On an airplane is not the time for Mommy & Daddy to "take a stand". Its just not fair to the other passengers. We took dd on a 36 hour flight to (and back from) Vietnam when she was 2 1/2. She certainly acted up some, but it was mostly crying out of being tired (i.e., she would cry/wimper/whine a little bit when she woke up unexpectedly in an unexpected place) - not a lot that can be done about that except to comfort her and hope it ends quickly.

I wouldn't have considered being confrontational with her over her behavior while on the flight. Basically, I'd do whatever was necessary in the immediate short-term to improve the behavior rather than exasperate it. There's plenty of time for that when I'm not on the plane.