Integrated Noise Model Accuracy for General Aviation Aircraft (2014)

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9 Suggested Implementation Plan ATM Implementation Options 9.1 As shown in Section 8, underlying changes to GA jet thrust settings must be applied to match observations in both aircraft profile altitudes and noise levels. Using the Assumed Temperature Method as a guide to adjust the thrust is the most direct and consistent method for altering thrust levels. It is this study’s conclusion that incorporated the ATM as a procedure, based on ATM2, to be followed by INM modelers at airports where GA jets are an important contributor to community noise exposure would be useful. The following two subsections elaborate on why this is the conclusion. Section 9.2 describes implementation plans for both ATM1 and ATM2. ATM1 is included as further background that supports the conclusion. Section 9.3 provides cost estimates. 9.1.1 Not a Preferred Option – Implementation of ATM1 Using the ATM1 method described in Section 8.2.1 would require updated Thrust Jet data in order to make reduced thrust departure profiles available as standard INM input. Generating these inputs would require coordination with aircraft manufacturers (as with the GIV evaluated in Section 8.2.1). Where updated information from manufactures is not available, an expanded operator survey and interpolated analysis (as with the Lear35 evaluated in Section 8.2.1) will be necessary to assemble the needed Thrust Jet inputs. Evaluation of not just the E thrust coefficient but the G speed coefficients with additional data not available for this project will be needed in order to complete any new Thrust Jet entries in the standard INM database. (See Equation 1, page 53, Equation 2, page 55 and Equation 3, page 55.) Additionally, standard profile procedures will need to be evaluated and potentially modified to be consistent with reduced thrust profiles, especially for profiles with segments incurring large thrust changes. Though Gulfstream was extremely helpful, for them to provide the information required some time from an engineer and not all manufacturers can be expected to have the resources to devote to this effort. Additionally, some of the aircraft are no longer manufactured and it is unlikely a manufacturer or engineer will be able to access the data needed to provide the information. Finally, locating an available pilot or operator able to discuss their procedures will be difficult, and even if there are pilots available, their information is likely to be in terms of EPR or N1, and there may be insufficient information in the INM database to translate these variables into the pounds thrust required for modeling. 9.1.2 Preferred Option – Development of guidelines for applying ATM2 Using the ATM2 method described in Section 8.2.2, no radar data, measured sound levels, pilot or manufacturer information is needed, however detailed guidance is necessary to ensure consistency of application. Conversion of profiles from the standard procedure database to the static profile points format that results from the ATM2 method creates profiles tailored to airport and runway layout and to the modeled temperature. These profiles are created as user defined input. The major variable in the ATM2 method will be choosing the assumed temperature for creating the profile. Profiles built in Section 8.2.2 relied on a target altitude and noise level at a defined evaluation location, derived from empirical radar and noise monitoring data, which in practice will not be readily available for most noise modeling. Where radar data are not available for a direct altitude validation, a relatively straight forward process will be described in the guidelines. All that needs to be known by the modeler is a modeling temperature, which is required in any case for INM modeling, and the approximate length of takeoff roll used by the 60

