Primer and Framework for Considering an Airport Noise and Operations Monitoring System (2022)

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6 Since the 1960s, basic tools to monitor aircraft noise and operations have developed into useful and integrated NOMSs. A growing number of airports have procured a NOMS and flight tracking tools to assist with the handling of aircraft noise issues. As overall technology, processing speeds, and software capabilities improve over time, so do NOMS features and func- tions. Aviation forecasts predict that the number of flights will continue to increase, which will potentially increase the need for aircraft noise and operations analysis. The following sections describe the history and future of NOMSs; the current state of NOMSs, including current events that may impact the need and use of NOMS; and the fundamentals of NOMSs. 3.1 History of Airport NOMSs The early years of noise monitoring systems in the United States are not well documented. Bragdon (1985) provides one of the earliest attempts to describe the history of noise monitoring. He identifies the systems installed at John F. Kennedy Airport (JFK) in 1967 as the first such system in the United States, but in fact, two airports on the West Coast installed noise monitoring systems that same year: Santa Monica Airport (SMO) and John Wayne Airport (SNA), both in Southern California. JFK and SNA both installed systems to enforce a single event noise limit for aircraft departure noise while SMO installed a system to limit departure and approach noise. Commercial aviation had been growing steadily for decades, but the introduction of commercial jet aviation in 1958 ignited a controversy regarding aircraft overflight of residential communities that continues to this day. By 1967, enough conflict had arisen between airports and communities regarding jet aircraft to warrant the monitoring of aircraft noise. There was little additional development of airport noise monitoring systems until California adopted the “California Airport Noise Regulations” in 1970,1 which were implemented in 1973. The implementation was preceded by a background document in 1971 (Wyle Laboratories 1971). The California regulations were landmark legislation for airport noise. The legislation estab- lished a mandatory noise limit of 65 Community Noise Equivalent Level (CNEL) for residential uses around airports, and airports were required to develop a management plan for achieve- ment, single event noise limits for aircraft noise, and a requirement for noise monitoring in the vicinity of civilian airports deemed to have a “noise problem.” A noise problem was defined as having residential uses within the 65 CNEL contour. The noise monitoring system had two purposes: first to enforce the single event noise limits and second to verify the location of the 65 CNEL contour. The single event noise limits were challenged by litigation and deemed in conflict with federal law and that portion of the regulation was repealed in 1975. The remainder C H A P T E R 3 NOMS Overview 1 California Administrative Code, Title 21, Division of Aeronautics, Subchapter 6, Noise Standards, 1970.

NOMS Overview 7   of the regulation remains in place to this day. As a result of this legislation, airport noise moni- toring systems were established at San Francisco International Airport (SFO), Norman J. Mineta San Jose International Airport (SJC), Oakland International Airport (OAK), Hollywood Burbank Airport (BUR), Long Beach Airport (LGB), Ontario International Airport (ONT), Los Angeles International Airport (LAX), San Diego International Airport (SAN), and Torrance Municipal Airport (TOA) in addition to systems already in place at SNA and SMO. In fact, of the 24 systems in the United States that were documented in 1985 by Bragdon (1985), 11 were in California. The California regulation was important because it defined the key components of an airport noise monitoring system and the required performance of such systems. The regulation identi- fied several requirements that are still in place today and are excerpted below: • The noise monitoring system shall measure with an accuracy within plus or minus 1.5 dB on the CNEL scale. • Specific locations of the monitoring system shall be chosen whenever possible, such that the CNEL from sources other than aircraft in flight is equal to or less than 55 dB. • The measurement microphone shall be placed 20 feet above the ground level, or at least 10 feet above neighboring roof tops, whichever is higher and has a clear line of sight to the path of aircraft in flight. No obstructions, which significantly influence the sound field from the aircraft, shall exist within a conical space above the measurement position, the cone being defined by a vertical axis and by a half angle of 75 degrees from that axis. • For continuous monitoring systems the number of monitoring locations will increase where necessary to provide ample information to ensure the accuracy tolerance of plus or minus 1.5 dB CNEL for loca- tion of the noise impact boundary in areas where land use is incompatible.2 Sections of the regulation dealing with the technical specifications of the monitoring system applied to 1970s technology and are now obsolete. These sections were mostly eliminated in a 1990 update of the regulation. All of the systems of the 1970s and 1980s were minicomputer- based systems, usually running on UNIX operating systems. At that time, “mini” appears to have meant “not larger than a full-size refrigerator.” Flight track data (discussed later) were transferred from FAA air traffic control to the airport via tape reels. At JFK, a day’s worth of tracks required 15 reels (1-inch tape and reels about 12 inches in diameter). Bragdon (1985) identified reasons for an airport to install a noise monitoring system: • Assess noise control for alternative flight procedures; • Assist in the investigation of specific public inquiries and complaints; • Instill public confidence that airport-related noise is being monitored to protect the public’s interest; • Validate noise modeling efforts for an extended period (1 year); • Address land use planning and noise-impact issues; • Indicate official concern for airport noise by the jurisdiction and its governing body; • Detect unusual flight events; • Educate airplane pilots, airlines, the airport proprietor, and the public about airport noise and its characteristics; • Obtain valid statistical data using an objective and scientific resource; • Apply research tools to assist the airport in performing certain tasks, as required or man- dated; and • Assess compliance with some voluntary or mandatory noise level, established by a govern- mental entity. Interestingly, these are still valid reasons for establishing an airport noise monitoring plan and later sections of this Primer will provide additional rationale for such programs. 2 California Administrative Code, Title 21, Division of Aeronautics, Subchapter 6, Noise Standards, 1970.

