Philippe A. Bonnefoy

Scalability and Evolutionary Dynamics of Air Transportation Networks in the United States

This work was supported by NASA Langley under grant NAG-1-2038 and by the FAA under contract DTFA01-01-C-00030’D.0#16.

EMERGENCE AND IMPACT OF SECONDARY AIRPORTS IN THE UNITED STATES

As major airports in the United States have reach ed their maximum capacity and beca me congested, available capacity at surrounding airports has been utilized by the emergence of secondary airports. Given the expectation of a larger number of operations in the National Airspace System (NAS) in the upcoming years, this trend of secondary airports emergence is likely to strengthen. In orde r to understand the dynamics of the regional airport systems, a s tudy of the factors that le d to th e emergence of secondary airports was performed. The distribution of population at the regional level, the existence and the proximity of a secondary basin of population close to secondary airports were identified as major factors. Ground acc ess and airpor t infrastructure we re also enabling factors. The nature of the regional airport system, in term s of “Hub” versus “non -Hub” was also identified as a contributing factor. The entry of a low cost carrier was determined to be the essential stimulus in the emer gence phenomenon. These entries modify the air port dynamics resulting in the stimulation of both local and peripheral markets. Following the entry of a low cost carrier several other car riers, both legacy and low cost , enter and consolidate the growth of t he emerging airport. As a consequence of the emergence of secondary airports and their integration into a region wide multi -airport system, they induce impacts on the NAS structure. Recent consolidations of TRACONs (Terminal Area Control) were identified as primary impacts. As there will be increasing pressure of demand on core airports in the upcoming years, the development of additional secondary airports will be required. The transition from a single core airport to region wide multi -airport systems and the emergence of new secon dary airports in existing multi -airport systems, impose new constraints that need to be taken into account in the NAS improvements.

Potential Impacts of Very Light Jets on the National Airspace System

Very light jets constitute a class of three to eight passenger turbofan-powered aircraft that will enter service in 2006 and will need to be integrated into the National Airspace System. An aircraft performance analysis showed similarities between the predicted performance and capabilities of very light jets and the performance of existing light jets. Based on this, an analysis of operating patterns of existing light jets was used to predict how very light jets will be operated. Using 396 days of traffic data from the FAA enhanced traffic management system, the operating patterns of existing light jets were analyzed. It was found that 64% of all the flights flown by lightjets had their origin, destination, or both within the top 23 regional airport systems in the continental United States. This concentration of light jet traffic was found in areas of the air transportation system that are currently exhibiting dense traffic and capacity constraints. The structure of the network of routes flown by existing light jets was also studied and a model of network growth was developed. It is anticipated that this concentration will persist with emerging very light jet traffic. This concentration of traffic at key areas in the system will have implications for air traffic control management and airport activity. For regional airport systems, core airports are expected to saturate and, reliever airports will become critical for accommodating traffic demand. The entry of very light jets will increase the traffic load at the terminal airspace: terminal radar approach control. These impacts need to be taken into account to allow a successful integration of these aircraft in the National Airspace System.

Investigation of the Impacts of Effective Fuel Cost Increase on the US Air Transportation Network and Fleet

The authors would like to thank the MIT Partnership on AiR Transportation Noise & Emissions Reduction (PARTNER) for access to the Piano-X software package and Brian Yutko for his assistance in its use. This work was supported by the MIT/Masdar Institute of Science and Technology under grant number Mubadala Development Co. Agreement 12/1/06.

Simulating air taxi networks

The U.S. air transportation industry is about to experience the emergence of on-demand air taxi networks enabled by a new generation of very light jets (VLJs). These new networks are unique in many ways and the top down design approach of air taxi enterprises generates challenging and complex questions. Simulation was found to be an essential technique for understanding, analyzing and evaluating the complex behavior of air taxi networks. The air taxi network simulator is a fast-time simulator that replicates the operations of fleets of air taxi aircraft over a network of hundreds of airports. Its capabilities include demand modeling, trip generation, aircraft routing and pilot assignment, unscheduled maintenance events with recovery mechanisms, etc. It provides key performance metrics that enable decision makers to test and evaluate various strategic and tactical scenarios.

Investigation of the Fuel Efficiency of the U.S. Air Transportation Network Structure

The combination of increasing demand for air transportation, high fuel prices and the growing environmental awareness motivates the need for fuel efficiency improvements and emissions reductions of the aviation sector. One potential approach to improve aviation’s fuel and CO2 emissions efficiency is to improve the structure of the air transportation network. This research focuses on alternative topologies for the US air transportation network, passenger routing and fleet composition. In order to identify and evaluate these alternatives, an optimization model was developed were the network topology, routing strategies and aircraft assignment are jointly optimized. It was found that the 2007 US air transportation network exhibits a topology that is close to its optimum and that further topological improvements may only yield a reduction in fuel burn of approximately 1%. Changes in aircraft assignment and alternative airline routing strategies between origin and destination markets appear to provide greater potential for efficiency improvements. It was found that improved passenger routing could decrease fuel burn by over 8% while the utilization of larger aircraft yields a reduction of 10%. These findings suggest that there is limited potential from structural network topological improvements for the US air transportation network. However, strategies and policies that would incentivize the use of larger aircraft and alternative aircraft and passenger routings would provide greater potential for fuel efficiency and climate change emission reductions.

Dynamics of Implementation of Mitigating Measures to Reduce Commercial Aviation's Environmental Impacts

Increasing demand for air transportation worldwide and growing environmental concerns motivate the implementation of measures to reduce CO2 emissions. Case studies of historical changes in the air transportation industry have shown that implementation generally follow s-curve dynamics with relatively long time constants . This research analyzes the diffusion characteristics of a portfolio of CO2 emission mitigating measures and their relative contribution to cumulative system wide improvements. A literature review identified over 90 proposed mitigating measures, which were aggregated into 41 unique measures. Those span: (1) technological improvements, (2) operational improvements, and (3) use of alternative fuels. It was found that in the near term, operational changes have the highest potential for improvements but are unlikely to significantly reduce CO2 emissions. In the medium term, both technology retrofit and operational measures have the potential to reduce emissions . In the long term, the use of 2 nd and 3 rd generation biofuels have significant potential for reducing the carbon footprint of aviation but are likely to have long diffusion times and may be limited for aviation use due to production scaling issues. Technology measures also have high potential for reducing CO2 emissions but primarily in the very long term due to slow turnover dynamics of the fleet.

Assessment of Carbon Dioxide Emission Metric Systems for an Aircraft Certification Standard

To mitigate aviation CO2 emissions, the International Civil Aviation Organization’s Committee on Aviation Environmental Protection is considering an aircraft CO2 emissions certification requirement. This paper presents an evaluation of potential CO2 metric systems for their suitability as a basis for an aircraft CO2 certification requirement. Candidate CO2 metric systems, consisting of a metric, a correlating parameter, evaluation conditions, and a notional limit line are assessed against a set of key criteria. The metric systems were chosen to reflect aircraft fuel consumption, which directly correlates with CO2 emissions for a given fuel type. Key criteria were identified to represent desirable attributes of the metric system, that is the ability to represent fuel efficiency performance improvements, validity across a range of aircraft types, correlation with fuel efficiency in actual operations, fairness across stakeholders, ease of measurement, and robustness against unintended consequences. The analy...