Frequently Asked Questions

A Part 150 Study is complex, which understandably raises many questions. We've listed some of the most common questions and answers to those questions here.


Why did the University prepare a Federal Aviation Regulation (FAR) Part 150 Study?


Airport sponsors such as The Ohio State University have the option of implementing noise mitigation programs. Should the sponsor wish to use Federal funding to pay for the program, the Sponsor is required to base the program on a Federal Aviation Administration (FAA)-approved Noise Exposure Map (NEM) and Noise Compatibility Program (NCP). Federal Aviation Regulation Part 150 is the FAA-approved process that is used to develop the NEM and NCP. A FAR Part 150 Study also provides an opportunity to secure the required Federal approvals for certain measures such as air traffic changes to reduce aircraft noise impacts. In addition, as a part of the FAR Part 150 process, the FAA formally accepts the Noise Exposure Maps, which creates the "official" noise contour maps for the airport. The maps can then be used by local planning agencies for compatible land use planning as well as alerting prospective residents to areas of aircraft noise exposure around the airport.


What did the study include?


The first phase of the study identified existing and future flight corridors and developed aircraft noise exposure maps for current and future conditions. See Noise Exposure Map (NEM) Report. The second phase of the study evaluated air traffic control procedures that could be implemented to reduce noise exposure over residential areas, considered land use controls that could be established to reduce future incompatible land uses from being developed within high noise areas, and evaluated means to mitigate noise impacts within high noise exposure areas. See Draft Noise Compatibility Program (NCP) Report.


How long did the Part 150 Study take to complete?


The Part 150 Study began in September 2007. The NEM Report was submitted to the FAA in December 2008. The FAA accepted that document in July 2009. The NCP portion of the report will be submitted to the FAA after final review and approval by the University. The review period by the FAA is 180 days, so it is anticipated that FAA response will be received in early 2011. Implementation of the study recommendations will be based on review and approval of the reports by the University and the FAA.


How was the public invited to participate and provide input?


Multiple opportunities were provided to the public to provide input during the Part 150 Study. Three public open-house meetings were held. All of these were open to the public. Thirty-day comment periods after each public meeting provided additional time to provide public input. All meeting presentation and handout materials were posted on this official noise study website for review and comment. All public meetings were announced in local neighborhood newspapers, published in editions of public newsletters, posted on this website, sent to public email lists, and shared through signage on the square of the City of Worthington.


Study progress was shared during the public sessions and input was encouraged. A public hearing was held in conjunction with the final open house to invite comment on proposed NCP recommendations.


Following the final open house and hearing on October 27, 2009, members of the public were given 45 days to provide written comments. The public testimony and all written comments received throughout the study are included in Part 150 documentation that has been submitted to the University, and will be included in the final submittal to the FAA.


Additionally, a Part 150 Advisory Committee representing organizations that use the airport as well as affected political jurisdictions, agencies and neighborhoods was formed to provide feedback and comment throughout the study. The Part 150 Committee met several times to review analysis and offer suggestions about the recommendations being considered. Membership was by invitation, but all meetings were open to the public and advertised on this website as meeting dates were confirmed. To see a summary of the public meetings, Part 150 Committee meetings and comments, see appendices M, S and Z of the Part 150 Noise Compatibility Study Update Revised Draft Report.


Were noise complaints considered in this process?


Yes. The primary use of aircraft noise complaint data in a Part 150 Study is to identify trends in the location and types of noise complaints. This information, supplemented with information on the types of operations and aircraft of concern, helped the consultants gain a better understanding of the environment surrounding OSU Airport. One such source reviewed was comments and complaints submitted to, a web-based flight tracking and complaint system available to the public, and specifically made available for OSU Airport neighbors since 2006. Complaint data was just one information source used in the study to gain a perspective on the noise environment around the airport.


What was the purpose of noise monitoring?


Onsite noise monitoring information allowed the study team to compare single event and cumulative noise levels with noise exposure levels developed by the Integrated Noise Model.


What is the Integrated Noise Model?


The Federal Aviation Administration's (FAA), Office of Environment and Energy (AEE-100) 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 UNM 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 build-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 sensitive locations.


For more detail on the noise modeling process and how various information sources were used in the Integrated Noise Model, see the links below.



When did noise monitoring take place at OSU Airport?


