National Academies Press: OpenBook
« Previous: 3 Selection of Modeling Method Overview
Page 14
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 14
Page 15
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 15
Page 16
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 16
Page 17
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 17
Page 18
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 18
Page 19
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 19
Page 20
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 20
Page 21
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 21
Page 22
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 22
Page 23
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 23
Page 24
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 24
Page 25
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 25
Page 26
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 26
Page 27
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 27
Page 28
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 28
Page 29
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 29
Page 30
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 30
Page 31
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 31
Page 32
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 32
Page 33
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 33
Page 34
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 34
Page 35
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 35
Page 36
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 36
Page 37
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 37
Page 38
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 38
Page 39
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 39
Page 40
Suggested Citation:"4 Modeling Process Details." National Academies of Sciences, Engineering, and Medicine. 2018. Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance. Washington, DC: The National Academies Press. doi: 10.17226/25264.
×
Page 40

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

  Page 14   Modeling Method Selection Process Figure 4 presents a flow chart that illustrates the analysis and decision-making process that can be used to select which of the profile modeling methods currently available in AEDT, and those that were developed during this ACRP project, should be used for a given modeling situation. This serves as a general guideline only. The best choice of modeling method for a given analysis, or even for a given flight operation within a larger analysis, depends on the available data, available modeling resources, available time, and ultimate purpose and goals of the modeling effort in question. Figure 4. Profile Modeling Flow Chart 4 Modeling Process Details This section of the Guidance Document provides examples of how to conduct profile modeling for airport noise, emissions, and fuel burn studies. This section illustrates the process to: collect and review profile data; compare the real-world profiles to AEDT and ACRP default profiles; determine whether or not to select a default profile; and, if not, how to develop a customized profile using ACRP or AEDT methods. As an overview, the key steps of the approach include:

  Page 15   1) Segregate profile altitude (and speed, if available) data by aircraft type or category, runway, operation type, and stage length (for departures). 2) Plot and review altitude profiles as a function of ground track distance. 3) Compare altitude values with the corresponding standard AEDT profile, to determine whether they are sufficient. Also compare to the ACRP 02-55 alternate default profiles. 4) If none of the AEDT or ACRP default profiles is appropriate, compute average altitudes along each track – for use in the PCT or as AEDT altitude controls. 5) Alternatively, gather input from aircraft operators to develop fully user-defined procedural profiles. Flight Trajectory Analysis The preferred source of data for aircraft trajectory information is often real-world aircraft position data (such as radar data). When using radar data, tracks should be divided up into smaller groupings according to: operation type (arrival versus departure); aircraft type or category (wide body, narrow body, regional jet, etc.); runway; and, for departures, stage length determined from trip distance. The size of the groupings is dependent on the needs of the study being performed, with smaller groupings generally producing more detailed, accurate trajectories with the tradeoff of needing more radar data to produce, more effort to process, and more effort to represent within AEDT. Table 3 shows the stage length definitions in AEDT in terms of great circle distance in nautical miles (NM). In addition, because air temperature affects climb performance, samples of radar data should be selected from a time period or season having weather that is similar to the annual average. Trajectory-based profiles can also be created in the absence of radar data, using navigational charts (e.g., SIDs, STARs, or Approach Plates). Using these published flight procedures, the user can define waypoints at certain altitudes, which can also be used as altitude controls for input to AEDT. Lastly, full or sometimes partial trajectory information can be obtained from other sources such as airports, Air Traffic Control, airlines, or pilots. This information may come in varied forms, be less complete, and require more processing to be used to generate target trajectories for modeling in AEDT. However sometimes it is the only source available. Table 3. Stage Length Definitions in AEDT Stage Length Minimum Range (NM) Maximum Range (NM) 1 0 499 2 500 999 3 1,000 1,499 4 1,500 2,499 5 2,500 3,499 6 3,500 4,499 7 4,500 5,499 8 5,500 6,499 9 6,500 11,000

