Fuel price varies among the stopovers, and potential savings can be realized by loading extra fuel (called tinkering) at a chapter location for use on subsequent flight legs. The disadvantage of tinkering is the excess burn of gasoline resulting from the extra weight. LP (and heuristics) is used to determine the optimum amount of tinkering that balances the cost of excess burn against the savings in fuel cost. The study, carried out in 1981, resulted in net savings of about $350,000 per year. Case 1 in Chapter 24 on the CD provides the details of the study. Interestingly, with the recent rise in the cost of fuel, many airlines are now using LP-based tinkering software to purchase fuel.