FAA Issues Record of Approval

Final Part 150 Study Document

SEPA Threshold Determination and Checklist

SEPA Final Determination

Detailed Noise Contours available

Contact Information

Stan Shepherd
Airport Noise Programs Manager
Port of Seattle
P.O. Box 68727
Seattle, WA 98168

Rob Adams
Part 150 Project Manager
Landrum & Brown
11279 Cornell Park Dr.
Cincinnati, OH 45242

Frequently Asked Questions


What is a 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. The Part 150 establishes 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:

  • Identification of airport noise and land use issues and incompatibilities;
  • Definition of current and future noise exposure contours;
  • 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);
  • Development of a Noise Compatibility Plan (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 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.

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Why prepare a 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 normally voluntary on the part of the airport operator. As part of the Record of Decision for the third runway EIS, the Port of Seattle committed to doing a Part 150 update approximately one year after the runway was operational.

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.

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How long will the Part 150 Study take to complete?

The Port of Seattle began early coordination of the Part 150 study in November 2009, and the consultant team began work in January 2010. The study is scheduled for completion by the end of 2013 and submitted to the FAA for review. The review period by the FAA is typically 6-9 months. Implementation of the study recommendations will be based on review and approval of the NCP by the Port of Seattle Commission and the FAA.

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What is the purpose of noise monitoring?

Field measurements from the airport's permanent monitoring system and the temporary monitors established as part of the study have been collected for use in the study. The measurements were compared with pre-existing database information related to aircraft noise level and performance characteristics in the 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. This information was used to ensure that the input data into the Integrated Noise Model was as accurate as possible.

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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 INM has been updated many times since 1978 to include improved metrics and current aircraft databases. The FAA requires the use of INM to develop noise exposure contours in Part 150 Studies.

The INM utilizes flight track information, aircraft fleet mix, aircraft flight 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 easy export to commercial Geographic Information Systems.

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What is DNL?

The Day-Night Average Sound Level 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, 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.

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What are Noise Exposure Maps (NEM)?

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 and helicopter activity.

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Since the third runway opened, have operations on the runway been more frequent than anticipated?

The third runway (16R/34L) opened officially on November 20, 2008. From March 30, 2009 to September 30, 2009, Sea-Tac's longest, easternmost runway (16L/34R) was closed for a comprehensive reconstruction. And from July 13, 2010 to September 3, 2010, the center runway (16C/34C) was closed for construction work. Both situations led to increased operations on the third runway.

Overall use of the third runway is actually comparable to the level predicted in the 1997 Supplemental Environmental Impact Statement (EIS) for Sea-Tac's Master Plan. The Supplemental EIS noise analysis projected the number of operations on all of the airport's runways, including the third runway, in the year 2010. The latest runway use percentages are available on the Port's Runway Statistics Web page

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Under what set of circumstances are aircraft expected to use the third runway?

During lower visibility conditions, arriving aircraft are directed onto the third runway (16R/34L) and the longest, easternmost runway (16L/34R), allowing Sea-Tac Airport to accept two streams of traffic with adequate separation. Prior to opening the third runway, Sea-Tac could use only one of its two runways for arrivals during lower visibility conditions. Directing all arriving aircraft onto one runway slowed things down and caused significant delays.

The third runway also is used during peak traffic periods when multiple aircraft are scheduled to arrive in the same time period. During these peaks, the third runway is used along with the easternmost runway for arrivals in order to help reduce delays regardless of the weather.

It is important to note that the FAA has the responsibility for managing air traffic at Sea-Tac, and, at any time they have the authority to change the way they use the runways to efficiently manage air traffic and ensure safety.

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Can Sea-Tac Airport restrict operations on its runways?

No. The FAA is the only entity that can manage aircraft runway operations or aircraft in flight at Sea-Tac Airport. Furthermore, as a recipient of grant funds from the FAA, the Port of Seattle, operator of Sea-Tac Airport, must abide by specific FAA-imposed obligations and conditions. One of these is that Sea-Tac will not restrict or limit airfield access based on noise. This means, for example, that a Port-imposed nighttime curfew preventing aircraft from landing on or departing from the third runway would violate FAA requirements.

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 provides for the complete phase out of all noisy Stage 1 and Stage 2 commercial aircraft over 75,000 pounds at all airports, including commercial airports like Sea-Tac, by the year 2000. Sea-Tac was one of the first airports to phase out Stage 1 and Stage 2 aircraft over 75,000 pounds before the federal deadline.

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Where does the Port of Seattle receive funding for noise mitigation projects?

When noise mitigation programs are approved by the FAA through a formal Part 150 Study, those programs then become eligible to receive FAA Grant funding of up to 80%. The remainder of the funding comes from revenues generated at the airport (parking fees, landing fees, etc.).