  Page 16   Developing a Strategy Due to the resources and large amounts of information (radar data, procedure definitions, etc.) necessary to conduct profile analysis, it is useful to first develop an analysis strategy. For example, the user may limit the analysis to the most frequently operated aircraft in the fleet mix. Or, limit the analysis to the loudest aircraft – such as the aircraft with noise certification levels within approximately 10 decibels of the loudest aircraft in the study. Similarly there may be specific regions of the geographical area to be modeled that are more sensitive to noise than others, so more attention may be paid to flight operations over those areas or even limited sections of the trajectories of those flight operations that are most likely to impact that region. If the selected method requires FAA approval of custom profiles, aircraft operator validation and concurrence will be required. When working with airlines and pilots to develop and confirm profiles, note that:  Profile graphs should be provided with time on the horizontal axis, instead of track distance;  Pilots tend to refer to climb rates in a departure procedure, more so than specific altitudes along a trajectory; and,  Pilots do not use thrust in pounds (as AEDT does), rather a percentage of the maximum thrust or a thrust setting is used. Developing a modeling strategy also has the benefit of informing all stakeholders (i.e., airport, FAA, other regulators responsible for project approval) up-front about the level of analysis to be conducted. This information can be included as part of the study scope or protocol. Examples of How to Create Target Trajectories from External Data This section will outline a general process for creating target trajectories that are to be modeled by AEDT. There are many different ways to accomplish this. This section will discuss the two most common methods, the first using historical radar data, and the second by using published terminal procedures information. Target Trajectory Creation Using Radar Data Radar or other aircraft position data (i.e., ADS-B, ASDE-X) is often the most widely available and most often used source of aircraft trajectory data for modeling in AEDT. Two common sources of radar data are the FAA’s National Offload Program (NOP) and the FAA’s Performance Data Analysis and Reporting System (PDARS). For the single-airport studies that are the focus of this document, radar data is generally obtained from a single Terminal Radar Approach Control Facility (TRACON). Aircraft position data can also be obtained from other sources such as the airport study sponsor or flight tracking systems associated with the airport’s noise monitoring system. The first step is obtaining an adequate amount of radar data for the modeling effort at hand. An adequate amount depends on the nature and requirements of the study being performed. A full year’s worth of radar data is often desirable as it captures everything that happened at the modeled airport for a typical study period, however that much data is not always easily obtained or processed. If the available time period is more limited or there is a desire to work with less data due to time or resource constraints, it is important that the covered time periods capture

  Page 17   elements important to the study at hand such as airport operations during different weather conditions and different seasons. This section will outline an example by generating a single target arrival and a single target departure trajectory using historical radar data obtained for Cleveland-Hopkins International Airport (KCLE) from PDARS. This data set was also filtered, grouped, and visualized using PDARS tools. Figure 5 shows historical radar data for operations arriving to KCLE as green lines.  Figure 5. Example Radar Data Arriving to KCLE   The next step is to group radar data flight tracks based on common characteristics, which can include, but are not limited to: operation type (arrival/departure), airport, time of day, aircraft weight class, aircraft performance class, runway, runway configuration, flight procedure, etc. As noted above the level of detail of the grouping process also depends on the nature and goals of the study. Figure 6 below shows radar tracks for large jet arrivals to runway 06L at KCLE during the day using the HIMEZ3 arrival procedure.

  Page 18   Figure 6. Grouped Radar Data Based on Common Characteristics   It can be observed from Figure 6 that when radar data is grouped based on common characteristics, it can be further divided into sub-groups based on various combinations of lateral and altitude profile groups. Create as many sub-groups as necessary to achieve the desired fidelity. Figure 7 shows a sub-group of radar flight tracks that have similar lateral trajectories. Figure 7. Sub-Group of Radar Data Based on Lateral Similarities   Figure 8 shows the same set of trajectories in Figure 7 in profile view.

  Page 19   Figure 8. Sub-Group of Radar Data Based on Altitude Profile Similarities   Figure 8 displays similar altitude profiles, especially the level off at an altitude of 10,000 feet. Using the sub-group for radar tracks, create a representative ground track to serve as the input in AEDT. The lateral view of the representative track is presented in Figure 9. Figure 9. Representative Trajectory of Sub-Group of Radar Data (Lateral View)     One of the advantages of using historical radar data is that the altitudes for the trajectory is also readily available. The altitude profile view of the representative target trajectory can be viewed in Figure 10.

  Page 20   Figure 10. Representative Trajectory of Sub-Group of Radar Data (Altitude Profile View)   Now that the target trajectory has been created it can be used to define a flight operation and an associated ground track and flight profile in AEDT. Target Trajectory Creation Using Terminal Procedures Definitions Another example of how a user might model a trajectory is by following the altitude restrictions and lateral trajectories defined by the terminal flight procedure. The FAA publishes terminal procedures at: https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dtpp/search/ . The lateral input trajectory can be created as the series of waypoints found in the terminal procedure terminating at the runway. The geographical coordinates of waypoints can be found in the FAA’s National Flight Data Center (NFDC) website at: https://nfdc.faa.gov/nfdcApps/services/ajv5/fixes.jsp .An example of a terminal arrival procedure to Denver International Airport (KDEN) is presented below in Figure 11.

