SAN FRANCISCO INTERNATIONAL AIRPORT CITY & COUNTY OF SAN FRANCISCO MEMORANDUM

Transcription

1 SAN FRANCISCO INTERNATIONAL AIRPORT CITY & COUNTY OF SAN FRANCISCO MEMORANDUM TO: MONTARA COMMUNITY FROM: SAN FRANCISCO INTERNATIONAL AIRPORT AIRCRAFT NOISE ABATEMENT OFFICE SUBJECT: MONTARA SHORT-TERM NOISE MONITORING REPORT DATE: OCTOBER 3, 017 The San Francisco International Airport () Aircraft Noise Abatement Office conducted aircraft noise monitoring in Montara to determine the noise levels within the community from aircraft operations at. The monitoring was made possible with the assistance of a Montara resident. The overall average daily noise level from all aircraft was 4dBA CNEL. The Community daily noise level was 51dBA CNEL. Noise from all aircraft over this location increased the total average daily noise level by 1dBA. aircraft attributed % of all aircraft noise events over Montara community. During the noise monitoring period there were no weather or other impacts that would cause delays, require use of reverse flow or alter the flight patterns in any way. Non-aircraft noise sources included dogs barking. Montara is a quiet suburban community with ambient noise levels of 48dBA. On an average day, Montara had 1 overflights out of which 65 exceeded the noise monitor threshold of 51dBA and recorded a noise event. Flights departing bound for destination airports in the south or southeast; will turn left over the peninsula and continue their path south using a published departure procedure or as directed by Federal Aviation Administration Air Traffic Controllers. As these flights overfly parts of coastal communities they represent percent of all aircraft noise events over Montara, and are typically at or above,000 feet. Oakland departures add additional percent to these flights. About 30 percent of aircraft noise events over Montara is low-flying general aviation traffic heading to Half Moon Bay Airport or transitioning to the smaller aviation airports such as San Carlos and Palo Alto. An average sound exposure level (SEL) for a single noise event for all aircraft were recorded at dba and maximum noise levels (LMax) at dba. and Oakland aircraft have lower LMax and SEL levels and are quieter than the general aviation traffic as they overfly the area about 8,000 feet higher. During the noise monitoring period Aircraft Noise Abatement Office received noise reports from six individuals in the Mid-Coast communities. Majority of aircraft noise events occurred between 9am and 9pm, and on average, there were only four nighttime noise events. In view of the fact that the monitoring location in Montara is located in a quiet suburban community with ambient noise in the quiet db range, any aircraft noise above this threshold may become a nuisance for the residents. dba- stands for A-weighted decibel. Decibel unit measures the loudness of a sound and is computed as the signal to noise ratio. A-weighting is used to adjust for frequency range of human hearing. An increase of ten decibels is perceived by human ear as a doubling of noise. SEL - Sound Exposure Level of a noise event is measured over time between the initial and final points when the noise level exceeds a predetermined threshold and its energy is compressed into one second. LMax - The maximum noise level is a measurement of the peak level of a noise event. CNEL- This metric is used to assess and regulate aircraft noise exposure in communities surrounding the airport. California Title 1 Noise Regulations established acceptable level of aircraft noise of 65dBA CNEL. Post Office Box 97 San Francisco California 9418 Tel Fax

2 AIRCRAFT NOISE EVENT FLIGHTS BY ALTITUDE All Flights General Aviation AT Departures 1L/1R Departures 8L/8R Flights Departures

