Warning - RANT
Why do most people appear unconcerned about IFR/IFR segregation?
Try looking at it from the big picture - outside the circuit an IFR/IFR pair has a much higher collision probability than an IFR/VFR pair.
1 - IFR aircraft on approach to the same airport will probably be using the same approach with the same vertical profile, with quite large variations in speeds. VFR aircraft on the other hand will be approaching from random directions and altitudes.
2 - When an IFR aircraft has to go around due to not being visual they generally head to the same hold where any other IFR aircraft will be holding. VFR aircraft will be holding in random locations or diverting elsewhere.
3 - A 100 hour private pilot can have an instrument rating. The 'do it yourself' system results in the segregation being dependent on his/her understanding of the traffic situation. In IMC there is no visual last defense option. Do you trust this guy/gal - you WILL be flying through EXACTLY the same piece of sky.
As much as anyone wants to discount it, the big sky theory is a risk mitigator. It is the predictability of the random decay of a radioactive isotope (ie statistics) that gives atomic clocks the accuracy that allows GPS to work. Likewise it is the predictably of the random nature of material science (statistics again) that allows maintenance systems to use an inspection program to determine airworthiness. The only requirement for using statistics for separation is that it has to be done on a sound scientifically defendable basis (which is the crux of the problem).
Now for those that argue that G is safer than E with the way it is implemented in Australia - you've got to be
joking.
1 - Outside a CTAF there is EXACTLY the same communication patterns - in both cases the IFR aircraft is talking to Centre (ATC) and the VFR aircraft is supposedly monitoring that frequency and announcing if in conflict - there is absolutely no difference there.
2 - Just about all VFR aircraft in E are required to have a transponder fitted AND operating mode C - in G they are only required to have it operating mode C if it is fitted. In any radar environment you can bet your arse that the controller is going to advise of any VFR aircraft as traffic even with an unverified altitude. If it's not and it's a large IFR jet it will have ACAS (I know ICAO doesn't recognize it as a safety mitigator for airspace design but it does add a level of safety). Yes I acknowledge that both of these defenses will work in both E & G, however the required transponder fitment is the difference.
3 - The weather doesn't change because the airspace is E rather than G.
4 - If we actually used ICAO G in Australia the differences would be far more significant. IMHO Australian G is really ICAO E without positive separation between IFR.
As to these ideas of making the zone bigger than Ben Hur - I have to concede that I agree with Dick on this one - you are going to take the focus away from the highest risk area for collisions which is the circuit. The other week I operated in D airspace that was quite busy at the time - almost constant radio traffic. Start including areas 30 miles away and you'll end up with restrictions and delays like they're experiencing at GAAPs at the moment. At Hamilton Island when the tower closes focus deteriorates as a result of the dozen or so aircraft operating between 6 and 25nm that are not conflicting airport traffic that are now broadcasting on the same frequency (and anyone says that they should shut up has rocks in their heads).
/RANT