  Page 21   Figure 11. BOSSS TWO Arrival Procedure Plate   There are many options to creating the altitude profile of the target trajectory, which are demonstrated in Section 4.5. The most convenient method given the nature of the procedure definition information is often the use of altitude control codes. In Figure 11, it can be observed that there are altitude restrictions at the ZPLYN, IDOLL, NIIXX, QUAIL, BSTON, and BOSSS waypoints. The user can identify the segments in the input ground track that are closest to these waypoints and assign the appropriate control codes, see Section 4.4.4.3 for altitude control code definitions. For the given example, the target trajectory could be modeled as follows: Table 4. BOSSS TWO Altitude Restrictions Waypoint Control Code Altitude (feet MSL) ZPLYN 3 30,000 IDOLL 3 26,000 NIIXX 3 19,000 QUAIL 1 19,000 BSTON 2 14,000 BOSSS 2 12,000 Note that the altitude window between 17,000 and 19,000 feet MSL at the QUAIL waypoint was chosen to be an “at or below” the top altitude if it is interpreted that it is the more restrictive. Other interpretations could place an “at” constraint at 18,000 feet MSL, which is in the middle of the altitude window.

  Page 22   It is important to note that real-world flights can deviate from these waypoints and altitude constraints based on Air Traffic Control (ATC) instructions. Interviews with air traffic controllers or other subject matter experts could further enhance this modeling strategy. Examples of the Profile Review and Modeling Process This section presents two examples of the profile review and modeling method selection process. The two examples were selected from data used in the research process for this study, and include examples of how to address a departure and an arrival. Each sub-section in this section will present one of the options along with advantages, disadvantages, usage within AEDT, and an example of the resultant approach and departure output altitude profiles that will further highlight some of the advantages and disadvantages. The target trajectories used in the example are for a Boeing 737-700 and are presented in Figure 12. While these target trajectories happen to have been developed using radar data, for the purposes of these examples the source of the target trajectories is irrelevant and the process would not change if they were developed from terminal procedure definitions, operator information, simulation output, or any other source. The only requirement is that they be represented as altitude profiles in terms of altitude versus ground track distance. Figure 12. Example 737-700 Target Trajectories 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 0 50000 100000 150000 200000 250000 300000 Al tit ud e  Ab ov e  Fi el d  El ev at io n  (ft ) Distance From Runway (ft) Arrival Target Trajectory Departure Target Trajectory

  Page 23   Option #1 – Existing AEDT Standard Procedures AEDT comes pre-packaged with various approach and departure altitude profiles, of which a subset are the default profiles to be used when modeling an associated combination of operation type, aircraft type, and stage length. Option #1 is to simply select the existing standard procedure that best matches the target trajectory. Advantages Option #1 provides the fastest and easiest way to model aircraft performance, emissions, and noise. No knowledge of the aircraft’s actual trajectory is required. A user need only know the operation type (arrival or departure), aircraft type, and trip distance of the operation to be modeled. No FAA approval is required to use an existing standard procedure. Disadvantages The available existing standard procedures may not adequately match the trajectory to be modeled. For arrivals, there is only one procedure to choose from, and it will either be a continuous 3 degree glide slope descent all the way to the runway, or it will have a single level segment at an altitude of 3,000 ft AFE. For departures, there are more profiles to choose from but they generally only vary by aircraft weight, all other aspects of the procedures follow the same pattern of procedure steps. Usage Simply select the correct standard procedure from the set of available procedures based on the aircraft type, operation type, and stage length (trip distance). Example Trajectory Results Figure 13 presents our example arrival target trajectory’s altitude profile compared to the single default approach 737700 altitude profile.

  Page 24   Figure 13. Option #1 - Approach   Note that in Figure 13 the altitude profile diverges at 3,000 feet AFE between the target trajectory and the default AEDT approach profile. Additionally, the default approach profile is modeled to less than 20 nautical miles (NM) of track distance, compared to the desired 50 NM of the input track. Figure 14 presents our example departure target trajectory altitude profile compared to the best matching standard departure 737700 altitude profile.

