Originally Posted by underfire
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)
Understand. But that's why the approvals/requirements for each are completely different, and the charts are completely different. There is no way anybody could "just fly" an RNP AR without knowing that they have to jump thru all the hoops... I would hope!
I think STBYRUD has a good handle on the whys and wherefores of the two approach types from what he posted with his question; he's just after what's needed for RNP APCH LNAVs.