Antony Evans

Mitigation of Aviation Emissions of Carbon Dioxide: Analysis for Europe

This paper investigates the interaction between economic, technological, and operational measures intended to reduce air transport-related emissions of carbon dioxide (CO2). In particular, the introduction of aviation to the European Union Emissions Trading Scheme (ETS) in 2012 may prompt increased uptake of presently available options for emission reduction (e.g., retrofitting winglets, expanding maintenance programs) by airlines operating in Europe. Carbon prices may also determine the use of options currently under development [e.g., open-rotor engines, second-generation biofuels, and improved air traffic management (ATM)]. The results of a several studies analyzing airline costs and emission reductions that are possible from different mitigation options are applied to a systems model of European aviation. With a set of nine scenarios (three internally consistent projections for future population, gross domestic product, oil and carbon prices, each run with three policy cases), technology uptake and the resulting effect on fuel life cycle CO2 emissions with and without an ETS are analyzed. Some options are rapidly taken up under all scenarios (e.g., improved ATM), others are taken up more slowly by specific aircraft classes depending on the scenario (e.g., biofuels), and others have negligible impact in the cases studied. High uptake of one mitigation option may also reduce the uptake of other options. European aviation fuel life cycle emissions could be reduced below 2005 levels before 2050 if cellulosic biomass fuels are made available by 2020. However, the land use requirements in this scenario may limit its practicality at currently projected cellulosic biomass yields.

Modelling Airline Network Routing and Scheduling under Airport Capacity Constraints

A flight routing and scheduling model is under development that predicts airline routing and scheduling under airport capacity constraints. It consists of several components describing different aspects of the air transport system, including passenger demand, airline competition, flight delay, and airline cost. These models are integrated into a flight routing and scheduling model in which an objective function is defined to maximize airline system profit within a routing network, subject to constraints. This framework allows the relationships between fares, passenger demand, infrastructure capacity constraints, flight delays, flight frequencies, and routing network to be simulated. In this paper the integrated flight routing and scheduling model is first applied to a series of simple theoretical routing networks to illustrate its capabilities. With increasing airport capacity constraints the results show an increase in average fares, a decrease in O-D passenger demand, and a shift in flight routing away from the most constrained airports. The model is then applied to a network of airports in the United States with 2005 population, income and airport capacity inputs. With further development the model is to be applied to forecasting air traffic system growth, including network and schedule changes resulting from increasing delays, in the Aviation Integrated Modelling (AIM) project under development at the University of Cambridge. Copyright

Simulating airline operational responses to environmental constraints

This work was supported by the Engineering and Physical Sciences Research Council and the Natural Environment Research Council [grant number EP/D060001/1].

Modelling Environmental and Economic Impacts of Aviation: Introducing the Aviation Integrated Modelling Project

The Aviation Integrated Modelling project is developing a policy assessment capability to enable comprehensive analyses of aviation, environment and economic interactions at local and global levels. It contains a set of inter-linked modules of the key elements relevant to this goal. These include models for aircraft/engine technologies, air transport demand, airport activity and airspace operations, all coupled to global climate, local environment and economic impact blocks. A major benefit of the integrated system architecture is the ability to model data flow and feedback between the modules. Policy assessment can be conducted by imposing policy effects on the upstream modules and following implications through the downstream modules to the output metrics, which can then be compared to a baseline case. A case study involving different evolution scenarios of the US air transportation system from 2000 to 2030 is used to show the importance of feedback and to model a sample policy scenario in order to illustrate current capabilities.

Airline-Driven Performance-Based Air Traffic Management: Game Theoretic Models and Multicriteria Evaluation

Defining air traffic management as the tools, procedures, and systems employed to ensure safe and efficient operation of air transportation systems, an important objective of future air traffic management systems is to support airline business objectives, subject to ensuring safety and security. Under the current model for designing air traffic management initiatives, the central authority overseeing and regulating air traffic management in a region makes trade-offs between specified performance criteria. The research presented in this paper aims instead to allow the airline community to set performance goals and thus make trade-offs between different performance criteria directly, before specific air traffic management strategies are determined. We propose several approaches for collecting inputs from airlines in a systematic way and for combining these airline inputs into implementable air traffic management initiatives. These include variants of averaging, voting, and ranking mechanisms. We also propose multiple criteria for evaluating the effectiveness of each approach, including Pareto optimality, airline profitability, system optimality, equity, and truthfulness of airline inputs. We apply a game-theoretic approach to examine the potential for strategic gaming behavior by airlines. We offer a broad evaluation of each approach, first by providing some theoretical insights, and then by simulating each of the approaches for a generic system using Monte Carlo methods, sampling values for input parameters from a wide range. We also provide an indication of how the approaches might perform in a real system by simulating ground delay programs at two airports in the New York City area. We first apply a simplified model that simulates the process of selecting only planned end times of a ground delay program, using Monte Carlo methods. Next, we apply a more detailed model that simulates the process of selecting planned end times and reduced airport arrival rates. Finally, we characterize the effectiveness of each of the considered approaches on the proposed criteria and identify the most desirable approaches. We conclude that voting schemes, which score highly on all criteria including airline profitability, system optimality, and equity, represent the most promising approaches among those considered to elicit airline preferences, thereby allowing the central authority to design air traffic management initiatives that optimize system performance while respecting the objectives of airlines.

