Document ID: FAA-2021-0037-0001
Agency: faa
Document Type: Notice
Title: Overview of FAA Aircraft Noise Policy and Research Efforts: Research Activities to Inform Aircraft Noise Policy
Posted Date: 2021-01-13T05:00Z

[Federal Register Volume 86, Number 8 (Wednesday, January 13, 2021)]
[Notices]
[Pages 2722-2728]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-00564]

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

[Docket No. FAA-2021-0037]

Overview of FAA Aircraft Noise Policy and Research Efforts: 
Request for Input on Research Activities To Inform Aircraft Noise 
Policy

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of research programs and request for comments.

-----------------------------------------------------------------------

SUMMARY: The FAA is releasing a summary to the public of the research 
programs it sponsors on civil aircraft noise that could potentially 
inform future aircraft noise policy. The FAA invites public comment on 
the scope and applicability of these research initiatives to address 
aircraft noise.
    The FAA will not make any determinations based on the findings of 
these research programs for the FAA's noise policies, including any 
potential revised use of the Day-Night Average Sound Level (DNL) noise 
metric, until it has carefully considered public and other stakeholder 
input along with any additional research needed to improve the 
understanding of the effects of aircraft noise exposure on communities.

DATES: Comments on this notice must identify the docket number and be 
received on or before March 15, 2021.

ADDRESSES: Send comments identified by docket number FAA-2021-0037 
using any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the online instructions for sending your 
comments electronically.
     Mail: Send comments to Docket Operations, M-30; U.S. 
Department of Transportation, 1200 New Jersey Avenue SE, Room W12-140, 
West Building Ground Floor, Washington, DC 20590-0001.
     Hand Delivery or Courier: Take comments to Docket 
Operations in Room W12-140 of the West Building Ground Floor at 1200 
New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday 
through Friday, except Federal holidays.
     Fax: Fax comments to Docket Operations at (202) 493-2251.
    Privacy: The FAA will post all comments it receives, without 
change, to http://www.regulations.gov, including any personal 
information the commenter provides. Using the search function of the 
docket website, anyone can find and read the electronic form of all 
comments received into any FAA docket, including the name of the 
individual sending the comment (or signing the comment for an 
association, business, labor union, etc.). DOT's complete Privacy Act 
Statement can be found in the Federal Register published on April 11, 
2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov.
    Docket: Background documents or comments received may be read at 
http://www.regulations.gov at any time. Follow the online instructions 
for accessing the docket or go to the Docket Operations in Room W12-140 
of the West Building Ground Floor at 1200 New Jersey Avenue SE, 
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays.

FOR FURTHER INFORMATION CONTACT:  Mr. Donald Scata, Office of 
Environment and Energy (AEE-100), Federal Aviation Administration, 800 
Independence Ave. SW, Washington, DC 20591. Telephone: (202) 267-0606. 
Email address: NoiseResearchFRN@faa.gov.

Contents

Supplementary Information
Overview of FAA Research on Aircraft Noise
(1) Effects of Aircraft Noise on Individuals and Communities
    Speech Interference and Children's Learning
    Neighborhood Environmental Survey
    Health and Human Impacts Research
    Impacts to Cardiovascular Health

[[Page 2723]]

    Sleep Disturbance
    Economic Impacts
(2) Noise Modeling, Noise Metrics, and Environmental Data 
Visualization
    Aviation Environmental Design Tool
    Noise Screening
    Environmental Data Visualization
    Supplemental Noise Metrics
(3) Reduction, Abatement, and Mitigation of Aviation Noise
Aircraft Source Noise Reduction
    Noise Abatement
    Noise Mitigation Research
    Aircraft Noise Policy Background
Comments Invited

Background Information

    Since the mid-1970s, the number of people living in areas exposed 
to significant levels of aircraft noise \1\ in the United States has 
declined from roughly 7 million to just over 400,000 today. At the same 
time, the number of commercial enplanements has increased from 
approximately 200 million in 1975 to approximately 930 million in 2018. 
The single most influential factor in that decline was the phased 
transition to quieter aircraft, which effectively reduced the size of 
the areas around airports experiencing significant noise levels. That 
transition was the result of the development of new technology by 
aircraft and engine manufacturers; establishment of increasingly 
stringent noise standards for civil subsonic aircraft,\2\ investments 
by U.S. airlines in newer, quieter aircraft; and requirements by the 
FAA and the United States Congress to phase out operations by older, 
noisier aircraft.
---------------------------------------------------------------------------

