Q4 – FLIGHT OPERATIONS AND NOISE REPORT
Beechcraft 60 Duke · Performance Data
Overview
This document provides a comprehensive overview of flight operations and noise levels associated with aircraft overflights in the City of Sunnyvale during the fourth quarter of 2025. It is intended for use by local authorities, residents, and aviation enthusiasts interested in understanding the impact of aircraft noise on the community. The report includes data collected from various noise monitoring terminals (NMTs) and details the types of aircraft operating in the area, their noise levels, and the times of day when overflights occur. The information is presented in a transparent manner, allowing stakeholders to assess the effects of aviation on local noise levels without interpretation from the City of Sunnyvale.
- In Q4 2025, there were 9,906 daytime flights, 1,161 evening flights, and 695 nighttime flights over Sunnyvale.
- 88% of RNP approaches to SJC were captured by the noise monitoring system.
- The peak day for South Flow approaches was November 16, 2025.
- The average altitude for RNP approaches was 3,136 feet.
- The maximum noise level recorded for RNP approaches ranged from 55-84 dBA.
Document
Source
Originally published by syv.noiselab.casper.aero. Sprinkle hosts a reference copy with an added summary, specifications and searchable full text.
Document details
- Type
- Performance Data
- Year
- 2025
- Pages
- 25
- File size
- 2.4 MB
- Publisher
- syv.noiselab.casper.aero
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- Pilot's Operating Handbook / AFM
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In this document
Introduction
The report outlines the objectives of the City of Sunnyvale in monitoring flight activity and associated noise levels. It emphasizes the importance of understanding how aircraft noise affects residents and provides guidelines for interpreting the data presented.
24 Hour View of Aircraft Noise
This section breaks down the number of aircraft overflights by time of day, indicating that the majority occur during daytime hours. In Q4 2025, there were 9,906 daytime flights, 1,161 evening flights, and 695 nighttime flights.
SJC Airport South Flow Data for Q4 – 2025
The report details the types of approaches flown by aircraft landing at San Jose International Airport (SJC) during South Flow operations. It highlights the differences between ILS/Visual and RNP approaches, with data showing that 88% of RNP approaches were successfully captured by the noise monitoring system.
Peak South Flow Day in Q4-2025
This section identifies November 16 as the peak day for South Flow approaches, detailing the number of aircraft and their noise levels during that day.
City of Sunnyvale Overflight Data for Q4 – 2025
The report quantifies overflights associated with multiple airports in the region, providing insight into the distribution of flights across the City of Sunnyvale.
ICAO Aircraft Code Reference
This section lists various aircraft types and their corresponding ICAO codes, including the Beechcraft 60 Duke (BE60), providing a reference for understanding the types of aircraft contributing to the noise data.
Full document text
2025 CASPER AIRPORT SOLUTIONS, INC. | 1055 Westlakes Drive, Suite 300, Berwyn, PA 19312 | https://casper.aero CITY OF SUNNYVALE Q4 – FLIGHT OPERATIONS AND NOISE REPORT 1 © 2024 Casper Airport Solutions, Inc. DISCLAIMER Casper Airport Solutions, Inc. provides the data in this report on behalf of the City of Sunnyvale for informational purposes only. It has no legal standing and is not recognized as an official source by either the State of California or the Federal Aviation Administration (FAA). The City of Sunnyvale is not an airport authority. It has no statutory reporting obligation under Title 21 of the California Department of Transportation. The sound level meters installed by Casper are certified by the manufacturer Larson Davis to meet all ANSI performance requirements for a Type 1 sound level meter. The FAA System Wide Information Management (SWIM) flight track position data has a stated minimum accuracy of + 150 feet and temporal accuracy of approximately 1 second. 