While no airlines impose a weight-based charge, the problem of seating for overweight passengers is becoming a pressing concern. Several major carriers require that overweight passengers who cannot fit comfortably within their seat with the armrests down must buy a second seat. Others require the same if the passenger can't buckle their seatbelt, with a seatbelt extension if necessary. Some airlines offer a discount on the second seat, with a full refund if the seat is unoccupied.
As well as passenger comfort, more weight equals more fuel burned. In 2016 Hawaiian Airlines discovered that its aircraft were using more fuel than projected on flights between Honolulu and American Samoa. The reason was found to be passengers' weight, and the average American Samoan man weighs in at 102.5kg.
Three years before Samoa Air introduced a charge for overweight passengers. The airline serviced several islands in the South Pacific including Tonga, another well-fleshed kingdom. The late Tongan King Tupou IV, who died in 2006, weighed 200kg. Samoa Air faded from view in 2015 and its successor, Samoa Airways, never adopted the same practice.