Is this fair?An Airline charges passengers based on weight :-)

In the interest of "keeping airfares fair," small South Pacific air carrier Samoa Air has started charging passengers by weight.

"We have to take care of every passenger. We have to take into account that not all people are the same shape and size. The bottom line is that airplanes run by weight; they don't run by seats," said Chris Langton, Samoa Air's chief executive.

Samoa Air flies just three aircraft, two 10-seaters and one four-seater, Langton said.

"We're pretty small, but the concept is very big," he said.

The airline serves Samoa, American Samoa, Tonga, Niue, Tokelau, the North Cook Islands and Wallis and Futuna islands in French Polynesia. Langton said the company is planning to purchase a much larger Airbus A320-200 this year for service to international destinations in the region including Australia, New Zealand and Fiji.

Samoa Air's policy went into effect in November. According to the airline's website, "your weight plus your baggage items is what you pay for. Simple."

Samoa Air says its program is the world's first fare structure that charges only by weight.

To book online, travelers enter their approximate weight and that of their luggage and prepay based on that "guesstimate." The airline is not equipped to process payments online, but that service is coming soon, Langton said.

Passengers and their luggage are weighed again at the airport.

And if your weight and that of your bags exceed your booking weight? Langton said the airline has a "fiddle factor" of about 2%. So Samoa Air will let a few kilos slide, but the airline is unlikely to provide a refund if passengers roll up to the tarmac with a lighter load.

Langton said families have been pleased with the pricing model because it often costs less to fly with children using the pay-by-weight model than it would to purchase flat-fare seats.

The idea of charging passengers by weight has been batted around before. A Norwegian economist recently published a paper advocating the practice.

Some travelers have criticized the weight-based fare concept as a "fat tax." Others say they believe it's only fair.

Some major U.S. airlines have policies for passengers of size, requiring those who do not fit into a seat comfortably to buy a second seat.

For a tiny carrier like Samoa Air, the fare model seems reasonable, according to airline analyst Vaughn Cordle, a partner at Ionosphere Capital.

"For U.S. airlines, I think this is an issue they will not touch with a 10-foot pole because of the negative publicity and the practical purposes of weighing people at the gate."

Should Nigerian airlines use weight based-fares?