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What type of noise mitigation projects can the Port of Seattle spend funds on?

Any noise reduction related project approved by the Port Commission and the FAA through a Part 150 Noise Study that demonstrates how it will have a measureable impact on noise can qualify for FAA funding and for Port of Seattle funding. For example, insulation projects inside the 65 DNL Contour, the FAA-established noise impact area that determines insulation eligibility, would qualify. The official noise boundary produced in a Part 150 study would typically be slightly larger than the noise contour and would take into account natural boundaries such as streets and neighborhoods. Conversely, proposed insulation projects far outside the 65 DNL would not qualify. FAA funding sources come with a number of stipulations and conditions that the Port agrees to when accepting funds. Additionally, the same FAA conditions would prevent the Port from using the revenues it generates at the airport (parking fees, landing fees, etc.) for projects that are unable to demonstrate a measureable community impact on noise.

Qualifying for FAA grants is the first step. Other steps include actually obtaining the grants from the FAA and receiving Port Commission approval authorizing the use of airport funds. The Port has long been successful at securing FAA grants and implementing noise mitigation projects in the surrounding communities.

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Can the Port of Seattle use tax levy funds for noise mitigation projects?

Other than funds allocated to the Highline School District for Aviation High School ($15 million) and for the insulation and associated repair and reconstruction of schools (a total Port of Seattle/FAA pledge of $100 million), the Port Commission has not authorized using the Port tax levy money for projects at the airport, because the airport is exclusively supported by user fees such as Passenger Facility Charges (PFCs) and landing fees.

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What noise mitigation efforts has the Port already undertaken?

Since 1976, the Port of Seattle has acquired approximately 1,466 single-family homes and five mobile home parks, containing 359 units. The Port also provided relocation benefits to all the residents, enabling them to relocate to quieter neighborhoods. In addition, the Port insulated more than 9,300 homes and five condominium complexes with a combined total of 260 units. Thirteen of 22 planned Highline Community College buildings were insulated and, in partnership with the FAA, the Port and FAA has so far contributed $50 million (from a total Port of Seattle/FAA pledge of $100 million) for sound insulation and related improvements at schools within the Highline School District. Seven schools have received sound insulation with eight remaining.

Sea-Tac Airport also implemented a number of noise abatement procedures to reduce the noise produced by aircraft while on the ground, during takeoffs and landings, and during flights over populated areas. These include Sea-Tac's noise abatement flight procedures,engine maintenance run-up guidelines, and the Fly Quiet Incentive Program that recognizes the quietest airlines operating at Sea-Tac each year. Because of its comprehensive noise abatement efforts and extensive sound insulation programs, Sea-Tac is recognized today as having one of the most complete and robust noise reduction programs in the nation.

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What set of circumstances makes noise reduction efforts for residents around Sea-Tac Airport a challenge?

Three things make noise reduction efforts a challenge. First, Sea-Tac Airport is situated in a highly populated area that has steadily grown around the airport. Second, the north-south configuration of Sea-Tac's three runways means that flights over the neighborhoods north and south of the Airport are unavoidable. The orientation of runways is based predominantly on wind direction because aircraft take off and land into the wind. And third, Sea-Tac Airport is the main international airport in the region and the state and is a vital part of the national transportation system. Rules and restrictions to reduce noise must be considered in the context of federal laws, air traffic procedures and with the involvement of all parties including the Port, the FAA, the community and the airlines.

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Is Sea-Tac Airport getting quieter due to improved aircraft technology?

Even with the addition of the third runway, the airport's overall noise footprint continues to decrease. One major contributing factor to reduced noise contours at Sea-Tac is that airlines continue to retire older, noisier aircraft from their fleets and replace them with more modern, quieter, fuel-efficient aircraft. For example, in 2008 Alaska Airlines retired its noisier MD-80 fleet and replaced them with newer, quieter Boeing 737-800 aircraft.

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What results can the communities around Sea-Tac Airport expect from the new Part 150 process once it is complete?

The current Part 150 Study, Sea-Tac's fourth, began in November 2009. As part of their work, the consultants have developed new noise maps showing how the airport's overall noise affects the community now and in the future. They have conducted a wide-ranging review of all of the airport's noise reduction efforts and an evaluation of new ways to improve upon the efforts. Through the public workshops, the public helped to identify and shape the noise reduction recommendations that are included in the Part 150 Study. The Port has been committed to a thorough and accessible public process throughout the Part 150 Study that continues to ensure there are multiple avenues for involvement and public comment.

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How can I get involved with the Part 150 Study as it progresses and where can I find information?

