Checking in airside in SFO
 

I will be connecting through SFO arriving on AC and will have about 1 hour 40 min before my departing flight on Qantas to SYD. I'm concerned that if I have one of those OLCI issues that doesn't let me complete the check in I will have to leave the secured side and go through the regular check in process with not much time to spare.

Is there a way to check in airside? I will only have a carry on.

this is also assuming that AC won't be able to check me in through to SYD. Though I don't know if they can.

Nope as AC is US domestic arrival. Check-in cutoff varies by class but usually 60 min so you have some spare time. AC won't check you in to SYD, ime.

You will need to leave the secured airside as Air Canada arrives in the G-Pier of the International Terminal and Qantas departs form the A-Pier of the International Terminal. There is no secure walkway between these two Terminals.

hmmm, i thought you could walk between terminals. is 1 hour 40 min enough time

There is limited airside connections at SFO (e.g. UA domestic to SQ etc).

1:40 is risky on separate tickets

Risky especially in SFO. But there is no airside way to transit from one side of the international terminal to the other; it's built kind of like an airplane, with the center (fuselage) serving as check-in and the two wings branching off. You'll need to exit one side, check-in, then cross to the other and go through security again. Easily doable if your inbound is on schedule.

OLCI will be your friend here, assuming it works.