Your US passport should allow you to board a commercial carrier. You will need to mention the fact that you're a PR to the CBSA officer, though. You might also need to show them your CoPR.
Sorry I should have been clearer in my original post. I'm not worried about being able to board the plan. I'm worried it'll cause issues with CBSA that I don't have a PR card. I read that someone was using their Nexus Card & US passport to cross back and forth without a PR card, but looking at the GOES account (for Nexus updates) there is no space to put anything about PR statuses. It's a bit confusing because I've read both things.
Nope. Because you're be a recent PR, you would be in no danger of not being able to fulfill the PR residency obligations (http://www.cic.gc.ca/english/newcomers/about-pr.asp) and therefore cannot be reported\denied entry. The worst the CBSA officer can do is give you a slight rebuke for travelling without a PR card.
Thanks. I also didn't think it would necessarily be an issue because I never talk to the CBSA (or US CBP) officers. I use the Nexus kiosk, get the printed receipt, hand it to the last CBSA officer and get told "Welcome to Canada." Unless something is flagged on the receipt, I can't see them questioning me.