A series of public workshops have been held at key milestones during the Part 150 Study. Open to all, each workshop was designed to make it easy for the public to provide input, ask questions and offer recommendations in a more personal setting. The fifth and final workshop was held in conjunction with a Public Hearing on May 15, 2013 to accept comments on the Draft Part 150 recommendations. Click here for additional information on this meeting. To keep up-to-date throughout the Part 150 process, sign up to receive email updates on the Port's website.

A dedicated Part 150 Study website has been established as the single location for all documentation connected to the study.

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What happened with the recommendations from the last Part 150 Study?

A number of ideas for noise mitigation were discussed during the 2002 Part 150 Study. Not all of those ideas were approved by the FAA, but many were, and nearly all of those have been implemented by the Port of Seattle. The following information provides details on the status of each of the FAA-approved recommendations from 2002.

2002 FAA-Approved Noise Reduction Measures

Actions Taken by the Port of Seattle

Develop and implement a Fly Quiet Program and establish a public follow-up committee.

The Fly Quiet Program was implemented in 2004 and remains in place for the foreseeable future. Airline operations are carefully monitored and airlines compete to be designated as the "quietest" at Sea-Tac. Winning airlines are rewarded with extensive publicity regarding their Fly Quiet efforts. Airlines are evaluated on their performance in complying with flight tracks, as well as their compliance with ground run-up regulations. An advisory committee worked in 2003 to assist the Port of Seattle in developing the program, and served as the "follow-up committee" per the 2002 recommendation. To find out more about the Fly Quiet program, visit the Port of Seattle's website.

Conduct a siting/feasibility study for a ground run-up enclosure (GRE/hush house).

The Port of Seattle completed a feasibility study in 2001, but since then a recommended site could not be finalized because of some serious airfield planning issues adjacent to the area that was designated for a future GRE. A GRE should be located in close proximity to the aircraft maintenance facilities of an airport's primary air carriers. The GRE has been reviewed again as part of the current Part 150 Study and is recommended for construction pending FAA approval.

Institute new run-up regulations, which include restrictions on run-up times and increases in fines for violations.

These recommendations have been implemented. Ground run-ups are prohibited between midnight and 7 a.m., and if absolutely necessary, can only be conducted with approval from the airport and only if no longer than two minutes in duration. Airlines get a warning for the first violation and are fined $1,000 for the second violation. This fine doubles for each repeat violation within a 12-month timeframe.

Install sound reduction measures (insulation and sound-dampening windows) in all schools within the 65 DNL.

Work has been ongoing for some time on sound mitigation of school buildings in the Highline School District. The Port of Seattle and the FAA are each contributing $50 million, for a combined total of $100 million toward this effort. To date, sound mitigation has been installed in 7 brand-new schools, with 8 schools remaining.

Install sound reduction measures in owner-occupied multi-family complexes within the 70 DNL.

Insulation and sound rated windows were installed in all 5 of the condominium complexes, with a total of 260 units. This work was completed in 2008.

Purchase mobile home parks within the 70 DNL noise contour.

This program was completed in 2009. The Port of Seattle acquired 5 mobile home parks with a total of 359 mobile homes units. Owners of those homes were relocated with financial and advisory assistance from the Port.

Purchase residential properties experiencing noise levels of 65 DNL or greater located within the Approach Transition Zones (ATZ) of the proposed third runway.

Completed in 2010, all residential parcels within the third runway's North ATZ have been purchased, for a total of 69 homes, and these homeowners have been relocated with financial and advisory assistance from the Port. A re-evaluation of the third runway's South Approach Transition Zone has been conducted as part of the current Part 150 Update. There are sixteen single-family residences and six apartment buildings remaining in the South ATZ that are eligible for voluntary acquisition.

Prepare Cooperative Development Agreements

Work with the local jurisdictions has been ongoing with the preparation of cooperative development agreements. To date, the Port has cooperatively worked with Burien on the North East Redevelopment Area (NERA) north of the third runway, and has signed a Development Agreement with the City of Des Moines on the Des Moines Creek Business Park

Amend zoning ordinances for property purchased by the Port.

All of the residential parcels purchased by the Port have been re-zoned as "airport noise compatible," which means that if and when they are redeveloped they can only be used for industrial/commercial purposes, not residential. The Port also evaluated residential building code requirements for all jurisdictions within the 1998 DNL contour and found that they either met or exceeded the FAA's noise reduction standards.

Use Flight Management System (FMS) to better manage airline flight tracks.

FMS is a computer system onboard aircraft that enables pilots to fly more precise routes. This, in turn, provides air traffic controllers with the ability to better manage flight tracks of incoming and outgoing aircraft. Following the 2002 Part 150, FMS departure procedures have been developed by the FAA for use of the Elliott Bay corridor and are routinely assigned to pilots.

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