SMO Right Turn Noise 091310 - Santa Monica · 2014-05-05 · 250° right turn was tested and the...

NOISE ANALYSIS 250° RIGHT TURN

SANTA MONICA MUNICIPAL AIRPORT

Prepared for

The City of Santa Monica

Prepared by

Mestre Greve Associates Division of Landrum & Brown

27812 El Lazo Road Laguna Niguel, CA 92677

September 13, 2010

Santa Monica Municipal Airport 250° Right Turn Noise Analysis 2

Table of Contents 1.0 INTRODUCTION....................................................................................................................................... 3

2.0 METHODOLOGY...................................................................................................................................... 3

3.0 CHANGE IN OPERATIONS .................................................................................................................... 3 3.1 YEAR SANTA MONICA MUNICIPAL AIRPORT OPERATIONS DATA ............................................................. 3 3.2 CHANGE IN FLIGHT TRACKS AND FLIGHT TRACK UTILIZATION ............................................................... 5

4.0 CHANGE IN CNEL.................................................................................................................................... 7 4.1 FAA GUIDELINES FOR DETERMINING SIGNIFICANCE OF NOISE IMPACTS ................................................. 7

5.0 CHANGE IN SINGLE EVENT NOISE LEVELS................................................................................... 9 ANNEX: CALENDAR YEAR 2009 CNEL CONTOURS SANTA MONICA MUNICIPAL AIRPORT


1.0 INTRODUCTION On December 10, 2009 the FAA began a 6 month test of a revised procedure for propeller aircraft performing instrument departures on Runway 21 at Santa Monica Airport [“Interim Review of Santa Monica Airport IFR Departure Heading Test,” FAA Western Services Center Operations Support Group, March 18, 2010]. This noise study was completed for the City of Santa Monica to determine, on a preliminary basis, the impacts of this change in operations relative to federal noise policy. The reader is referred to the Interim report cited above for the rationale for the change in procedures. Exhibit 1-1 shows a day of radar flight tracks before the 250° right turn was tested and the same day one year later during the right turn test. This shows all flights over Santa Monica including SMO and other aircraft to and from other airports as well. The red and green tracks are SMO flights and purple tracks are from other airports. In April of 2009 the MGA Division of Landrum & Brown completed the calendar year 2009 CNEL noise contours for Santa Monica Airport (SMO). That study provides a description of the noise environment around SMO in terms of measured noise levels, modeled noise contours and aircraft operations data. That report is attached as an annex. The analysis presented here updates the calendar year 2009 CNEL contours to reflect the change in operations associated with the 250° right turn from Runway 21. In addition, changes in single event noise levels are addressed.

2.0 METHODOLOGY The analysis presented here was done using the FAA’s Integrated Noise Model Version 7.0b. This model and its operation are described in more detail in the Annex. The modeling for the year 2009 was rerun using a new right turn flight track for Runway 21 and assuming the average number of aircraft that use this turn on a daily basis. This is described in more detail in the following sections.

3.0 CHANGE IN OPERATIONS

3.1 YEAR SANTA MONICA MUNICIPAL AIRPORT OPERATIONS DATA Existing year 2009 aircraft operations at Santa Monica Municipal Airport totaled 111,688 of which some 13,888 are jet aircraft operations. These data were obtained from traffic counts kept by the FAA Air Traffic Control Tower and Santa Monica Airport staff. Note that an operation is defined as a takeoff or a landing. Therefore, 111,688 operations translate into 55,844 takeoffs and 55,844 landings during the year. Of the total operations, 66,216 were itinerant operations and 45,472 were local operations. A local operation is an operation in the local traffic pattern (also know as a touch and go). When counting local operations, the departure part of the touch and go is counted as one operation and the landing part is counted as another operation.


Exhibit 1-1: Example of Flight Tracks Over Santa Monica Pre Test and During Test


The annual operations data are summarized by aircraft type using the INM aircraft types available. Single Engine propeller aircraft were divided into high performance singles (GASEPV) for aircraft such as the Bonanza, C210 and Cirrus 22 aircraft and low performance (GASEPF) for aircraft such as the C150 and C172. Table 3-1 presents a summary of the annual operations by aircraft type used in the noise modeling.