2 INTRODUCTION The City of Sunnyvale's primary goal in procuring a Noise and Operations Monitoring System (NOMS) is to monitor flight activity and the aircraft noise associated with overflights that affect residents living within the ci2025ty limits. Secondly, to provide this data to interested parties in a transparent and unfiltered way. The data contained in this report is presented with that goal in mind. On each page, you will find an explanation of how to read the various charts and definitions of the different metrics and data types. What you will not find is any interpretation by the “City” about the data in this report. For a more detailed explanation of the various noise metrics, general aircraft operations, or ATC procedures discussed in this report, please refer to the Education section of the City of Sunnyvale's NoiseLab website (https://syv.noiselab.casper.aero). The website also contains interactive data browsers that allow interested parties to view detailed noise and flight operations statistics concerning areas around the City of Sunnyvale. When reading this report, it is essential to consider the following factors: ● This report's data may vary from San Jose International Airport's (SJC) information as this report does not include South Flow arrivals to SJC that did not overfly the “City”. ● Not every aircraft overflight is captured by one of the four NMTs due to spikes in ambient noise levels, which may obscure the aircraft event or environmental factors such as wind speed and direction. ● The maximum noise level of a specific flight may vary based on the point of closest approach (PCA) slant distance and altitude of the aircraft in relation to the NMT. In addition, aircraft engine power settings, flap position, and landing gear state also influence the maximum noise level and event duration. ● The City's noise monitors capture noise events from all sources such as people, vehicles, animals, trains, and planes. The NOMS system analyzes every noise event captured by each NMT to determine if it meets the parameters to identify it as an aircraft noise event. Once the system identifies the source of a noise event as an aircraft, the NOMS system then attempts to match the noise event based on the time stamp, altitude, and lateral distance from the noise monitor to a specific flight. 24 HOUR VIEW OF AIRCRAFT NOISE Most aircraft overfly the City during daytime hours between 7:00 AM and 7:00 PM when ambient noise levels tend to be higher due to increased community activity. Aircraft overflight volumes during the evening (7:00 PM to 10:00 PM) and nighttime (10:00 PM to 7:00 AM) periods are significantly reduced. However, individual events during these periods can be more disturbing to residents due to the lower ambient noise levels in the City. Below is the breakdown of flights by time of day in Q4-2025. SUNNYVALE OVERFLIGHTS BY TIME OF DAY DAY = 9,906 EVENING = 1,161 NIGHT = 695 3 SJC AIRPORT SOUTH FLOW DATA FOR Q4 – 2025 One of the City of Sunnyvale's primary objectives in installing a Noise and Operations Monitoring System (NOMS) was to monitor and report on South Flow arrivals that overfly the City on their approach to land to Norman Y. Mineta San Jose International Airport (SJC). There are two types of approaches flown by airplanes landing in South Flow at SJC Airport. The widely dispersed ILS/Visual approach is shown in yellow. The highly concentrated RNP approach is shown in blue on the facing page. The ILS/Visual approach has a wide lateral footprint because the pilots are flying vectors (headings) under ATC's direction. The controller determines their turn onto the final approach. By contrast, the RNP approach is a precision instrument procedure that utilizes fixed GPS waypoints that must be precisely overflown and have very small lateral error tolerances. Because of the wide dispersion caused by the ILS/Visual approach, a single noise monitoring terminal (NMT) cannot capture a noise event for each flight. However, the concentrated flight path of the RNP approach makes it possible to capture noise events at SYV-2 Dona Ave. for the vast majority of aircraft flying this approach. In the 4th Quarter of 2025, the Casper system successfully captured noise events for 88% of the total South Flow RNP approaches flown to SJC Airport, the distribution of which is shown in the chart below. 