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Frequently Asked Questions
- What is FAR Part 150 Study?
- Why prepare an FAR Part 150 Study?
- What will the study include?
- How long will the Part 150 Study take to complete?
- How can I be involved?
- When did noise monitoring take place at TUS?
- What is the purpose of noise monitoring?
- What is the Integrated Noise Model?
- What is DNL?
- What are Noise Exposure Maps (NEM)?
What is FAR Part 150 Study?
Part 150 is a section of the Federal Aviation Regulations (FAR) that sets forth rules and guidelines for airports desiring to undertake airport noise compatibility planning. Through FAR Part 150, the FAA established regulations governing the technical aspects of aircraft noise analysis and the public participation process for airports choosing to prepare airport noise compatibility plans.
The Part 150 planning process involves the methods and procedures an airport operator must follow when developing a Noise Compatibility Plan (NCP). A Part 150 Study involves six major steps:
- Identification of airport noise and land use issues and problems;
- Definition of current and future noise exposure patterns;
- Evaluation of alternative measures for abating noise (e.g., changing aircraft flight paths), mitigating the impact of noise (e.g., sound insulation), and managing local land uses (e.g., airport-compatible zoning);
- Development of a NCP;
- Development of an implementation and monitoring plan; and
- FAA review and approval of the recommended NCP, including the analysis of alternatives, the compatibility plan, and the implementation and monitoring plan.
The Part 150 Study process is designed to identify noise incompatibilities surrounding an airport, and to recommend measures to both correct existing incompatibilities and to prevent future incompatibilities. For Part 150 Study purposes, noise incompatibilities are generally defined as residences or public use noise-sensitive facilities (libraries, churches, schools, nursing homes, and hospitals) within the 65 Day-Night Average Sound Level (DNL) noise contour.
Why prepare an FAR Part 150 Study?
The purpose for conducting a Part 150 Study at an airport is to develop a balanced and cost-effective plan for reducing current noise impacts from an airport's operations, where practical, and to limit additional impacts in the future. By following the process, the airport operator is assured of the FAA's cooperation through the involvement of air traffic control professionals in the study and the FAA's review of the recommended Noise Compatibility Program (NCP). The decision to undertake noise compatibility planning is entirely voluntary on the part of the airport operator. An airport with an FAA-approved NCP also becomes eligible for funding assistance for the implementation of measures in the NCP.
Among the general goals and objectives addressed by a Part 150 Study are the following:
- To reduce, where feasible, existing and forecasted noise levels over existing noise-sensitive land uses;
- To reduce new noise-sensitive developments near the airport;
- To mitigate, where feasible, adverse impacts in accordance with Federal guidelines;
- To provide mitigation measures that are sensitive to the needs of the community and its stability;
- To minimize the impact of mitigation measures on local tax bases; and
- To be consistent, where feasible, with local land use planning and development policies.
What will the study include?
The study will identify existing and future flight corridors, develop aircraft noise exposure maps for current and future conditions, evaluate air traffic control procedures that could be implemented to reduce noise exposure over residential areas, consider land use controls that could be established to reduce future incompatible land uses from being developed within high noise areas, and evaluate means to mitigate noise impacts within high noise exposure areas.
How long will the Part 150 Study take to complete?
The Part 150 Study began in March 2009 and is scheduled for completion by the end of 2010. Implementation of the study recommendations will be based on review and approval of the reports by the TAA and the FAA. The review period by the FAA is 180 days.
How can I be involved?
During the Part 150 Study, three public workshops will be held. Study progress will be shared during these meetings and the public will be encouraged to provide input. A public hearing will be held in conjunction with the final workshop to invite comment on proposed recommendations. The dates and locations of these sessions will be published in local newspapers and on this website.
Additionally, a Project Advisory Committee (PAC) representing organizations that use the airport as well as affected political jurisdictions, agencies and neighborhoods has been formed to provide feedback and comment throughout the study. The PAC will meet five times to review analysis and offer suggestions about the recommendations being considered.
When did noise monitoring take place at TUS?
A noise measurement program was conducted the week of May 18, 2009, following Federal Aviation Regulations (FAR) Part 150 Guidelines.
What is the purpose of noise monitoring?
This field measurement program was intended to provide numerous measurements of individual aircraft overflight events. The measurements will be compared with pre-existing database information related to aircraft noise level and performance characteristics in FAA's Integrated Noise Model. The information collected during the measurement program included acoustical output, as measured at known locations, as well as flight trajectory data (the aircraft's three-dimensional location) relative to the noise measurement site.
What is the Integrated Noise Model?
The FAA has developed the Integrated Noise Model (INM) for evaluating aircraft noise impacts in the vicinity of airports. The INM has been the FAA's standard tool since 1978 for determining the predicted noise exposure in the vicinity of airports. The FAA requires the use of INM to develop noise exposure contours in FAR Part 150 Noise and Land Use Compatibility Studies.
The INM utilizes flight track information, aircraft fleet mix, standard and user defined aircraft profiles and terrain as inputs. The INM produces noise exposure contours that are used for land use compatibility maps. The INM includes built-in tools for comparing contours and utilities that facilitate easy export to commercial Geographic Information Systems. The INM also calculates noise levels at specific sites such as hospitals, schools or other noise sensitive locations.
What is DNL?
The DNL metric describes the total noise exposure during a given period. However, DNL, by definition, can only be applied to a 24-hour period. In computing DNL, an extra weight of 10 dB is assigned to any sound levels occurring between the hours of 10:00 p.m. and 7:00 a.m. This is intended to account for the greater annoyance that nighttime noise is presumed to cause for most people. This extra weight treats one nighttime noise event as equivalent to 10 daytime events of the same magnitude.
What are Noise Exposure Maps (NEM)?
NEMs identify the noise exposure of the current operating conditions, and projected future conditions. Included within this analysis will be the operating conditions currently taking place at the airport including existing departure and arrival procedures, daytime and nighttime activity, touch and go operations and helicopter activity.