8 Primer and Framework for Considering an Airport Noise and Operations Monitoring System There is a history of flight track analysis that is worth noting. In 1985, only two airports had flight track recording systems: Dulles International Airport (IAD) and what is now known as Ronald Reagan Washington National Airport (DCA). The proprietor for both of these airports at the time was the FAA. Because the FAA was both the proprietor of these two airports (DCA and IAD) and the operator of the air traffic control system and its associated flight tracking system, airport staff was able to access to the flight tracking data. Such access was readily granted within the FAA. The same access was not granted for other airports. The Port of New York pioneered, over approximately a 10-year period, a process by which other airports could obtain flight tracking data. By the late 1990s, access to flight tracking data greatly improved the accuracy of airport noise monitoring systems. Before airport systems had access to flight tracking data, they relied on noise pattern mapping to assist in identifying aircraft noise events. For example, at SNA, there are seven monitors in the departure corridor. An aircraft would fly over Sites 1 and 2 first, then Site 3, and then Sites 4 and 5 nearly simultaneously (as they were on either side of the flight path), and finally Sites 6 and 7. Based on the speed of the aircraft, an expected time window relative to the first sites would allow the system to determine the likelihood that a noise event belonged to an aircraft. Flight tracking data greatly improved event identifications as long as the noise monitor clocks were synchronized to the radar system clock, a serious issue in the early days of obtaining radar data. 3.2 The Current State of NOMSs To ensure that the current state of NOMSs in the United States was broadly evaluated and to gather relevant information from airports in the United States, the research team developed a list of airports that operate a NOMS (NOMS airports), airports that do not operate a NOMS (non-NOMS airports), and a separate hybrid category (other airports). The research team contacted each of the worldwide NOMS vendors and asked them to provide a client list of NOMS airports in the United States. For the non-NOMS airports, the research team developed a list of all U.S. commercial service and general aviation (GA) airports in the 50 states and the territories of American Samoa, Guam, Northern Marianas, Puerto Rico, and the U.S. Virgin Islands that did not already operate a NOMS. Other airports were a hybrid form of the non-NOMS airport list. The sections that follow provide more detailed information on the development of the airport lists. 3.2.1 NOMS Airports As the name implies, a NOMS includes components that capture noise and aircraft opera- tions. However, not all airports choose to procure noise monitors. Therefore, the research team contacted vendors that provide noise monitors as well as those that do not provide noise moni- tors. As previously mentioned, NOMS vendors worldwide were contacted and asked to supply a list of the systems they had installed in the United States. The vendors include the following: • Virtower LLC (U.S.-based with 40 U.S. systems), • Envirosuite Ltd. (Australia-based with 38 U.S. systems), • L3Harris Technologies (U.S.-based with 32 U.S. systems), • Vector Airport Systems (U.S.-based with 9 U.S. systems), • Casper Aero (Netherlands-based with 6 U.S. systems), • HMMH (U.S.-based with 3 U.S. systems), • Other (U.S.-based with 1 U.S. system), • ACOEM/01dB (France-based with 0 U.S. systems), and • TopSonic (Germany-based with 0 U.S. systems).

