The FAA's substitution list recommends conditions at Georgetown Municipal the BEC58P, the Beech Baron, to Airport. (Measured single event noise represent the light twin-engine aircraft information is for comparative purposes such as the Piper Navajo, Beech Duke, only and cannot be used as input into Cessna 31, and others. The CNA441 the INM.) Both the loudest sound levels effectively represents the light (Lmax) and the Sound Exposure Levels turboprop and twin-engine piston (SEL) for various aircraft types were aircraft such as the King Air, Cessna recorded during the noise measurement 402, Gulfstream Commander, and program at each noise monitoring site. others. A detailed INM grid point analysis can then be prepared that generates Lmax The INM provides data for most of the and SEL values for the corresponding business turbojet aircraft in the aircraft types at each noise monitoring national fleet. The MU3001 effectively site for comparison. The resulting represents the Cessna Citation I, II and measured and predicated Lmax and V series aircraft. The CIT3 represents SEL values can then be compared. the Cessna Citation III, IV, and VII series aircraft. The GlIB designator Table 3E depicts the range of measured represents the Gulfstream II and III Lmax and SEL values from monitor series aircraft. The LEAR35 effectively sites one and three and the predicted represents the Lear 30 and 50 series, Lmax and SEL values from the INM for the Sabreliner 65, the Falcon 10, 50, these sites. (Monitor sites one and three and 200, and the Hawker 700 and 800 were used because they received the series aircraft. vast majority of aircraft overflights due to weather and wind conditions during General aviation helicopter operations the observation period). As previously are modeled using the Jet Ranger and discussed, Lmax is the peak noise level Hughes 500 helicopters. The Jet of the aircraft overflight. SEL is the Ranger and Hughes 500 helicopter data total noise energy (taking into account was extracted from the FAA's Heliport the peak and duration) of the aircraft Noise Model Version 2.2 (HNM). overflight.
All substitutions are commensurate In most cases the INM is very close, and with published Part 150 FAA in many cases, over-predicts the noise of guidelines. individual aircraft types in the vicinity of the airport. It should be noted, however, that there may be sizable Single Event Analysis differences between measured and predicted Lmax and SEL levels in some Measured single event noise levels for cases. There are several potential individual aircraft, taken during the reasons for these differences: noise monitoring program, are helpful in validating the noise modeling • Small noise measurement sample assumptions for existing and future SIze;
3-10 • Differences in distances from the • Differences in aircraft operating aircraft to the monitor; procedures and pilot techniques; and
• Differences in specific aircraft • The effect of weather conditions configurations within the general (temperature, wind direction, and aircraft type; wind velocity) on aircraft performance.
TABLE3E Summary of Measured and Predicted Single Event Noise Levels Georgetown Municipal Airport
Departures
Measured Measured Lmax,dBA I Predicted SEL, dBAI Predicted 2 Aircraft Type (Monitor Site 1) Lmax,dBA (Monitor Site 1) SEL, dBA 2
Single GA Prop Fixed Pitch Pro!1eller Cessna 152 63.5·76.1 70.0 - 76.8 69.1 - 86.5 80.0 - 85.0 Cessna 172 62.6 - 78.0 70.0 - 76.8 73.6 - 85.2 80.0 - 85.0 Piper Archer 60.6 - 74.5 70.0 - 76.8 67.8 - 83.9 80.0 - 85.0 Variable Pitch Pro!1eller Cessna 182 74.6 - 74.7 69.8 - 81.6 81.3 - 84.0 65.4 - 90.2
Twin GAProp Cessna 310 72.4 65.4 - 86.1 82.0 89.3 - 93.1 Beech Barron 74.3 - 82.4 65.4 - 86.1 83.5 - 89.3 89.3 - 93.1 Piper Seneca 75.4 65.4 - 86.1 84.5 89.3 - 93.1
Business Jet Beech Jet 90.0 84.4 - 93.9 94.6 91.5 - 98.2 Cessna Citation 86.3 - 95.0 84.4 - 93.9 94.1 - 102.11 91.5 - 98.2
Arrivals
Measured Measured Lmax, dBA Predicted SEL, dBA Predicted Aircraft Type (Monitor Site 3) Lmax,dBA (Monitor Site 3) SEL, dBA
Single GA Prop Fixed Pitch Pro!1eller Cessna 152 63.0 - 65.4 62.0 - 76.8 66.3 - 72.1 62.3 - 82.0 Cessna 172 63.3 - 68.4 62.0 - 76.8 70.6 - 74.8 62.3 - 82.0 Piper Archer 65.3 - 69.2 62.0 - 76.8 73.1 - 77.3 62.3 - 82.0 Variable Pitch Pro!1eller Beech Bonanza 74.1 - 74.6 70.7 - 87.4 76.1 - 81.8 60.3 - 89.7
