There is no justifiable reason to charge Australian airline passengers extra based purely on their weight, an aviation expert has said, in the wake of Samoa Air's introduction of the world's first "pay as you weigh" flights.
The variable weight of passengers was not a key concern of the larger commercial airlines in Australia when they considered their fuel consumption, according to aviation consultant Trevor Bock.
"I don't think it's a matter of trying to recoup the cost of carrying a heavy person versus a light person [in terms of fuel usage]," Mr Bock said.
"If a pilot is worried about the weather, they will throw on a tonne of fuel. Now, that is more than what having a plane full of heavy people would weigh anyway.
"It's not a significant amount of money [the airlines would save], especially not per sector."
Just because you weigh a bit over the average, you shouldn't have to pay.
Under the new system introduced by Samoa Air, passengers must type in their weight and the weight of their baggage into the online booking section of the airline's website. The rates vary depending on the distance flown, from $1 a kilogram on the airline's shortest domestic route to about $4.16 a kilogram for travel between Samoa and American Samoa.
Samoa Air chief executive Chris Langton said that introducing a new payment policy based on weight was the "fairest way of travelling".
Samoa Air's fleet of three- to nine-passenger planes are tiny compared with the usual commercial planes, but Irish low-cost airline Ryanair has previously mooted the introduction of a "fat tax", following a survey conducted by the airline that suggested about a third of passengers supported it.
None of Australia's commercial airlines have indicated that they plan to introduce a pay-by-weight ticketing system.
However, some foreign carriers already encourage obese customers to purchase an extra seat if they are unable to fit into one comfortably.
Mr Bock said that was understandable if an airline could not sell a seat next to an overweight person because of their size.
"Some airlines will insist that you have to buy two seats if they can't sell the middle seat because you're too big," he said.
"But just because you weigh a bit over the average, you shouldn't have to pay, I don't believe."
A spokesman for the Civil Aviation Safety Authority said the standard passenger weight on flights in Australia had not changed in the past decade.