GA jets to be modeled. The guidelines will describe the use of an assumed temperature that will provide the profile, which is then run at the modeling temperature. The takeoff roll is checked to verify that it is within some identified tolerance of the observed roll, and if not, iterations of the assumed temperature are run until the modeled takeoff roll is within the tolerance. This approach provides an airport specific departure profile for any GA jet departure. In cases where GA jets are known to use maximum thrust takeoffs, no adjustment is needed. The advantage of providing these guidelines is the simplicity and proven accuracy of the method. In addition, developing the guidelines will be relatively uncomplicated, see Section 9.2.2. The only additional information required is the approximate length of takeoff roll, which could be acquired by observation, if necessary. Before implementation of these guidelines however, development will require testing of the method, as described in Section 7.1, for the other seven aircraft identified (Table 7). This testing will show whether or not the standard INM NPD curves are reasonable, or as shown in Section 8.3 for aircraft like the Lear 35, need to be revised before the guidelines can be finalized.32 Implementation should also include final testing at two or more specific airports that have detailed data on aircraft ground movements – ASDE-X. Implementation Process 9.2 9.2.1 Implementation of an ATM1 Process Implementation of the ATM1 method would require input and contribution from FAA as well as aircraft manufacturers. To include ATM profiles as standard input in the INM, two key database features would need to be updated to include new information: Update the INM thrust jet (thr_jet.dbf) database: This database includes the regression coefficients required to compute corrected thrust at a given speed, altitude and temperature. With the exception of the Gulfstream II aircraft, no reduced thrust departure profiles are currently included as standard INM data for GA jets. Updated coefficients for aircraft using reduced thrust departures would need to be produced. • For aircraft currently in production, operators could be requested to provide these data, where new coefficients would then be calculated directly. • For aircraft currently out of production an interpolative approach would be used to approximate the coefficients. Possible methods for this approach may include: o Determining the static thrust coefficient for ATM departures through expanded operator surveys; then look for functional dependencies across the entire standard database of GA jets for the higher order speed, altitude and temperature coefficients as a function of thrust. o Determine an approximate physical relationship on an aircraft by aircraft basis between thrust and the higher order coefficients. Highly accurate radar or on-board flight data, capable of capturing acceleration as a function of time and distance for known aircraft weights would have to be available. 32 Because four of the remaining ten aircraft use the LEAR35 INM types as the substitution aircraft, testing will show if the changed NPD curves for the LEAR35, as suggested in Section 8.3, are appropriate for these four aircraft as well. 61