Twin GAProp Beech Barron 74.5 - 79.0 72.5 - 87.2 82.5 - 85.4 60.2·89.7 Piper Seneca 75.2 72.5 - 87.2 82.2 60.2 - 89.7
Twin GA Turboprop Beech King Air 79.6 - 86.4 83.3 - 86.3 84.9 - 90.9 86.2 - 87.7
Business Jet Cessna Citation 82.8 - 88.5 84.4 - 87.4 88.5 - 92.2 87.1 - 88.8
I Measurements were taken April 4 and 5, 2001. This information is for comparative purposes only and not for input into the Integrated Noise Model. 2 Data from detailed grid analysis for 2003 base conditions. Source: Coffman Associates Analysis
3-11 TlME-OF-DAY RUNWAY USE
The time-of-day at which operations Runway usage data is another essential occur is important as input to the INM input to the INM. For modeling due to the 10 decibel weighting of purposes, wind data analysis usually nighttime (10:00 p.m. to 7:00 a.m.) determines runway use percentages. flights. In calculating airport noise Aircraft will normally land and takeoff exposure, one operation at night has the into the wind. However, wind analysis same noise emission value as 10 opera provides only the directional tions during the day by the same air availability of a runway and does not craft. The Georgetown Municipal consider pilot selection, primary runway Airport currently does not have an operations, or local operating Airport Traffic Control Tower (ATCT). conventions. At Georgetown Municipal Consequently, specific counts for Airport, the crossIng runway nighttime operations are not available. configuration offers four directions of However, discussions with airport staff choice. and experience at similar airports around the country provides a basis for Continuous records ofthe runway usage some reasonable assumptions about the at Georgetown Municipal Airport were nighttime activity at the airport. An not available due to the lack of an estimate of 10 percent of the total ATCT. However, airport staff and local annual operations that occur between aircraft operators provided an estimate 10:00 p.m. and 7:00 a.m. was used for of runway use. Table 3F summarizes modeling the 2003 noise exposure the runway use percentages for the contours. This percentage was applied existing and future conditions. to the future forecast scenario.
TABLE3F Existing Runway Use
Turboprop! Single Engine Runway Business Jet Multi-Engine Piston
Arrivals and Departures
18 70.0% 70.0% 56.0% 36 30.0% 30.0% 24.0% 11 0.0% 0.0% 10.0% 29 0.0% 0.0% 10.0%
Touch-And-Go's
18 NA NA 56.0% 36 NA NA 24.0% 11 NA NA 10.0% 29 NA NA 10.0%
3-12 ------
FLIGHT TRACKS airport occasionally cross over the top of the airport to join the traffic pattern. Local and standard aIr traffic procedures, input from the airport staff, Exhibit 3G illustrates the touch-and-go and a review of previous noise studies pattern tracks and the helicopter flight were used to develop consolidated flight tracks developed for this analysis. The tracks. The result is consolidated flight series of concentric oval-shaped tracks tracks describing the average corridors represent the observed variance in the that lead to and from the Georgetown size of the training pattern at Municipal Airport. Georgetown Municipal Airport. These tracks represent the observed At a general aviation airport such as dispersion of the touch-and-go traffic Georgetown, aircraft traffic is expected and are adequate for modeling over most areas around the airport. purposes. The helicopter routes The density of the air traffic generally represent an average of those observed increases closer to the airport. The and represent both arrival and flight tracks were developed to reflect departure traffic. these common patterns and to account for the inevitable flight track dispersions around the airport. ASSIGNMENT OF FLIGHT TRACKS Exhibit 3E illustrates the flight tracks used for the modeling of the departure The final step in developing input data operations at Georgetown Municipal for the INM model is the assignment of Airport. The departure traffic tends to aircraft to specific flight tracks. Prior to follow similar procedures on both the this step, specific flight tracks, runway north and south sides of the airport. In utilization, and operational statistics for order to avoid noise-sensitive the various aircraft models using residential areas, most of the traffic at Georgetown Municipal Airport were Georgetown Municipal Airport evaluated. departing