Keg................... the diversion you speak of was many many years ago (20?) where on a final command check on a 747 into Perth, the aircraft diverted to Learmonth, made an NDB approach and missed out. The fellow under check decided to let down over the water and proceed back to the airfield visually which he did successfully. He was also successful in passing the check ride!
This event with the A330 and others like it have been discussed many times before, the problem for Perth being:
1. Unreliable forecasts.
2. Lack of low vis landing aids i.e. Cat III ILS with the required procedures. Compared to overseas, we are well behind in not having one CAT III system in Australia even though they have been available for thirty odd years.
3. Suitable diversion airfields being quite a distance away. Note that carrying an alternate is not always the answer as the above shows. I also don't think YPKG as a suitable planned alternate for large jet aircraft.
4. Casa fuel requirements are on the lean side when compared to other international regulators.
5. Fix items 1. & 2. and the problem will mostly go away.
BTW at times I take extra fuel and have never been questioned by the company, nor have I heard of anyone else being questioned.