By all accounts (and I stand to be corrected) the opposition to the IMCR (or something similar) in Europe does not come from the NAA's but from certain professional pilot's associations who do not want non-professional pilots in their exclusive 'professional' airspace - and they do have some clout.
2Close
I dont think it is so much that but freeing up airspace for less congestion and reducing ATC workload.
There is a problem in Europe with Slot Times and those slot problems are not dictated by enroute delays. Although Light GA would not use the busy upper levels larger faster aircraft do have to be descended through or climbed through those low levels in various areas.
Depart out of London in a Corporate jet and see the amount of radar headings you get and way off course headings you get before being allowed to climb into the upper levels or to your airways routing.
The fact that a light 4 seater single takes almost as much workload as a large aircraft and causes hell on the speed differential and climb rates and you can see why the reluctance to encourage more in certain areas. Ie they dont want to encourage what they see as half trained PPLs clogging up the system flying their hoard of PA28s in the airways. They dont like it now in certain areas. We are tolerated rather than welcomed.
Even in a Citation business jet you are always being questioned on climb rates or speeds.
take a light twin around London at peak times and you can feel the reluctance to have you there. You are often directed miles off track or shoved down to the bottom of CAS to such an extent that you wonder if its worth bothering filing IFR and far quicker to stay below and almost go direct.
One fear could be that rather than licence restrictions there could be aircraft performance restrictions on aircraft using CAS IE if it doesnt climb well enough or cruise fast enough it cant fly in CAS. I could only envisage that happening in certain areas?
Pace