to the south from Runway 18 turns to the southeast. Departure The radar flight track data was used to tracks are also provided for the determine flight track percentages for straight-out and turns to the west. each aircraft type. The radar flight tracks that formed the consolidated The consolidated arrival flight tracks tracks and sub-tracks were first for Georgetown Municipal Airport are counted. Then each consolidated track presented in Exhibit 3F. Arrival was assigned a percentage based on the patterns to all four runway ends are total number of tracks for each runway. generally straight-in close to the airport. Arrivals from the direction To determine the specific number of air opposite the runway flow typically enter craft assigned to anyone flight track, a the traffic pattern at about a 45-degree long series of calculations was angle and follow it around and into the performed. This included a number of airport. Aircraft approaching the specific aircraft of one group factored by
3-13 runway utilization and flight track ysis for current and forecast noise expo percentage. A detailed breakdown of sure conditions, as developed from the the flight track assignments can be Integrated Noise Model. found in Appendix C. 2003 NOISE INMOUTPUT EXPOSURE CONTOURS
Output data selected for calculation by Exhibit 3H presents the plotted results the INM were annual average noise of the INM contour analysis for 2003 contours in DNL. F.A.R. Part 150 conditions using input data described in requires that 65, 70, and 75 DNL the preceding pages. The areas within contours must be mapped in the official each contour are presented in Table Noise Exposure Maps. This section 3G. presents the results ofthe contour anal-
TABLE3G Comparative Areas Of Noise Exposure Georgetown Municipal Airport
Area In Square Miles
DNLContour 2003 2008
65 0.360 0.506 70 0.171 0.241 75 0.071 0.108
The shape and extent of the contours COMPARATIVE reflect the underlying flight track MEASUREMENT ANALYSIS assumptions. The 65, 70, and 75 DNL noise contours remain close to the A comparison of the measured versus runway. The 65 DNL contour has a the computer-predicted cumulative small bulge northwest of the extended DNL noise values for each runway centerline off airport property. measurement site has been developed. Small bulges in the 65 DNL contour In this case, it is important to extend off airport property to the remember what each of the two noise southeast and southwest. The 70 and levels indicates. The computer-modeled 75 DNL contours remain on airport DNL contours are analogous to the property. climate of an area and represent the
3-14 LEGEND
••••••••• Detailed Land Use Study Area
, ...... , Municipal Boundary ---- Airport Property Consolidated Departure Tracks
Departure Sub Tracks c::==J Residential Low Density
Residential Medium Density
Recreational Vehicle Park -c::==J Noise Sensitive Institutions School "• Day Care Facility • Community Center 1 C Residential Care Facility Place of Worship *2J Cemetery
Source, Aerial Photography, dated April 4, 2001 Corrigan Consulting, Inc. Coffman Associates Analysis.
o 3000 I I ~ SCALE IN FEET MUNICIPAL AIRPORT l(iit'(f'€(f'(C: Exhibit 3E EXISTING AND FUTURE DEPARTURE TRACKS LEGEND
••••••••• Detailed Land Use Study Area , ...... , Municipal Boundary ---- Airport Property Consolidated Arrival Tracks
Arrival Sub Tracks C=::J Residential Low Density c::::=::J Residential Medium Density
Recreational Vehicle Park -C=::J Noise Sensitive Institutions -' School • Day Care Facility • Community Center 1 0 Residential Care Facility .- Place of Worship tJ Cemetery
Source, Aerial Photography, dated April 4, 2001 Corrigan Consulting. Inc. Coffman Associates Analysis.
3000 I ~ f I SCALE IN FEET MUNICIPAL AIRPORT ~i"ff,€tr(i~(f' Exhibit 3F EXISTING AND FUTURE ARRIVAL TRACKS LEGEND
••••••••• Detailed Land Use Study Area Municipal Boundary
Airport Property
Consolidated Touch & Go Tracks
Touch & Go Sub Tracks
Consolidated Helicopter Departures
Consolidated Helicopter Arrivals
Residential Low Density
Residential Medium Density
_ Recreational Vehicle Park
c:::::=::::J Noise Sensitive Institutions
" School 1 • Day Care Facility • Community Center Residential Care Facility
Place of Worship
Cemetery
Source. Aerial Photography, dated April 4, 2001 Corrigan Consulting, Inc. Coffman Associates Analysis.
