There is absolutely no way a 27 will go on board as carry on. The box is HUGE and it is custom made to protect the screen. A 21 out of the box and in a carry on bag, MAYBE, but you are taking a big risk not having it in a protective box. I would just put it into another box and check it. I would not try to put the apple box through checked luggage as is. It's a retail box, not meant to be shipped through conveyor belts etc.