HC,
"You say your UNS can do NPA approaches - does it have TSO 145 GPS receiver? If only TSO 129 I don't think you would be allowed to do NPA approaches with gps as the sole aid in most of the world (except USA)."
No, it's TSO-129, but the point is that you don't use it as the sole aid: you MUST have the raw data available to monitor (see photos of the P-ILS in the other S-92) thread.