  Page 25   Figure 14. Option #1 - Departure   Note that in Figure 14 the altitude profile diverges around 2,000 feet AFE between the target trajectory and the standard AEDT departure procedure’s altitude profile. Additionally, the standard AEDT departure altitude profile climbs more quickly and is modeled to ~12 NM, compared to the desired 17 NM of the target trajectory. Option #2 – Newly Developed AEDT Altitude Profiles Option #2 involves using one of the newly developed set of AEDT procedures that were developed in this ACRP Project 02-55, Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles. Advantages As these newly developed procedures have a wider variety of altitude profiles than the existing standard procedures they provide more options to possibly match a target trajectory’s altitude profile. If they are eventually incorporated into AEDT they will be able to be used without FAA approval. If they are not incorporated into AEDT they still represent a ready-made collection of procedures to choose from. Disadvantages This option requires more effort compared to Option #1 due to the additional analysis required to select an altitude profile that best matches the input altitude profile. Another disadvantage is that even though they provide more choices, the newly developed procedures may still not adequately match a particular target trajectory.

  Page 26   Usage To utilize Option #2 to model a given target trajectory, a user can review the newly developed altitude profiles for the given track, select the most appropriate altitude profile, and associate the air operation(s) to the selected profile. It may be helpful to visualize each of the available altitude profiles by running potential altitude profiles in AEDT to generate aircraft performance data that can be reviewed to select the most desired altitude profile. If these new procedures are implemented in AEDT a user will be able to simply select them from the list of available profiles in AEDT. If they are not implemented in AEDT a user can take the definition of the appropriate new procedure from Appendix D of the ACRP 02-55 Final Report and import it into AEDT via the AEDT Standard Input File (ASIF), or through a SQL query (both formats provided). Note, however, that since the current version of AEDT does not implement the de- rated thrust functionality, those profiles will not work as intended. Example Trajectory Results The lines in Figure 15 display the approach example input track altitude profile compared to other newly available altitude profiles. Figure 15. Option #2 - Approach   Note that the input track’s altitude profile is between the altitude profiles of SS07 and SS12 in Figure 15 (see the ACRP 02-55 Final Report for more details on the newly developed procedures). Compared to the default approach profile in Option #1, SS07 and SS12 provide a better altitude profile match; however, the location of the level segment is not at the desired altitude. The SS07 altitude profile is modeled to traverse ~35 NM and the SS12 altitude profile is modeled to traverse ~70 NM, neither of which matches the desired 50 NM of track distance traversed by the input track.

  Page 27   The lines in Figure 16 display the departure example input track altitude profile compared to other available altitude profiles. Figure 16. Option #2 - Departure   The input track’s altitude profile is similar to FF43, SS41, and SS44’s altitude profiles. Compared to the default departure altitude profile in Option #1, FF43, SS41, and SS44 would be a better altitude profile match; however, none of these newly developed profiles provide an exact match to the target altitude profile. In addition, none of the track distances of newly developed profiles match the input track’s track distance, with FF43 as the closest. 4.4.2.4.1 Altitude Profile Selection In the given example, the selection of the altitude profile that is closest to the input track was done qualitatively. Possible profiles were chosen based on its visual proximity to the altitude profile of the input track. Another method of choosing the appropriate altitude profile is by creating a metric that measures the difference between each profile. The trajectory score developed for this ACRP is an example of such a metric. Details regarding the definition and calculation of the trajectory score is discussed in Section 3.2.5.1 of the Final Report. Table 5 presents the trajectory scores when applied to the approach example (note that lower scores indicate a closer match to the altitude profile of the input track). It can be observed that the two altitude profiles chosen based on visual proximity, SS07 and SS12, did indeed have the lowest trajectory scores. Table 5. Option #2 Approach Altitude Profile Trajectory Scores Altitude Profile Trajectory Score SS07 397.9

