Class D Towers can use TSAD for situational awareness and can use it for certain tasks that do not require continuous screen monitoring; one example is to confirm that an aircraft has left the airspace they are responsible for.
Dick is correct that the device is not approved by CASA (Using ICAO standards) to be used for separation (prohibited is the wrong word);
1. Because it does not meet the ICAO requirements to be a separation tool; and,
2. Because the Tower controllers job is to look out of the windows.
In the case above that Dick describes,
Re the Class C. It is more expensive because it requires an approach radar system with primary and secondary radar to operate safely.
The FAA does not establish Class C without radar coverage but Australia has vast amounts of Class C airspace that do not have surveillance coverage
Otherwise the controller would quite often not know the exact location of the VFR traffic.
The controller without surveillance only knows the position of aircraft, IFR or VFR, on the basis of pilot reports; that is why the procedural separation standards take up much more space than surveillance standards
Let’s say a VFR aircraft flew across the approach airspace 20 miles north of Launy. How would the controller ever know?
Only from the pilot's position reports unless the aircraft was fitted with a transponder and was squawking, then it would appear on the TSAD. (Utilising information from the Tasmanian Multilat system)
How would a controller know the position of a VFR aircraft crossing at 6500’ from East to west 20 miles north of Albury?
See above
“Keep left of that farm in front of you”. What a joke.
Possibly however being able to fix position relative to a known point on the ground is probably the oldest form of navigation and separation
VFR aircraft can fly straight through to approach airspace of these non radar class C airports and the tower controller would most likely never know.
True but ATC is based on pilot cooperation backed up by legislation, and why would a pilot want to fly through the approach airspace of any aerodrome without announcing themselves?
I hope this explanation helps