The benefit that we see with RNP approaches—I'll go back to this—is that when you're close to an airport, for a safety perspective we fly what is a 3° gradient path, so that's roughly 300 feet per nautical mile. Regardless of what we're able to accomplish beyond that, when you're close in proximity to the airport, three miles back, you're roughly going to be a thousand feed above ground. That hasn't changed from the 1960s to where we are today.
On December 11th, 2018. See this statement in context.