Why, Brian? Because it's a rumour network.
The fact is RPT aircraft, light GA (VFR & IFR), ultralights, gliders and even fast military traffic have been mixing it to a greater or lesser degree in non-radar, non-transponder environments in many areas of Australia for years now. At times these have also been effectively non-radio environments when aircraft have been on wrong or adjacent FIA frequencies. E.G. For RPT landing at Dubbo, CURRENTLY go from "C" to "E" at FL 200 (if they get that high), from "E" to "G" at FL125, from "G" to "MBZ" at 5000' - I don't recall hearing any great uproar of gnashing of teeth at this! There are also regular scheduled services to CTAFs surrounded by G.......(*gasp*)
There have been no en-route collisions in these environments that I am aware of. There have been what have been perceived as near misses in the "terminal area" avoided by visual means and, it seems, extremely rarely in the en-route environment. The only mid-airs that I recall have been in GAAP environments, one of which was an MBZ at the time and an other in parallel runway ops. There have also been a couple of cases of aircraft landing on top of another aircraft on the runway - again in GAAP/MBZ environments.
So, class G and CTAFs seem to have demonstrated safe operations IN AUSTRALIA - even with the minimal calls recommended by CASA in recent years. Many of the NAS changes are similar to what goes on now in our airspace in many areas. The question remains as to what level of traffic density can this type of airspace be expanded to with comparable
demonstrated levels of safety.
To me this has been the major failing of NASIG - there has been no data comparing apples with apples and oranges with oranges. If the US has
demonstrated enroute and terminal area safety in areas of similar (or heavier) traffic density AND radar coverage, then surely there can be little objection.
Such data has not been forthcoming. Sure, anyone can understand the logic of collision risk decreasing in proportion to the cube of the distance from the aerodrome area, but this doesn't explain enough of the other variables and is almost insultingly facile to use as a sole safety case. Sure, modelling can be done, but it must be cross-checked with real world data - where do we have this?
You're right, Brian, little of the NAS debate has been based on facts, and on both sides of the argument there are opinions aplenty, but so few facts to be had.....
Safe flying
NOtimTAMs