Ah, Malcolm....you'e fallen into a bit of a trap here!
A Great Circle course always starts off aiming towards the pole of the hemisphere you are flying (or sailing) in.
Once you cross the equator the great circle first heads towards the opposite pole and then diverges from it.
So, in fact he'd be heading away from Australia (to the west) if such a course was being followed. His actual trajectory would be in the shape of a shallow "S". Sorry my friend, but if "your" course was followed they should be looking somewhere about 800 miles west of Aussie. A lot of water in that vicinity!.
Back to the drawing board, I think. Bryan.