A tiny Samoan airline that is the first to introduce a fare system based on passengers' weight hailed the success of its policy Wednesday and predicted it would become a global norm. Four months after introducing the "fare-weight" system -- the lighter the passenger the lighter the fare -- Air Samoa chief executive Chris Langton said the feedback from fliers of all sizes has been positive. "We started the system back in November and it's taken on," Langton told AFP as his commuter airline extended pay-by-weight from domestic flights to international services linking neighbouring Pacific island states. "The people who are heavy are recognising that pay-by-weight is the fairest system despite the fact that they pay more than a lighter person." A 2007 World Health Organisation report put obesity in urban Samoa as high as 75 percent and Langton said his world-first charging system was helping people better understand the issue of obesity. Although no other airline has yet followed the Apia-based carrier, Langton believes it is only a matter of time before they do "because people will drive this and the airlines will be obliged to take stock". "In our airline a kilo is a kilo. You only pay for what it weighs and everyone pays the same rate and it's the fairest system that you can get." In an industry where the weight on board matters more than the number of seats sold because of the impact on costs, Samoa Air fares are calculated on the weight of the passenger and baggage, and the length of the flight. Passengers travelling within Samoa pay about 1.32 tala per kilogram (58 cents per 2.2 pound) and from Samoa to American Samoa the rate rises to 3.8 tala. Pay-by-weight flights are due to start to Tonga and the Cook Islands later this year. There were particular benefits for families, said Langton, as it was the size of the children that mattered, rather than the industry standard age 11 barrier between half-fare and adult fare, which does not apply. For travel agents booking early for passengers the airline does have a set fare equivalent to 120 kilograms of weight. "We allow a factor to ensure that we won't be caught out and we always try to get the actual weights as early as possible so we can load efficiently," said Langton, whose airline operates two 10-seat aircraft and one four-seater.