The airline seat power is usually 15V DC in an "Empower" socket, and you need an adapter to step this up/down to whatever the laptop requires. I got a cheap adapter from CPC here in the UK, it cost £20 and worked fine, but ony supplied up to 75W. I got a higher power unit for my boss's Sony but he said it didn't work on any of the flights he took on a trip to Australia, however I don't know if it overloaded the adapter, the seat power or sometime else, I keep meaning to test in in the car and see if it works there.

Gareth