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Page 34
Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2022. Primer and Framework for Considering an Airport Noise and Operations Monitoring System. Washington, DC: The National Academies Press. doi: 10.17226/26527.
Page 35
Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2022. Primer and Framework for Considering an Airport Noise and Operations Monitoring System. Washington, DC: The National Academies Press. doi: 10.17226/26527.
Page 36
Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2022. Primer and Framework for Considering an Airport Noise and Operations Monitoring System. Washington, DC: The National Academies Press. doi: 10.17226/26527.
Page 37
Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2022. Primer and Framework for Considering an Airport Noise and Operations Monitoring System. Washington, DC: The National Academies Press. doi: 10.17226/26527.
Page 38
Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2022. Primer and Framework for Considering an Airport Noise and Operations Monitoring System. Washington, DC: The National Academies Press. doi: 10.17226/26527.

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34 Airport Improvement Program (AIP): A federal funding program for airport improve- ments. AIP is periodically reauthorized by Congress with funding appropriated from the Aviation Trust Fund. Proceeds to the Aviation Trust Fund are derived from excise taxes on airline tickets, aviation fuel, and so forth. Airport operations: Arrivals, departures, and touch-and-gos from a local airport, and an overflight from a non-local airport. Air traffic control: A service operated to promote the safe, orderly, and expeditious flow of air traffic. Airport traffic control tower (ATCT): The airport traffic control facility located on an airport that is responsible for traffic separation within the immediate vicinity of the airport and on the surface of the airport in order to provide for safe and efficient flow of aircraft. Ambient noise: The noise level that is typical at a site where a noise meter is located without any aircraft or significant community noise taking place. Also referred to as background noise. Area Navigation (RNAV): RNAV enables aircraft to fly on any desired flight path within the coverage of ground- or space-based navigation aids, within the limits of the capability of air- craft self-contained systems, or a combination of both capabilities. Attenuation: An acoustical phenomenon whereby sound energy is reduced between the noise source and the receiver. This energy loss can be attributed to atmospheric conditions, terrain, vegetation, other natural features, and human-made features (e.g., sound insulation). Automated Radar Terminal System (ARTS): Computer-aided radar display subsystems that are capable of associating alphanumeric data—such as aircraft identification, altitude, and airspeed—with aircraft radar returns. Aviation Environmental Design Tool (AEDT): FAA-developed software system that models aircraft performance in space and time in order to estimate fuel consumption, emissions, noise, and air quality consequences. A-weighted sound (dBA): A system for measuring sound energy that is designed to represent the response of the human ear to sound. Sound energy at frequencies more readily detected by the human ear is more heavily weighted in the measurement, while less-well-detected frequencies are assigned lower weights. A-weighted sound measurements are commonly used in studies where the human response to sound is the object of the analysis. Background noise: See ambient noise. Community Noise Equivalent Level (CNEL): See day-night average sound level (DNL). Glossary

Glossary 35   Commuter aircraft: Commuters are commercial operators that provide regularly scheduled passenger or cargo service with aircraft seating fewer than 60 passengers. A typical commuter flight operates over a trip distance of less than 300 miles. Controlled airspace: Airspace of defined dimensions within which air traffic control service is provided to flights subject to instrument flight rules (IFR) and flights subject to visual flight rules (VFR) in accordance with the airspace classification. Controlled airspace is designated as Class A, Class B, Class C, Class D, or Class E. Aircraft operators are subject to certain pilot qualifications, operating rules, and equipment requirements as specified in federal aviation regulation (FAR), Part 91, depending upon the class of airspace in which they are operating. Coronavirus (COVID-19) pandemic: The COVID-19 pandemic began in December 2019 and significantly reduced air travel worldwide. As the COVID-19 situation has evolved, air travel has increased, and people living around airports may perceive an increase in noise, which may increase the need for noise and aircraft operations analysis, flight tracking systems, and Noise and Operations Monitoring Systems (NOMSs). Day-night average sound level (DNL): A noise measure used to describe the average sound level over a 24-hour period, typically an average day over the course of a year. In computing DNL, an extra weight of 10 decibels (dB) is assigned to noise occurring between the hours of 10:00 p.m. and 7:00 a.m. to account for increased annoyance when ambient noise levels are lower and people are trying to sleep. The CNEL is used by airports in California and includes an additional 5 dB penalty assigned to noise occurring between 7:00 p.m. and 10:00 p.m. to account for increased annoyance during evening hours. CNEL/DNL may be determined for individual locations or expressed in noise contours. Decibel (dB): Sound is measured by its pressure or energy in terms of decibels. The decibel scale is logarithmic. A 10-decibel increase in sound is equal to a tenfold increase in sound energy. Easement: The legal right of one party to use part of the rights of a piece of real estate belonging to another party. This may include, but is not limited to, the right of passage over, on, or below the property; certain air rights above the property, including view rights; and the rights to any specified form of development or activity. Enplanements: The number of passengers boarding an aircraft at an airport. Does not include arriving or through passengers. Environmental Assessment (EA): A concise document that assesses the environmental impacts of a proposed federal action. It discusses the environmental impacts of the proposed action and alternatives. An EA should provide sufficient evidence and analysis for a federal determination of whether to prepare an Environmental Impact Statement (EIS) or a Finding of No Significant Impact (FONSI). The cornerstone of the EA process is public participation and consultation with other federal, state, and local agencies. Environmental Impact Statement (EIS): An EIS is a document that provides a discussion of the significant environmental impacts that would occur as a result of a proposed project and informs decision-makers and the public of reasonable alternatives that would avoid or mini- mize adverse impacts. The cornerstone of the EIS process is public participation and consulta- tion with other federal, state, and local agencies. Equivalent sound level (Leq): The steady A-weighted sound level over any specified period of time (not necessarily 24 hours) that has the same acoustic energy as the fluctuating noise during that period (with no consideration of nighttime weighting). It is a measure of cumulative acoustical energy. Because the time interval may vary, it should be specified by a subscript (such as Leq8 for an 8-hour exposure to noise) or be clearly understood from the context.

