RNav/GPS
 

Hi Folks

Could someone please explain, in not too difficult terms, the difference between an Rnav and a GPS approach.

Thanks .........

A GPS approach requires GPS to be available and be used.
RNAV approaches can be flown without GPS, as long as other means of area navigation ensure the required position accuracy (normally 0.3 NM if RNAV stand alone, 0.5 NM if NDB or VOR overlay).
That would normally be DME/DME by means of an FMS.

That is not allowed in the U.S. It was for a few years until some serious maps shifts occurred on a couple of RNAV IAPs that were not in a DME rich environment at lower altitudes.