You will find the main reason it's allowed over in the states is the fact that they have two geostationary satellites and a bunch of ground based, Wide-area Reference Stations (WRS) to ensure the integrity of the signal, whereas there is just the one over the pacific.
???? My GPS's (all 3 of them) are usually receiving data from 10 satellites at any one time.
GPS approaches are available for many aerodromes in Australia, providing you're equipped with a TSO-149 certified GPS as this includes WAAS. These approaches often use ground based navigation aids such as a VOR or NDB, I'm unsure if it would any less legal if your GPS simply overlayed the approach on a map...
Nope! Where are you getting this stuff from ??? If you wanna be Biggles you will need to get your facts right.
You don't need a TSO-145/6 (not 149) GPS to fly a GPSRNAV Appr in Oz. I fly them regularly with my TSO-129 Garmin 430, perfectly legally!
If you are referring to GPS precision ILS type approaches - then yes, you do need a TSO-145/6 GPS -and you need to be somewhere other than in Oz because even though a TSO-145/6 GPS is WAAS capable (at least that is the case for Garmin 430/530) -
WE DONT HAVE WAAS in Oz.
I have flown NDB overlay approaches (or George has anyway) using the Garmin 430 many times in Oz (in VMC) - works like a charm.
SDK 