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

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i Table of Contents Section Title Page Executive Summary……………………………………………………………………………….…ii List of Participants……………………………………………………………………………...........iv List of Tables…………………………………………………………………………………………v List of Figures………………………………………………………………………………………...v Initialisms and Acronyms……………………………………………………………………….…...vi 1 Introduction…………... ........................................................................................................ 1 2 Task 1 and 2 Results: Literature Search and Review of AEDT Model Inputs ...................... 2 3 Research Approach and Findings .......................................................................................... 3 3.1 Time-in-Mode ........................................................................................................ 4 3.1.1 Default Taxi Times .......................................................................................4 3.1.2 Default Taxi Speed .....................................................................................11 3.2 Fuel Flow Rates (FFRs) .......................................................................................... 13 3.3 Emission Indices (EI) .............................................................................................. 15 3.4 Additional Considerations ...................................................................................... 18 3.4.1 Reduced Engine Taxiing ............................................................................ 18 3.4.2 Alternative Taxi Systems ........................................................................... 19 3.4.3 Airfield Emission Distribution (Dispersion Analysis Only) ...................... 19 4 Stakeholder Outreach ...................................................................................................... 20 4.1 Taxi Time ...................................................................................................... 20 4.2 Taxi Speed ...................................................................................................... 20 4.3 Fuel Flow Rates (FFRs) .......................................................................................... 21 4.4 Emission Indices (EIs) ............................................................................................ 21 4.5 Reduced Engine Taxiing ......................................................................................... 21 4.6 Alternative Taxi Systems ........................................................................................ 21 4.7 Airfield Emission Distribution ................................................................................ 21 5 Recommended Near-Term Model Improvements and Implementation Steps ..................... 25 5.1 Near-Term Model Improvements for Time-in-Mode (TIM) Factor ....................... 25 5.1.1 Default Taxi Time ...................................................................................... 25 5.1.2 Default Taxi Speed .................................................................................... 26 5.2 Near-Term Model Improvements for Fuel Flow Rate (FFR) Factor ...................... 26 5.3 Near-Term Model Improvements for Emission Index (EI) Factor ......................... 26 5.3.1 Prediction of HCs and CO ......................................................................... 26 5.3.2 Prediction of NOx ...................................................................................... 27 5.4 Near-Term Model Improvements for Additional Considerations ........................... 27 Appendix A – Task 3 Working Paper: Literature Review and Review of EDMS/AEDT Modeling Inputs Appendix B – Relevance of Test Data Engines Appendix C – Emission Index Adjustment Factors for CO and HC

ii Executive Summary Within the current framework of the Federal Aviation Administration (FAA) Aviation Environmental Design Tool (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 of full thrust, based on International Civil Aviation Organization (ICAO) engine test conditions. However, relevant 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 these factors, the primary objectives of this ACRP 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. For the purposes of this research, the Research Team targeted three fundamental elements (i.e., factors) within the current AEDT framework that the model uses to calculate aircraft engine emissions during the taxi/idle mode. These factors are identified and represented as follows: Taxi/idle emissions = TIM x FFR x EI Where:  Time-in-mode (TIM) = the time aircraft engines are operating in the taxi/idle mode (seconds);  Fuel flow rate (FFR) = the rate of fuel intake (kilograms (kg) per second); and  Emission index (EI) = the emissions generated per mass of fuel burned (grams (g) per kg of fuel burned). Based upon the outcomes of the research, the following improvements to AEDT are proposed: Proposed AEDT Improvements Factors Parameter(s) Improvement Option(s) Priority (Near-/Long-Term) Time-in-mode (TIM) Default taxi time 1) Change default taxi in and taxi out times to values derived for all airports. --7 minutes taxi in / 16 minutes out Near-term 2) Provide user query for type of airport and number of runways in GUI – link to new database. Long-term 3) Default to average of five years of data for specific airport being evaluated. Long-term Default taxi speed 1) Change default assumption to weighted average value based on FDR data. -- 11 knots (12.66 mph) Near-term 2) Allow users to indicate whether a taxiway is used for aircraft taxiing in or out. -- 13 knots (14.96 mph) for taxi in taxiways and 10 knots (11.51 mph) for taxi out taxiways Long-term

