There are two kinds of airline adapters, not counting a few that provide North American standard 110V AC. The emPower kind uses a small, unique plug. The other kind uses a plug that's physically identical to an auto "cigarette lighter" plug. Every airline adapter I've seen, including my Kensington, supports both. The cable has an emPower plug on the end. A cigarette lighter adapter slides over it for the other kind. So, if you get any airline power adapter, you'll be set for US and for other airlines, such as AA, that use the other style. (You have to make sure, in using a cigarette lighter outlet, that you don't pull out just the emPower plug and leave the adapter sleeve behind in the outlet.)

As for which airlines, cabins and seats have power: try www.seatguru.com. It also says what kind.