(THEAGE) — Former Qantas chief economist Tony Webber caused a stir when he suggested airlines should charge heavier passengers more for their ticket. In this follow-up piece he looks at the reasons why it’s not happening.

There are numerous forces that drive fuel consumption aside from the weight of the empty aircraft and its payload (the people and the freight on the plane).

They include, but are not limited to, the distance traveled, the weight of the fuel itself, the flight path taken, the speed at which the aircraft travels, the descent trajectory, the age of the aircraft, congestion in the air and on the ground at the airport, weather conditions and pilot discretion.

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