  Page 28   SS08 1158.6 SS09 1632.5 SS10 416.9 SS11 537.2 SS12 357.2 Similarly, Table 6 presents the trajectory scores when applied to the departure example. The altitude profiles with the lowest scores (FF43, SS41, and SS44) were the same as the ones chosen visually. Table 6. Option #2 Departure Altitude Profile Trajectory Scores Altitude Profile Trajectory Score FF41 1384.6 FF42 1372.0 FF43 670.3 FF44 2167.9 SS41 1047.2 SS42 1058.8 SS43 1487.8 SS44 1045.1 The advantage of using the trajectory score is that it can be used to automate the selection process rather than depending on visual inspection. Option #3 – Profile Customization Tool Option #3 is to use the Profile Customization Tool (PCT) created for this ACRP project in order to modify an existing standard procedure to better match the target trajectory. Advantages When implemented in AEDT, the PCT would generate a custom altitude profile given a very limited amount of input information. This information can be determined even in cases where radar or procedure definition information is not available. As this profile is customized based on the target trajectory, the resulting altitude profile could better match the target trajectory’s altitude profile than Options #1 or 2. In addition, as this tool would be built into AEDT it could presumably be used without requiring separate FAA approval for the resultant procedures. Disadvantages Option #3 requires more effort than Options #1 and 2 as the user would have to use the tool, as simplified as it is, to create new procedures rather than simply selecting from a set of existing procedures. A separate custom profile would have to be created for each target trajectory. Usage To modify the existing standard procedure to better match our example target arrival trajectory, a user would identify the standard procedure, determine the length of the level segment in the target trajectory (209,626 ft in our example), determine the altitude of the level segment (2,800 ft in our example) and enter that information into the PCT. The PCT would use those inputs to create a new procedural arrival profile that better matches our example.

  Page 29   To modify an existing standard procedure to better match our example target departure trajectory, a user would identify the best matching standard procedure, and in the case of the 737-700 decide how they would like to alter the second acceleration segment in the standard procedure to better match the target. They would specify the desired initial altitude for that acceleration step, the desired acceleration segment length, and the desired rate of climb. In our example, we moved the second acceleration segment and merged it with the first acceleration segment, retaining the details of the first acceleration segment to produce a new procedure that better matches the target departure trajectory. Example Trajectory Results Figure 17 presents our example approach target altitude profile compared with a simple custom arrival profile that would be generated by the PCT once implemented. Note that the PCT is able to place the level segment at the appropriate altitude, which is better than Option #2. However, the shallow descent of the input altitude profile around 10 NM from the runway is still not captured. Figure 17. Option #3 - Approach   Figure 18 presents our example departure target trajectory altitude profile compared with a simple custom departure profile that would be generated by the PCT once implemented. Note that this custom profile is able to follow the input altitude profile more closely to about 3,000 feet AFE before it begins to diverge. For our example this procedure is a better choice compared to Option #1, and comparable to altitude profiles available in Option #2. The ground track distance covered by the custom profile is still shorter than what would be desired.

  Page 30   Figure 18. Option #3 - Departure   Option #4 – Altitude Controls Option #4 utilizes the altitude control functionality in AEDT. Advantages Option #4 can generally match the target trajectory’s altitude profile with high fidelity as AEDT will attempt to model match those altitudes as closely as possible within given aircraft performance and altitude control code constraints. If it can be modeled, i.e., flight performance constraints do not cause errors to occur during AEDT processing, the resulting altitude profile should follow the input trajectory more closely compared to the first three options. Another advantage of Option #4 is that the ground distance traversed by the input track is flown as close as possible without truncation or extension. Disadvantages Option #4 requires more effort compared to Option #1, #2, or #3 because this option requires strategic design and implementation of altitude control codes on the input ground track. This design could be simple or complex as needed. Additionally, the set of altitude control codes used on the input track may result in a failure to be modeled by AEDT. This can occur for various reasons, primarily due to conflicts between the user’s desired trajectory and the flight performance capabilities defined for the given aircraft within AEDT. Any errors require that the control codes be altered and run again until they can be successfully processed by AEDT. Usage Altitude control codes impose altitude constraints along the input ground track. Control codes are applied to geographic latitude/longitude points at the beginning of each track segment along

  Page 31   the track and are associated with an altitude. Null controls function as if no controls are present for the track segment to which they are attached. Three different non-null controls are available. They are:  At or Below - controls specify that the trajectory must be at an altitude equal to or less than the altitude specified in the altitude control. This code is enumerated as ‘1’ in AEDT.  At - controls require the track to hit a specific altitude at a specific latitude/longitude point exactly. This code is enumerated as ‘2’ in AEDT.  At or Above - controls specify that the track must be at an altitude equal to or greater than the altitude specified in the altitude control. This code is enumerated as ‘3’ in AEDT. Altitude control codes which cannot be met within tolerance generate an error; the operation being modeled fails and is noted in an error log by AEDT. Option #4 requires a user to identify the altitude control code strategy that best matches the user’s use case in order to achieve an altitude profile that resembles the input track’s altitude profile. For the examples of this option, a strict design was implemented by placing an altitude control code of “2” at each track point above 500 feet AFE (AEDT ignores all altitude control codes below 500 feet AFE). Example Trajectory Results Figure 19 presents our example approach target trajectory’s altitude profile compared with the altitude control functionality’s output altitude profile using altitude control codes of “2” placed at each track point. Figure 19. Option #4 - Approach

