• Our guide to SEA’s Part 150 noise study

    Airplane noise is probably the most immediate and obvious impact of living near an airport. The Port is updating the Part 150 noise program that will guide SeaTac airport (SEA) noise decisions for years to come. The study will shape which areas are mapped (which homes, apartments, schools, care facilities, and other places where people live, learn, and receive care) that may qualify for sound insulation or other protection—what operational changes the Port considers, and how quickly approved measures are delivered.

    The FAA reviews the Port’s proposed program, but the Port is responsible for developing it and carrying it out. This is your chance to make sure the plan reflects what you actually experience.

    WHAT YOU CAN DO

    ➣ Read our draft comment and share what is missing from your experience.

    1. What this Part 150 will decide (Why you should care)

    2. Count the full exposure

    3. Measure what residents experience

    4. Reduce noise at its source

    5. Deliver protection to existing communities

    6. Prevent future harm without displacement

    7. Monitor, Report, and improve

    8. Fund the commitments and deliver them

    ➣ Tell us where and when airport noise affects your sleep, work, school, health, or daily life.

    ➣ Follow the Part 150 schedule. Look at the documents, and attend the public workshops.

    • Saturday, Oct. 17, 10 a.m. – 12 p.m.
      Location: Cedarhurst Elementary School
      611 S 132nd St, Burien, WA 98168

    • Monday, Oct. 19, 6 – 8 p.m.
      Location: McMicken Heights Elementary School
      3708 S 168th St, SeaTac, WA 98188

    • Tuesday, Oct. 20, 6 – 8 p.m.
      Location: Midway Elementary School
      22447 24th Ave S, Des Moines, WA 98198

    ➣ Submit a comment.

  • Our experience & why we’re writing

    Part 150 is the airport noise plan that can shape our communities for years. (The last one was in 2014!) It decides how the Port maps current and future aircraft noise, which homes, schools, and care facilities may qualify for sound insulation or other protection, which noise reduction measures are considered, and how those measures are funded and delivered.

    Our comment here reflects our own experiences, as well as conversations with residents of Burien, Des Moines, Federal Way, Normandy Park, SeaTac, Tukwila and neighboring communities who bear the health effects and disruption of aircraft noise throughout the day and night.

    People living under the flight paths rarely describe noise in decibels. They describe waking at 2 a.m., teachers stopping mid-lesson, thoughts and phone calls put on hold until a jet passes. Each flight brings a spike in sound, then a quiet stretch between them (where you can have a normal voice conversation). More flights, as currently planned, mean more spikes and both shorter and fewer quiet periods.  Because DNL spreads that pattern over a full year, a meaningful rise in loud events can register as only a slight shift in the annual number.

    Think of it this way: A friend who interrupts you every one to three minutes makes conversation hard. Now imagine this plane friend not only interrupts you more frequently, they stay longer each day, arriving earlier, leaving later and showing up in the middle of the night to ‘talk’. That’s what it means for people living near airports and under flight paths.

  • 1. What Part 150 needs to get right

    The Part 150 process has two main parts. (14 CFR Part 150)

    First, the Port maps current and future aircraft noise exposure through its Noise Exposure Maps. The FAA reviews the maps to define who is affected by airport noise and help determine who may qualify for federally supported protection.

    Second, it develops a Noise Compatibility Program-–a set of measures to reduce noise, protect people already exposed, prevent new incompatible development, and track whether the program is working. The program determines what help is offered, who receives it and when. 

    So.  Both parts need to reflect the full extent of community exposure—not only the 65 DNL contour used in current federal eligibility rules.

  • 2. Count the full exposure

    The Noise Exposure Maps are the foundation of the program. They determine which homes, schools, care facilities, and neighborhoods are counted as exposed. This is why the maps must do more than show the minimum required contours. They should accurately describe current conditions, projected growth, and the nighttime exposures residents actually experience.

    The Port should also report and use lower level exposure information that can help guide available non-federal funding for local mitigation, and to help prioritize assistance.