5 218 721 169 5 0 100 200 300 400 500 600 700 800 55-59 dBA 60-64 dBA 65-69 dBA 70-74 dBA 75-79 dBA 80-84 dBA RNP/ILS APPROACH MAXIMUM NOISE LEVEL Lmax in A-weighted Decibels The chart at right illustrates the maximum noise level (Lmax) recorded at the Dona Ave (SYV- 2) permanent noise monitor for aircraft that flew the RNP Approach to Runway 12L or 12R at SJC Airport and passed over the City of Sunnyvale. The number above each bar represents the total number of aircraft noise events in which the Lmax fell within the specific five decibel bucket identified on the chart. 4 ILS/Visual RNP Average Altitude ft. 3,233 3,153
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Runway 12L App. 25 37 Runway 12R App. 1,386 1,234 Total Approaches 1,411 1,271 SOUTH FLOW APPROACHES IN Q4-2025 September 1 – December 31 53% 47% ILS/Visual Approach RNP Approach 1 2 3 4 5 PEAK SOUTH FLOW DAY IN Q4-2025 November 16 66% 34% ILS/Visual Approach RNP Approach ILS/Visual RNP Average Altitude ft. 3,189 3,136 Runway 12L App. 9 1 Runway 12R App. 143 74 Total Approaches 144 75 2 4 3 1 6 The chart at left illustrates the Top 10 SJC South Flow Peak Day aircraft noise events ranked by maximum noise level (Lmax) as measured at SYV-1 in the 4th Quarter of 2025. Below each bar is the date of the event and the four-letter ICAO aircraft code of the aircraft type involved. Events with no aircraft type denote that an aircraft type was not identified in the FAA data. The chart at left illustrates the Top 10 SJC South Flow Peak Day aircraft noise events ranked by maximum noise level (Lmax) as measured at SYV-2 in the 4th Quarter of 2025. Below each bar is the date of the event and the four-letter ICAO aircraft code of the aircraft type involved. Events with no aircraft type denote that an aircraft type was not identified in the FAA data. The following charts detail the Peak South Flow Approach Day Top 10 loudest (by Lmax) noise events measured at SYV-1 and SYV-2 noise monitoring terminals (NMTs) during the 4th Quarter. Keep in mind that these events only pertain to aircraft that overflew the City of Sunnyvale on a South Flow Approach to SJC Airport and were not necessarily the loudest overall for the Quarter. For information on the loudest overall aircraft noise events, see the individual NMT summaries starting on page 10. 76.0 74.1 74.1 73.5 73 70.6 70.2 69.8 69.5 69.3 11-16 11-16 11-16 11-16 11-16 11-16 11-16 11-16 11-16 11-16 4:08 PM 1:35 PM 11:10 AM 2:37 PM 2:13 PM 10:34 PM 4:11 PM 6:28 PM 9:00 PM 4:35 PM ILS 12R ILS 12R ILS 12R ILS 12R ILS 12R RNP Z 12L/R ILS 12R RNP Z 12L/R RNP Z 12L/R ILS 12R CL30 CL35 CL30 CL35 B38M B739 P180 B738 B738 B38M KBED KMDW KBFI KGPI KLGA KATL KVNY KPHX KDEN KSLC 95+ dBA 85-94 dBA 75-84 dBA 65-74 dBA 55-64 dBA 77.4 76.7 75.3 75.0 73.5 73.3 73.0 72.7 72.1 71.6 11/16 11/16 11/16 11/16 11/16 11/16 11/16 11/16 11/16 11/16 7:09 PM 11:10 AM 11:34 PM 2:37 PM 9:06 PM 3:36 PM 10:20 AM 10:32 PM 4:09 PM 6:18 PM ILS 12R ILS 12R RNP Z 12L/R ILS 12R RNP Z 12L/R RNP Z 12L/R RNP Z 12L/R RNP Z 12L/R ILS 12R ILS 12R CL30 CL30 B738 CL35 B38M B737 B738 B738 CL30 B737 KSDL KBFI KLAS KGPI KPHX KPHX KDFW KDEN KBED KEUG 95+ dBA 85-94 dBA 75-84 dBA 65-74 dBA 55-64 dBA SYV-1 PEAK SOUTH FLOW DAY A/C NOISE EVENTS IN Q4-2025 SYV-2 PEAK SOUTH FLOW DAY A/C NOISE EVENTS IN Q4-2025 7 The following charts show the most frequent aircraft types and operators to fly the South Flow approach to SJC for the 4th Quarter and the Peak South Flow Approach Day. The total for each column is derived by adding the number of ILS/Visual, and RNP approaches flown. Keep in mind that this data only pertains to aircraft that overflew the City of Sunnyvale on a South Flow Approach to land at SJC Airport. 