Rules state "Air Power cards must be played as if they were Air Sortie cards instead"
This really just means that the Air Power card (if used with the Air Rules in effect) is used like an Air Sortie. In other words, it cannot use it's direct effect as printed on the card, rather it is used to either bring a plane onto the board or order a plane that is already on the board.
Also note; unlike an Air Sortie card, it is played directly to the hand and counts toward your limit there. It also can't be played in conjunction with another command card like the real Air Sortie can.
Hope that helps.