There are some comments on here that reflect very poorly indeed on their authors.
Geoff Fairless has pointed out the service Dick Smith has given to aviation and his continuing attempts to improve aviation safety in this country.
In turn, let me point out that Geoff has a lifetime of experience in Air Traffic Control and as a consultant to aviation ANSPs in other nations.
These are people who truly know what they are talking about.
I hold both Australian and US pilot licenses and an Australian ATC licence.
In the USA it is very simple indeed; IF you are operating IFR it is assumed you can not see to separate yourself therefore ATC separate you from other aircraft. To avoid delay to yourself and others, you are expected to announce when you can proceed VFR. There is little class G airspace and it is at levels where you had better be VFR because you are below LSALT for IFR.
The Mangalore mid air collision was not the fault of the ATCs on the console even if they could see what was about to happen. Geoff F points out the ICAO requirement that the function of ATC is to prevent collisions between aircraft BUT the Airservices Act specifies that it is up to Airservices to decide the extent of services that they will provide (where, when and to whom). IF Airservices management decides no separation is to be provided to IFR aircraft in an airspace it would be untenable for some controllers to nevertheless provide it and some to not do so - the confusion would itself be a safety risk.
The concept of "traffic is" separation for IFR aircraft is and always has been a flawed concept. An aircraft on an IFR approach is, by regulation, compelled to remain on the published track and to follow the published approach (or go around but still following the published track) It matters not what the ATC says the traffic is, the pilot is legally required to follow the procedure. Likewise on IMC departure, the pilot must follow the route chosen for terrain clearance until LSALT is reached.
The management of Airservices needs to consider its lack of professional pilot input to their decision making - their level of service does not meet the ICAO requirements now and never has. Since people like Geoff Fairless and Merv Fowler left Airservices, even their incidental knowledge of aviation user needs has vanished. Not too many professional pilots left in CASA either though there are a frew - maybe they can push CASA into pushing Airservices, maybe??
That accident occurred in Victoria; which has a rare (for Australia) stature on Corporate Manslaughter. Applicable or not is beyond my legal knowledge but........