Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 2: Research Report (2018)

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7 1 Summary The primary tool that airport operators use to measure the environmental consequences attributed to aviation is the Federal Aviation Administration’s (FAA’s) Aviation Environmental Design Tool (AEDT). AEDT is a software tool that models aircraft flight performance in space and time to compute fuel burn, emissions, and noise. AEDT replaces legacy environmental analysis tools including the Integrated Noise Model (INM), the Noise Integrated Routing System (NIRS), and the Emissions and Dispersion Modeling System (EDMS). AEDT offers enhanced aircraft arrival and departure profile modeling capabilities that allow users to more accurately define operational procedures and better estimate environmental impacts. AEDT contains standard departure and approach profiles for every aircraft type in its database. These standard profiles and their associated aircraft performance data have been developed by the FAA in collaboration with the aircraft manufacturers to ensure valid three- dimensional flight trajectories that lie within the aircraft performance envelope. However, through the implementation of NextGen capabilities, aircraft are using arrival and departure profiles that are not found in AEDT. As a result, practitioners often develop customized profiles that require FAA approval to incorporate them into their modeling effort, a complex and lengthy process. This project focused on developing additional standard or default aircraft approach and departure profiles that are not currently available within AEDT, additional methods to model custom approach and departure profiles in AEDT, and technical guidance on selecting the optimal AEDT profiles given a user situation. These efforts will help to close the gap between real-world and AEDT approach and departure profiles and will allow AEDT users to more quickly and accurately represent the real-world environmental consequences of aviation. During this research we used radar trajectory data from operations at 29 US airports to identify, prioritize, and define in a manner directly usable by AEDT, 840 potential new arrival procedures and 1410 potential new departure procedures covering the commercial aircraft supported by AEDT. The new departure procedures were created in three sets, each using a different set of assumptions. One set covers existing AEDT usage of aircraft thrust and weight assumptions, and the other two use new assumptions that could be adopted by AEDT in the future to handle thrust and weight differently. We also defined a tool that could be implemented within AEDT to allow users to make simple modifications to existing AEDT arrival and departure profiles based on a limited amount of input data to help them better match the trajectories they are trying to model. Lastly, we created a standalone guidance document to provide a succinct, easy-to-use resource for AEDT modelers on the topic of arrival and departure profiles. 2 Preface The standard flight profiles available in the current publicly available version of AEDT, AEDT 2d, have a very long history. They were originally developed for INM which got its start in the 1970’s. The standard profiles are made up of steps that still generally conform to the original version of SAE Aerospace Information Report (AIR) 1845 “Procedure for the Computation of Airplane Noise in the Vicinity of Airports”4. The quality and quantity of available standard profiles varies greatly across different aircraft types with the key variables being the age of the aircraft type and the size of the aircraft manufacturer. Flight profile data is generally provided by aircraft manufacturers as they, of course, have the best access to the data required for their generation and best knowledge of how their aircraft are designed to fly. The larger aircraft manufacturers like generally have more sophisticated processes in place for supplying standard profile data to the FAA than smaller manufacturers due to a combination of the nature of their

8 relationships with FAA, funding due to their priority in terms of aircraft fleet coverage, and also more internal resources that can be leveraged for standard profile generation. Therefore, the larger manufacturers generally supply a wider range of profiles covering more airframe engine combinations, trip distances, and procedure variations. Some smaller manufacturers provide more limited sets of profiles. For some aircraft types there is no formal relationship between the manufacturer and the FAA related to standard profile generation and they are created by external organizations such as the Volpe National Transportation Systems Center. Standard profile generation processes and assumptions have evolved over time, so newer aircraft types tend to have more up to date and more comprehensive sets of available profiles compared to older aircraft types. There are two fundamentally different types of standard profiles currently available in AEDT – procedural standard profiles and fixed-point standard profiles. Procedural standard profiles are defined as a series of procedure steps that the model follows, using accompanying aircraft-type specific aircraft flight performance parameters to calculate a trajectory. Because they exist only in conjunction with underlying performance data, procedural profiles can be modified to produce realistic, alternative trajectories through the creation of user-defined profiles. Procedural profiles are also able to account for changes in airport elevation and atmospheric conditions (wind, temperature, pressure) when calculating trajectories. Fixed-point profiles, on the other hand, live up to their name – they are a set of fixed points that define a single trajectory that cannot be modified by a user while still producing realistic thrust values due to the lack of underlying aircraft performance data. Fixed-point profiles are insensitive to all external factors including airport elevation and atmospheric conditions. As such, AEDT aircraft types that are limited to having only fixed-point standard profiles are very problematic when attempting to model more realistic trajectories. Fortunately, fixed-point profiles have become rarer over the years due to efforts by the FAA (with ATAC support) to reduce them. In AEDT, they are generally limited to military aircraft types and some standard arrival profiles for civilian aircraft. The distinction is still important to make in the context of this ACRP project as fixed-point profiles limit the potential for improvements for some aircraft types. When originally created, standard profiles were intended to calculate trajectories for airport noise studies in an era where airport noise was dominated by jet noise caused by departure operations using low bypass-ratio engines and was mostly of interest relatively close to airport boundaries. At that time, aircraft position information based on radar data was rarely available to airport noise modelers and available computing power was very limited. Also, the resultant calculated trajectories were generally used for the calculation of average annual day noise metrics for land use compatibility purposes, diminishing the perceived need for closely matching individual real-world trajectories. Given this context, many simplifying assumptions were made. The following sections describe the details for standard departure and arrival profiles separately given the different treatment they have historically received. Existing Standard Departure Profiles Standard departure profiles are the most detailed and extensive of the available AEDT standard profiles. All civilian aircraft types in AEDT have at least one standard procedural departure profile, and many aircraft types have a collection that represent up to three different procedure types (standard, International Civil Aviation Organization (ICAO) A, ICAO B) and up to nine different trip distances depending on the aircraft type’s range. For AEDT standard profiles trip distance is used as a surrogate for aircraft weight, a critical parameter for aircraft flight performance. The procedure steps used to define standard departure procedures are also very extensive and do a very good job of calculating realistic thrust values in a wide range of circumstances.