Table 3-1 Summary of 2008 Annual Operations By Aircraft Type

Itinerant: GASEPV 4,291 GASEPF 43,328 BEC58 2,878 CNA441 1,831 CIT3 212 CL600 809 CNA500 1,079 CNA750 1,357 EMB145 379 FAL20 250 GIV 1,632 IA1125 244 LEAR35 3,319 MU3001 4,607 Local: GASEPF 45,472 Total: 111,688

3.2 CHANGE IN FLIGHT TRACKS AND FLIGHT TRACK UTILIZATION The flight tracks at Santa Monica Municipal Airport are well established to take advantage of the runway configuration and prevailing wind conditions. Runway 3/21 is approximately 5,000 feet long and is the only runway at the airport. With winds predominantly coming from the ocean, aircraft typically depart to the west and arrive from the east on Runway 21. Only during Santa Ana wind conditions or other winds that move toward the ocean does the flow reverse with departures to the east and arrivals from the west. East flow occurred approximately 4 percent of the time in 2009. Departures to the west are grouped into 2 major tracks. Small aircraft doing visual departures follow a track that proceeds over the golf course and pilots are instructed to not turn prior to Lincoln Boulevard. Larger aircraft doing instrument departures proceed straight along the extended runway centerline. All twins, turboprops, and business jets were modeled on the straight out departure. These aircraft are generally doing an Instrument Flight Rules (IFR) departure and are instructed to fly straight out to the shoreline.


The change introduced by the FAA applies to propeller aircraft doing an IFR departure on Runway 21. The change is to require these propeller IFR aircraft to make a right turn to a heading of 250° (magnetic). Since the runway has a heading a approximately 210° (magnetic) this turn is a turn through about 40°. The City maintains a radar tracking system as part of its permanent noise monitoring system. This tracking system gets its radar feed from the FAA Aircraft Surveillance Radar system. Exhibit 3-1 shows a month of flight tracks that appear to be using the 250° right turn (the red bar represents a gate used to select the right turn aircraft). As can be seen in Exhibit 3-1 there is a very a great amount of dispersion of these tracks primarily associated with the wide variation in where the aircraft begin the turn.

Exhibit 3-1: A Sample of Radar Flight Tracks Including the Right Turn Recorded During the Month of February 2010. Based on FAA data and the flight tracking data it was determined that approximately 8 propeller aircraft per day were changed from the usual straight out flight track to the 250° right turn. Note that this varied considerably from day to day , but the overall average was about 8 per day.


4.0 CHANGE IN CNEL The CNEL contours used to depict existing noise exposure at Santa Monica Municipal Airport were developed using the INM Version 7.0a. Exhibit 4-1 shows the airport basic flight tracks (arrival in red, touch & go in green and departure in blue). The new turn is labeled. Also shown are the 55, 60 and 65 dB CNEL contours. In addition there are shaded areas that depict the change in CNEL due to the right turn. An increase in CNEL is shown in the warmer colors with the largest change being a +3 dB shown in red. The decrease in CNEL (moving aircraft from one place to another will increase noise under the new track and decrease them under the old path) is shown in cooler colors with the largest decrease of -3 dB shown in the small black shaded area. Note that the right turn does not affect the size or shape of the 55, 60 or 65 CNEL contour because the turn generally occurs after the contours have closed. Note that for purposes of this modeling the aircraft were assumed to follow a single track. In reality, as the radar tracks show, there is great dispersion. If that dispersion were modeled it would not affect the noise contours as the 55 CNEL closes prior the location of most turns. Also, if in some time in the future this turn were to be developed into an RNP/RNAV procedure the dispersion would be greatly reduced.

4.1 FAA GUIDELINES FOR DETERMINING SIGNIFICANCE OF NOISE IMPACTS The FAA has published guidelines for determining the significance of an increase in noise per the requirements of the National Environmental Policy Act (NEPA). These guidelines are contained in FAA Advisory Circular 1050-1E. Exhibit 4-2 is a copy of the relevant section from AC 1050-1E. The noise guidelines in AC 1050-1E are in terms of the noise metric Day Night Noise Level (DNL), however, later in the AC the FAA allows airports in the State of California to use CNEL for noise analyses. The key part of the FAA requirements for determination of significant impact is that the noise increase must be at least 1.5 dB and that increase must occur on noise sensitive land uses within the 65 CNEL contour. While the right turn does generate a noise increase in some residential areas greater than 1.5 dB, this occurs in areas with noise exposure well below 65 CNEL and in fact in areas with aviation noise levels below 55 CNEL.


EXHIBIT 4-1: The CNEL Contours 55, 60, and 65 Including the Right Turn And the Change In CNEL Due to the Right Turn.


EXHIBIT 4-2: An Excerpt From FAA Advisory Circular 1050-1E Identyfing FAA Criteria For Determining Significant Impact.

