Cpt Bloggs,
Forget about the nomenclature for a minute.
The obstacle clearance areas for RNAV and RNP approach procedures are completely different in the criteria.
I see a fatal fault in blending the two (in the OP's original post)
As you have the designation 'U', it appears you are in AUS, and of course, with the much more common sense down-under, one would not expect such issues.
Enjoy!
Last edited by underfire; 20th Aug 2013 at 02:00.