Methodology to Improve AEDT Quantification of Aircraft Taxi/Idle Emissions (2016)

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1 1. Introduction Over the past two decades, considerable emphasis has been placed on the potential effects of airport- related air emissions on ambient (i.e., outdoor) air quality. In response to this concern, an increased reliance on computer models has emerged as a means of assessing this impact. The most commonly relied-upon computer model is the Federal Aviation Administration’s (FAA’s) Aviation Environmental Design Tool (AEDT), which officially replaced the FAA’s previous model – the Emissions and Dispersion Modeling System (EDMS) - on May 29, 2015. Within the current framework of AEDT is the simulation of commercial jet engine taxi/idle conditions, producing an estimate of the emissions that would result under these low-thrust conditions. Presently, the model defines the standard thrust setting for this operational mode at seven percent (7%) of full thrust, based on International Civil Aviation Organization (ICAO) engine test conditions. However, other research and observations suggest that the thrust settings in actual practice may differ from this value. Other factors that may also affect taxi/idle emissions include aircraft size, engine type, airport layout, and meteorological conditions. Based on the above, the primary objectives of the ACRP 02-45 (Methodology to Improve EDMS/AEDT Quantification of Aircraft Taxi/Idle Emissions) Research Project was to develop and provide the following: Primary Objectives  A prioritized list of potential improvements to AEDT that will improve the predictive accuracy for estimating jet aircraft emissions during the taxi/idle phase of operation; and  Detailed documentation of select near-term, high-priority improvements to AEDT. To achieve these primary goals, three main areas of research were considered important to the successful outcome of the project. They were as follows: Main Areas of Research  An assessment of “real-world” in-service engine performance data compared to AEDT modeling assumptions;  An evaluation of model inaccuracies and the implications to emissions inventories; and  Collection and evaluation of stakeholder feedback from subject matter experts on modeling, aircraft emissions, and airport operations. In order to accomplish the goals and cover the intended research areas of the ACRP 02-45 project, the Work Plan was subdivided into an 11-task assignment, the first three of which were entitled as follows: Initial Tasks  Task 1: Literature Review,  Task 2: Review of AEDT Modeling Inputs, and  Task 3: Task 1 and 2 White Paper (originally published in 2013 as a separate document and included in this Final Report as Appendix A). NOTE: The reviewer should note that the initiation of this research pre-dated the sunset of the FAA EDMS model and, therefore, the research title still contains reference to EDMS. Since the sunset of EDMS has now occurred, this Final Report refers only to the AEDT model tool, unless the specific reference requires noting some aspect of the no-longer-in-use EDMS model.