5.0 CHANGE IN SINGLE EVENT NOISE LEVELS The change in CNEL associated with a relatively small change in the number of flyovers may not be the most effective method of identifying the impact of a change in operations. Introducing an average of 8 flights over an area not normally flown by these aircraft may result in a large change in single event noise levels and small change in cumulative noise levels like CNEL. Exhibit 5-1 is a plot of the Single Event Noise Exposure Level (SENEL) for the straight departure of a high performance single engine propeller aircraft such as the Bonanza or Cessna 210. Shown are the 95 and 85 SENEL contours. SENEL is a measure of the maximum noise level and the duration of a single event caused by one flyover. An 85 SENEL noise event will typically have a maximum noise level of 75 dBA associated with it and a duration of 20 to 30 seconds. Normal face to face conversation is in the range of 60 to 65 dBA, so an Lmax of 75 dBA is well into the range of speech interference. Exhibit 5-2 shows the SENEL 85 contour for the same aircraft, but one which flys on the new 250° right turn procedure. As can be seen, this procedure introduces people to more flyover noise than would occur with the straight out departure path. Note that the FAA does not have any guidelines or standards relative to single event noise. The FAA does recognize the use of such supplemental metrics as helpful in explaining the effects of aircraft noise, but does not use them for the purposes of determining the significance of noise on residential communities. The procedures used at SMO are represented here as a noise abatement takeoff to ensure compliance with the noise limits. The aircraft power cutback results in relatively shallow climb and hence a long drawn out noise contour.


Exhibit 5-1: Single Event Noise Contours (SENEL 85 and 95 dB) For a Typical Departure.


Exhibit 5-2: Single Event Noise Contour (SENEL 85) For a 250° Right Turn


Exhibit 5-3: Difference in Single Event Noise Exposure Level (SENEL) Between 250° Right Turn and a Typical Departure.


ANNEX: CALENDAR YEAR 2009 CNEL CONTOURS

SANTA MONICA AIRPORT

Table of Contents 1.0 OUTLINE OF NOISE ANALYSIS ........................................................................................................... 3

2.0 METHODOLOGY...................................................................................................................................... 3 2.1 BACKGROUND............................................................................................................................................ 3 2.2 COMPUTER MODELING .............................................................................................................................. 3

3.0 EXISTING NOISE ENVIRONMENT ...................................................................................................... 4 3.1 EXISTING SANTA MONICA MUNICIPAL AIRPORT NOISE ............................................................................ 4 3.1.1 SANTA MONICA BACKGROUND .............................................................................................................. 4 3.1.2 EXISTING SANTA MONICA MUNICIPAL AIRPORT OPERATIONS DATA .................................................... 5 3.1.3 EXISTING SANTA MONICA MUNICIPAL AIRPORT FLEET MIX DATA....................................................... 7 3.1.4 SANTA MONICA MUNICIPAL AIRPORT RUNWAY AND FLIGHT TRACK UTILIZATION.............................. 9 3.1.5 SANTA MONICA MUNICIPAL AIRPORT NOISE MONITORING DATA......................................................... 9 4.1 HISTORY OF CNEL MEASUREMENT DATA, 1988 TO 2008 ...................................................................... 16

5.0 REFERENCES .......................................................................................................................................... 16

Santa Monica Municipal Airport Calendar Year 2009 CNEL Contours 3

1.0 OUTLINE OF NOISE ANALYSIS Year 2009 CNEL contours were developed using the calendar year 2009 operations and noise measurement data for the airport. The methodology used for the year 2009 CNEL contours has been updated to reflect current noise measurement data and an update in the FAA noise model. This report contains 3 major sections including this introduction. Section 2 describes the methodology used for this study. Section 3 describes the existing noise in the environs of Santa Monica Municipal Airport including the 2009 CNEL contours. Section 4 presents historical CNEL measurement data for the airport.

2.0 METHODOLOGY

2.1 BACKGROUND The methods used here for describing the existing noise environment in terms of CNEL rely heavily on noise measurements made by the airport’s permanent noise monitoring system and computer noise modeling. The noise environment is commonly depicted in terms of lines of equal noise levels, or noise contours. These noise contours are supplemented here with specific noise data for selected points on the ground. The computer noise model used here is described in the following below.