N o 0 3000 *H ~I ___"" ___ 1 ~
I SCALE IN FEET MUNICIPAL AIRPORT ~(~((.€.(.l. Exhibit 3G EXISTING AND FUTURE TOUCH AND GO TRACKS LEGEND ••••••••• Detailed Land Use Study Area Municipal Boundary
Airport Property
2003 DNL Noise Exposure Contour, Significant Effect
7 r
Source. Coffman Associates Analysis.
N o ~ 0 3000 H ~I ~_'--'.... I ~ I SCALE IN FEET MUNICIPAL AIRPORT t; f: a- t' ~ Pc t' i ,: ~ i Exhibit 3H 2003 NOISE EXPOSURE CONTOUR noise levels on an average day of the calculated noise, particularly at levels period under consideration. In contrast, above 65 DNL. Additional deviation is the field measurements reflect only the expected at levels below 65 DNL. In noise levels on the specific days of this case, all the noise monitor sites fall measurement. Additionally, the field outside the 65 DNL noise contour. The measurements consider all of the noise measured and predicted 2003 noise events that exceed a prescribed exposure contours for the annual threshold and duration, while the average condition are presented for computer model only calculates the each aircraft noise measurement site on noise due to aircraft events. As Exhibit 3J and Table 3H. previously discussed, the field measure ments can easily be contaminated by As seen in Table 3H, in all cases the ambient noise sources other than INM over predicted sound levels at the aircraft around the measurement sites. noise monitor sites. As previously With this understanding in mind, it is discussed, the reduced operation levels useful to evaluate the comparative due to the weather may have aircraft DNL levels ofthe measurement contributed to the measured noise levels sites. being lower than predicted levels at each measurement site.
DNL Comparison A review of annual fuel sales and fuel sales for the five-day measurement This analysis provides a direct period were done to determine the comparison of the measured DNL(24) amount operations were reduced during and predicted values for each noise the monitoring period. This assessment measurement site. In order to facilitate indicated that AvGas sales were off 48 such a comparison, it is necessary to percent for the five-day measurement ensure that the computer model input is period. Jet fuel sales were off 10 representing the observed reality as percent during the same five-day accurately as possible within the period. In addition, the Gulfstream III capabilities of the model. aircraft also did not operate at Georgetown Municipal Airport during During the measurements, low cloud the five day measurement period. For ceilings with brief periods of rain comparative purposes, propeller occurred during the monitoring period. operations were reduced by 48 percent, This may have reduced the number of jet operations were reduced by 10 aircraft operations during the percent, and the Gulfstream III aircraft measurement period. The airport also operations were removed from the INM operated primarily in a south flow on batch file and a grid point analysis was Runway 18-36 and very few operations prepared. The results of this analysis were observed on Runway 11-29. are presented for each measurement site in Table 3H. As seen in Table 3H, A difference of three to four DNL IS the adjusted 2003 predicted levels are generally not considered a significant well within the INM tolerances (ranging deviation between measured and from 0.1 to 3.1 DNL).
3-15 TABLE3H Noise Measurement DNL(24) vs. Predicted DNL Values Georgetown Municipal Airport Monitor Measured! Predicted Site (DNL[24]) 20032 Difference Adjusted 20033 Difference 1 58.9 64.5 +5.6 60.4 +2.3 2 51.1 57.1 +6.0 54.2 +3.1 3 58.4 62.0 +3.6 58.5 +0.1 4 50.5 56.2 +5.7 53.1 +2.6
Source: Coffman Associates Analysis 1 Measurements were taken April 2-7, 2001. This information is for comparative purposes only and not for input into the Integrated Noise Model. 2 Annual average 2003 noise exposure contours. 3 Adjusted annual average 2003 with 48 percent few propeller operations, 10 percent fewer jet operations, and no Gulfstream III operations.
2008 NOISE The 2008 65 DNL contour is more EXPOSURE CONTOURS elongated that the 2003 65 DNL contour. To the north, the 65 DNL The 2008 noise contours represent the noise contour extends 600 feet off estimated noise conditions based on the airport property. The 65 DNL contour forecasts of future operations. This extends approximately 700 feet off analysis provides a near-future baseline airport property to the south. Small which can subsequently be used to bulges in the 65 DNL contour extend off judge the effectiveness of proposed noise airport property to the northeast, abatement procedures. Exhibit 3K southeast, and southwest. presents the plotted results of the INM contour analysis for 2008 conditions Small portions of the 70 DNL contour using input data that has been extend off airport property to the described in the preceding pages. southeast and southwest. The 75 DNL noise contour follows the crossing Generally, the 2008 noise contours are runway system and remains on airport similar in shape to their 2003 property. counterparts. This is due to the use of similar modeling input assumptions for The surface areas of the 2008 nOIse the consistency of the baseline case. exposure are presented for comparison The contours are slightly wider and in Table 3G. more elongated than the 2003 contours due to the forecast Increase In operations.
