Originally Posted by
joanneoelofsen
Hope someone can help. I'm traveling on Qantas from Johannesburg South Africa arriving in Sydney at 14h45 T1, then need to transfer to T3 to catch a connecting Qantas flight to Melbourne departing at 16h15 - only 90 minute layover. Any advice to ensure I don't miss my connecting flight to Melbourne?
When I return to Johannesburg I depart Melbourne, arriving in Sydney T3 at 09h35 and need to catch my connecting flight departing at 10h35. My bags will be checked in straight to Johannesburg from Melbourne. Again, any advice?
I guess what I really need are some directions around the airport so that I don't waste time getting lost.
Welcome to Flyer Talk
joanneoelofsen 
T1 and T3 at Sydney are quite a distance apart so both of your connections are very tight.
I hope your flights are on a single ticket. If the connections are across 2 tickets then there is a very high risk of misconnecting and I'd look to change to a later SYD-MEL flight and an earlier MEL-SYD flight.
After arriving at Sydney from Johannesburg you will need to clear immigration and customs. Rush - do not waste time at duty free as the connection is tight. Once through customs and landside turn right and head towards the end of the terminal. There will be signs for Qantas domestic transfers which leads to the bus to domestic. These leave every 15-30 minutes and take about 10-15 minutes. You can see why 90 minutes is not much time to allow for all of this. I generally allow 3 hours for international to domestic connections at Sydney (on same ticket). At least if you are on a single ticket there are lots of later Qantas flights to Melbourne and so you will probably be able to be rebooked on one of those.
In the opposite direction after leaving the aircraft follow the signs for Qantas international transfer. You will clear immigration and security after the bus ride to the international terminal.