0 100 200 300 400 500 600 700 ILS RNP 0 10 20 30 40 50 60 B737 E75L B738 B38M GLF6 CL60 A320 CL35 GLF5 C68A ILS RNP 0 200 400 600 800 1000 1200 SWA SKW EJA ASA DAL QXE AAL LXJ UAL VOI ILS RNP 0 10 20 30 40 50 60 70 80 90 SWA SKW EJA QXE ASA UAL TWY DAL LXJ VJA AAL ILS RNP SOUTH FLOW APPROACH BY AIRCRAFT TYPE IN Q4-2025 SOUTH FLOW APPROACH BY OPERATOR IN Q4-2025 PEAK SOUTH FLOW DAY APPROACH BY OPERATOR IN Q4-2025 PEAK SOUTH FLOW DAY APPROACH BY AIRCRAFT TYPE IN Q4-2025 8 CITY OF SUNNYVALE OVERFLIGHT DATA FOR Q4 – 2025 While SJC Airport is the closest major airport to the City of Sunnyvale, residents are overflown by aircraft arriving and departing from many different airports in the region. The data in this section quantifies overflights associated with each of the eight primary airports of interest listed below and helps explain the distribution of flights across the four zip codes that fall within the City limits. AIRPORTS OF INTEREST ● KHWD – Hayward Executive Airport ● KNUQ – Moffett Federal Airfield ● KOAK – Metro Oakland Int’l Airport ● KPAO – Palo Alto Airport ● KRHV – Reid-Hillview Airport of Santa Clara County ● KSFO – San Francisco Int’l Airport ● KSJC – Norman Y Mineta San Jose Int’l Airport ● KSQL – San Carlos Airport 0 1,000 2,000 3,000 4,000 KSJC KRHV KNUQ KPAO KSQL KSFO KHWD KOAK Number of Takeoff and Landing Overflights per Airport CITY OF SUNNYVALE OVERFLIGHTS BY AIRPORT Landing Takeoff 9 The City of Sunnyvale is comprised of four primary zip codes (94085, 94086, 94087, 94089), which bisect the City forming four unique zones from North to South. The volume of overflights on any given day can vary significantly across the City. Seasonal wind patterns play the most significant role in dictating the arrival and departure patterns into a specific airport. The current wind direction largely determines which Sunnyvale neighborhoods are overflown by aircraft during their arrival or departure to that airport. The charts below illustrate the pattern of overflights for each of the four zip codes for the 4th Quarter of 2025. 120 1020 174 979 334 137 1243 386 Overflights by Airport in Zip Code 94086 KHWD KNUQ KOAK KPAO KRHV KSFO KSJC KSQL 95 1197 129 744 343 114 441 227 Overflights by Airport in Zip Code 94085 KHWD KNUQ KOAK KPAO KRHV KSFO KSJC KSQL 112 955 182 1914 181 140 2888 978 Overflights by Airport in Zip Code 94087 KHWD KNUQ KOAK KPAO KRHV KSFO KSJC KSQL 48 311 47 335 69 99 1828 131 Overflights by Airport in Zip Code 94089 KHWD KNUQ KOAK KPAO KRHV KSFO KSJC KSQL 10 SYV-1 ORTEGA PARK NMT DATA Q4 – 2025 Noise Monitoring Terminal SYV-1 is in Ortega Park. Its primary purpose is to capture RNP arrivals to SJC Airport in South Flow and secondarily flight activity associated with Moffett Field, Palo Alto, Reid-Hillview, and San Carlos Airports. The image below is an aerial depicting the location of the NMT in the park and a photo of the installed equipment. The chart at left illustrates the Top 10 aircraft noise events ranked by maximum noise level (Lmax) as measured at SYV-1 in the 4th Quarter of 2025. Below each bar is the date of the event and the four-letter ICAO aircraft code of the aircraft type involved. Events with no aircraft type denote that an aircraft type was not identified in the FAA data. 81.0 80.0 77.5 77.5 76.8 76.1 76.0 76.0 76.0 75.9 11/6 10/8 11/30 12/24 10/26 12/24 11/16 12/24 12/26 10/8 8:44 AM 10:52 AM 9:35 AM 11:41 AM 2:46 PM 10:22 PM 4:08 PM 11:29 AM 6:00 PM 12:58 PM GLEX B737 PC12 CL30 CL35 B738 CL30 CL35 CL35 CL35 KBFI KAUS KVNY KLGB KSAN KBED KLAS MYNN KHPN 95+ dBA 85-94 dBA 75-84 dBA 65-74 dBA 55-64 dBA SYV-1 TOP 10 AIRCRAFT NOISE EVENTS IN Q4-2025 11 The charts below illustrate the relationship between aircraft and community noise and their contribution to the total noise environment measured by the noise monitoring terminal SYV-1 in Ortega Park. Noise events captured by the NMTs are