Originally Posted by NYCflyerUA1k

If your tickets are standard award tickets -- eg milage award in Y, then they should not ordinarily be upgardeable at all -- not with miles or SWUs. Usually the computer simply won't accept you on the upgarde waitlist, but even if it clears when asked to support the upgrade at check in they will probably notice. Good luck -- maybe an oversold situation in Y will get you up to C, but sounds unlikely.