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Part 150 Noise Compatibility Study

Frequently Asked Questions

Part 150 is a section of the Code of Federal Regulations (CFR) that sets forth rules and guidelines for airports desiring to undertake airport noise compatibility planning. The Part 150 regulations establish guidelines for technical aspects of aircraft noise analysis and the public participation process for airports choosing to prepare airport noise compatibility plans.

Part 150 Study involves six major steps:

1. Identification of airport noise and land use issues and incompatibilities
2. Definition of current and future noise exposure contours
3. Evaluation of alternative measures for abating noise that impact the 65 Day Night Level (DNL) noise contour (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)
4. Development of a Noise Compatibility Plan (NCP)
5. Development of an implementation and monitoring plan
6. 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 sensitive land uses surrounding an airport, and to recommend measures to both correct existing incompatibilities and to prevent future incompatibilities. For Part 150 Study purposes, noise sensitive land uses are generally defined as residences or public use facilities (libraries, churches, schools, nursing homes and hospitals) within the 65 Day-Night Average Sound Level (DNL) noise contour, the area the FAA defines as impacted by aircraft noise.

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 normally voluntary on the part of the airport operator. As part of the Record of Decision for Environmental Impact Statement for the relocation of the south runway at CMH, the Columbus Regional Airport Authority (CRAA) has committed to reviewing the Part 150 Study at CMH.

An airport with an FAA-approved NCP also becomes eligible for funding assistance for the implementation of approved measures.

Among the general goals and objectives addressed by a Part 150 Study are the following:

  • – To reduce, where feasible, existing and future 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;
  • – 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.

The GRAA officially began the Study in December of 2019. The study is scheduled for completion in the 3rd quarter of 2022 when it will be submitted to the FAA for review. The FAA review period is typically 6-9 months.

The FAA has developed the Aviation Environmental Design Tool (AEDT) for evaluating aircraft noise impacts in the vicinity of airports. The AEDT is the FAA’s standard tool for determining the predicted noise exposure in the vicinity of airports. The FAA requires the use of AEDT to develop noise exposure contours in Part 150 Studies. The AEDT utilizes flight track information, aircraft fleet mix, aircraft flight profiles, and terrain as inputs. The AEDT produces noise exposure contours that are used for land use compatibility maps. The AEDT includes built-in tools for comparing contours and easy export to commercial Geographic Information Systems.

The AEDT replaced the previous noise modeling software, the Integrated Noise Model, in 2015 which was used for the 2013 NEM Update at RFD.

The Day-Night Average Sound Level (DNL) metric describes the total noise exposure during a given period. DNL is a metric used for predicting the average long-term noise exposure on a population. In computing DNL, 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.

Noise Exposure Maps (NEMs) identify the noise exposure of the current operating conditions, and projected future conditions. Included within this analysis will be the operating conditions taking place at the airport including departure and arrival procedures, daytime and nighttime activity, touch and go operations, runway use, and flight track patterns.

No. The FAA is the only entity that can manage aircraft runway operations or aircraft in flight at RFD. Furthermore, as a recipient of grant funds from the FAA, the GRAA, must abide by specific FAA-imposed obligations and conditions. One of these is that GRAA will not restrict or limit airfield access at RFD based on noise or time of day.

Some airports, like John Wayne Airport in Orange County, still have airfield access limitations, such as curfews on commercial aircraft at night that were instituted prior to the 1990 federal Airport Noise & Capacity Act (ANCA). Except for those that were implemented prior to November 1990, ANCA prohibits regulations or amendments to existing restrictions that limit airfield access. ANCA also required the complete phase-out of all louder Stage 1 and Stage 2 commercial aircraft over 75,000 pounds at all airports, including commercial airports like RFD, by the year 2000.

Airlines continue to retire older, noisier aircraft from their fleets and replace them with more modern, quieter, fuel-efficient aircraft. This helps reduce noise levels at airports often times even as the number of aircraft operations increase.  Many of the older, louder aircraft that operated at CMH at the time of the 2007 Part 150 Study have been phased-out or been significantly reduced from commercial airline fleets.

The Greater Rockford Airport Authority (GRAA) is committed to continuously reviewing and updating the Noise Compatibility Program for the betterment of the communities surrounding RFD. This current Part 150 Study will update the previous NCP study completed in 2002 and the previous NEM study completed in 2013.

A recent Environmental Assessment (EA) was completed in 2019 at RFD. The EA was conducted based on the expansion of Cargo activities at RFD. That EA identified incompatible land use within the 65 DNL noise contour. This current study will update the official Noise Exposure Maps and identify any areas that would be eligible to receive mitigation funding as part of the updated Noise Compatibility Program (NCP). At this time, it is unknown if the results of the study will identify any areas as eligible for mitigation.

A series of public workshops will be held at key milestones during the Part 150 Study. Each workshop will be open to the public to give individuals the opportunity to provide input, ask questions, and offer recommendations throughout the course of the study.  Meeting dates will be advertised in the local newspaper and published on this website’s Home Page and Public Meetings sections.

To keep up-to-date throughout the Part 150 process, sign up to receive email updates on our Contact page.

RFD Part 150

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