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2 The findings and results from those first three tasks were intended to serve as the basis and guidance for developing the scope of work and methodology for the subsequent research tasks, as described in later sections of this Final Report. By way of background, it is noteworthy that the 02-45 Research Project was aimed principally at addressing emissions resulting from the operation of commercial jet aircraft during the taxi/idle mode.1,2 The primary emphasis is on the emissions inventory components of AEDT, although the dispersion modeling capabilities of the model were also considered. The pollutant types (and their precursors) addressed in the research primarily comprise the following: ï§ Carbon monoxide (CO), ï§ Nitrogen oxides (NOx), and ï§ Volatile organic compounds (VOCs).3 Emissions of sulfur oxides and carbon dioxide (CO2) were considered, but only with respect to the emission rates of these pollutants as they relate to fuel flow. Similarly, emissions of hazardous air pollutants (HAPs) were also considered, but only as they relate to emissions of VOCs. Finally, because aircraft-related emissions of particulate matter (PM) equal to, or less than 10 micrometers (PM10), and PM equal to, or less than 2.5 micrometers (PM2.5), are being studied by others (i.e., E-31, the SAE International Aircraft Exhaust Emissions Measurement Committee, and the European Aviation Safety Agency), emissions of PM were not addressed as part the ACRP 02-45 project. 2. Task 1 & 2 Results: Literature Search and Review of AEDT Model Inputs The initial two tasks conducted to help address the ACRP 02-45 research objectives were to (i.) review and summarize relevant scientific and industry literature, published guidance, and other pertinent research on the combined topics of aircraft taxi/idle emissions and AEDT (i.e., the Task 1, Literature Review) and to (ii.) review the relevant assumptions, algorithms, database coverage, and outputs of AEDT (the Task 2, AEDT Review). The outcomes from these tasks were published in a separate Working Paper and accompanied by a comprehensive annotated bibliography prepared under Task 3.4 The information from Tasks 1 and 2, as summarized in the working paper at Appendix A, served as the foundation upon which the ACRP 02-45 research proceeded. Importantly, the Research Team was mindful of the following questions during the course of the literature and AEDT reviews, because the corresponding answers were necessary to develop a prioritized list of potential improvements to AEDT: Guiding Research Questions ï§ What are the factors that affect an aircraft departing an airport from the time the aircraft leaves the airportâs gate until the aircraft reaches a runway (i.e., the taxi out process)? ï§ What are the factors that affect an aircraft arriving at an airport from the time the aircraft exits a runway until the aircraft reaches a gate (i.e., the taxi in process)? ï§ What thrust settings do pilots use for aircraft engines during the taxi out/in process? ï§ Are there readily available air pollutant/pollutant precursor emission indices for low engine thrust settings other than those already in the AEDT databases? 1 Other aircraft operational modes included in AEDT comprise take-off, landing, and cruise, which are not addressed as part of the 02-45 research. 2 Other airport-related emission sources, such as ground support equipment (GSE), auxiliary power units (APUs), fuel storage facilities, motor vehicles, and stationary sources (i.e., boilers, emergency generators, incinerators, etc.) are also not included as part of the 02-45 research. 3 For the purposes of this document, the terms VOCs and hydrocarbons (HC) are used interchangeably. 4 That working paper is included in its original form as Appendix A to this Final Report.