Update procedure profile database: Once the reduced thrust levels for the ATM departure profiles have been determined with the updated thrust jet database, the standard procedural departure steps would need to be reviewed for compatibility with reduced thrust. Due to the more gradual climb out rates, the thrust cutback points specified for the standard profiles are no longer likely to be applicable. After obtaining or interpolating new reduced thrust coefficients from manufacturers or other FAA programs, a validation program comparing radar data altitude flight profiles as well as noise measurement correlations is recommended to ensure the provided data results in accurate modeled results compared to in practice flight procedures. 9.2.2 Implementation of an ATM2 Process Implementation of an ATM2 process would be through FAA development of a procedure to be followed by modelers. ATM2 Profiles can be built within the INM by using features within the model to generate all of the necessary inputs. The steps outlined here describe a procedure that could be followed by those modelers familiar with the INM, its databases and terminology. Building an ATM2 Profile Using INM Profile Graphs Data Step 1: Setup two INM cases for each aircraft requiring an Assumed Temperature Method (ATM2) profile. The cases should be identical except that the first (here termed “C_STD”) should have the temperature defined as actual local temperature to be modeled and the second (“C_ATM2”) should have the temperature initially defined at an estimated elevated level. This estimated level is arbitrary, but doubling the local temperature can often be a reasonable first estimate. Table 28 gives an example of the values stored in the INM case.dbf file for both these cases. Table 28 INM case.dbf example for standard vs. Initial ATM2 profile Step 2: Within INM open the CIVIL // Profile Graphs menu and select the desired aircraft and runway combination. Export the profile graphs then export the profile graph data from File // Export As. Do this for both the C_STD and C_ATM2 INM cases. This will result in two INM calc_prof_pts.dbf files. Table 29 and Table 30 show these outputs for the standard profile and ATM2 profile respectively. Table 29 INM calc_prof_pts.dbf for standard profile CASE_ID CASE_DESC DATE TEMPERATUR PRESSURE DO_HUMID HUMIDITY HEADWIND C_STD Actual Local Temperature 59.9 29.98 Y 62.0 8.0 C_ATM2 Assumed Temperature 120.0 29.98 Y 62.0 8.0 CASE_ID ACFT_ID OP_TYPE RWY_ID PROF_ID1 PROF_ID2 PT_NUM DISTANCE ALTITUDESPEED THR_SET OP_MODE C_STD LEAR35 D 09 STANDARD 1 1 0.0 0.0 0.0 3410.35 D C_STD LEAR35 D 09 STANDARD 1 2 2672.5 0.0 144.8 2852.91 D C_STD LEAR35 D 09 STANDARD 1 3 4691.2 205.6 160.1 2795.53 D C_STD LEAR35 D 09 STANDARD 1 4 11595.4 1500.0 163.2 2795.27 D C_STD LEAR35 D 09 STANDARD 1 5 15391.0 1833.6 189.9 2698.84 D C_STD LEAR35 D 09 STANDARD 1 6 16391.0 2006.6 190.4 2428.98 D C_STD LEAR35 D 09 STANDARD 1 7 22134.8 3000.0 193.3 2433.84 D C_STD LEAR35 D 09 STANDARD 1 8 42356.8 4547.0 270.3 2211.66 D C_STD LEAR35 D 09 STANDARD 1 9 50161.8 5500.0 274.2 2222.54 D C_STD LEAR35 D 09 STANDARD 1 10 67809.1 7500.0 282.8 2253.56 D C_STD LEAR35 D 09 STANDARD 1 11 92456.8 10000.0 294.1 2307.96 D 62

Table 30 INM calc_prof_pts.dbf for ATM2 profile Step 3: Repeat Steps 1 and 2 for different Assumed Temperatures defined for C_ATM2 until a suitable target initial departure roll distance (as specified in the DISTANCE column for PT_NUM=2) is achieved or a target altitude at a given track distance is reached. The target departure roll and / or target altitude would be based either on radar data or on operator/stakeholder input. Comparisons to measured noise levels can also be done to determine the validity of the selected assumed temperature. Step 4: Once appropriate targets have been reached, the calc_prof_pts.dbf file can be converted to a prof_pts.dbf file by removing the CASE_ID and RWY_ID fields and renaming the PROF_ID1 field to reflect the ATM2 method and runway. Table 31 gives the final inputs for the ATM2 prof_pts.dbf profile with an accompanying profile.dbf entry shown in Table 32. Table 31 INM prof_pts.dbf data for final ATM2 profile using profile graphs export Table 32 INM profile.dbf data for final ATM2 profile Building an ATM2 Profile Using INM flight.txt Data A variation to the Profile Graphs data method described above is to