9 The whole modeling process for departure profiles has received the lion’s share of the attention from a modeling method and data perspective, relative to other operation types, due to the aforementioned dominance of departure operations on the airport noise the models were originally created to predict. The main issue with current standard departure profiles is that they represent manufacturer-defined ideals without consideration of local airspace/Air Traffic Control (ATC) effects. Again, based on the model’s founding assumptions, real-world variations in departure profiles were relatively unimportant as they generally occur farther from the airport where noise impacts have generally been of lesser importance. Close to the airport, there is generally very little variation in real-world departure profiles due to operational considerations. However, with a growing recognition that there are significant differences in some cases between AEDT standard and real-world departure profiles, the desire for more accurate environmental modeling results, and the move away from noise-centric considerations due to AEDT’s expanded capabilities, the need for improvements such as those driven by this ACRP research project is much more apparent than it has been in the past. Existing Standard Arrival Profiles The story for standard arrival profiles is much different than that for departures. Civilian aircraft types in AEDT have only one available standard arrival profile, and that one profile for some aircraft types is fixed-point rather than procedural severely limiting the ability of AEDT users to modify profiles for those aircraft types to better match reality. Until recently, aircraft manufacturers including Boeing and Airbus were unhappy with the ability of the then SAE AIR 1845/INM methods available for calculating procedural arrival profiles to represent the way their aircraft truly performed. They therefore started generating only fixed-point standard arrival profiles for new aircraft types being added to the model. ATAC worked with the FAA and the SAE A-21 Aircraft Noise Measurement and Noise and Aviation Emissions Modeling Committee to implement new arrival procedure step types including Level-Decel, Level-Idle, Descend- Decel, and Descend-Idle steps to improve arrival profile modeling and satisfy the aircraft manufacturers’ concerns. The result is that Boeing and Airbus changed course and started providing procedural profiles again, in many but not all cases replacing previously provided fixed-point profiles with procedural ones through coordination with the FAA. Arrival profiles in AEDT are limited to one per aircraft type, fewer than those available for departures, while in actual operations the variation in flown arrival profiles is much greater than that for departures. The single arrival profile per aircraft comes in one of two forms. Older arrival profiles generally consist of a constant 3-degree glideslope from an altitude of 6,000 ft. Above Field Elevation (AFE) to the runway. Newer profiles generally consist of a 3 degree glideslope from an altitude of 6,000 ft. AFE to 3,000 ft. AFE, a level segment a few miles long at 3,000 ft. AFE, and then a 3 degree glideslope from 3,000 ft. AFE to the runway. There is, therefore, a great deal of inconsistency in available standard arrival profiles – when using them in AEDT some aircraft types will always level-off at the same altitude and other aircraft types will never level-off — not based on operational realities, but rather just based on available profile data. Neither form of available standard arrival profiles in AEDT realistically represents the many profiles flown in real life, nor do they allow AEDT users to determine the effects of changes in real-world arrival procedures. Research Benefits This research hopes to provide information necessary to improve the ability of aviation environmental modelers using AEDT to more closely match real-world aircraft trajectories than they could prior to this research being conducted. Per the Statement of Work this improvement

10 is focused on single-airport, terminal area modeling which generally relies on the use of existing default flight profiles, with a small number of users creating their own customized profiles in a cumbersome, manual way that requires FAA approval for Federal regulatory studies. By learning lessons from practitioners who have gone through the custom profile process in the past, increasing the number of default profiles available to choose from within AEDT, filling in a gap in AEDT’s currently available mechanisms for creating custom profiles, and providing accompanying guidance, this research gives AEDT developers the ability to provide more options for meeting AEDT user’s modeling needs along with the guidance required to exercise them. Report Contents This report is organized into the following sections: 1 Executive Summary 2 Preface 3 Research Results 3.1 Industry Review Findings 3.2 New Profile Identification and Prioritization 3.3 New Profile Development and Validation 3.4 New Profiles Developed for AEDT 3.5 New Methods to Customize Profiles 4 Guidance Document Overview 5 Implementation Plan 6 List of References In addition, due the large nature of the various datasets used and generated during this research effort, there is a collection of appendices containing most of the detailed results: Appendix A – Initial Baseline and Candidate Profile Comparisons Appendix B – New Arrival Procedure Plots (new procedure data is also provided in Excel format) Appendix C – New Departure Procedure Plots (new procedure data is also provided in Excel format) Appendix D – New Procedure Definitions (also available in ASIF and SQL formats) Appendix E – New Procedure Generation Metrics Appendices A through E of this document are not published herein, but are available on the Supporting Materials for ACRP Web-Only Document 36 microsite on the TRB website.