Originally Posted by
NOLAnwGOLD
So looking on DL.com, the SYD flight arrives at TBIT as clearly stated by flight status. Customs at T5 isn't open that early. Also I though that TBIT is walkable now airside to T4. I thought you could get from T4 to T5 to T6 via underground tunnel. The part I'm not 100% sure is the T4-5 bit.
Yes there is a connector from TBIT to T4 and it is possible to walk from TBIT to T6 airside. But, the OP will still have to reclear security either at TBIT or T6. The security lines may be shorter/easier at T6 than at TBIT as there is no TSA Pre at TBIT, plus after that many hours on a plane it may be worth it to get outside and get some relatively fresh air.