Simulating flight routing network responses to airport capacity constraints in the US

This paper presents a model which simulates changes in the airline system flight routing network under alternative policy scenarios. The model simulates a game between airlines, in which each airline increases flight frequency in order to maximize its own profit. The underlying modeling framework allows the relationships between changes in fares, passenger demand, infrastructure capacity constraints, flight delays, flight frequencies, and routing network to be simulated. The model is validated for a network of airports in the United States in 2005, before being applied to simulate changes in the same network through 2030 under two policy scenarios. Both scenarios limit airport capacity expansion: (i) in the whole system, and (ii) at Chicago O’Hare International, a primary hub airport, only. Simulated passenger demand, air traffic, flight delays, system CO 2 emissions and Chicago O’Hare NOx emissions are compared to a baseline scenario in which airport capacity is expanded as planned by the FAA. Despite a significant impact on flight delays, the results show little impact of airport capacity constraints on system passenger demand, air traffic growth or CO2 emissions, but show a shift of connecting traffic away from congested hub airports at which capacity is limited to other less congested hub airports, thus reducing traffic growth at these congested airports, and reducing the growth in NOx emissions.

Network and environmental impacts of passenger and airline response to cost and delay

* † ‡† * *† § The Aviation Integrated Model is a policy assessment tool designed to simulate the operation and economic/environmental effects of local and world airline networks over the next 30-50 years within a modular framework. Feedback between demand, capacity, air traffic delays and policy measures is a key part of this model. For example, unconstrained model projections of US air transportation system growth with no passenger, airline or policy response included show average arrival delays of over two hours at major US airports in 2030, a condition that is unlikely to materialize. A more likely situation is that a combination of responses act to bring the air transport system to a new equilibrium at which higher fares, extra capacity or increased operational efficiency reduces the delays to a more acceptable level. Similarly, the application of policies designed to mitigate some of the environmental impacts of air transportation will also alter the system equilibrium state. In this paper we use the Aviation Integrated Model to systematically examine these feedback effects, concentrating specifically on the passenger response to increases in travel time, airfare, and policy responses to environmental concerns. We contrast the reference case in which the main feedback effect is passenger and airline response to air traffic delay with sample policy scenarios.

Emissions and Aviation: Towards Greener Air Transport

Air travel revolutionized intercity transport, and today it contributes significantly to economic growth worldwide. However, aviation growth has a number of negative consequences, including environmental impacts on air quality, noise and the global climate. A number of new technologies and aircraft operating procedures are under development to mitigate these impacts. These, including revolutionary new aircraft and engine technology, biofuels, improvements in air traffic management, and new airline operating procedures, are discussed in detail in this chapter. A further topic of discussion is policy intervention. Because of the rapid growth in demand for air travel, policy intervention is likely to be required to drive much of the technological developments described and to speed up their uptake into the global fleet. With a combination of technological developments and policy intervention, however, significant progress towards greener air transport is possible.

A Comparison of Aviation Greenhouse Gas Emission Mitigation Policies for Europe

This paper integrates the results of a set of studies looking at UK and European aviation environmental policy measures. It uses a model of the European air transport system to assess the economic costs and environmental benefits associated with proposed emission mitigation strategies. In particular, we con centrate on the potential penetration of fuelsaving technologies and operations, lower carbon alternative fuels and high-speed rail in response to the European Union Emissions Trading Scheme, and the effect on CO2 emissions that this has in both the UK and Europe. A special emphasis is placed on the interaction effects of multiple mitigation policies. We find that a combination of policies could potentially allow UK and European lifecycle aviation CO2 emissions in 2050 to be reduced to below year-2005 levels. Although other operational and technological measures can reduce aviation CO2 emissions by up to 15% compared to an unconstrained base case, the largest part of this reduction comes from the interaction between carbon trading and cellulosic biomass fuels.