pb,
The method used for years of aircraft for whatever reason following slightly different paths was perfectly accesptable and there were no good reasons given as to why the new method was required
That method only 'existed' because aircraft once navigated using pilot-interpreted, ground-based radio navigation aids. Over the decades we've seen aircraft manufacturers develop ever more accurate, computer-interpreted navigation systems, such as automatic DME/DME triangulation, inertial reference, VOR/DME RNAV and space-based systems. This means that aircraft themselves navigate incredbily accurately along procedures designed in the 1950s, such as at LHR.
The 'mew method' hasn't been 'required', hasn't been instigated by airports, it just 'is'. Saying we should revert is like asking all the ships using the oceans to determine speed by trailing a knotted rope and counting the knots that run through, or to determine depth under keel by dropping a weighted line
PBN/RNAV does give more options for flexbility, such as a selection of centrelines (1nm left, centre, 1nm right etc) for each route, which could be swapped each day/week, much as runway use is today.
as Gonzo hints the way things go in the UK any current flying and ATCO staff of any seniority will be retired by the time R3 is built
I'm not sure that's what I was hinting at.
I was hinting that many people seem to
assume that either no work is going on, or that there are several insurmountable problems, or that a new runway would just be plonked down in the middle of the current set-up with no changes. Or a mixture of all of them.