Noise monitoring occured between Oct. 18, 2007 and Oct. 26, 2007.


How was this particular time period selected?


Given the schedule of work that was required for this type of study, the noise monitoring, as well as a review of all flight activity from the past year, was done early in the process. The week of October 18, 2007 in particular was selected in order to pick up the extra traffic generated by homecoming weekend at OSU.


How long did the noise monitoring last?


Four sites in neighborhoods less than a mile from the airport had monitors for seven or eight days. Three more monitors were moved around to different locations every one or two days based on the type of aircraft activity that was occurring at OSU Airport and weather conditions.


Was this enough time to get an adequate reading of the noise levels?


Yes. Typically, a day or two worth of noise measurements provides a representative sample of individual noise events. The number of operations is captured through the noise modeling process described above.


Was the noise monitoring successful? Where were the monitors located?


Yes. An extensive amount of noise monitoring data was collected at 13 sites over eight days. Click here for a list and map of these locations. These sites were selected based on our review of flight tracks and aircraft noise concerns expressed by airport neighbors relating to touch and go operations, helicopter flights, overnight flights and the 50-degree turn made by pilots when they depart to the east from OSU Airport, toward Worthington.


Did you evaluate single event noise?


Yes. While not required for a Part 150 Study, SEL, we reviewed single event sound levels from aircraft as well as other sounds such as trains, ambulances, trucks and lawn mowers. These types of sounds helped us understand how aircraft noise levels compare to other community noise sources. Monitoring and review was conducted for operations from both the north and south runways.


What guidelines were used to construct single event noise maps in the study?


It is standard practice to generate Sound Exposure Level (SEL) contours for the loudest aircraft. SEL contours were prepared for the south runway for the existing case. SEL contours also were prepared for the north runway using current departures to show the effect of the shift of some jet aircraft from the south runway to the north runway. It was deemed inappropriate to show the SEL contours on both runways on the same map because the contours depict a single aircraft operation and the runways would not be used for simultaneous jet departures on the 50 degree heading.


Did you evaluate the cumulative noise environment?


Yes, cumulative noise exposure is the key element of the OSU Airport Part 150 Noise and Land Use Compatibility Study.


What are FAA regulations regarding the cumulative noise environment?


FAA land use compatibility guidelines have established 65 Day-Night Average Sound Level (DNL) as the level above which noise sensitive land uses are considered incompatible with aircraft noise.


What is DNL?


Day-Night Average Sound Level (DNL) was developed as a single number measure of community noise exposure. DNL was introduced as a simple method for predicting the effects on a population of the average long term exposure to noise. DNL is an enhancement of the Equivalent Sound Level (Leq) metric through the addition of a 10 decibel (dB) penalty for nighttime (10 p.m. to 7 a.m.) noise intrusions. The incorporation of the 10 dB penalty is in recognition of the increased annoyance that is generally associated with noise during the later night hours. DNL employs the same energy equivalent concept as Leq and uses a 24-hour time integration period. DNL was developed under Environmental Proteection Agency (EPA) guidance and reflects extensive research into the relationship between noise exposure and human annoyance.


Are aircraft restricted from flying during nighttime hours?


No. The FAA does not have designated nighttime hours for operational purposes. However, for purposes of calculating the DNL, the period between 10 p.m. and 4 a.m. is designated as "nighttime". Noise events occurring during this period are subject to the 10 dB penalty.


What are decibels?


Sound levels are measured in decibels (dB), which are logarithmic measures of the magnitude of a sound as the average person hears it. Decibel means 1/10 of Bel (named after Alexander Graham Bell). Under the decibel unit of measure, a 10 dB increase will be perceived by most people to be doubling in loudness, i.e., 80 dB seems twice as loud as 70 dB.


What were the noise monitoring findings?


See the links below for the noise monitoring findings.

Noise Monitoring Locations

Measurement Results - East

Measurement Results - West

SEL Findings


What are noise exposure maps?


Noise Exposure Maps (NEMs) were developed in Phase I of the Part 150 Study. They identified the noise exposure for current operating conditions, and projected future conditions, at the OSU Airport. The analysis indicated that the 65 DNL contour - the FAA's threshold for significant noise - falls mainly within Airport property. Land uses falling outside the 65 DNL contour are considered compatible.