  Page 32   It can be observed that the target and output altitude profiles are very similar when using Option #4 in this case. Also, note that the input and output track have very similar track distances. Figure 20 presents an example departure input track’s altitude profile compared with the output trajectory’s altitude profile using altitude control codes of “2” placed at each track point. Figure 20. Option #4 - Departure   Note in Figure 20 how similar the input and output altitude profiles are for this example. Also, note that the input and output track have very similar track distances. Option #5 – Full User-Defined Profile This option requires a user to fully specify a complete ANP flight procedure. Advantages This option gives a user complete control over their procedure and resultant trajectory within the limits of AEDT flight performance specifications. It is therefore very flexible and in many cases could result in the best match to the target trajectory depending on the circumstances. The need to handle potential errors associated with processing altitude controls in AEDT is eliminated. Disadvantages This option requires an in-depth knowledge of ANP procedure steps, the required input per step type, and how adjacent step types interact with each other. An overview of the components involved is presented in Table 2 above. As such, this is the most complex option from the perspective of most AEDT users and many may not have the knowledge or time required to use it. It is also subject to the potentially difficult and time consuming process of obtaining FAA approval for the created procedures. An overview of that process is given in Section 4.6 below.

  Page 33   When there is a need to generate many customized procedures these factors may make this option impractical for even the most expert users. Usage To generate a new, fully customized flight procedure a user could choose from several starting points and follow different methods. The one commonality is that there are no tools built into AEDT or other publicly available software to guide or support this process. One way would be to start from an existing procedure, the way the PCT does, and modify individual procedure steps as appropriate. Another way would be to start from scratch and define a completely new set of procedure steps. In any case the new procedure and its component steps need to be defined per ANP specifications and imported into AEDT either via ASIF or directly into the appropriate AEDT study database. For our example we generated new fully customized flight procedures to best match the target trajectories. Example Trajectory Results Figure 21 presents our example approach target trajectory’s altitude profile compared with the output trajectory’s altitude profile using Option #5. Figure 21. Option #5 - Approach   It can be observed that in this case the target and output altitude profiles are very similar when using Option #5. Also, note that the target and output track have very similar track distances. Additionally, the shallow slope from ~1500 feet AFE to ~3000 feet AFE is captured, which is an improvement compared to Option #3. Figure 22 presents our example departure target trajectory’s altitude profile compared with the output trajectory’s altitude profile using Option #5.

  Page 34   Figure 22. Option #5 - Departure   Note in Figure 22 how similar the input and output altitude profiles are for this example. Also, note that the input and output ground tracks have very similar track distances. Environmental Results Comparisons Each of the five options above result in a different trajectory being modeled within AEDT, which each produce different levels of fuel burn, emissions, and noise. In our example and in the typical usage of AEDT the absolute correct values of the fuel burn, emissions, or noise produced by each flight being modeled are not known. There is no “gold-standard” for comparison. The results below do not attempt to quantify any amount of error or pass judgement on which option produced the most correct result. Rather they just show the magnitude of differences between the five available modeling options that resulted for our two example flight operations. Any other application of these options for other trajectories with other inputs and assumptions will yield varying amounts of differences between the five modeling options. Example Fuel Burn Results Comparisons Figure 23 shows the fuel burn results, in pounds (lbs.), for the example approach input track for each of the options presented in Section 4.4. For Option #2, the profiles that appeared closest in trajectory (SS07 and SS12) are presented.

  Page 35   Figure 23. Fuel Burn Comparison - Approach   Similarly, Figure 24 shows the fuel burn results for the example departure input track for each of the five modeling options. For Option #2, the profiles that appeared closest in trajectories (FF43, SS41, and SS44) are presented.