    In 2014, the Port of Seattle narrowed the Noise Remedy Boundary (the Port’s boundary used for its sound insulation program) because it expected exposure to keep declining.   But current projections show the opposite. The Port's preliminary 2032 data place 9,918 housing units and 26,240 people inside 65 DNL (Highline Forum Part 150 Update, Sept. 23, 2026, slide 9, Table 5-5), or an increase of 6,100 more homes (2.5x higher) and 16,500 more people (4x higher) than the 2014 numbers used to justify narrowing the boundary.

    The projected 2032 contour would also include more places where people learn, receive care, and gather: in total, 13 schools, two hospitals, 43 nursing homes, 23 places of worship, and two libraries (Highline Forum deck, slide 9).  These projections assume the SAMP Near Term Projects, which model an increase in nighttime operations (flights) from about 64,000 to 76,600 a year.

    Washington State Department of Ecology likewise noted that the SAMP Action Alternatives would expose 4,439 more people to 65+ DNL noise, and cautioned that FAA’s 1.5 dB significance threshold “may understate the severity and impact of noise effects in communities already facing chronic exposure”. The Port should recommend mitigation that is proportional to the projected increase in exposure and the cumulative harm residents experience.

  • 3. How noise is measured and counted

    The way the Port measures noise determines who is recognized as harmed and who may qualify for help. Part 150 relies on an annual average called DNL, and eligibility for federally funded noise mitigation generally begins at 65 DNL (Congressional Research Service). But that system is under federal review because the FAA is reconsidering whether DNL and the 65 DNL threshold adequately reflect how people experience aircraft noise (FAA Noise Policy Review). The FAA Reauthorization Act of 2024 directed the FAA to update the Part 150 noise standards and created an Aircraft Noise Advisory Committee (DWU Consulting summary of §§ 786 and 792). 

    SEA must use the current federal rules for this study. But the mitigation program created through this process will continue long after those rules may change. The Port can—and should—report noise exposure below 65 DNL, as well as information that better reflects what residents experience: the number of loud flights, their peak noise levels, nighttime noise, and how often noise disrupts sleep or daily life.

    At the Part 150 Technical Review Committee (TRC) Meeting #7, the Port’s consultant said the Port “recognizes aircraft noise affects areas beyond the DNL 65 contour” and that, although Part 150 is centered on DNL 65, the Noise Compatibility Program “is evaluating measures intended to reduce noise at lower exposure levels as well.” The glideslope (the angle at which planes descend toward the runway) analysis showed “larger reductions in the DNL 60 contour and expected further reductions at lower noise levels” (TRC Meeting #7). The draft should publish those analyses, including the affected population counts, assumptions, and maps, and use them to guide mitigation choices.

    That fuller picture matters because 65 DNL is not a health-protective benchmark. In 1974, EPA identified 55 DNL outdoors and 45 DNL indoors as safe levels to protect public health and welfare (EPA Levels Document; EPA announcement). Ecology recommended that the Port adopt those thresholds and “expand the noise study area to where impacts are actually felt” (Ecology letter, p. 7), and apply them “to expand the noise boundary and provide mitigation for any new impacts” (p. 8). The World Health Organization recommends lower limits for aircraft noise: 45 dB Lden (day-evening-night) and 40 dB at night (WHO Environmental Noise Guidelines, 2018).

    DNL is useful for comparing annual exposure, but it does not show what residents experience flight by flight—especially at night. The FAA's Neighborhood Environmental Survey of more than 10,000 residents near 20 airports found “a substantial increase in the percentage of people who are highly annoyed by aircraft noise,” including at lower noise levels, compared with the older curve used in federal policy (FAA Neighborhood Environmental Survey). Federal Way has asked for analysis of individual loud events (Highline Journal). Burien, Des Moines, and SeaTac have asked for flight counts, peak levels, and exposure estimates below 65 DNL (three-city SEPA letter, p. 20).