Were specific noise abatement suggestions from the public considered, such as those associated with current airport operations and practices?


Yes. Every noise abatement recommendation was reviewed, including those provided by the public as well as those offered by the University and the Part 150 Advisory Committee. Some suggestions were implemented as part of the final recommendations. Others did not receive further analysis if deemed unable to be implemented for reasons such as safety. See Chapters 9 and 12 of the OSU Airport Part 150 Noise and Land Use Compatibility Study Revised Report.


Was the 50-degree turn looked at in the Part 150 Study?


Yes. The Noise Compatibility Plan (NCP) section of the Part 150 Noise and Land Use Compatibility Revised Draft Report summarizes the evaluation of a wide range of potential noise mitigations measures, including optimization of departure flight tracks, such as those associated with the so-called "50 degree turn" made by pilots when departing to the east, over Worthington. Air Traffic Control (ATC) determined that any turn greater than 50 degreees would conflict with Port Columbus Airspace. Further analysis of more northerly turns, such as turns of 40 and 45 degress, respectively , were determined to present a net noise exposure increase. See Chapter 9: Aircraft and Airport Operational Alternatives for more detail on this and other proposed noise abatement alternatives.


How were population counts determined?


U.S. census data was used to prepare population counts for contours and flight tracks in the Part 150 Study. This data counts individuals and is based on the overall Sound Exposure Levels (SEL), not jurisdictions. Counts for large gathering spaces, such as school or churches, were not included, as this data would inflate and possibly double the number of residents already included in the census population counts. The methodology used was consistent with FAA guidelines.


Will there be an environmental review?


An environmental review under the National Environmental Policy Act (NEPA) would occur at the very end of the Part 150 procsess, and only if the Part 150 process results in the need for any Federal approvals or decisions that trigger NEPA. For example, NEPA documentation would be required if the NCP contains recommended changes to departure flight tracks or other changes to air traffic control procedures, and if the FAA finds that those changes are acceptable and feasible from an operational/aviation safety perspective. However, the draft NCP submitted does not include any actions that would trigger the need to prepare NEPA documentation. Thus, it is not anticipated that the approval of the Part 150 Study would require NEPA documentation.


How do you forecast future operations?


There have been a number of questions relating to the operations forecast - including what is an operations forecast? How is it used in a Part 150 Study process? How did the consultants conduct the operations forecast? When do certain aircraft "retire"? Were Very Light Jets considered in the forecasted operational fleet mix? For answers to these and other operations forecast questions, see Chapter 2 of the Part 150 Study report below.


How are noise contours calculated?


Noise contours are calculated based on the data that is put into the Integrated Noise Model. See Operational ForecastOperational Fleet Mix, and the Integrated Noise Model to learn more.


How can I find more information related to noise metrics, such as "Single Event Noise Level," and other noise monitoring information?


See the study materials below.



What is a Noise Compatibility Program?


The Noise Compatibility Program (NCP) portion of the Part 150 Study process addressed the noise concerns expressed by local residents. Alternative operational, land use, and administrative measures were reviewed to determine which measures can contribute to further reducing noise exposure for residents surrounding OSU Airport, reduce the amount of non-compatible land uses, and provide steps to effectively implement the selected alternatives.


How were proposed noise compatibility strategies evaluated?


Criteria for evaluating the alternatives were established at the beginning of the study with input from stakeholders. Those criteria included:

  • Develop a balanced and cost effective program for reducing noise without limiting airport utility, aviation efficiency, or adversely affecting safety
  • Improve the overall noise environment, while not shifting noise from one community to another
  • Measures for reducing the highest noise levels affecting the greatest number of people, without adversely affecting one community over another, will be given highest priority
  • NCP measures must be technically and legally feasible, and approved by the FAA (flight procedures) and local governments (land use measures)
  • Measures subject to FAR Part 161 evaluation will not be part of the study recommendations


What are the draft Part 150 Noise Compatibility Program recommendations?


After extensive input from the public and neighboring communities, a list of 41 operational, land use, and administrative alternatives were reviewed using the criteria above. See the Noise Abatement Technical Analysis Memo. Following the review of these alternatives, there are 21 recommendations being proposed. Some of the recommendations are existing programs that will continue, while others are new programs that will need to be developed and implemented. See Chapter 13 of the Part 150 Study for more details.