It sounds like a hangover from the RAAF 1FTS days, when there were a number of sub-areas making up one big one which went over the areas described above - pretty much all the Bellarine peninsula, out almost to Bacchus Marsh, west to Moriac and Bannockburn (this would be ringing a bell with all the students who had to stand up and quote the area boundaries from memory at morning brief!), around Avalon's airspace, etc.