iii Factors Parameter(s) Improvement Option(s) Priority (Near-/Long-Term) Fuel Flow Rate (FFR) -- 1) Adjust FFRs in databases only for those aircraft for which there are FDR data. * 2) Adjust the FFRs for those aircraft for which there are Flight Data Recorder (FDR) data or for which the data are representative. * 3) Use a single, global adjustment to all commercial jet engines. Near-term Emission Indices (EI) Carbon monoxide (CO) and hydrocarbons (HC) 1) Apply a global adjustment factor assuming all engines CO and HC EIs follow same temperature/FFR dependence as the CFM56- 7B family of engines. Near-term 2) Apply an engine specific adjustment factor. * 3) Apply adjustment factors only to the CFM56 family of engines. * Nitrogen oxides (NOx) There is only one option to adjust emissions of NOx. To what engines it would be applied would depend on the FFR adjustment option described above. Near-term Additional considerations Assumptions regarding single/reduced engine taxi procedures to be included in modeling When selected by user, apply factor of 0.995 to FFRs for taxi in operations and 0.96 to FFRs for taxi out operations. Near-term Allow for e-taxi procedures to be included in modeling Allow users to specify the percentage that taxi- related emissions should be reduced. Long-term Emission distribution across airfield Allow users to define areas other than the runway queue area where aircraft are delayed. Long-term * This improvement is considered to be an alternative to the recommended near-term improvement. With the exception of the improvements to the emission indices for carbon monoxide (CO) and hydrocarbons (HC) and only if this improvement is considered in isolation, all of the near-term improvements listed above would reduce estimates of the emissions associated with commercial jet engine taxi/idle conditions. The magnitude of the reduction would depend on the number of (i.e. combination of) improvements incorporated in to the AEDT.

iv ACRP 02-45 Participants ACRP Senior Program Officer Joe Navarrete Research Project Panel - Kris Russell, Dallas/Ft. Worth International Airport - Richard Fox, Honeywell Aerospace - Diane Heinze, Port of Oakland - Kim Hughes, HNTB Corporation - Sarav Arunachalam, UNC Institute for the Environment FAA Liaisons - Chris Sequeira, Office of Environment and Energy - Peggy Wade, Office of Airport Planning Research Team KB Environmental Sciences, Inc. - Mike Kenney - Carrol Fowler University of Massachusetts, Amherst - Ezra Wood ATAC Corporation - Eric Dinges - Michael Yaworski Sierra Research - Jim Lyons - Jeremy Heiken

v List of Tables No Title Page 1 Summary of EDMS/AEDT Shortcomings Related to Taxi/Idle Emissions .................... 3 2 EDMS/AEDT Taxi/Idle Emission Improvement Research Approach ............................ 6 3 ASPM Aircraft Taxi Times ............................................................................................. 8 4 ASPM Aircraft Taxi Times by Airport ........................................................................... 9 5 FDR Unimpeded Aircraft Taxi Speeds (knots) ............................................................. 12 6 Fuel Flow Rates (FFRs) ................................................................................................ 14 7 Stakeholder Review and Feedback ................................................................................ 22 8 Prioritized List of Potential Improvements to AEDT .................................................... 28 List of Figures No Title Page 1 CFM56-7B22 Fuel Flow/Temperature Adjustment Factors for CO and HC EIs .......... 16 2 Relationship of NOx Emissions to FFR ........................................................................ 17

vi Initialisms and Acronyms AAFEX Alternative Aviation Fuel Emissions Experiment AAM Aircraft Acoustic Module ACRP Airport Cooperative Research Program AEDT Aviation Environmental Design Tool AEE Office of Environment and Energy AEM Aircraft Emissions Module APE Aerospace Particulate Emissions APEX Aircraft Particulate Emissions Experiments APM Aircraft Performance Module APU Auxiliary Power Unit ASIF AEDT Standard Input Format ASPM Aviation Policy's Aviation System Performance Metrics ATC Air Traffic Control AWP Amplified work plan BTS Bureau of Transportation Statistics C2H4 Ethene CAA Clean Air Act CRUD Create, Read, Update, Delete CO Carbon monoxide ECAC European Civil Aviation Conference EDMS Emissions and Dispersion Modeling System EGTS Electric Green Taxiing System EPA U.S. Environmental Protection Agency FAA Federal Aviation Administration FDR Flight Data Recorder FID Flame Ionization Detection FSC Fuel sulfur content GSE Ground support equipment GUI Graphical Users Interface HAPs Hazardous air pollutants HC Hydrocarbons HCHO Formaldehyde ICAO International Civil Aviation Organization INM Integrated Noise Model ISA International Standard Atmosphere LTO Landing-Takeoff Cycle MAGENTA Model for Assessing Global Exposure to the Noise of Transport Aircraft NAAQS National Ambient Air Quality Standard NEPA National Environmental Policy Act NIRS Noise Integrated Routing System NMHC Nonmethane hydrocarbons NOx Nitrogen oxides PMFO Fuel organics particulate matter PMNV Nonvolatile particulate matter PMSO Volatile sulfates particulate matter ROG Reactive organic compounds RPM Revolutions per minute SAGE System for Assessing Aviation's Global Emissions SO2 Sulfur dioxide

vii SOx Sulfur oxides THC Total hydrocarbons TIM Time-in-mode TOG Total organic gases UHC Unburned hydrocarbons UK United Kingdom US United States VOC Volatile organic compounds