3-16 LEGEND
••••••••• Detailed Land Use Study Area Municipal Boundary
Airport Property ® Temporary Noise Monitor Terminal r.~",3~. t------;;Measured DNU24l 1 ~ INM-Predicted
I
Georgetown Municipal Airport 1 Measured DNU24l is the average DNL for the measurement period at each site. This information is for comparative purposes only and not for input into the intergrated noise model. "--1"(' ..••., 58.9 i •• •••••• ·······7 60.4 I ~"...... :: j ,. .. u.J ~ .. . :....::• ..: ••••••••••••* t·····...... ,.~...... •..• ....• '. 4: •••.•••• Source. Coffman Associates Analysis. ••••••• 1'_ j ~.. '\). ~,. f('
N o R 0 3000 ~ I~~ __ J-~ __~ I ~
I SCALE IN FEET MUNICIPAL AIRPORT ;,t.t':t'e¥~~,:€" Exhibit 3J MEASURED AND MODELED NOISE SUMMARY sales and based aircraft that indicates no significant change in operations. The The information presented in this current contours are presented as the chapter defines the noise patterns for 2003 noise exposure contours. The 2008 current and future aircraft activity, forecasts of noise exposure levels without additional abatement around the airport can be expected to measures, at Georgetown Municipal increase slightly as the airport becomes Airport. It does not, however, make an busier in the future. attempt to evaluate or otherwise include that activity over which the It is stressed that DNL contour lines airport has no control -- such as other drawn on a map do not represent aircraft transiting the area and not absolute boundaries of acceptability or stopping at the airport. unacceptability in personal response to noise, nor do they represent the actual The current contours are based on a noise conditions present on any specific series of operational counts lasting two day, but rather the conditions of an weeks each quarter during calender average day derived from annual year 2000 and a review of current fuel average information.
3-17 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~ :.:.::/"" \ ..... ~\ .. .J ...... ~ ~ \. --'...... ~ ~ \ ~ \\ ~ ..."" \ .•...... \ \ .. ~ o /'" I I······· ••••••••• .~\ \ ..••~ .. LEGEND ./ ~~ ._...... :i ...... ~.~ ~ \'" , ...... , Detailed Land Use Study Area i \)tl\ ••,. .. -.. \...... •, ...... :: .... ::.: .. .' ~l:...... ~~ .... \. \ ~ ...... Municipal Boundary .•••••••. '" ••• 'n.... " .' .-•••• ,,-•• - ..... -~~ .....: .• "'",...... e~ ••- y-V- ...... f· .. · ..... ! ...... -~... ill'" i •• , ...... 1 ~ ••- ...... _...... ; ~...... ~.",. I •• ---- Airport Property {.'i... \ ,.... •...... ···········1 .! I ."' .. .. ••• .,.-...... ! f '. 2008 DNL Noise Exposure Contour. ...if...... i: \ ...... l...... ,...... " f • Significant Effect
•••••••••••••••••••••••••••••• t:.:··~~······ .. ···:.:7 f t •• ·······················.! }! .""'~ ••• t ..••\ : \ ...... B-nmtll Road ! f , . ~. : '\\ ,i '-..- 1 / '. \ ~ .....; >. "...... ,. \. 1 :.. 1 / \ \...... t...- I ...._.... . i i ~ ... l I , ...... • "q t···········.r·...... -., ". .. • \..... \ "--;·7···· 'e>o •••••••••• :s ~ •••••J...... i \ \. \. r oed Jf!. l···•• f ". • \ .i Ca~ It -? .: ...... \'" • .:.....• ' \.... #~ 65 •\ l l ,.....I •... I
•...... ). \., !:q / \:·:.::i. \.'::'.1\ " A\\\\\\~;\~.. ~- ~:~. 70 . I t I \ SQr.> :1::1: , ~\\\\\":A",." \ ~.. ".. 75 ~~~.. \, ~:.'..'.'.'.' ! tz! ! \ '. \ • ...... _~...... :.;J: \...... • I ::~:......