Originally Posted by pitz

Yeah, but you were connecting to a Canadian flight. I don't see why it would be different than booking AC LGA-YYZ-HKG (ie: US-Int'l), where you wouldn't see your bags either. Except in this case, because the flight leaves T3, you can't make a sterile connection (ie: Customs B).

I don't want to hold myself out as an 'authority' on this, but I'm pretty sure AC can check you in for a CX flight ex-LGA, and tag the bags through to HKG.