5. Conclusion
This paper has estimated a simple model of airline fuel usage, connecting usage to a small set of crucial variables. The results are important because they allow an easy appraisal of how changes in an airline's fleet and operating characteristics, and in the fuel price it faces, affect fuel usage and level of carbon emissions, which is proportional to this usage. One message of the results, which reinforces the arguments of Morrell (2009), is that operation of larger aircraft is beneficial, reducing fuel usage and carbon emissions, holding an airline's overall capacity fixed. While an innate network characteristic such as stage length, also shown to be beneficial, cannot be altered easily, the paper identifies another operational change that lowers fuel usage and emissions and can be achieved by public policy: a reduction in flight delays. The paper thus suggests that policies for reducing airport congestion (such as peakhour congestion pricing) have benefits that go beyond the recognized savings in passenger time costs. For example, the environmental benefits from a hypothetical 3-point reduction in the average delay percentage amount to $48 million per year, a value that can be added to the other passenger and airline gains from fewer delays. Airport congestion pricing or other policies for improving the functioning of the air transport system can thus produce environmental benefits.