    The health evidence reinforces the need for a broader analysis. The draft should explain how the projected changes in nighttime and single-event noise relate to sleep disturbance and other documented health effects. Studies near Heathrow and around U.S. airports have linked aircraft noise with cardiovascular hospital admissions and deaths (Hansell et al., BMJ 2013; Correia et al., BMJ 2013), and a Swiss study linked nighttime aircraft noise with cardiovascular deaths in the hours that followed (European Heart Journal, 2021). Locally, Public Health – Seattle & King County documented higher heart disease hospitalization and death rates near the airport, and life expectancy two to five years lower than in the rest of King County (Public Health – Seattle & King County, 2021).

    To make the noise maps transparent and useful to affected communities, the draft should:

    Show the full picture:

    • Show homes, residents, schools, childcare sites, and care facilities within the 55, 60, 65, and 70 DNL contours for 2022 and 2032, and show how those counts change under each proposed measure.

    • Report nighttime and single-event exposure alongside DNL, including peak noise levels, the number of events above a stated threshold, and estimated sleep disruption at homes, schools, and care facilities.

    Show how the numbers were made:

    • Compare modeled noise with measured levels at each permanent monitor, explain any gaps, and describe how monitoring was used to check the model, even if FAA rules require modeling rather than monitoring to define the official DNL contour.

    • Identify the flight track, runway use, aircraft fleet, nighttime operation, weather, seasonal, and growth assumptions used in the model; test reasonable alternative 2032 track patterns.

    • If the FAA revises the Part 150 metric or threshold, the Port should publish an implementation plan and schedule for updating SEA’s analysis and program, instead of waiting for the next routine update cycle.

    Show who benefits:

    • Identify the health disparities ranking and sensitive use locations for each area affected by a proposed operational measure, including both the communities receiving relief and those that would receive additional noise.

    • State clearly which exposure counts and boundaries will govern eligibility if Part 150 and SAMP analyses produce different results.  For example, the Port’s 2032 counts range from about 9,900 to 10,700 housing units depending on the presentation (TRC Meeting #7).

    • Use current land use and population data, including recent permits, so new homes and sensitive facilities are not missed.

  • 4. Reduce noise at its source

    The first responsibility of the Noise Compatibility Program is to reduce noise at its source where it can. The Port is already evaluating operational measures that could change where, when, and how aircraft noise is experienced. Each option should be evaluated not only by its regional DNL total, but by whether it reduces nighttime noise, avoids transferring harm to another neighborhood, and provides relief to communities with the greatest existing burden. No community should receive new or increased aircraft noise as the price of relief for another community without transparent analysis, meaningful consultation, and a plan to avoid or mitigate the added harm.

    An independent review commissioned by Burien, Des Moines, and SeaTac found that increased use of the third runway, 16R/34L, including at night, is a major reason the contours have moved west over neighborhoods previously outside 65 DNL (three-city SEPA letter, p. 21). Because DNL adds a 10 dB penalty to each flight between 10 p.m. and 7 a.m., counting it as roughly equal to ten daytime flights, shifting even a small share of night operations can substantially change the contour (Federal Way Quiet and Healthy Skies Task Force). 

    We ask the Port to:

    • Publish daytime and nighttime operations by runway for 2022 and 2032, and explain the reasons for third runway use increases.

    • Report what happened to the 2014 program’s preferential runway measures intended to limit third runway use.

    • The Port should work with the FAA and airlines to test different ways of reducing nighttime noise. This should include different flight routes or approach paths, including routes over Elliott Bay, and different ways of using the airport’s runways at night.

    • For every option, show which communities would get less noise, which might get more, and whether that option can be used safely without causing major delays or shifting the problem to another community. The analysis should use the Washington Environmental Health Disparities Map and identify nearby schools, childcare sites, health care facilities, and other places where people need quiet—not population density alone.

    • Quantify the noise and altitude effects of changing the Runway 34R glideslope, which is planned to go from 2.75 to 3.0 degrees as part of the SAMP Taxiway A/B Extension (TRC Meeting #7). Federal Way has asked for altitude changes at its northern and southern borders and over the Steel Lake Park neighborhoods (Highline Journal).

    • For every noise reduction option the Port does not advance, publish the analysis and a plain language explanation (NOT a technical appendix) of why it was not selected, including expected noise benefit, affected communities, operational constraints, cost, and the authority needed to implement it.

