Here I go again, answering Dick's questions. Maybe one day he will answer mine. Here goes;
C change, what separation standard do the tower controllers use between IFR and VFR when they are operating the entire combined airspace as you claim?
First up its not a claim, its fact. They combine when traffic dictates, ie weekends, late at night. All bases do. The separation standards do not change whether combined or not. Class C is still class C. What changes is where the service is provided from. When combined, the Approach controller is in the Tower and provides both the Tower and Approach service, ie you are talking to the Approach controller when combined, who is also providing the Tower service. It is the Approach controller who "owns" all the airspace and they release portions (5nm, CTZ etc) to the Tower controller for aerodrome operations, as required. The tower controllers number one tool in separating planes (and helicopters) is the good old human eyeball, "Visual separation". Thats why I keep asking you, if you asked for direct tracking to the airfield, where the tower controller may have been able to visually separate you and the kingair.
It doesn't matter who is providing the service, the person cannot reduce the separation standard in place (3Nm or 1000', yes I know there are more) until both aircraft are sighted by Tower and on the same frequency, or its assigned to the pilot.
Why is it only in Canberra class C that the tower controls the airspace to the zone boundary? What advantages are there in this and why can't willy airspace copy this proven system?
Very difficult to answer as I have never worked there. Speculation only maybe, maybe it is easier for Tower, as there are plenty of well known landmarks to use as geograhpical features to separate with. Maybe its endorsements, qualifications, maybe Radar coverage is poor due to terrain? I don't know, you would have to ask them.
Are the tower controllers at willy approved to use a radar separation standard when they are in the tower?
That depends on the individual in question and their job. As I said 'Vis sep" is the primary tool for a Tower controller and they can use the radar for certain information. There are too many variables to list here, thats why we have MATS. Also remember the person doing Tower may not have done the "Radar" course yet, ie not employed as an Approach controller yet. They could have just arrived and still doing training and only completed Tower. Please note that they are all Air Traffic Controllers, who can be employed in either Tower or Approach, if they are qualified and endorsed. An example would be a PPL who only flies a R22. They are a qualified helicopter pilot, but not checked out on a gas turbine, or multi engine As355 etc. I'll leave it at that, as the variables are huge and I'll be here all day.
Do they have the correct equipment to do this in the tower?
The equipment is exactly the same, just a smaller screen in the Tower. If it was the same screen size as used in Approach room, it would block visibilty of the Runways/Airfield and that could be disastrous.
Because it is smaller, the decison to combine must be made carefully. It is harder to provide Approach on, due to the smaller size but its still safe. The sun on the screen is another factor and obviously traffic densities. You don't want an arrivals sequence of half a dozen planes or more, whilst trying run an aerodrome with 5 in the circuit. Its just dangerous and you can't watch them all.
This is not something new and has been done for many years. AsA also combine sectors when traffic dictate. Both organisations have a book full of rules and procedures for when to combine or not.
I hope that this has helped answer some of your questions. As its a beautiful sunny day, I'm off fishing before the wind gets up.