j_t:
Putting to one side any constraints which might be imposed by Regulatory pressure, I don't think that either Mutt or I have any problem with reduced protected areas predicated on modern RNAV capabilities.
Any reduction would not occur at the DER, rather starting a mile or two beyond the DER. But, that reduction would see the linear containment areas being navigated with performance based navigation instead of a heading or some marginal (at best) VOR radial or NDB bearing.
I can't speak to regulatory requirements elsewhere, but such a modern concept would have no issues with FAA regulations. To the contrary, the path for approval already exists. From what I know, many "first world" nations would have no quarrel using PNB for the OEI flight path. And, some two years ago, Naverus provided just such an OEI flight path for China to use at Lhasa. The Airbus A319 was recently added to that approval:
Naverus | Performance Based Navigation & Required Navigation Performance
Also from their web site:
RNP AR procedures designed to Naverus’ criteria include:- Instrument approach procedures including missed approaches
- Departure procedures
- Non-normal (engine inoperative) departure procedures