Should airlines charge passengers by weight? A Norwegian economist has published a paper in support of this. But writer Chris Torney explains why a fat tax won't fly.
To some it may seem a ludicrous invasion of privacy.
To others, it is just a logical extension of many airlines' charging policies.
But it is now being seriously suggested that passengers should join their baggage on the scales at check-in and face ticket prices in line with how much they weigh.
Weigh more, pay more
A Norwegian economist, Dr Bharat Bhatta of Sogn og Fjordane University College, has weighed into the debate.
Dr Bhatta has published a paper explaining why it makes sense for flight operators to charge heavier passengers more for their seats.
He says that air fares at present do not accurately reflect the costs to airlines.
According to him, this is because overweight travellers – who cost more to transport – pay the same amount as their more svelte co-flyers.
He has put forward three possible charging methods.
How the system might work
His first proposition is that ticket prices are based solely on weight.
A second option involves charging a base fare, with a premium added for the most overweight passengers.
But Dr Bhatta's favoured option is to charge more for travellers who are 25 per cent or more above a certain weight, with discounts for those who weigh 25 per cent less.
Is a 'fat tax' reasonable?
Air passengers are well used to paying more for heavier baggage.
We're even used to being charged extra to board early, reserve a seat on a flight or buy our ticket with a credit or debit card.
So to many of us, the concept of some form of "fat tax" might not appear all that outlandish, regardless of whether we think it is a good idea.
Some people may even wonder why the likes of Ryanair haven't thought of this already.
Ryanair 'fat tax' proposal
Well the truth is they have.
Four years ago, Ryanair published the results of a survey which found that a third of its customers supported extra charges for overweight flyers as a way of reducing prices for other passengers.
At the time a spokesman said: "These charges, if introduced, might also act as an incentive to some of our very large passengers to lose a little weight and hopefully feel a little lighter and healthier."
But the fact that even as ruthless a cost-cutter as Ryanair has made no progress on implementing a fat tax hints at the difficulty likely to be associated with introducing this kind of system.
To many people, the idea of being forced to tell an airline – or any company – how much they weigh would be a huge invasion of privacy.
An operator which pioneered such charges would be likely to face a sharp drop in custom, not only from overweight travellers, but also from others who opposed the policy.
And then there are practical considerations: does the airline simply trust passengers to be honest about how much they weigh, or will there be spot checks?
What happens if I put on half a stone between the time I book and when I board the aircraft? Or if I overindulge on paella or gelati while I'm abroad?
And surely not even Ryanair boss Michael O'Leary would suggest putting an extra set of scales at the check-in.
How many of us would happily take part in that kind of public humiliation?
In fact, Dr Bhatta's paper, attention-grabbing as it is, does not make a particularly strong case for introducing a pay-as-you-weigh scheme.
Fares are currently determined to a large extent by when tickets are bought.
This is an approach that seems to work perfectly well both for airlines and for those of us who plan holidays well in advance.
All in all, it's difficult to see a fat tax taking off.