1. For calculation of airport and navigation charges a modified version of the Association of European Airlines (AEA)28,29model is used. Charges are a function of the aircraft and the mission characteristics: take-off weight, range and payload. The economic model of U.S. Airline Operating Expenses by Harris30is used in a modified version for estimating the costs for: cockpit crew and flight attendants, assurance, and maintenance. This model incorporates cost-estimating equations which were developed from cost data from 67 airlines as reported to the Department of Transportation (DOT) in 1999. Technology factors such as suggested by Scholz31can be applied to influence the maintainability and reliability of the airframe and the different systems. Costs for depreciation are derived from an estimated aircraft list price and a specific timeframe of depreciation. The DOC tool was validated against available DOC data of current commercial transport aircraft.
2. The fuel price has significant influence on the economics of the different concepts. Therefore, the sensitivities of DOC on fuel price are also briefly investigated. For the sake of clarity only results of LR002-1stop design and of the NLF040 design are plotted in figure 16, together with the results for the conventional reference aircraft LR001. Figure 16 shows that fuel price has a linear influence on DOC. The slope of the curves is a direct measure for the fuel efficiency of the different designs. Already from figure 14(a) we saw that the multi-stop designs offer the highest potential for fuel savings. The same can be observed from the slopes of the different curves in figure 16. The more the fuel price increases, the higher are the costs savings of the two concepts. Independent from the assumed fuel price, the multi-stop design offers the lowest costs.