2.2 COMPUTER MODELING Noise contour modeling is a very key element of creating noise contours. Generating accurate noise contours is largely dependent on the use of a reliable, validated, and updated noise model. It is imperative that these contours be accurate for the meaningful analysis of airport noise. Airport noise contours were generated using the INM Version 7.0b. [1] The original INM was released in 1977. The latest version, INM Version 7.0b, was released for use in September 2008 and is the state-of-the-art in airport noise modeling. The INM is a large computer program developed to plot noise contours for airports. The program is provided with standard aircraft noise and performance data for over 100 civilian aircraft types that can be tailored to the characteristics of the airport in question, as well as a database of military aircraft types. Version 7.0b represents a minor revision to the computational algorithms used in the model and an updated aircraft noise database. One of the most important factors in generating accurate noise contours is the collection of accurate operational data. The INM program requires the input of the physical and operational characteristics of the airport. Physical characteristics include runway coordinates, airport altitude, and temperature and optional topographical data. Operational characteristics include various types of aircraft data. This includes not only the aircraft types and flight tracks, but also


departure and arrival procedures that are specific to the operations at the airport. Aircraft data needed to generate noise contours include:

• Number of aircraft operations by type • Types of aircraft • Day/Evening/Night time distribution by type • Flight tracks • Flight track utilization by type • Flight profiles • Typical operational procedures • Average Meteorological Conditions

3.0 EXISTING NOISE ENVIRONMENT

3.1 EXISTING SANTA MONICA MUNICIPAL AIRPORT NOISE

3.1.1 SANTA MONICA BACKGROUND Santa Monica Municipal Airport serves as a general aviation airport. The use of Santa Monica Municipal Airport is heavily regulated as a result of its limited area and facilities, environmental sensitivity of the local area, and because of a long history of airport related litigation extending back at least to the 1960’s. The operation of Santa Monica Municipal Airport is limited by the 1984 Settlement Agreement. Santa Monica Municipal Airport has a long history of noise analyses and was one of the very early airports to install a permanent noise monitoring system. Extensive data from its noise monitoring system enables accurate modeling and prediction of noise levels. Both CNEL and SENEL are monitored and calculated for each day and each aircraft operated at the airport. CNEL data are collected at each of the 6 permanent noise monitoring sites. These sites are shown in Exhibit 3-1. Note that site 6 is a new site that was put into operation during the year 2009. The emphasis of the Santa Monica Municipal Airport noise control program, as agreed to in the 1984 Settlement Agreement, is on regulating and limiting single event noise. This is in response to residents concerns about high noise levels associated with some aircraft operations at the airport. Santa Monica is one of the very few airports that limit aircraft single event noise. Other airports that limit single event noise include John Wayne Airport, Long Beach Municipal Airport, Torrance Municipal Airport, and Hayward Air Terminal. Of these airports the noise limits vary and are difficult to compare because the location of the enforcement microphones at the various airports are not located in similar positions to the microphones at Santa Monica. Estimating the noise limits at all these airports using a common microphone location indicates that the John Wayne Airport and Long Beach Municipal Airport are much less stringent than Santa Monica (both include jet air carrier operations), Hayward Air Terminal is about 3 dB less stringent than Santa Monica and Torrance Municipal Airport noise limits are about the same as Santa Monica. No airport has limits more stringent than Santa Monica Municipal Airport.


3.1.2 EXISTING SANTA MONICA MUNICIPAL AIRPORT OPERATIONS DATA Existing year 2009 aircraft operations at Santa Monica Municipal Airport totaled 111,688 of which some 13,888 are jet aircraft operations. These data were obtained from traffic counts kept by the FAA Air Traffic Control Tower and Santa Monica Airport staff. Note that an operation is defined as a takeoff or a landing. Therefore, 111,688 operations translate into 55,844 takeoffs and 55,844 landings during the year. The total operations represent a decrease in operations from the year 2008 of approximately 9%. The jet operations represent a decrease of approximately 12% relative to the year 2008. Of the total operations, 66,216 were itinerant operations and 45,472 were local operations. A local operation is an operation in the local traffic pattern (also know as a touch and go). When counting local operations, the departure part of the touch and go is counted as one operation and the landing part is counted as another operation.


3.1.3 EXISTING SANTA MONICA MUNICIPAL AIRPORT FLEET MIX DATA The type of aircraft using Santa Monica Municipal Airport during the year 2006 were determined using the flight information data from the airports noise monitoring system that is known as Airscene. All aircraft noise events for all of the year 2006 were downloaded and analyzed by aircraft type, operation, and runway used. Not all of the aircraft types that fly at Santa Monica are represented in the INM. The INM uses substitute aircraft to represent similar aircraft types. Table 3-1 lists the jet aircraft types that were recorded at Santa Monica and the INM substitution used to model that aircraft.

