAV approach procedures under the GROMET trials. Some States, amongst Namibia, have published those after a two year trial period. SAA was kind enough and provided a A319 for those final tests, that were done in Dec 2006. These RNAV saves a lot of fuel and time and is most convenient for both pilots and ATC. As far as I understand, the State approves those procedures irrespective where the aircraft is registered.