You are allowed to carry it on, but be ready for some ignorant annoying people. A flight attendent may ask, but if TSA is down, you should be all good. And they have always been down in my experiences. JUst let the flight attendant know that it was ok with TSA and she/he should be cool with it. It might be easier if you have the board connected to your backpack, so its part of your luggage or something. Businessmen have come up to me, telling me its a weapon. One went as far as to try and tell me "next time, just leave the board and home." Unfortunately for them, they are not in charge. I like to unload on assholes like that.