    The Part 150 Technical Review Committee Meeting #7 supports further analysis of these options. The consultant said it had modeled a 3.5-degree glideslope across all times of day “to demonstrate the maximum benefit,” but that “other variations on time of day and steepness of the glideslope could be analyzed.” It also acknowledged that “nighttime noise is more sensitive to the community” and that there “may be more flexibility” at night because of lower traffic volumes (TRC Meeting #7).

    The Port already limits engine run-ups during the quiet hours between 10 p.m. and 7 a.m., with limited exceptions when an aircraft must be checked before departure. The program should show how often those exceptions happen, where the run-ups occur, and how the Port checks that airlines follow the rules.

    Because engine run-ups are expected to increase, the Port should also study ways to reduce their noise. This could include limiting where and when they happen, using a sound barrier or enclosed testing area, providing gate power so planes do not need to run auxiliary engines, and enforcing limits on those engines while planes are parked.

  • 5. Deliver protection to existing communities

    When changes to flight operations cannot do enough to reduce noise, the program must help people who are already living with it. That includes renters and homeowners, people living in apartments, condos, mobile homes, care homes, nursing homes, extended stay motels, as well as children in schools and childcare settings.

    Sound insulation cannot replace quieter flights, but it is important protection for homes, schools, care facilities, and long term housing that remain exposed to noise. The Port should clearly explain who qualifies, when help will be available, and how it will reach the people most affected.

    Actual delivery matters as much as eligibility. The SAMP review reports that 2,674 housing units inside the 2022 65+ DNL contour are not sound insulated, rising to 4,984 by 2032 even without the projects. The cities’ review also reports that construction on some insulation commitments from the 2014 program did not begin until 2025 (three-city SEPA letter, p. 22).

    The final program should also include a public, time-bound delivery plan–-not an open-ended commitment–-that states when eligibility will be confirmed; when outreach, enrollment, design, and construction will begin; how many homes and facilities will be completed each year; which communities will be served first; and how the Port will report progress.

    We support broader eligibility, including:

    • Homes built after the existing construction date cutoffs (Dec 3, 1986, in Des Moines; Sep 6, 1987, elsewhere), as well as apartments, condominiums, and mobile homes (TRC Meeting #7).

    • Hotel and motel rooms used as long term housing. Define “long term transient lodging” so it reaches families living in extended stay motels.

    • The 43 nursing homes in the preliminary data. Clarify if adult family homes are included and near the front of the delivery schedule.

    • Schools, childcare facilities, and transitional housing where eligibility can be established.

    • For each type of building, the Port should explain what is possible: estimated costs, what funding rules apply, and what barriers—such as owner permission, building condition, or construction disruption—would need to be addressed.

    At TRC Meeting #7, the Port described possibly expanding eligibility to “a portion of homes” built after the existing code dates, and identifying hotels or motels within the current Noise Remedy Boundary that function as long term housing. Its consultant also said some properties outside 65 DNL could become eligible through boundary revisions and block-rounding, though “the numbers … would likely be limited” (TRC Meeting #7). The draft documentation should turn these possibilities into clear eligibility standards, property counts, a funding plan, and a public timeline.

    For schools, the 2002 Port–FAA commitment to insulate 15 Highline schools is still incomplete. Highline Public Schools has identified Beverly Park Elementary, Hilltop Elementary, and older buildings at the Puget Sound Skills Center as still waiting, and has asked for interim sound improvements rather than waiting for rebuilds. The Port has said remaining school sound-insulation funding is available (Highline Journal). The Port should publish a schedule for completing sound insulation commitments. If a full project will take years, the Port should also consider shorter term improvements that reduce noise inside classrooms while students wait.

    The Port has stated that the Sound Insulation Repair and Replacement Pilot is separate from this Part 150 study. Please explain clearly how residents with failing Port installed insulation should navigate between the pilot, the existing sound insulation program, and the updated Part 150 program.