use the output from the INM flight path report. This approach has the potential to be more accurate, however may be less accessible to those not sufficiently familiar with the model. The Profile Graphs output, while based on the same data as in flight.txt, and easily accessed through the INM graphical interface, are summary outputs. The flight profile information given in the flight path report, flight.txt, is more complete and better reflects the internal data INM uses during modeling. The main advantage of utilizing the flight path report data occurs for profiles where rapid changes in thrust or speed occur such as in early thrust cutbacks. Where these transitional profile configurations CASE_ID ACFT_ID OP_TYPE RWY_ID PROF_ID1 PROF_ID2 PT_NUM DISTANCE ALTITUDESPEED THR_SET OP_MODE C_ATM2 LEAR35 D 09 STANDARD 1 1 0.0 0.0 0.0 2943.14 D C_ATM2 LEAR35 D 09 STANDARD 1 2 3565.6 0.0 153.0 2385.70 D C_ATM2 LEAR35 D 09 STANDARD 1 3 7875.1 414.5 169.6 2349.23 D C_ATM2 LEAR35 D 09 STANDARD 1 4 15589.7 1500.0 172.5 2402.63 D C_ATM2 LEAR35 D 09 STANDARD 1 5 22079.4 2038.7 201.4 2331.93 D C_ATM2 LEAR35 D 09 STANDARD 1 6 23079.4 2178.9 201.8 2098.76 D C_ATM2 LEAR35 D 09 STANDARD 1 7 28938.4 3000.0 204.4 2141.32 D C_ATM2 LEAR35 D 09 STANDARD 1 8 62640.6 5418.2 289.9 2013.94 D C_ATM2 LEAR35 D 09 STANDARD 1 9 63442.8 5500.0 290.3 2017.56 D C_ATM2 LEAR35 D 09 STANDARD 1 10 83625.5 7500.0 299.6 2106.12 D C_ATM2 LEAR35 D 09 STANDARD 1 11 110593.6 10000.0 311.8 2216.81 D ACFT_ID OP_TYPE PROF_ID1 PROF_ID2 PT_NUM DISTANCE ALTITUDESPEED THR_SET OP_MODE LEAR35 D ATM2_09 1 1 0.0 0.0 0.0 2943.14 D LEAR35 D ATM2_09 1 2 3565.6 0.0 153.0 2385.70 D LEAR35 D ATM2_09 1 3 7875.1 414.5 169.6 2349.23 D LEAR35 D ATM2_09 1 4 15589.7 1500.0 172.5 2402.63 D LEAR35 D ATM2_09 1 5 22079.4 2038.7 201.4 2331.93 D LEAR35 D ATM2_09 1 6 23079.4 2178.9 201.8 2098.76 D LEAR35 D ATM2_09 1 7 28938.4 3000.0 204.4 2141.32 D LEAR35 D ATM2_09 1 8 62640.6 5418.2 289.9 2013.94 D LEAR35 D ATM2_09 1 9 63442.8 5500.0 290.3 2017.56 D LEAR35 D ATM2_09 1 10 83625.5 7500.0 299.6 2106.12 D LEAR35 D ATM3_09 1 11 110593.6 10000.0 311.8 2216.81 D ACFT_ID OP_TYPE PROF_ID1 PROF_ID2 WEIGHT LEAR35 D ATM2_09 1 18300 63

occur, INM profiles using the smaller more discrete intervals between profile steps available from the flight path report better capture the flown profile. Step 1: The same processes outlined in Steps 1 through 3 for the Profile Graphs method can be repeated, even using the same Profile Graphs output to determine the target level to match in order to define the assumed temperature. One exception to this may be if radar data is going to be used to compare directly to the model profile. Exporting the full flight path report for each iteration may be warranted in this case to better compare subtleties in the flown flight profile. Step 2: Determine the final profile once an assumed temperature has been determined. The flight path report can be run after an INM case has been run. To generate this flight path data assign one operation per aircraft of interest to each runway of interest on a simple straight out INM vector track. Choose a noise output, either a contour, standard or detailed grid in order for the INM to run, but only the flight path report and not the noise results will be evaluated. Step 3: Once the INM run has completed, select Output // Flight Path Report in the INM menu. This will output the flight path report to flight.txt in the Scenario/Case folder. Step 4: For each aircraft and runway combination entered in Step 2, there will be an entry in flight.txt containing the modeled operations data as shown in Table 33. These data contain a header with the aircraft type, runway, profile name and other parameters followed by a table of data containing the distance, altitude, speed, and thrust data. Step 5: Once the flight path report data have been generated for the final assumed temperature, the flight.txt file must be manually reformatted into a prof_pts.dbf file using the data column mapping shown in Table 34. The final formatted prof_pts.dbf file as shown in Table 35 can then be included in the INM pared with the profile.dbf file shown in Table 32. Note that comparing the data in Table 35 to Table 31 more profile steps are generated with more discrete steps in each parameter. 64

