(((Cannot stay airside as CX and QF use different terminals at PER, as others would have said))).
Very troublesome tho.
As you would have passed incoming immi at PER T1, then trudge to T3, and do similar this time with D BP.
Can't use Smartgate.
Also have to do int sec screening twice, HKG then PER T3.
Incoming if they decide to check you at PER T1 by DAFF.... then again if DAFF decide its needed in SYD T1.
Different terminals all the way, is one thing, the trudge is another, triple immi Aust procedures...
As much as I love flying, this will be a tough odyssey.
Aus passport I hope.
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It's NOT QF9 you need or want.
It's QF6 PER -> SYD.
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CX can't do the D BP.
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Will be a very tight and tiring run all up.