  • 6. Prevent future harm without displacement

    The Port should work with cities and King County to keep new homes, schools, childcare sites, and healthcare facilities out of the noisiest areas. The Port can provide noise information and recommendations to inform local governments make zoning and building code decisions.

    Before recommending new land use rules, the Port should identify their likely effects on existing residents and consider whether they could make housing less affordable or pressure current residents to move. It should discuss possible safeguards with affected communities and local governments.

  • 7. Monitor, report, and adjust

    The program must be transparent enough for residents to determine whether it is working. The Port operates 24 permanent noise monitoring stations, first installed in the late 1980s and upgraded in 2015. The Port is now considering another system upgrade that would review existing monitor locations and identify potential new sites (TRC Meeting #7).

    The final program should clearly state:

    • Where noise monitoring will occur

    • What data and information will be published

    • How often the information will be updated

    • How residents can use the data to identify concerns and request follow-up

    The Port already publishes monitoring data and monthly noise comment reports. The updated program should explain how it uses this information to find recurring problems, especially in places without a permanent noise monitor. It should show when reports may lead to an investigation, temporary monitoring, a closer look at flight operations, or another response—and publish what happened.

    The program should also establish clear triggers for review and corrective action. If monitoring results, flight track changes, runway use changes, or updated forecasts show that a neighborhood is receiving materially more noise than was modeled or anticipated, the Port should publish its findings, notify affected communities, evaluate corrective measures, and provide a timeline for response.

    We support the Port’s planned review of monitor locations and improved online community tools. The review should prioritize areas where exposure is growing, especially under the third runway’s paths. The online tools should report nighttime and single event results, not only annual averages.

    The Port has said its monitor network is “valuable” and helps “provide context on noise levels in the community” (they are still useful evidence for checking if the computer model reflects conditions people actually experience), even though the FAA requires modeling for Part 150 contours. It has also identified possible monitor relocations or additions, better public flight tracking tools, and improved public access to noise and operational data (TRC Meeting #7). The draft program should turn those concepts into a public plan, with siting criteria, implementation dates, and regular reporting.

    If the Port pilots an Active Noise Control System, it should publish where it would be used, what noise it is expected to reduce, how much improvement is expected, what it will cost, and how the public will know whether it works (Highline Forum deck, slide 13). It should not be treated as a replacement for quieter operations, sound insulation, or broader monitoring.

  • 8. fund and deliver the program

    An approved measure is not the same as a delivered measure. For every measure in the final program, the Port should identify the responsible entity, funding source, local share, expected timing, and the communities it is intended to serve. The program should clearly distinguish among measures the Port commits to carry out, measures that depend on FAA approval or another agency’s agreement, and measures the Port will only study further. A possible future action should not be presented as a completed mitigation commitment.

    Before enrollment begins, the Port should publish how it will prioritize sound insulation and other protection. The method should consider overall and nighttime noise exposure, nearby schools and care facilities, health disparities, housing type and condition, and how long a community has waited—not only the order in which applications are received. The Port should publish the order in which neighborhoods will be served, beginning with communities carrying the greatest combined burden.

    At SEA, eligible noise projects funded through the FAA’s Airport Improvement Program can receive an 80 percent federal share (FAA AIP overview; FAA AIP Handbook, ch. 4). The Port should state the remaining local share, all other funding sources, the expected delivery timeline, and any funding gaps or conditions that could delay implementation.

    Also, many program management measures do not require FAA approval. The Port should begin actions it can take under its existing authority rather than wait for the FAA Record of Approval (probably in 2028). For measures requiring FAA or another agency’s action, the Port should state what approval is needed, who is responsible for obtaining it, and when it expects a decision.

    The Port should maintain a public implementation dashboard for every Part 150 measure. For each measure, the dashboard should show the responsible entity; whether FAA or another approval is needed; funding source and estimated cost; schedule; affected communities; implementation status; and the reason for any delay. It should also show the status of every outstanding commitment from the 2014 program.

  • Conclusion

    This update will shape airport-noise decisions for years. The Port should use it to reduce noise at the source, protect the people already living with it, and deliver commitments on a clear public schedule.

    Respectfully submitted,

    STACC4J