NOMS Overview 9   The total number of airports in the United States (including all 50 states and the territories) that have installed a NOMS was 89. Virtower provided an additional 40 systems that do tracking and operations monitoring without noise monitoring. Since this research was conducted, addi- tional installations may have occurred. 3.2.2 Non-NOMS Airports Several sources were used to develop the list of airports in the United States (including all 50 states and territories) that have not installed a NOMS. First, an online search was performed of all U.S. airports that offered commercial service. Any airports that were already classified as NOMS airports were removed from the list. The total amount of commercial service, non- NOMS airports was 306. Second, data from the FAA Air Traffic Activity Data System (ATADS) listing for 2019 itinerant GA activity ranked the 200 top GA airports in the United States, including all 50 states and territories. Once the NOMS GA airports were removed from the list, the total number of GA service, non-NOMS airports was 110. 3.2.3 Other Airports Two other groups of airports were placed in the “other” airport category. These airports fit neither of the categories previously discussed, but instead fall into a hybrid category. These airports were identified through industry knowledge and discussion with some of the NOMS vendors. Some airports initiated the procurement process but did not complete the installation process. A total of three airports fall into this portion of the category. The remaining two airports procured and installed a NOMS, but for various reasons, the systems are no longer operable. 3.3 Future of NOMSs The technology of NOMSs has evolved since the late 1960s when the first aircraft noise monitoring system appeared in the United States. It wasn’t until the mid-1980s that the first flight tracking system appeared at U.S. airports. As mentioned previously, at the time, all of the systems were minicomputer-based systems, usually running on UNIX operating systems. Flight track data were transferred manually from FAA air traffic control to the airport via tape reels, making public portals and public access to the data non-existent. Since then, NOMSs have become highly integrated and provide virtually real-time access to noise and flight track data. The computers are smaller, more efficient, and highly automated. At many airports, the public has direct access to noise and flight data to research and file aircraft noise complaints. The air- craft noise and operations monitoring industry has come a long way in the last 50 years. In the next 50 years, the industry will likely improve exponentially. The future of the noise and operations monitoring industry will focus on two main areas, as described in the following sections. 3.3.1 Software Development and Hardware Technology As NOMSs evolve in the future, new software enhancements/concepts and new hardware technology will greatly improve NOMS functionality. New software enhancements will likely include increased use of cloud storage, more use of virtual noise monitoring terminals (NMTs),3 3 Virtual NMTs are user-selected points around the airport where noise exposure is calculated by the NOMS. The noise exposure calculations are based on noise modeling data and NOMS noise event-to-track correlations algorithms.

10 Primer and Framework for Considering an Airport Noise and Operations Monitoring System more automation of reports and complaint investigation, and more data analytics and busi- ness intelligence tools. New hardware technology will soon include increased use of tablets and other mobile platforms, a better radar data capture rate, air quality/emissions monitoring, more affordable NMTs, increased use of Automatic Dependent Surveillance-Broadcast (ADS-B) transmitters and less reliance on passive transmitters, and fully live (no delay) public display of data. A wish list of the future for NOMSs includes real-time data feeds, better ability to track area navigation (RNAV) and required navigation performance (RNP) procedures, higher quality tools for the public to use in self-service noise complaint monitoring, more accurate noise prediction models, enhanced tools to communicate with the public, better reports for making informed decisions, improved data quality and reduction in data loss from the source, and superior noise- to-flight track correlation rates. 3.3.2 Urban Air Mobility/Unmanned Aerial Vehicles The new frontiers in air transportation include urban air mobility (UAM) and unmanned aerial vehicles (UAVs). These are likely to become the fastest-growing sectors in aviation, and airports need to consider how to accommodate these new aircraft in their NOMS. UAVs, or “drones,” are being used to inspect infrastructure, provide emergency response support, survey agriculture, and deliver supplies and products to customers in urban and rural environments. UAMs are small vehicles used to transport people by air and are used to reduce traffic on con- gested highways and roads. Most vendors are already layering in features for the inclusion of UAM/UAV into NOMSs. Within 5 years, it is expected that UAMs and UAVs will be in common use. Package use (UAVs) will likely come first, followed by personal vehicles (UAMs). Airports will need to consider a fun- damental change in aircraft monitoring as the potential exists for a large number of UAMs/UAVs to be flying and possibly creating noise