Merlin magic -
A common night sortie involves coming off the range at Evans Head and blasting northwards up the coast at low level. Probably started on TFR and then maybe came off it for a bit of night hand flying practice over water (instrument scan at low level and 500+ kts over water is hugely demanding and part of the usual instrument rating renewal). Either that or they've run a target to the north and have cruised down Fraser on RTB.
Either way, usual practice was to pop up from low level passing the northern tip of Straddie, and contact Brissie approach for direct Amberley at around 5000 ft. That track usually takes you over the inner north and western suburbs as you manoeuvre to pick the low TACAN approach from the NE- maybe diverting a bit left or right to check out your house with the Pave Tack pod - just to make sure that the missus doesn't have any unauthorised visitors in the driveway!
Wouldn't have been very quick though I don't expect - no more than 350-400 knots or so. Probably just a clear and quiet night to help the sound carry.
(Although I did get asked by a Brisbane controller one night for "best possible speed until clear of the Brisbane CTR". Having waited years for the opportunity I was able to say - "Are you SURE you want my best speed? How about I just give you 600 knots and we save ourselves the bill for the broken glass?"
cheers
SW