Originally Posted by
CBreezy
If you are using GPS RNAV, RAIM is still very much used. The two are interconnected. RAIM ensures the receiver is getting enough satellites for GPS navigation and WAAS/LAAS provide a correction to a signal to allow for more accurate approaches. No RAIM, WAAS is worthless.
I do not believe this is correct. WAAS do not have RAIM, since WAAS uses GEO satellite to send signal ( I believe there is one or two only). RAIM is used by old fashioned GPS and makes sure that the signal from the Satellite is not corrupted. So, it uses t least 5 or 4 plus a barometric altimeter. When the corrupted satellite is to be removed, RAIM requires 6 SATs. 6-1 bad one.