issues well outside the environs of the airport. Many, if not most, of these operations will not be associated with an airport. While aircraft noise levels will become less of an environmental and annoyance issue, visual pollution and privacy issues will become the main concern. It is likely that including UAM/UAV monitoring will be a separate module within existing NOMSs or flight tracking systems. The new UAM/UAV aircraft will be required to operate a transponder that will respond to Mode-S interrogation. These new aircraft will have registration/tail numbers and Mode-S codes and will show up in standard registry databases, although the registry may be separated from conventional aircraft. Either way, the new aircraft registries will be able to recognize aircraft ownership through a NOMS. 3.4 Current Events That Could Impact the Need for and Use of a NOMS As research was being conducted for this Primer, two major events occurred that may have an impact on the future need and use of NOMSs: The COVID-19 pandemic and the FAA’s Neighborhood Environmental Survey (NES). The potential impacts of these events on airports and the need for NOMSs are briefly discussed below. 3.4.1 Coronavirus (COVID-19) Pandemic The COVID-19 virus was discovered in December 2019. Millions of people worldwide have contracted the virus and died. To prevent the spread of COVID-19, countries around the world closed their borders and restricted air travel to minimal levels in the spring of 2020. Global

NOMS Overview 11   passenger counts decreased to 52% of pre-COVID-19 levels. As air travel restrictions lifted later in 2020 and into 2021, flight operations and passenger counts increased. In 2023, global passenger counts are expected to be approximately 105% of pre-COVID-19 levels (IATA 2021). In addition to air travel restrictions, “stay at home” restrictions were enforced by various states, counties, and private businesses. Online meetings replaced face-to-face meetings in a matter of weeks. Many people were able to work from home while essential workers and first responders were allowed at their place of work. The spatiotemporal distribution (Metron Aviation, Inc., and DGW Consulting Group, LLC 2020) of population shifted from office buildings and educa- tional facilities to residential areas. Depending on their location relative to an airport and flight paths, some people that worked from home experienced increased annoyance from aircraft noise during working hours compared to their experience in office building environments. Whether people continue to work from home or return to their normal workplace environ- ment, air traffic will increase by approximately 100% by 2023. This increase in aircraft opera- tions from COVID-19 reduced levels could potentially significantly increase reports of aircraft noise annoyance and complaints and increase airport staff workload relative to aircraft noise complaints, investigation, and analysis. As described in Appendix G: Airport NOMS Questionnaire & Summary of Findings, over half of the airports that responded to the questionnaire said that they would evaluate procuring a NOMS if complaints increased. Approximately 15% of airports would evaluate procuring a NOMS if there was political/public pressure to monitor aircraft operations. Therefore, the perceived increase in aircraft operations due to the lifting of travel restrictions related to the COVID-19 pandemic could potentially increase public/political pressure on airports and increase the demand for flight tracking systems, NOMSs, and the analysis of aircraft operations. 3.4.2 NES To update the aircraft noise-to-annoyance relationship represented by the Schultz Curve,4 the FAA conducted a nationwide survey, the NES, on annoyance associated with aircraft noise (Miller et al. 2021). More than 10,000 residents living near 20 representative airports in the United States responded to the survey. The NES results, published in 2021, showed a sub- stantial increase in the percentage of people who are highly annoyed by aircraft noise over the entire range of noise levels considered, including at lower noise levels. The NES findings were included in an FAA Federal Register notice soliciting public comment. The comment period closed in April 2021 with over 4,000 comments, indicating substantial interest from the public, airports, and aviation industry groups. The FAA’s responses to these comments were not available while research was being conducted for this project. However, the research team believes that the combination of increased aircraft noise-related annoyance and the FAA’s solicitation for public feedback on the next steps to aircraft noise-related analysis could potentially increase public desire for airports to verify the location of the day- night average sound level (DNL) 50 through 65, and perform aircraft noise and operations analysis. Additionally, NES results may shape revisions to policy on airport sound insulation programs and “significant” noise impacts, which are both currently based on the location of the DNL 65. A revision in policy may also lead to an increased need for aircraft noise and operations analysis. 4 The Schultz Curve is the accepted standard for describing the transportation noise exposure-annoyance relationship. Results of the Schultz Curve are based on surveys conducted in the 1970s and revalidated in 1992. Results from the NES show that the standards based on the Schultz Curve are outdated.