Table 3-1 Jet Aircraft Flown At Santa Monica and the INM Substitution

Note: Aircraft names are shown using Santa Monica/Air Traffic Control 4 letter code and the INM Substitution name is the INM aircraft naming convention.

Aircraft INM substitionASTR IA1125BE40 MU3001C25A CNA500C25B CNA500C500 CNA500C501 CNA500C550 MU3001C551 MU3001C560 MU3001C650 CIT3C750 CNA750CL60 CL600E135 EMB145F900 LEAR35FA10 LEAR35FA20 FAL20FA50 FAL20G150 IA1125GLF4 GIVGLF4 GIVH25B LEAR35LJ31 LEAR35LJ35 LEAR35LJ45 LEAR35LJ55 LEAR35MU30 MU3001WW24 IA1125


The annual operations data were then summarized by aircraft type using the INM aircraft types available. Single Engine propeller aircraft were divided into high performance singles (GASEPV) for aircraft such as the Bonanza, C210 and Cirrus 22 aircraft and low performance (GASEPF) for aircraft such as the C150 and C172. Table 3-2 presents a summary of the annual operations by aircraft type used in the noise modeling. Note that the airport noise monitoring system does not record all flights and some flights are labeled as ‘unknown’ if the aircraft is flying under visual flight rules (VFR) and does not broadcast its identification. The single engine propeller aircraft operations were adjusted to increase these operations in order to replicate the total operations as reported by the FAA Tower in its annual operations report.

Table 3-2 Summary of 2008 Annual Operations By Aircraft Type

Itinerant: GASEPV 4,291 GASEPF 43,328 BEC58 2,878 CNA441 1,831 CIT3 212 CL600 809 CNA500 1,079 CNA750 1,357 EMB145 379 FAL20 250 GIV 1,632 IA1125 244 LEAR35 3,319 MU3001 4,607 Local: GASEPF 45,472 Total: 111,688


3.1.4 SANTA MONICA MUNICIPAL AIRPORT RUNWAY AND FLIGHT TRACK UTILIZATION The flight tracks at Santa Monica Municipal Airport are well established to take advantage of the runway configuration and prevailing wind conditions. Runway 3/21 is approximately 5,000 feet long and is the only runway at the airport. With winds predominantly coming from the ocean, aircraft typically depart to the west and arrive from the east on Runway 21. Only during Santa Ana wind conditions or other winds that move toward the ocean does the flow reverse with departures to the east and arrivals from the west. East flow occurred approximately 4 percent of the time in 2009. Departures to the west are grouped into 2 major tracks. Small aircraft doing visual departures follow a track that proceeds over the golf course and pilots are instructed to not turn prior to Lincoln Boulevard. Larger aircraft doing instrument departures proceed straight along the extended runway centerline. All twins, turboprops, and business jets were modeled on the straight out departure. These aircraft are generally doing an Instrument Flight Rules (IFR) departure and are instructed to fly straight out to the shoreline. Arrivals are from the east and are on a straight in track by the time they get within the airport environs. The local pattern is a left hand pattern. Flight tracks are shown on Exhibit 3-2. The tracks were refined using radar data collected from the airport’s Airscene system. Sample radar tracks are attached to this report. When winds dictate flow to the east, the aircraft are assumed to operate on straight in and straight out flight tracks. The day/evening/night distribution of operations was derived from noise monitoring system data for the year 2009. The data logs show 90.8 percent of the operations during daytime hours (7 am to 7 pm), 7.8 percent during the evening hours (7 pm to 10 pm), and 1.4 percent of the operations during the night hours (10 pm to 7 am).

3.1.5 SANTA MONICA MUNICIPAL AIRPORT NOISE MONITORING DATA The remote monitoring sites were shown in Exhibit 3-1. The CNEL measured at each of these sites during calendar year 2009 are shown in Table 3-3.