36 Primer and Framework for Considering an Airport Noise and Operations Monitoring System Federal Aviation Administration (FAA): The FAA is the federal agency responsible for ensuring the safe and efficient use of the nation’s airspace, fostering civil aeronautics and air commerce, and supporting the requirements of national defense. The activities required to carry out these responsibilities include safety regulations; airspace management and the establishment, operation, and maintenance of a system of air traffic control and navigation facilities; research and development in support of the fostering of a national system of air- ports, promulgation of standards and specifications for civil airports, and administration of federal grants-in-aid for developing public airports; various joint and cooperative activities with the Department of Defense; and technical assistance (under State Department auspices) to other countries. Federal Aviation Regulations (FARs): The body of federal regulations relating to aviation. Published as Title 14 of the Code of Federal Regulations. Geographic information system (GIS): An information system that is designed for storing, integrating, manipulating, analyzing, and displaying data referenced by spatial or geographic coordinates. Global positioning system (GPS): A system of 24 satellites used as reference points to enable navigators equipped with GPS receivers to determine their latitude, longitude, and altitude. The accuracy of the system can be further refined by using a ground receiver at a known loca- tion to calculate the error in the satellite range data. This is known as differential GPS (DGPS). Hub: An airport that services airlines that have centralized operations. Instrument flight rules (IFR): That portion of the FARs (14 CFR 91) specifying the procedures that are to be used by aircraft during flight in instrument meteorological conditions. These procedures may also be used under visual conditions and provide for positive control by air traffic control. (See also VFR). Instrument Landing System (ILS): An electronic system installed at some airports that helps to guide pilots to runways for landing during periods of limited visibility or adverse weather. Integrated Noise Model (INM): A computer model developed, updated, and maintained by the FAA to predict the noise exposure generated by aircraft operations at an airport. INM has been replaced by AEDT as the approved computer noise model. Landing and takeoff (LTO) cycle: The time that an aircraft is in operation at or near an airport. An LTO cycle begins when an aircraft starts its final approach (arrival) and ends after the aircraft has made its climb-out (departure). Land use compatibility: The ability of land uses surrounding the airport to coexist with airport- related activities with minimum conflict. Leq: See equivalent sound level. National Environmental Policy Act of 1969 (NEPA): The original legislation establishing the environmental review process for proposed federal actions. Neighborhood Environmental Survey (NES): An FAA-sponsored national survey that col- lected information relative to aircraft noise annoyance from residents living around airports in the United States. The NES provided an update to past aircraft annoyance surveys conducted in the 1970s. Noise abatement: A measure or action that minimizes the impact of noise on the environs of an airport. Noise abatement measures include aircraft operating procedures and use or disuse of certain runways or flight tracks.