  Page 36   Figure 24. Fuel Burn Comparison - Departure   A user would not typically make this comparison during the modeling process because it would require performing all five options. These charts are presented to show the range and variability of fuel burn result differences for a given example target trajectory. Note that having similar altitude profiles do not necessarily translate to similar fuel burn. Aircraft weight and speed differences, and the resultant thrust differences that they cause influence the fuel burn calculated by AEDT. It is up to the AEDT user and the specifics of their study purpose, sensitivity, available input data, and potential impact on their results to determine which of the 5 modeling options is the best choice for a particular flight operation or set of operations from a fuel burn perspective. Example Emissions Results Comparisons Table 7 presents the emissions results, in lbs., for the example approach input track for each of the options presented in Section 4.4. A percentage difference comparison with the default output (Option #1) is presented in Table 8. For Option #2, the profiles that appeared closest in trajectory (SS07 and SS12) are presented. Table 7. Approach Emissions Comparison Option (lbs.) #1 #2 (SS07) #2 (SS12) #3 #4 #5 Fuel 410.07 998.32 1424.79 1755.51 976.68 1310.51 CO 2.17 3.23 7.21 5.16 5.81 4.3 HC 0.15 0.18 0.47 0.33 0.39 0.23 TOG 0.18 0.2 0.54 0.38 0.45 0.27 VOC 0.18 0.2 0.54 0.38 0.45 0.27 NMHC 0.18 0.2 0.54 0.38 0.45 0.27 NOx 3.36 8.84 11.36 17.42 7.16 11.58

  Page 37   PMNV 0.02 0 0.21 0.02 0 0 PMSO 0.01 0 0.07 0.01 0 0 PMFO 0.08 0 0.83 0.08 0 0 CO2 1293.78 3149.71 4495.22 5538.62 3081.43 4134.66 H20 507.26 1234.93 1762.47 2171.56 1208.16 1621.1 SOx 0.53 1.29 1.84 2.27 1.26 1.69 PM 2.5 0.11 0 1.11 0.1 0 0 Notes: CO – Carbon Monoxide HC – Hydrocarbon TOG – Total Organic Gas VOC – Volatile Organic Compound NMHC – Non-Methane Hydrocarbon NOx – Nitrogen Oxide Table 8. Approach Emissions Percentage Difference to Standard Profile Option % difference to Standard #2 (SS07) #2 (SS12) #3 #4 #5 Fuel 143.5% 247.5% 328.1% 138.2% 219.6% CO 48.8% 232.3% 137.8% 167.7% 98.2% HC 20.0% 213.3% 120.0% 160.0% 53.3% TOG 11.1% 200.0% 111.1% 150.0% 50.0% VOC 11.1% 200.0% 111.1% 150.0% 50.0% NMHC 11.1% 200.0% 111.1% 150.0% 50.0% NOx 163.1% 238.1% 418.5% 113.1% 244.6% PMNV -100.0% 950.0% 0.0% -100.0% -100.0% PMSO -100.0% 600.0% 0.0% -100.0% -100.0% PMFO -100.0% 937.5% 0.0% -100.0% -100.0% CO2 143.5% 247.4% 328.1% 138.2% 219.6% H20 143.5% 247.4% 328.1% 138.2% 219.6% SOx 143.4% 247.2% 328.3% 137.7% 218.9% PM 2.5 -100.0% 909.1% -9.1% -100.0% -100.0% Table 9 presents the emissions results for the example departure target trajectory for each of the options five modeling options. A percentage difference comparison with the default output (Option #1) is presented in Table 10. For Option #2, the profiles that appeared closest in trajectories (FF43, SS41, and SS44) are presented. Table 9. Departure Emissions Comparison Option (lbs.) #1 #2 (FF43) #2 (SS41) #2 (SS44) #3 #4 #5 Fuel 928.96 1293.86 1029.17 1342.04 918.45 1206.12 999.3 CO 0.52 0.72 0.57 0.75 0.51 0.67 0.55 HC 0.1 0.14 0.11 0.15 0.1 0.13 0.11 TOG 0.12 0.17 0.13 0.17 0.12 0.16 0.13 VOC 0.12 0.17 0.13 0.17 0.12 0.15 0.13 NMHC 0.12 0.17 0.13 0.17 0.12 0.16 0.13 NOx 22.24 30.91 24.78 32.39 21.98 28.92 24.08 PMNV 0.12 0.18 0.1 0.18 0.11 0.16 0.12 PMSO 0.08 0.11 0.09 0.11 0.08 0.1 0.09 PMFO 0.37 0.59 0.26 0.57 0.32 0.5 0.37

