Upvote:-1
I wish that there was somewhere to get the correct information all in one place. I have dual citizenship with Canada and Australia. I found out with plenty of time before I travel back to Canada that under new Canadian regulations I require a valid Canadian passport to enter Canada and cannot use my Australian passport to enter as of Oct 2016. As we are routing through the USA even though I have a Canadian passport as I am arriving via air I DO require an ESTA. If I were traveling via land between Canada and the USA I would not. My partner (Australian) requires an ESTA as well as the eTA Canadian equivalent to travel through both the USA and Canada. To leave Australia and re-enter Australia I must use my Australian passport. To enter Canada and leave Canada I must use my Canadian passport. Make sure you have both and they are not due to expire under 6 months just to be safe. The USA may want to see both.
Upvote:3
What you propose is pretty much exactly what you need to do.
Feel free to show the airline both passports if there are any questions. No problem at all doing that, they see dual citizens all the time. They will ask to see your AU passport on your return trip to Sydney (if they don't already have that info in your record).
There is no US customs exit, so you won't need your Canadian passport to exit the US.
An ESTA applies to a person, not to a passport. You do not need an ESTA because you are a Canadian citizen.
The smart gates might get confused.
Last time I did a trip similar to yours (I'm dual NZ/Canadian), I had difficulty with the smart gate leaving NZ, no problem had to go visit an officer in the non-smartgate queue. I was admonished for entering the US in the wrong queue, so as a Canadian citizen you should go for the US Citizen/Permanent Resident queue even though the sign doesn't say Canadians (the signage was incorrect in SFO, LAX might be properly signed). You can use the electronic passport reader for entering the US.