analyzed on the fly as they happen. Based on their categorization as community or aircraft noise, the system automatically calculates an hourly Aircraft, Community, and Total LEQ (equivalent continuous sound level). Equivalent signifies that the total acoustical energy associated with the continually fluctuating noise level (during the specified period); in this case, a month is equal to the total acoustic energy associated with the steady noise level. Hourly LEQs are averaged to derive a Daily LEQs, which is averaged to derive a monthly LEQ. The Total LEQ considers both the aircraft and community contributions to the noise environment. 167 99 147 301 406 532 0 100 200 300 400 500 600 700 800 Oct Nov Dec Aircraft Community 54.5 53.9 54.6 54.5 53.8 54.5 36.8 38.2 39.8 0.0 10.0 20.0 30.0 40.0 50.0 60.0 Oct Nov Dec Total LEQ Community Aircraft SYV-1 LEQ NOISE LEVELS FOR Q4-2025 SYV-1 TOTAL RECORDED NOISE EVENTS IN Q4-2025 12 While most singular noise events are expressed in Lmax or LEQ dB(A), cumulative noise exposure originating from aircraft expressed over longer periods of time are typically done in DNL, or day-night average sound level. This adds more “weight” to aircraft noise levels during more sensitive times of the day, typically during night hours. However, the State of California uses a slightly modified version of DNL called CNEL, or Community Noise Equivalent Level. Taken from the FAA’s website on guidance for managing community noise, “While DNL is the primary metric FAA uses to determine noise impacts, FAA accepts the Community Noise Equivalent Level (CNEL) in California as California adopted the use of CNEL prior to FAA adopting DNL. While CNEL, like DNL, adds a ten times weighting (equivalent to a 10 dBA "penalty") to each aircraft operation between 10:00 p.m. and 7:00 a.m., CNEL also adds a three times weighting (equivalent to a 4.77 dBA penalty) for each aircraft operation during evening hours (7:00 p.m. to 10:00 p.m.)” DNL and CNEL are most effective when calculating for only aircraft noise events, or acne. The below chart displays the trend in CNEL over the course of the last quarter 38.5 41.7 43.1 36.0 37.0 38.0 39.0 40.0 41.0 42.0 43.0 44.0 Oct Nov Dec Aircraft CNEL SYV-1 CNEL FOR Q4-2025 13 SYV-2 DONA AVE NMT DATA Q4 – 2025 Noise Monitoring Terminal SYV-2 is on Dona Ave. Its primary purpose is to capture RNP arrivals to SJC Airport in South Flow and secondarily flight activity associated with Moffett Field, Palo Alto, Reid-Hillview, and San Carlos Airports. The image below is an aerial depicting the location of the NMT and a photo of the installed equipment. The chart at left illustrates the Top 10 aircraft noise events ranked by maximum noise level (Lmax) as measured at SYV-2 in the 4th Quarter of 2025. Below each bar is the date of the event and the four-letter ICAO aircraft code of the aircraft type involved. Events with no aircraft type denote that an aircraft type was not identified in the FAA data. 84.1 82.5 80.3 78.3 77.6 77.4 77.4 77.3 77.1 76.7 11/18 12/10 11/19 11/1 11/1 11/11 11/16 12/25 12/24 11/16 3:45 PM 3:58 PM 3:25 PM 3:35 PM 7:10 PM 3:51 PM 7:09 PM 9:31 AM 11:42 AM 11:10 AM COL4 P46T CL30 CL35 CL30 CL30 KLMT KNUQ KYKM KNUQ KSDL MMSD KVNY KBFI 95+ dBA 85-94 dBA 75-84 dBA 65-74 dBA 55-64 dBA SYV-2 TOP 10 AIRCRAFT NOISE EVENTS IN Q4-2025 14 The charts below illustrate the relationship between aircraft and community noise and their contribution to the total noise environment measured by the noise monitoring terminal SYV-2 on Dona Avenue. Noise events captured by the NMTs are analyzed on the fly as they happen. Based on their categorization as community or aircraft noise, the system automatically calculates an hourly Aircraft, Community, and Total LEQ (equivalent continuous sound level). Equivalent signifies that the total acoustical energy associated with the continually fluctuating noise level (during the specified period); in this case, a month is equal to the total acoustic energy associated with the steady noise level. Hourly LEQs are averaged to derive a Daily LEQs, which is averaged to derive a monthly LEQ. The Total LEQ considers both the aircraft and community contributions to the noise environment. 