why shouldnt BA charge a fee? how much? enough to refill it, what about the cost of maintaining it and buying the tank itself. Just as fuel costs vary Im sure that so does O2. I hope it doesnt become a for profit product. But at the same time it shouldnt cause the carrier any $$$ either out of pocket.
Heck in many locals if you get an ambulance cause you or someone dialed 911 etc, theres a very good chance you'll be receiving a bill for it.