A clear demonstration of the inherent danger of NPAs, whether conventional or RNP, compared to an ILS, you are reliant on a pressure setting to define your vertical profile. The aviation world is making, in my opinion, an unwise rush backwards in safety with the proliferation of new RNP approaches that may look all shiny and new but have the same flaws as older NPA's. In some ways it is worse as we have inconsistent terminology and procedures between various organisations, states, manufactures and airlines, they have all combined to make it a bit of a mess.