244 227 184 740 883 1,136 0 200 400 600 800 1000 1200 1400 Oct Nov Dec Aircraft Community 53.4 54.6 53.3 53.2 54.4 52.8 39.7 42.4 43.6 0.0 10.0 20.0 30.0 40.0 50.0 60.0 Oct Nov Dec Total LEQ Community Aircraft SYV-2 LEQ NOISE LEVELS FOR Q4-2025 SYV-2 TOTAL RECORDED NOISE EVENTS IN Q4-2025 15 While most singular noise events are expressed in Lmax or LEQ dB(A), cumulative noise exposure originating from aircraft expressed over longer periods of time are typically done in DNL, or day-night average sound level. This adds more “weight” to aircraft noise levels during more sensitive times of the day, typically during night hours. However, the State of California uses a slightly modified version of DNL called CNEL, or Community Noise Equivalent Level. Taken from the FAA’s website on guidance for managing community noise, “While DNL is the primary metric FAA uses to determine noise impacts, FAA accepts the Community Noise Equivalent Level (CNEL) in California as California adopted the use of CNEL prior to FAA adopting DNL. While CNEL, like DNL, adds a ten times weighting (equivalent to a 10 dBA "penalty") to each aircraft operation between 10:00 p.m. and 7:00 a.m., CNEL also adds a three times weighting (equivalent to a 4.77 dBA penalty) for each aircraft operation during evening hours (7:00 p.m. to 10:00 p.m.)” DNL and CNEL are most effective when calculating for only aircraft noise events, or acne. The below chart displays the trend in CNEL over the course of the last quarter 41.4 45.8 46.6 38.0 39.0 40.0 41.0 42.0 43.0 44.0 45.0 46.0 47.0 Oct Nov Dec Aircraft CNEL SYV-2 CNEL FOR Q4-2025 16 SYV-3 COMMUNITY CENTER PARK NMT DATA Q4 – 2025 Noise Monitoring Terminal SYV-3 is in Community Center Park. Its primary purpose is to capture RNP arrivals to SJC Airport in South Flow and secondarily flight activity associated with Moffett Field, Palo Alto, Reid-Hillview, and San Carlos Airports. The image below is an aerial depicting the location of the NMT and a photo of the installed equipment. The chart at left illustrates the Top 10 aircraft noise events ranked by maximum noise level (Lmax) as measured at SYV-3 in the 4th Quarter of 2025. Below each bar is the date of the event and the four-letter ICAO aircraft code of the aircraft type involved. Events with no aircraft type denote that an aircraft type was not identified in the FAA data. 95.7 79.5 77.7 76.7 76.4 76.4 76.1 75.7 75.2 73.8 12/14 12/26 12/08 10/02 10/02 10/07 10/01 12/17 12/07 10/16 10:04 AM 9:55 AM 1:28 PM 11:39 PM 11:32 PM 9:03 AM 2:57 PM 7:45 AM 11:45 AM 5:59 AM B38M E55P LJ40 B737 CL35 GL7T BE9L SYV KDEN KHCR SYV KVNY KAUS KCCR KTEB KPHX 95+ dBA 85-94 dBA 75-84 dBA 65-74 dBA 55-64 dBA SYV-3 TOP 10 AIRCRAFT NOISE EVENTS IN Q4-2025 17 The charts below illustrate the relationship between aircraft and community noise and their contribution to the total noise environment measured by the noise monitoring terminal SYV-3 in Community Center Park. Noise events captured by the NMTs are analyzed on the fly as they happen. Based on their categorization as community or aircraft noise, the system automatically calculates an hourly Aircraft, Community, and Total LEQ (equivalent continuous sound level). Equivalent signifies that the total acoustical energy associated with the continually fluctuating noise level (during the specified period); in this case, a month is equal to the total acoustic energy associated with the steady noise level. Hourly LEQs are averaged to derive a Daily LEQs, which is averaged to derive a monthly LEQ. The Total LEQ considers both the aircraft and community contributions to the noise environment. 