12 Primer and Framework for Considering an Airport Noise and Operations Monitoring System 3.4.3 Current Events Summary Together, the perceived increase in airport operations due to the lifting of travel restrictions related to the COVID-19 pandemic, the NES results, and the FAA’s solicitation for public feed- back may increase the public’s interest in engaging airports to solve noise problems. This could lead to the following outcomes: • Increase in aircraft noise complaints; • Increase in the public’s need for aircraft noise and operational information and flight tracks; • Increase in airport staff workload; • Increased need for airport staff resources; • Increased need for noise and airspace analysis beyond the DNL 65; • Increased need for noise measurement, flight data, and technological tools to process and analyze data (a NOMS); • Increased need for comprehensive environmental analyses; • Increased need for developing creative ways to describe noise impacts to the general public; and • Increased need to develop airport noise management programs that engage the public on an ongoing basis to discuss noise abatement performance. Managing the above outcomes would be challenging for airports, especially those without a NOMS or flight tracking system. An airport without a NOMS could propose the use of a NOMS during noise compatibility planning efforts and include this in its noise compatibility program (NCP), which is prepared pursuant to 14 CFR Part 150.5 Additionally, the use of a NOMS may be recommended during an analysis pursuant to the National Environmental Policy Act (NEPA). As described in Section 5.1, System Funding, (in this Primer) and Section A.2, FAA Guidance (in Appendix A), airports seeking federal financial assistance for a NOMS have to meet certain requirements to be eligible for federal funding (e.g., use of a NOMS specified in the NCP or in a decision document associated with an environmental review under NEPA). If noise mitigation measures such as a NOMS or NOMS components (NMTs) are not eligible for federal funding, airports may use airport, state, and local funding sources. 3.5 Fundamentals of a NOMS A NOMS is a technical tool used by airports for data and information gathering and is designed to meet an airport’s need to plan, monitor, and update noise abatement and other airport programs. A NOMS is an advanced computer-controlled system used for recording and measuring noise, tracking flights, gathering weather data, and storing noise complaints and airport staff’s responses to those complaints. It uses a relational database that combines geographic information with ongoing noise and flight data acquisition. A NOMS includes many components, including a network of permanent and/or portable noise monitors that measure the noise environment around an airport, a system that receives data from FAA’s air traffic con- trol radar or passive antennas that capture aircraft flight tracks, and other external data such as weather and radio voice recordings. All of the collected data are stored in local computers and/or hosted by the NOMS vendor remotely or on the cloud. Today’s systems can be accessed from anywhere with internet access, giving airport staff the flexibility to work on the system from their home office or their airport office. 5 Code of Federal Regulations, Part 150, “Airport Noise Compatibility Planning,” 1984.

NOMS Overview 13   The data from a NOMS are generally utilized to facilitate the development and management of noise abatement programs at an airport. However, data from a NOMS can also be used to support other airport functions such as planning, gate management, and accounting. 3.5.1 Core NOMS Features and Functions A NOMS provides an airport with an integrated approach to addressing noise issues. A NOMS is an information system that allows airport personnel to plan, monitor, and update a noise abatement program and to provide information for other airport departments. The system includes the following components: • Advanced computer-controlled devices for recording and measuring noise, flight tracks, and weather; • Relational database combining existing geographical information with ongoing data acquisition; and • Data input interface to manage information and produce customized letters, reports, and maps. A NOMS gathers and combines data from numerous sources including aircraft noise recorded on remote permanent or portable NMTs, operations data from the FAA Terminal Radar Approach Control (TRACON) facility’s System-Wide Information Management (SWIM) data, proprietary NOMS vendor data, flight track data from a non-FAA multilateration or ADS-B passive receiver, concerns and complaints reported by the community surrounding an airport, information about aircraft registration (owners), local weather data, census data, and geographic map data. A NOMS processes and integrates data by automatically linking noise events at each of the NMTs to specific aircraft operations and logged complaints. As a result, the system user can accurately and efficiently identify the aircraft noise source and its effect on the community. The NOMS focuses on data acquisition, processing, and analysis. The NOMS user can apply NOMS data and features to address and solve local noise problems and engage the impacted community. Finally, a typical NOMS can produce numerous standard tables, graphs, maps, letters, and reports that assist the NOMS user in communicating aircraft noise and operations information to the public. NOMS data are used in many ways, including: • Processing—Processing includes matching noise events to aircraft operations (flight tracks), matching complaints to noise events and flight track operations, and generating input data for the FAA’s airport noise contouring program. • Analysis—Reporting tools are provided for examining the data. These tools include both textual and graphical approaches. • Replay—Replay shows animated tracks and noise events in two or three dimensions. • Browsers/modules—Browsers or modules display lists of complaints, noise events, and oper- ations for a specified time period. Matches between operations and noise events or complaints can be edited. • Flight track profile—Flight track profile graphs display the flight altitude versus range for selected tracks. • Gate penetration analysis—Gate analysis graphs display gate penetrations for selected tracks through a gate, which is a two-dimensional cross-section of airspace. • Point of closest approach (PCA)—The distance from each flight track to a noise monitor or complaint location is calculated and stored in the database. PCA tables show the closest (shortest) distance between a point on the ground and a flight track.

