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Â Page 11 Â 3 Selection of Modeling Method Overview The motivations for this ACRP project originated from the typical questions AEDT users face when conducting analysis of airport noise and emissions. Subject to the many constraints posed by the project, the user must decide when and how to conduct detailed analysis of aircraft arrival and departure procedures. There are several benefits to modeling detailed flight profiles, however in the current version of AEDT, significant resources can be required to develop customized profiles. The goal of this Guidance Document is to assist AEDT users with selection of the appropriate profile modeling methodology and to introduce the reader to the new tools and data sources provided by ACRP 02-55. Based on Requirements of the Project When considering enhanced modeling of arrival or departure profiles at an airport, the first factor to account for is the needs of the study or project. In some types of studies, detailed profile modeling â that is, anything beyond using the default AEDT profile â is not typically necessary, or is not supported by the fidelity of the available data. For example, environmental analysis in support of an airport Master Plan typically does not demand or support customized profile modeling. On the other end of the spectrum, Environmental Impact Statements (EIS) often require highly-detailed noise and emissions modeling including customized flight tracks and profiles. Figure 2 illustrates the spectrum of the types of noise and emissions studies that commonly do â or do not â involve custom profile modeling. Simple emissions inventories, Master Plans, and Categorical Exclusions (CatEx) typically do not require custom profile modeling, nor would such studies benefit significantly from detailed profile modeling. Examples of studies that may involve custom profile modeling include: Environmental Assessments and Environmental Impact Statements, noise contouring for state or other regulatory reports, and 14 CFR Part 150 and Part 161 studies. It is important to note that these are general guidelines for analysis, and not regulatory policies. If anything, the new tools provided within AEDT and from the ACRP 02-55 research should enable more users to model profiles with greater fidelity within resource and data constraints. Also of note, as shown at the top of Figure 2, some of these studies are only for noise, some are only for emissions, whereas NEPA studies (CatEx, EA, and EIS) involve analysis of both noise and emissions. Common questions about profile modeling include: - What types of projects require profile analysis? - What data are needed as input to AEDT? - What is the impact on noise and emissions results?
Â Page 12 Â Figure 2. Profile Modeling Based on Project Needs Based on the Data and Resources Available Based on the information in Figure 2, the AEDT user can begin to determine whether or not customized profiles are necessary and beneficial to a particular project or study. Next, the decision of the specific method to use should be made based on the availability of data and resources. That is, the user must determine if the following data are available and can be developed for input to AEDT within the budget and schedule of the project: ï§ Radar tracking data, including altitude and optionally speed; ï§ Trip distance or destination, for departures; ï§ Aircraft weight data, for departures; ï§ Information on reduced-thrust levels, for departures; ï§ Published procedure definitions; and, ï§ Operator- or pilot-specific flight procedures. In most cases, not all of the above data will be available. When modeling existing operations radar data is often ideal because it provides the three-dimensional trajectory of each flight in the dataset, and may also include speed. In the absence of radar data, information about flight profile altitudes can be gathered from published flight procedure charts or by interviewing operators, pilots, and/or air traffic controllers. Trip distance information is often available, either from radar, historical flight records, flight schedules, or operator interviews. When modeling future operations radar data is not available and users will need to obtain information on what the future trajectories will look like from other sources. Full or partial definitions of the procedures that these future flight operations will be following are often available from airports, the FAA, or airlines. This information can be used on its own or in conjunction with radar data covering existing traffic to produce a representation of the future trajectories.
Â Page 13 Â Aircraft weights, reduced-thrust information, and flight procedures for a given airport, air carrier, and time period are often more difficult or even impossible to collect and require greater resources to obtain and verify. Therefore, the new default profiles and profile modeling tools provided by ACRP 02-55 are aimed at achieving better accuracy in the absence of these types of data. Figure 3 presents a comparison of the AEDT and ACRP profile modeling methods described previously in Section 2 of this Document. The data requirements, resource needs, and FAA approval requirements are summarized in this figure. The methodologies are arranged from top to bottom in the order of increasing data, resource, and modeling expertise required. The first four methods involve selection of the appropriate profile from the available AEDT and ACRP defaults. The latter methods at the bottom half of the figure require custom profile development using various tools and techniques either currently available within AEDT or developed during this research (the PCT). Figure 3. Profile Modeling Based on Data and Resource Needs Is a custom profile necessary? Begin by comparing a sample of actual flight altitudes to the default profiles, graphed versus track distance. This will determine whether an AEDT or ACRP default profile will suffice, as opposed to developing a customized profile. If actual flight altitude information is not available then the creation of custom profiles is not possible.