Source: The Sydney Morning Herald
quote: Looking at the Boeing 767-400, operating empty weight is 229,000lbs and max take off weight is 450,000lbs giving about 220,000lbs of cargo and passenger weight.So the actual percentage increase in fuel costs if you double passenger weight, assuming fuel costs are linear with weight ( it isn't, 1% reduction in weight only gets you a 0.75% reduction in fuel use), is ((450,000/(229,000+110,000))-1)*100= 33%.
quote: It makes more sense to distribute the cost of the plane's weight on a per pound of payload basis. Your 767 has a maximum payload of 220,000. The 300 pound person consumes 0.136% of that. The 150 pound person takes 0.068% of that. And they should pay accordingly.