14 Primer and Framework for Considering an Airport Noise and Operations Monitoring System • Reporting—A NOMS contains a query generator for producing text reports and/or displaying flight track data. There are also several preformatted reports delivered with each system. • Billing—A NOMS can produce operations information to be used by an airport’s billing department for landing fees. • Gate management—A NOMS can assist an airport with aircraft arrival and departure infor- mation to assist in the management of gates. • Geofencing—A NOMS can count and identify aircraft that cross geographic boundaries on airport property, such as taxiways and runways, and airspace boundaries near noise- sensitive areas. Note that non-NOMS tools like stand-alone flight tracking systems and video camera logging systems may perform some of the listed functions that are not related to noise monitoring. 3.5.2 Types of Data Collected A NOMS gathers and combines data from numerous information sources, as follows: • Noise, audio, and weather data from permanent and portable NMTs; • Operations data from FAA’s flight track feed and aircraft databases; • Flight track data from SWIM (or passive multilateration and/or an ADS-B sensor); • Aircraft owner data from SWIM aircraft registration databases; • Noise complaints logged by NOMS users and submitted by the airport community; • Weather data from local National Weather Service or local weather sensors; • Air traffic control and pilot voice transmissions from voice recorders; • Video of aircraft operations from video recording systems; and • Geographic information system (GIS) data from system vendor at installation and imported from various sources. Additional information on data being collected is provided in the following sections. Noise Data A NOMS acquires noise data from noise monitors placed around the airport. These monitors can be either permanent (fixed to the ground) or portable (on tripods or handheld) and powered by public utilities, batteries, or solar panels. Permanent noise monitors have a fixed location and are integrated into a NOMS. Portable noise monitors need special consideration relative to security and theft protection. Noise data may be obtained from a noise monitor by the NOMS via a phone land line or a wireless cellular signal in multiple daily uploads or in real time. A NOMS has noise event detec- tion algorithms based on a fixed noise level threshold or a floating (not fixed) threshold. A floating threshold is generally used at locations with fluctuating background (non-aircraft) noise. The audio of noise events may also be recorded, uploaded, and stored by the NOMS. This feature is often used when trying to determine whether noise events were caused by aircraft, the community (e.g., lawnmower, barking dog, or motorcycle,), or weather (e.g., wind or lightning). Operations, Flight Track, and Aircraft Owner Data Operations, flight track, and aircraft owner data are obtained from the FAA aircraft databases and air traffic control systems, often delayed by a few minutes. A NOMS combines the flight and operations data in a table format with records that at a minimum include the following: • Date and time of operation, • Airport code of origin and destination of flight, • Operation type (arrival, departure, touch and go, overflight),

NOMS Overview 15   • Runway used, • Aircraft type, • Airline and flight ID, • Aircraft registration and owner name, and • Beacon code. Additional operational information may be provided depending on the type of data origin and system. Flight track data provide the information listed plus information at specific points of the flight track such as aircraft speed, altitude, heading, and climb/descent rate. Noise Complaints Airports generally receive aircraft noise complaints from the public via phone, e-mail, postal mail, online complaint form, phone applications, NOMS vendor applications, third-party appli- cations, or in person. Noise complaints can be manually entered into the NOMS complaint database via a system user interface or automatically entered from an online complaint form, phone applications, or third-party applications. Third-party complaint applications may submit complaints to the NOMS via a web form or programmed “buttons” or “clickers” that can instantly submit complaints without much complainant interaction. Third-party complaint applications have been increasing in popularity over the last few years and, at some airports, have been the medium for the majority of complaints. The third-party application developer formats complaints to be accepted by an airport NOMS, and the airport and NOMS vendor allow the NOMS complaint database to accept the complaints. Once a complaint is in the complaint database, NOMS users can investigate and respond to it, if necessary. Weather Data Weather data can be collected from sensors placed at certain noise monitors, separate National Weather Service sensors at other locations, and weather radar