[arm958]

Charge by the pound!

That's fair. When you send a package via FedEx you pay by the pound; why should human cargo be any different? I weigh 160 lbs. and I don't want to subsidize some glutton's plane ticket. My daughters weigh much less. Why should they pay the same fair that someone three times their weight pays?

[Hap]

Unfortunately, charging by the pound doesn't fix the "spillover" problem.

I think the real solution is to have some seats 25 or 50% larger than others, then charge passengers who want to use them 25 or 50% more. I'd bet that even people who were not overweight might purchase those seats just to be more comfortable.