Originally Posted by
mmthomps
This means that in order to fly from Sydney to Perth, and then from Perth to Melbourne, I'd have to buy separate tickets (Qantas, or Virgin Australia). My question is: what would it take to change planes from an inbound United flight at Sydney to one of those other airlines; and then from one of those carriers to United at Melbourne. I don't know those airports. If we checked any luggage, would we have to claim it and recheck? Is that possible and, if so, how long a layover would we need? We could try to do all carry on, but we'll be there hiking, etc., for 3 weeks.
When making a split-ticket cross-alliance I/D or D/I connection like this, think of it as the least connected as you possibly can. At SYD, the domestic and international "terminals" are more like two airports which share the same runway. You will collect your baggage at SYD and then clear Australian customs, after which you can find a counter to check in with either VA or QF (who will accept your checked baggage and then put you on a bus to the domestic terminal). I have not done this transfer it MEL, but it would be similar -- collect your bags and walk them to the international terminal where you would check them in with UA before clearing security and passport control to leave Australia.
I think 4h00 is a good guideline for making this kind of connection, but be aware that you are completely on your own if e.g. LAX-SYD cancels and you arrive a day late. Still, this may be one of your better options as PER is just really hard to get to on *A. My last time doing a split ticket connection at SYD (NZ int'l to VA domestic), it was about 45 minutes from the door of the inbound aircraft to being airside in the SYD domestic lounge, but that was about as smoothly as it could possibly go. The 4h00 is to guard against the fact that you are completely unprotected against any delays.