3 ShortTerm NoiseMonitoringReport MontaraSeptember,017 September9-4 AircraftCNEL:4dBA CommunityCNEL:51dBA TotalCNEL:5dBA SEL:dBA LMax:dBA AmbientNoise(Leq):48dBA NoiseMonitorTreshold:51dBA AircraftNoiseEvents:39perday OperationsFlow:WestFlow (aldays) CauseofAircraftoverflightsoverMontara:and OAKDepartures,HalfMoonBayAirportandGeneral Aviationtraffic X DailyNoiseEventAverages DailyAverage September Date NoiseEvents Non- Avg.SEL Avg.LMax NoiseEvents Avg.SEL Avg.LMax Community NoiseEvents Avg.SEL Avg.LMax Eventsare:SingleAircraft,MultipleAircraft,SimultaneousandNon-Aircraft,andSimultaneousAircraftandCommunity. SEL-SoundExposureLevelofanoiseeventismeasuredovertimebetweentheinitialandfinalpointswhenthenoiselevelexceedsapredeterminedthreshold anditsenergyiscompressedintoonesecond. Lmax-Themaximum noiselevelisameasurementofthepeaklevelofanoiseevent. CNEL-Thismetricisusedtoassessandregulateaircraftnoiseexposureincommunitiessurroundingtheairport.CaliforniaTitle1 NoiseRegulations established acceptablelevelofaircraftnoiseof65dbacnel. CommunityNoiseEquivalentLevel(CNEL) SoundExposureLevel(SEL)Comparison 65 acceptablenoiselevelstandard 90 dba dba only Aircraft 35 AlAircraft Date Total Community Aircraft Date AircraftNoiseEventsbyDay(7am-7pm),Evening(7pm-pm)andNight(pm-7am) Day Evening Night Noise Events 4 1 Noise Events(%) % 18% 11% Avg.SEL Min.SEL 6 Max.SEL 8 Avg.LMax Min.LMax Max.LMax 79 7 Avg. Duration (sec) Min. Duration (sec) Max. Duration (sec) 53

4 AircraftNoiseEvents NoiseEventsbyHouroftheDay 8% 6% 4% % 0% 3AM 6AM 9AM 1PM 3PM 6PM 9PM HouroftheDay Nighttime(Midnight-6am) 7,000ft 8,000ft 9,000ft,000ft>,000ft 5% Onlyaircraftthatregisteredanoiseeventonthemonitor areshown. Airport OAK HAF Others Top5AircraftTypes DeparturesAltitude 6% 13% % 16% 17% 3% % % AircraftNoiseEvents 5 0 September NightlyAverage= Noise Reporters Noise Reports Total * *individualreporters Date Mid-CoastCommunitiesNoiseReporters Locations x 4% ofoverflightsregisteredanoiseevent. (1avgdailyoverflightsofwhich65created anoiseevent) Theequipmentusedtomeasure thesoundlevelwasan EnvironmentalMonitorUnit 00noisemonitorandType 41DM-microphone manufacturedbybruel&kjaer. Themeasurementsconsistedof monitoringthea-weighted decibelsinaccordance withproceduresandequipment whichcomplywithinternational ElectrotechnicalCommission, andmeasurementstandards establishedbytheamerican NationalStandardsInstitutefor TypeIinstrumentation. CessnaC17 EmbraerE1 AirbusA30 Boeing7-0,0,900 A31 Other78 AircraftTypes NoiseMonitoronLocation Microphone Monitor 7% 4% 16% 44% 4% 6% XNoiseMonitorLocation Themicrophonewascalibratedpriortothestartofthemeasurement.The monitorwashousedinaweatherproofcaseandpoweredbyastandardexterior electricalwaloutlet.themicrophonewasmountedonatripodataheightof7 feet,asseenabove.thesoundlevelsatthesitewerecontinuouslymonitored,the datawasstoredontheonboardmemoryandtransferedtoaremovablememory stickfordecoding.thedecodednoisedatawasthenprocessedintheairport NoiseandOperationsManagementSystem (ANOMS)foridentification,noiseto flighttrackmatchingandcommunitynoiseequivalentlevel(cnel)noisemetric calculations.

5 San Francisco Bay Area Major Jet Arrival and Departure Routes West Flow Plan Note: Image not to scale and not all flights paths are shown.

6 0 Noise Exposure Map The California Code of Federal Regulations, Title 1, Division.5, Chapter 6, paragraph 501 states, The standard for the acceptable level of aircraft noise for persons living in the vicinity of airports is hereby established to be a community noise equivalent level of 65 decibels. Since the average Aircraft CNEL was measured at 4dBA for Montara, this residential area has an acceptable level of aircraft noise as defined by state law. The extent of the 65dBA CNEL noise impact contour at is shown above. This noise contour was generated using Federal Aviation Administration s Integrated Noise Model (version 7.0d). The Federal Aviation Administration accepted this map as part of the Noise Exposure Map update under Federal Aviation Regulations Part 0 on January 9, 016. The results of the field monitoring validate the extent of the 65dBA CNEL noise impact boundary confirming Aircraft CNEL is less than 65dBA CNEL for this location.