Table 3-3 CNEL Measured During Calendar Year 2009

Site 2009 CNEL, dB 1 55.7 2 52.9 3 56.2 4 50.7 5 60.9 6 60.8


The noise monitoring system data were reviewed by aircraft type to determine the single event noise levels associated with each aircraft type. This was done in 2007 in order to develop aircraft flight profiles needed to use in the INM in order to get noise model results to match noise measurement results. Because of the strict noise limits at Santa Monica Airport, aircraft generally use procedures that are not represented by the typical aircraft flight procedures that are contained in the INM. Exhibit 3-3 shows the results of the SENEL analysis by aircraft type for noise measurements made at site RMS 1 for aircraft departures and site RMS 2 for aircraft arrivals. Note that the quantity shown is the energy average SENEL. Energy average is a form of averaging used for logarithmic data such as decibels. The energy average is biased towards the higher values in the distribution. For example, the more typical arithmetic average of the 2 numbers 50 and 100 is a value of 75. But the energy average of the decibel values 50 and 100 results in an energy average of 97 decibels. Note also that in computing the averages, the number used for the sample size was the actual number of measured noise events plus the number of noise flights that were tracked but did not generate a noise event. For the flights that did not generate a noise event and assumed SENEL was included that was based on the loudest an aircraft could be without triggering a noise event in the noise monitoring system. Note also that aircraft types shown in Exhibit 3-3 represent the aircraft indicated plus all the aircraft for which this aircraft was the INM substitute. For example, the noise level for the aircraft shown as the MU3001 included the Beechjet 400, C550, C551, and the C560 aircraft.


3.1.6 Santa Monica Municipal Airport Year 2008 CNEL Contours The CNEL contours used to depict existing noise exposure at Santa Monica Municipal Airport were developed using the INM Version 7.0a. The 60, 65 and 70 dB CNEL contours are depicted on Exhibit 3-4. Table 3-4 compares the measured CNEL with the CNEL predicted by the INM model at the 5 measurement sites.

Table 3-4 Comparison of Measured CNEL with Modeled CNEL

Site Measured CNEL Modeled CNEL 1 55.7 55.5 2 52.9 53.0 3 56.2 53.9 4 50.7 53.6 5 60.9 60.2 6 60.8 62.3

The comparison of measured versus modeled results is considered a very good correlation for all sites, except at Site 3 which has unique issues. Site 3 is located in the maintenance area at the golf course and is subject to substantial interfering maintenance noise thus showing a higher noise level than the modeled prediction. Note that a noise monitoring system is expected to provide an overall end-to-end accuracy of at least plus or minus 1.5 dB CNEL. The measurement system, while very good, cannot match the human ear and brain for identifying sound sources. Computers, with appropriately connected microphones, can measure sound level accurately, but cannot identify the sound source precisely. Near the airport the aircraft sound can be more successfully classified than at more remote sites where ambient noise can confuse the system. Some caution is warranted when reviewing the noise contours. The noise contours at the east end of the airport are shaped by 2 types of operations, arrivals to Runway 21 and noise aft of the aircraft generated during departure on Runway 21. The noise generated aft of the aircraft during pre-takeoff engine run and takeoff roll is modeled in the INM using a generic aircraft directional pattern that may or may not be representative of the aircraft that operate at Santa Monica Municipal Airport. Noise measurements were made in 2002 and reported in the 2002 annual report that shows the INM matches or tends to overestimate noise levels near the east end of the airport. CNEL tends to be more influenced by the noise levels associated with the most frequently flown aircraft as opposed to the noise associated with a few very loud aircraft. Historically, jet aircraft tend to produce the highest single event noise but the CNEL was dominated by the more frequently flown high performance single engine propeller aircraft. As the number of propeller aircraft operations at the airport has dropped and the number of jets has increased, there is no clearly dominate aircraft type at Santa Monica. The jets and propeller aircraft contribute very


similar amounts of energy to the total aircraft CNEL at Santa Monica. By a very small amount, jets dominate at RMS 1 and similarly, by a very small amount propeller aircraft dominate at RMS 2.


4.0 HISTORICAL NOISE MONITORING DATA

4.1 HISTORY OF CNEL MEASUREMENT DATA, 1988 TO 2008 The original noise monitoring system was installed in the 1970’s and replaced in 1988. The present noise monitoring system has been in operation since 1988 and a major system software upgrade completed in 2004. The historical CNEL data from the existing system are plotted in Exhibit 4-1. CNEL measurements recorded prior to 1988 are available and were reported occasionally. Data for the years 1982, 1983, 1985 and 1987 were found for Site 1. These are listed in Table 4-1.

Table 4-1 Pre-1988 CNEL Measurement Data for Site 1

Year CNEL 1982 62.1 1983 61.5 1985 58.8 1987 57.9

5.0 REFERENCES

1. U.S. Department of Transportation, Federal Aviation Administration, "Integrated Noise Model (INM) Version 7.0 User's Guide," April, 2007.


Attachment

Sample Radar Tracks From Airscene

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