Sounds like Ryanair may have a competitor for most controversial airline: On Samoa Air, passengers are being charged by their weight. Rates start at $1 per kilo (about 2.2 pounds), which includes the weight of both the flyer and his or her baggage. The CEO explains to ABC Radio why it's fair: "People have always traveled on the basis of their seat, but as any airline operator knows, airplanes don't run on seats," he says. "They run on weight." For longer routes, rates run as high as $4.16 per kilo.
He points out that the fares work in favor of families, whose presumably lightweight children are typically forced to pay the same price as a heavier adult. The airline's website explains the process: You "guesstimate" your weight when booking, and prepay that amount. But "don't worry" about not being exact: The airline will helpfully weigh you again at the airport! (Ryanair recently urged its crew members to slim down in an attempt to cut costs.)