I did not see anything in the ATSB report about the efficacy or otherwise of the ground based warning system that Airservices must surely have in place when aircraft get too low and provides a warning to the Approach controller.
Surely the flight was already low when the pilot contacted the TWR?
I am sure Dick Smith and others in the past have mentioned that the ATC system has warnings like this.
I will have to enquire with my controller acquaintances??