  Page 38   CO2 2930.87 4082.14 3247.05 4234.12 2897.72 3805.3 3152.78 H20 1149.12 1600.51 1273.09 1660.1 1136.13 1491.97 1236.13 SOx 1.2 1.67 1.33 1.73 1.19 1.56 1.29 PM 2.5 0.57 0.87 0.46 0.86 0.51 0.76 0.58 Notes: CO – Carbon Monoxide HC – Hydrocarbon TOG – Total Organic Gas VOC – Volatile Organic Compound NMHC – Non-Methane Hydrocarbon NOx – Nitrogen Oxide Table 10. Departure Emissions Percentage Difference to Standard Profile Option # % difference to Standard #2 (FF43) #2 (SS41) #2 (SS44) #3 #4 #5 Fuel 39.3% 10.8% 44.5% -1.1% 29.8% 7.6% CO 38.5% 9.6% 44.2% -1.9% 28.8% 5.8% HC 40.0% 10.0% 50.0% 0.0% 30.0% 10.0% TOG 41.7% 8.3% 41.7% 0.0% 33.3% 8.3% VOC 41.7% 8.3% 41.7% 0.0% 25.0% 8.3% NMHC 41.7% 8.3% 41.7% 0.0% 33.3% 8.3% NOx 39.0% 11.4% 45.6% -1.2% 30.0% 8.3% PMNV 50.0% -16.7% 50.0% -8.3% 33.3% 0.0% PMSO 37.5% 12.5% 37.5% 0.0% 25.0% 12.5% PMFO 59.5% -29.7% 54.1% -13.5% 35.1% 0.0% CO2 39.3% 10.8% 44.5% -1.1% 29.8% 7.6% H20 39.3% 10.8% 44.5% -1.1% 29.8% 7.6% SOx 39.2% 10.8% 44.2% -0.8% 30.0% 7.5% PM 2.5 52.6% -19.3% 50.9% -10.5% 33.3% 1.8% It is up to the AEDT user and the specifies of their study purpose, sensitivity, available input data, and potential impact on their results to determine which of the 5 modeling options is the best choice for a particular flight operation or set of operations from an emissions perspective. Example Noise Results Comparisons Figure 25 presents the Sound Equivalent Level (SEL) Noise results for the example approach track for receptors placed every two nautical miles along the input track for each of the altitude profile modeling options (note that the vertical axis scale starts at 45 dB). The noise result for Option #1 decreases at the last receptor point because the output trajectory ends before reaching that distance (see Figure 13).

  Page 39   Figure 25. Noise Comparison - Approach Figure 26 presents the SEL noise results for the example departure target trajectory for receptors placed every two nautical miles along the ground track for each of the altitude profile modeling options (note that the vertical axis scale starts at 45 dB). Note that noise values decrease sharply at varying points for some of the options because the output trajectory ends before reaching that distance (see Figure 14 and Figure 16).

  Page 40   Figure 26. Noise Comparison - Departure It is up to the AEDT user and the specifies of their study purpose, sensitivity, available input data, and potential impact on their results to determine which of the 5 modeling options is the best choice for a particular flight operation or set of operations from a noise perspective. Environmental Results Comparisons Summary For our single example arrival and departure operations, each of the five available modeling options produced different fuel burn, emissions, and noise output. In actual usage, the degree of difference between the options will vary depending on the nature of the target trajectories being modeled and the way in which each of the options is applied. The AEDT user will need to decide how significant these potential differences may be and how important that is to their overall study when deciding which of the options is most appropriate for their use. Additional guidance on this decision process is given in Section 5 below. FAA Approval Process For any flight profiles that are not provided as defaults in the AEDT, or generated by any of the functionalities built into AEDT, the FAA’s review and approval process for custom profiles must be completed. Examples of the types of profiles and methods that are considered to be non- standard by FAA are shown in Table 11. The approval process is defined in the FAA’s Order 1050.1F Desk Reference and includes the following elements:  Background – Description of the project.  Statement of Benefit – Description of the need for custom profiles (in terms of altitude, speed, and thrust) including why the default method or data are not sufficient.

Next: 5 Interpretation of Results »
Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

TRB's Airport Cooperative Research Program (ACRP) Web Only Document 36: Enhanced AEDT Modeling of Aircraft Arrival and Departure Profiles, Volume 1: Guidance supplements the Aviation Environmental Design Tool (AEDT), which computes noise, emissions, and fuel burn as a result of aircraft operations. The guidance document provides users of AEDT with information about varying approaches to profile modeling.

Accompanying the guidance, Volume 2: Research Report documents the approaches used to develop the AEDT guidance outlined in ACRP Web Only Document 36: Volume 1. Appendices A-E of volume 2 are available on a microsite: Supporting Materials for ACRP Web-Only Document 36.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!