imagery that show the effects of weather patterns. The data can be useful for analyzing flight operation modes and noise. The NOMS will store weather data including temperature, humidity, barometric pressure, wind speed, and wind direction with noise events and can store hourly weather data averages. Geographic Data GIS features are generally integrated into a NOMS. At a minimum, NOMS GIS data include a large-scale map that covers the extent of flight track coverage for generally 25 to 50 nautical miles from the airport. Additional GIS data include streets, water, municipal boundaries, landmarks, land use, and aerial imagery. Other GIS data that may be collected and imported by NOMS users include flight corridors/gates and airport noise contours. Flight track data shown on a NOMS interface can be exported as GIS files and loaded onto separate GIS software for map- ping and analysis. 3.5.3 How NOMSs Are Used Airports and NOMS vendors have worked together to expand basic NOMS features to address airport-specific, NOMS-related needs. Modern NOMSs have become informational tools to support airport needs beyond just monitoring noise. A NOMS can support needs such as Remain Overnight management, monitoring of runway crossings, pavement utilization, and airport planning. The list in “How Airports Use a NOMS” presents the many ways that airports can use a NOMS that were noted in the Airport Questionnaire developed for this research.

16 Primer and Framework for Considering an Airport Noise and Operations Monitoring System 3.5.4 Degree of Public Access A NOMS allows airport staff to disseminate a variety of information related to aircraft opera- tions and related noise through an airport’s complaint handling process and community out- reach programs. Airports may share NOMS information as part of a complaint investigation and response process, a special report for an individual or group, or upon request. Additionally, airports may prepare periodic reports and announcements relative to topics such as noise abatement procedure or operational agreement compliance, runway use, run-ups, complaint statistics, and noise levels at monitors. These reports and announcements can be shared in printed format during public meetings, in electronic format as e-mails, and posted on the airport’s website and social media platforms. NOMS vendors also provide online resources to share information with the public. Online NOMS data include near-live flight tracking, flight replay, address locator, and noise levels at noise monitors. How Airports Use a NOMS • Monitor flights in general • Monitor specific noise abatement flight procedures • Monitor noise abatement runway use • Monitor noise levels/limits at monitors • Monitor airspace use • Monitor aircraft departure and approach profiles • Monitor community noise levels • Monitor compliance with agreements/ mandates, i.e., community commitments • Monitor nighttime curfews • Monitor run-ups • Monitor taxiing • Monitor nighttime noise levels • Support special studies by consultants • Monitor pavement utilization • Monitor capacity utilization of departures • Manage Remain Overnight parking • Produce and validate airport noise contours* • Educate and communicate with the public • Investigate noise ordinance/limits violations • Support airport planning • Assess fleet mix • Supplement information to other airport proprietor departments and government agencies • Investigate incursions • Analyze performance-based navigation/Metroplex route impacts and compliance • Cross-check airlines’ self-reporting records • Measure off-airport temporary helistops • Monitor runway crossings • Monitor airspace utilization (geofencing) *NMT noise measurements provide better estimates of aircraft noise compared to noise modeling wherever the signal-to-noise ratio in the vicinity of the monitor is satisfactory. Where the signal- to-noise ratio is poor, noise modeling will provide a better estimate. The uncertainty of noise measurements, where signal-to-noise ratio is satisfactory, is +/- 1.5 decibels (dB). Modeling uncertainty is far less well defined. Large contributors to modeling uncertainty are estimates of actual aircraft thrust and modeling assumptions of a homogenous atmosphere, among others. Note that noise modeling is the only practical way to determine the community noise impacts related to future or proposed airport operational scenarios.

NOMS Overview 17   Many airports facilitate various levels of public access to NOMS data as part of their com- munity outreach. While some airports allow limited or no public access to NOMS information, many permit the public to follow and review operations in the vicinity of their homes. Airports with comprehensive community outreach programs develop robust public websites or portals that offer community engagement solutions that provide self-investigation, education, and reporting tools, which have improved trust and transparency between airports and their surrounding communities.