Table 33 INM flight.txt data for example ATM2 profile Table 34 INM flight.txt to prof_pts.dbf data mapping AIRPLA OPERATIONS 0 acft_id = LEAR35 eng_type = J (Jet,Turboprop,Piston) stat_thrust = 3500 (Pounds) thrust_type = L (P=PercL=Poun X=Other) owner_cat = G (Commercial,GenAviation,Military) op_type = D (A=appr,D=dep,T=touch&go,F=circuit,V=overflight,R=runup) numb_ops = 1.0000, 0.0000, 0 (day,eve,ngt) frst_a_nois = 0 numb_a_no= 4 frst_p_nois = 4 numb_p_no= 4 model_type = I (Inm,Noisemap) spect_nums= 216, 113, 0 (approach,depart,afterburner) flt_path = D-09-09_D-0-STANDARD-1 numb_segs= 24 seg start-x start-y start-z unit-x unit-y unit-z length speed d.spd thrust d.thr op flaps bank duration 0 0 0 0 1 0 0 55.7 0 18.1 2943.1 -69.7 D -NONE- 0 3.6 1 55.7 0 0 1 0 0 167.1 18.1 18.1 2873.5 -69.7 D -NONE- 0 3.6 2 222.9 0 0 1 0 0 278.6 36.2 18.1 2803.8 -69.7 D -NONE- 0 3.6 3 501.4 0 0 1 0 0 390 54.4 18.1 2734.1 -69.7 D -NONE- 0 3.6 4 891.4 0 0 1 0 0 501.4 72.5 18.1 2664.4 -69.7 D -NONE- 0 3.6 5 1392.8 0 0 1 0 0 612.8 90.6 18.1 2594.7 -69.7 D -NONE- 0 3.6 6 2005.7 0 0 1 0 0 724.3 108.7 18.1 2525.1 -69.7 D -NONE- 0 3.6 7 2729.9 0 0 1 0 0 835.7 126.9 18.1 2455.4 -69.7 D -NONE- 0 3.6 8 3565.6 0 0 0.9954 0 0.0957 554.6 145 2.2 2385.7 -4.9 D -NONE- 0 2.2 9 4117.7 0 53.1 0.9954 0 0.0957 661.9 147.2 2.6 2380.8 -5.8 D -NONE- 0 2.6 10 4776.6 0 116.5 0.9954 0 0.0957 787.2 149.8 3.1 2375 -6.7 D -NONE- 0 3.1 11 5560.1 0 191.9 0.9954 0 0.0957 992.9 152.9 3.8 2368.3 -8.3 D -NONE- 0 3.8 12 6548.5 0 286.9 0.9954 0 0.0957 1332.8 156.7 4.9 2360 -10.8 D -NONE- 0 5 13 7875.1 0 414.5 0.9902 0 0.1393 7790.6 161.6 2.8 2349.2 53.4 D -NONE- 0 28.3 14 15589.7 0 1500 0.9966 0 0.0827 3124.4 164.5 14.5 2402.6 -35.3 D -NONE- 0 10.8 15 18703.4 0 1758.5 0.9966 0 0.0827 3387.6 178.9 14.5 2367.3 -35.3 D -NONE- 0 10.8 16 22079.4 0 2038.7 0.9903 0 0.1388 1009.8 193.4 0.4 2331.9 -233.2 D -NONE- 0 3.1 17 23079.4 0 2178.9 0.9903 0 0.1388 5916.2 193.8 2.6 2098.8 42.6 D -NONE- 0 18 18 28938.4 0 3000 0.9974 0 0.0716 5791.2 196.4 17.1 2141.3 -25.5 D -NONE- 0 16.7 19 34714.8 0 3414.5 0.9974 0 0.0716 6274.5 213.5 17.1 2115.8 -25.5 D -NONE- 0 16.7 20 40973.2 0 3863.5 0.9974 0 0.0716 6757.8 230.6 17.1 2090.4 -25.5 D -NONE- 0 16.7 21 47713.6 0 4347.2 0.9974 0 0.0716 7241 247.7 17.1 2064.9 -25.5 D -NONE- 0 16.7 22 54936.1 0 4865.4 0.9974 0 0.0716 7724.3 264.8 17.1 2039.4 -25.5 D -NONE- 0 16.7 23 62640.6 0 5418.2 0.9948 0 0.1014 806.4 281.9 0.4 2013.9 3.6 D -NONE- 0 1.7 24 63442.8 0 5500 0.9951 0 0.0986 20282 282.3 9.3 2017.6 88.6 D -NONE- 0 41.9 25 83625.5 0 7500 0.9957 0 0.0923 7548.5 291.6 3.5 2106.1 31.4 D -NONE- 0 15.2 26 91141.7 0 8196.8 0.9957 0 0.0923 19535 295 8.8 2137.5 79.3 D -NONE- 0 38.7 27 110593.6 0 10000 0.9957 0 0.0923 1 303.8 0 2216.8 0 D -NONE- 0 0 prof_pts flight.txt ACFT_ID header: acft_id OP_TYPE header: flt_path PROF_ID1 header: flt_path PROF_ID2 header: flt_path PT_NUM seg incremented by one DISTANCE calculated from start-x and start-y ALTITUDE start-z SPEED speed THR_SET thrust OP_MODE op 65