177 215 240 189 218 248 0 100 200 300 400 500 600 Oct Nov Dec Aircraft Community 61.4 58.9 59.8 61.4 58.9 59.7 37.1 37.2 43.2 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 Oct Nov Dec Total LEQ Community Aircraft SYV-3 TOTAL RECORDED NOISE EVENTS IN Q4-2025 SYV-3 LEQ NOISE LEVELS FOR Q4-2025 18 While most singular noise events are expressed in Lmax or LEQ dB(A), cumulative noise exposure originating from aircraft expressed over longer periods of time are typically done in DNL, or day-night average sound level. This adds more “weight” to aircraft noise levels during more sensitive times of the day, typically during night hours. However, the State of California uses a slightly modified version of DNL called CNEL, or Community Noise Equivalent Level. Taken from the FAA’s website on guidance for managing community noise, “While DNL is the primary metric FAA uses to determine noise impacts, FAA accepts the Community Noise Equivalent Level (CNEL) in California as California adopted the use of CNEL prior to FAA adopting DNL. While CNEL, like DNL, adds a ten times weighting (equivalent to a 10 dBA "penalty") to each aircraft operation between 10:00 p.m. and 7:00 a.m., CNEL also adds a three times weighting (equivalent to a 4.77 dBA penalty) for each aircraft operation during evening hours (7:00 p.m. to 10:00 p.m.)” DNL and CNEL are most effective when calculating for only aircraft noise events, or acne. The below chart displays the trend in CNEL over the course of the last quarter 42.7 41.1 44.7 39 40 41 42 43 44 45 Oct Nov Dec Aircraft CNEL SYV-3 CNEL FOR Q4-2025 19 SYV-4 WASHINGTON PARK NMT DATA Q4 – 2025 Noise Monitoring Terminal SYV-4 is in Washington Park. Its primary purpose is to capture RNP arrivals to SJC Airport in South Flow and secondarily flight activity associated with Moffett Field, Palo Alto, Reid-Hillview, and San Carlos Airports. The image below is an aerial depicting the location of the NMT and a photo of the installed equipment. The charts below illustrate the relationship between aircraft and community noise and their contribution to the total noise environment measured by the noise monitoring terminal SYV-4 in Washington Park. The chart at left illustrates the Top 10 aircraft noise events ranked by maximum noise level (Lmax) as measured at SYV-4 in the 4th Quarter of 2025. Below each bar is the date of the event and the four-letter ICAO aircraft code of the aircraft type involved. Events with no aircraft type denote that an aircraft type was not identified in the FAA data. 85.7 84.3 84.2 84.2 82.8 80.2 77.7 77.5 77.4 77.2 12/03 12/03 10/29 11/01 11/04 10/09 10/21 12/03 11/04 12/17 12:32 PM 12:36 PM 10:21 AM 6:48 PM 9:56 AM 8:07 AM 7:38 PM 12:28 PM 9:59 AM 7:45 AM C172 B738 GLF5 C68A E75L CL35 KNUQ KNUQ KCVH KSNS KPHX EINN KOKC KNUQ KLAX KCCR 95+ dBA 85-94 dBA 75-84 dBA 65-74 dBA 55-64 dBA SYV-4 TOP 10 AIRCRAFT NOISE EVENTS IN Q4-2025 20 Noise events captured by the NMTs are analyzed on the fly as they happen. Based on their categorization as community or aircraft noise, the system automatically calculates an hourly Aircraft, Community, and Total LEQ (equivalent continuous sound level). Equivalent signifies that the total acoustical energy associated with the continually fluctuating noise level (during the specified period); in this case, a month is equal to the total acoustic energy associated with the steady noise level. Hourly LEQs are averaged to derive a Daily LEQs, which is averaged to derive a monthly LEQ. The Total LEQ considers both the aircraft and community contributions to the noise environment. While most singular noise events are expressed in Lmax or LEQ dB(A), cumulative noise exposure originating from aircraft expressed over longer periods of time are typically done in DNL, or day-night average sound level. This adds more “weight” to aircraft noise levels during more sensitive times of the day, typically during night hours. However, the 2,296 2,030 1,826 348 388 403 0 500 1000 1500 2000 2500 3000 Oct Nov Dec Aircraft Community 56.8 55.7 56.0 56.7 55.6 55.9 38.4 39.0 38.1 0.0 10.0 20.0 30.0 40.0 50.0 60.0 Oct Nov Dec Total LEQ Community Aircraft SYV-4 LEQ NOISE LEVELS FOR Q4-2025 SYV-4 TOTAL RECORDED NOISE EVENTS IN Q4-2025 21 State of California uses a slightly modified