I have just heard from a retired US air safety expert and air traffic controller. He said in a situation such as Benalla, and
the aircraft goes below the MDA, the automation will initiate a Low Altitude Alert. At this point the controller is required to issue the alert and restate the MDA - in the case of a non precision approach - for example, a GPS approach.
I wonder why the ATSB didn’t recommend that Airservices look at such a proposal here? Yes, I’ve heard all the claims about cost etc, but surely to do it at one airport (say, Proserpine, with large jet movements) the cost would not be prohibitive and the safety improvement would be important.