CHICAGO, Ill. --  It has long been the goal of airlines to base their fares on the weight of the passengers and luggage carried. After all, the economics is simple: Heavier objects cost more to put in air and to keep in the air than do lighter ones.

So far, however, the obstacle to implementing such a pricing policy has been stymied because no airline could afford to alienate flying customers who are overweight or obese — up to two thirds of commercial passengers, as estimated by the International Air Travel Federation.

Now Monument Airlines believes it has found a solution to the "Pay-By-The-Pound" air fare issue without specifically targeting overweight or obese passengers. "Instead of a direct dollars-per-pound fare," said Mandy Weuthery, spokesperson for Monument, "we are reconfiguring the seating in all of our planes to offer three choices of seat sizes among which passengers can select. Fares then will be based on seat selection rather than traveler weight load." (Pictured here is a photo supplied by the airline showing a mockup of possible seat dimensions and configurations in an early laboratory study.)

Called "Deluxe," "Superior" and "Executive" by the airline, these seating options will not be assigned by Monument but will be self-selected by each passenger when he makes his reservation. According to information distributed by Monument, the narrowest seat — the "Deluxe" — is 14 inches wide and will account for 12 percent of the available seats. The mid-range "Superior" seat is 18 inches wide and will make up another 22 percent of passenger seating. The remaining "Executive" class seats are 41 inches wide and will provide the bulk of available seating.

While Monument has not yet released ticket pricing information, Err Travel has learned from sources inside the airline that there will likely be a fare price differential of about 16 percent between the Deluxe and the Superior seats and another 36 percent difference between the Superior and the Executive seats.

When asked about how the distribution of the three different sizes was determined, Weuthery replied that the three sizes of seats were in the same proportion that diners at fast food eateries order "large," "extra large" and "jumbo" meals, respectively. "It was the most reliable measure we could find,” said Weuthery.