version of DNL called CNEL, or Community Noise Equivalent Level. Taken from the FAA’s website on guidance for managing community noise, “While DNL is the primary metric FAA uses to determine noise impacts, FAA accepts the Community Noise Equivalent Level (CNEL) in California as California adopted the use of CNEL prior to FAA adopting DNL. While CNEL, like DNL, adds a ten times weighting (equivalent to a 10 dBA "penalty") to each aircraft operation between 10:00 p.m. and 7:00 a.m., CNEL also adds a three times weighting (equivalent to a 4.77 dBA penalty) for each aircraft operation during evening hours (7:00 p.m. to 10:00 p.m.)” DNL and CNEL are most effective when calculating for only aircraft noise events, or acne. The below chart displays the trend in CNEL over the course of the last quarter Note: The noise monitor at site 4 was undergoing maintenance from June 12 to June 30. The noise events from this time are not reflected in this quarterly report and are not included in the averages in the charts on pages 19, 20, and 21. Flight information was not affected during this time, nor were the noise data points for NMTs 1, 2, or 3. ICAO AIRCRAFT CODE REFERENCE 40.3 41.1 40.0 39.4 39.6 39.8 40.0 40.2 40.4 40.6 40.8 41.0 41.2 Oct Nov Dec Aircraft CNEL SYV-4 CNEL FOR Q4-2025 22 Below is a list of the ICAO aircraft codes referenced in the Top-10 Aircraft Noise Event charts. ICAO Aircraft Code Common Name Type A109 AugustaWestland 109 General Aviation Helicopter A124 Antonov An-124 Ruslan Cargo Jet A306 Airbus A300-600 Commercial Jet A21N Airbus A321neo Commercial Jet A319 Airbus A319-100 Commercial Jet A320 Airbus A320-200 Commercial Jet AC50 Aero Commander 500 General Aviation Piston AJET Dassault Alpha Jet Military Jet Trainer B38M Boeing 737 MAX 8 Commercial Jet B407 Bell Helicopter 407 General Aviation Helicopter B430 Bell Helicopter 430 General Aviation Helicopter B733 Boeing 737-300 Commercial Jet B737 Boeing 737-700 Commercial Jet B738 Boeing 737-800 Commercial Jet B763 Boeing 767-300 Commercial Jet BCS1 Airbus A220-100 Commercial Jet BCS3 Airbus A220-300 Commercial Jet BE9L Beechcraft 90 King Air General Aviation Turboprop BE20 Beechcraft 200 Super King Air General Aviation Turboprop BE35 Beechcraft 35 Bonanza General Aviation Piston BE36 Beechcraft 36 Bonanza General Aviation Piston BE60 Beechcraft 60 Duke General Aviation Piston C25B Cessna Citation CJ3 Business Jet C680 Cessna Citation Sovereign Business Jet C68A Cessna Citation Latitude Business Jet C172 Cessna Skyhawk General Aviation Piston C180 Cessna 180 Skywagon General Aviation Piston C182 Cessna 182 Skylane General Aviation Piston C185 Cessna 185 Skywagon General Aviation Piston C206 Cessna 206 Stationair General Aviation Piston C208 Cessna 208 Caravan General Aviation Turboprop C414 Cessna 414 Chancellor General Aviation Piston C56X Cessna Citation Excel Business Jet CL30 Bombardier Challenger 300 Business Jet CL35 Bombardier Challenger 350 Business Jet CL60 Bombardier Challenger 600 Business Jet E300 Extra EA-300 General Aviation Piston E55P Embraer Phenom 300 Business Jet E75L Embraer 175 (Long Winglet) Commercial Jet EC45 Airbus Helicopters EC-145 General Aviation Helicopter FA50 Dassault Falcon 50 Business Jet F900 Dassault Falcon 900 Business Jet GL5T Bombardier Global 5000 Business Jet GLEX Bombardier Global Express Business Jet GLF3 Gulfstream III Business Jet GLF4 Gulfstream IV Business Jet GLF5 Gulfstream V Business Jet GLF6 Gulfstream G650 Business Jet H25B Hawker Beechcraft 800 Business Jet 23 HELO Generic Helicopter General Aviation Helicopter LJ60 Bombardier Learjet 60 Business Jet M20P Mooney M20 General Aviation Piston MD11 McDonnell Douglas MD-11 Commercial Jet P180 Piaggio P.180 Avanti Business Jet PC12 Pilatus PC-12 General Aviation Turboprop RV8 Van’s Aircraft RV-8 General Aviation Piston S22T Cirrus SR22 Turbocharged General Aviation Piston SR20 Cirrus SR20 General Aviation Piston T6 North American T-6 Texan Military Piston Trainer TBM7 Socata TBM 7 General Aviation Turboprop 24