Glossary 37   Noise and Operations Monitoring System (NOMS): An airport NOMS generally consists of components such as software, computer processors, noise monitors, and peripherals (printers, plotters, speakers, etc.). Airports use a NOMS to collect, manage, analyze, and communicate data such as aircraft flight tracks and flight procedures, flight altitude, aircraft identification, noise measurements, aircraft noise complaints, and weather. Noise compatibility program (NCP): A program developed in accordance with FAR Part 150 guidance that contains provisions for the abatement of aircraft noise through aircraft operating procedures, air traffic control procedures, or airport facility modifications. It also includes provisions for land use compatibility planning and may include actions to mitigate the impact of noise on incompatible land uses and recommendations for amending local land use con- trols in order to affect future land uses and development. The program must contain provisions for updating and periodic revision. Noise compatibility study: The processes, methods, and procedures provided in FAR Part 150 to develop an NCP, including the development of noise exposure maps and public participation. Noise contour: A map feature representing average annual noise levels summarized by lines connecting points of equal noise exposure. Primary runway: The runway on which the majority of operations take place. Profile: The position of the aircraft during an approach or departure in terms of altitude above the runway and distance from the runway end. Reliever airport: An airport which, when certain criteria are met, relieves the aeronautical demand on a busier air carrier airport. Required navigation performance (RNP): Similar to RNAV, with the addition of an onboard performance monitoring and alerting capability. RNP enables the aircraft navigation system to monitor the navigation performance it achieves and inform the crew if the requirement is not met during an operation. This onboard monitoring and alerting capability enhances the pilot’s situational awareness and can enable reduced obstacle clearance. Run-up: A routine procedure for testing aircraft systems by running one or more engines at a high power setting. Engine run-ups are normally conducted by airline maintenance personnel checking an engine or other onboard systems following maintenance. Runway use program: A noise abatement runway selection plan crafted to further noise abate- ment efforts for communities around airports. A runway selection plan is developed into a runway use program. It typically applies to all turbojet aircraft that are 12,500 pounds or heavier. Turbojet aircraft that weigh less than 12,500 pounds are included only if the airport proprietor determines that the aircraft creates a noise problem. These programs are coordinated with the FAA in accordance with FAA Order 8400.9, National Safety and Operational Criteria for Runway Use Programs, and are administered as either “formal” or “informal” programs. A “formal” program is an approved runway use program outlined in a Letter of Understanding among the FAA Flight Standards District Office, FAA Air Traffic Service, the airport proprietor, and the users. It is mandatory for aircraft operators and pilots as provided for in FAR Section 91.87. An “informal” program is an approved runway use program that does not require a Letter of Understanding. Participation in the program by aircraft operators and pilots is voluntary. Schultz Curve: 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 surveys that were revalidated in 1992. Results from recent international surveys

38 Primer and Framework for Considering an Airport Noise and Operations Monitoring System show that aircraft noise annoyance levels are higher than those shown on the Schultz Curve. Results from the recent NES show that the standards based on the Schultz Curve are outdated. Single event: One noise event. For many kinds of analysis, the sound from single events is expressed using the sound exposure level (SEL) metric. Slant-range distance: The distance along a straight line between an aircraft and a point on the ground. Sound: Sound is the result of vibration in the air. The vibration produces alternating bands of relatively dense and sparse particles of air, spreading outward from the source in the same way as ripples do on water after a stone is thrown into it. The result of the movement is a fluc- tuation in the normal atmospheric pressure or sound waves. Sound exposure level (SEL): A standardized measure of a single sound event, expressed in A-weighted decibels, that takes into account all sound above a specified threshold set at least 10 decibels below the maximum level. All sound energy in the event is integrated over 1 second. Terminal Radar Approach Control (TRACON): An FAA air traffic control facility that uses radar and two-way communication in order to provide separation of air traffic within a specified geographic area in the vicinity of one or more airports. Traffic: The traffic flow for aircraft landing and departure at an airport. Typical components of the traffic pattern include upwind leg, crosswind leg, downwind leg, base leg, and final approach. Unmanned aerial vehicle (UAV)/urban air mobility (UAM): UAVs or “drones” are aircraft (generally lighter than 50 lb) that 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 congested highways and roads. Visual flight rules (VFR): Rules and procedures specified in 14 CFR 91 for aircraft operations under visual conditions. Aircraft operations under VFR are not generally under positive control by air traffic control. The term VFR is also used in the United States to indicate weather condi- tions that are equal to or greater than minimum VFR requirements. In addition, VFR is used by pilots and controllers in order to indicate a type of flight plan.

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Airports use Noise and Operations Monitoring Systems (NOMSs) to collect, manage, analyze, and communicate data such as flight tracks and procedures, aircraft identification, noise measurements, noise abatement program performance, and weather. NOMSs are also used to respond to community noise complaints and provide stakeholders with information about aircraft activity and noise, thus fostering trust and transparency.

The TRB Airport Cooperative Research Program's ACRP Research Report 237: Primer and Framework for Considering an Airport Noise and Operations Monitoring System is a comprehensive resource to help airport industry practitioners assess the potential benefits and costs of acquiring, maintaining, and updating a NOMS or flight tracking tools without permanent noise monitors.

Supplemental to the report are Appendices A though K.

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