Table 35 prof_pts.dbf data for final ATM2 profile using flight path report Implementation Costs 9.3 9.3.1 ATM1 For aircraft still in production, the first step in the development of ATM1 profiles would be the creation of a revised requirement document analogous to what is currently requested of manufacturers to provide INM input data, including the thrust coefficients, at time of aircraft certification. This document will include a description of the reduced thrust profile to be flown. New reduced thrust coefficients derived from data generated through this process will then be used for inclusion in the INM. Cost to update the requirement document to include the reduced thrust departures would fall on FAA internally and would also cost manufacturers for generating the data needed to derive new INM thrust coefficients is unknown. For FAA, the authors are not in a position to estimate internal costs, but an estimate would likely be on the order of one or two or more person months. For manufacturers, the costs may be considerable if new flight or simulator operations are required to produce the needed data. For existing aircraft types, there are two different costs: one for aircraft currently being manufactured, and one for aircraft no longer manufactured. For both types, flying or use of simulators may be required – at considerable expense one can assume. For aircraft being manufactured, the costs should be lower than for those no longer manufactured. Costs will include time spent by manufacturer engineers, FAA (or contractor) for collection of radar data and validation of resulting profiles. If surveys of pilots / operators ACFT_ID OP_TYPE PROF_ID1 PROF_ID2 PT_NUM DISTANCE ALTITUDE SPEED THR_SET OP_MODE LEAR35 D ATM2_09 1 1 0 0 0 2943.1 D LEAR35 D ATM2_09 1 2 55.7 0 18.1 2873.5 D LEAR35 D ATM2_09 1 3 222.9 0 36.2 2803.8 D LEAR35 D ATM2_09 1 4 501.4 0 54.4 2734.1 D LEAR35 D ATM2_09 1 5 891.4 0 72.5 2664.4 D LEAR35 D ATM2_09 1 6 1392.8 0 90.6 2594.7 D LEAR35 D ATM2_09 1 7 2005.7 0 108.7 2525.1 D LEAR35 D ATM2_09 1 8 2729.9 0 126.9 2455.4 D LEAR35 D ATM2_09 1 9 3565.6 0 145 2385.7 D LEAR35 D ATM2_09 1 10 4117.7 53.1 147.2 2380.8 D LEAR35 D ATM2_09 1 11 4776.6 116.5 149.8 2375 D LEAR35 D ATM2_09 1 12 5560.1 191.9 152.9 2368.3 D LEAR35 D ATM2_09 1 13 6548.5 286.9 156.7 2360 D LEAR35 D ATM2_09 1 14 7875.1 414.5 161.6 2349.2 D LEAR35 D ATM2_09 1 15 15589.7 1500 164.5 2402.6 D LEAR35 D ATM2_09 1 16 18703.4 1758.5 178.9 2367.3 D LEAR35 D ATM2_09 1 17 22079.4 2038.7 193.4 2331.9 D LEAR35 D ATM2_09 1 18 23079.4 2178.9 193.8 2098.8 D LEAR35 D ATM2_09 1 19 28938.4 3000 196.4 2141.3 D LEAR35 D ATM2_09 1 20 34714.8 3414.5 213.5 2115.8 D LEAR35 D ATM2_09 1 21 40973.2 3863.5 230.6 2090.4 D LEAR35 D ATM2_09 1 22 47713.6 4347.2 247.7 2064.9 D LEAR35 D ATM2_09 1 23 54936.1 4865.4 264.8 2039.4 D LEAR35 D ATM2_09 1 24 62640.6 5418.2 281.9 2013.9 D LEAR35 D ATM2_09 1 25 63442.8 5500 282.3 2017.6 D LEAR35 D ATM2_09 1 26 83625.5 7500 291.6 2106.1 D LEAR35 D ATM2_09 1 27 91141.7 8196.8 295 2137.5 D LEAR35 D ATM2_09 1 28 110593.6 10000 303.8 2216.8 D 66

are required, costs will be for collection and harmonization of reported thrust use and climb rates (pilots will not all necessarily use identical procedures for a given aircraft type), regression of results to determine speed coefficients, and validation of resulting profiles. A very rough estimate, including manufacturer costs or for us of pilot data and regressions to produce the coefficients is from $100,000 per aircraft to $500,000 per aircraft. 9.3.2 ATM2 Steps include verifying the process with the seven aircraft types not analyzed in this study. The draft procedures would then be written and reviewed. The draft procedures should be tested at several airports with available radar and measured sound level data. Ideally, the procedures will also be applied at two or three airports that have Airport Surface Detection Equipment, Model X (ASDE-X). This equipment provides accurate aircraft ground locations, including during takeoff roll, and would provide the takeoff roll length for verification of the ATM2 method. Costs for developing and test of ATM2 procedures are estimated to be about $250,000 to $500,000, depending on how much additional validation is deemed necessary. 67