Depends on the airline and the size of the board and destination and how nice you are
When I travel to / from puerto rico on american airlines I always get charged no matter the size of the board
When I travel to the Gorge with my small board I hardly never get charged for a small board
Advice, pack small underweight packages and tell 'em its a wakeboard or wakeski or boogieboard:lol: That'll almost always get the small boards thru gratis