    \1\ Under longstanding FAA policy, the threshold of significant 
aircraft noise exposure in residential areas is a Day-Night Average 
Sound Level of 65 decibels (dB). See the ``Aviation Noise Abatement 
Policy,'' issued by the Secretary of Transportation and the FAA 
Administrator in 1976. This document is available on the FAA website 
at https://www.faa.gov/regulations_policies/policy_guidance/envir_policy/.
    \2\ Consistent with International Civil Aviation Organization 
standards, FAA has set increasingly more stringent aircraft 
certification noise standards, such as the Stage 5 noise 
certification standard. 82 FR 46123 (October 4, 2017).
---------------------------------------------------------------------------

    A second factor has been cooperative efforts by airports, airlines 
and other aircraft operators, State and local governments, and 
communities to reduce the number of people living in areas near 
airports exposed to significant levels of aircraft noise. Under the 
FAA's Airport Noise Compatibility Planning Program,\3\ airports may 
voluntarily initiate a collaborative process to consider measures that 
reduce existing noncompatible land uses and prevent new noncompatible 
land uses in areas exposed to significant levels of aircraft noise. 
Since 1983, more than 250 airports have used this process to consider 
changes to local land use planning and zoning, sound insulation, 
acquisition of homes and other noise-sensitive property, aircraft noise 
abatement routes and procedures, and other measures. Over $6 billion in 
funding has been provided for airports to undertake noise compatibility 
programs and implement noise mitigation measures. The FAA encourages 
the process by providing financial and technical assistance to airport 
sponsors to develop Noise Exposure Maps and Noise Compatibility 
Programs, and implement eligible noise-related mitigation measures 
recommended in the program, depending upon the availability of funding.
---------------------------------------------------------------------------

    \3\ This process is outlined under 49 U.S.C. 47501 et seq., as 
implemented by 14 CFR part 150.
---------------------------------------------------------------------------

    In addition to noise compatibility planning, the FAA also issues 
grants to airport operators and units of local government to fund 
mitigation projects, most notably to sound-insulate homes, schools, and 
other noise-sensitive facilities. While sound insulation reduces indoor 
noise levels, it does not address concerns about noise interfering with 
the enjoyment of the outdoors. Moreover, there are limits to the 
effectiveness of sound insulation. In some areas with elevated noise 
levels, sound insulation may not sufficiently reduce interior noise 
levels to meet established interior noise standards.\4\ Conversely, in 
areas where overall noise levels are lower, interior noise standards 
may already be met without additional sound insulation treatments.\5\
---------------------------------------------------------------------------

    \4\ FAA Order 5100.38D, Appendix R.
    \5\ P.J. Wolfe et al., 2016 Costs and benefits of US aviation 
noise land-use policies Transportation Research Part D 44 (2016) 
147-156, http://dx.doi.org/10.1016/j.trd.2016.02.010.
---------------------------------------------------------------------------

    Today's civilian aircraft are quieter than at any time in the 
history of jet-powered flight. The FAA, aircraft manufacturers, and 
airlines continue to work toward further reducing aircraft noise at the 
source.\6\ As an example, the noise produced by one Boeing 707-200 
flight, typical in the 1970s, is equivalent in noise to 30 Boeing 737-
800 flights that are typical today.\7\ As a result, for many years 
there was a steady decline in the number of people exposed to 
significant noise in communities located near airports. In recent 
years, however, as aviation industry growth has led to an increase in 
operations in many areas, the number of people and the size of the 
areas experiencing significant aircraft noise has started to show a 
gradual expansion. The introduction of Performance Based Navigation 
(PBN) procedures, as needed to safely and efficiently modernize the 
national air transportation system,\8\ has also provided noise benefits 
for many by allowing for new and more efficient flight paths, but has 
in some places resulted in community concerns, particularly related to 
increased concentration of flights. In 2016, the FAA released an update 
to the FAA Community Involvement Manual to reaffirm the FAA's 
commitment to inform and involve the public, and to give meaningful 
consideration to community concerns and views as the FAA makes aviation 
decisions that affect community interests. The FAA has since developed 
and begun implementing a comprehensive and strategic approach to 
transform and enhance FAA community involvement practices, including 
working through airport community roundtables, to equitably discuss 
opportunities to shift or, when possible, reduce aircraft noise 
exposure.
---------------------------------------------------------------------------

    \6\ See, for example, information on the FAA's ``Continuous 
Lower Energy, Emissions, and Noise'' (CLEEN) Program at: https://www.faa.gov/about/office_org/headquarters_offices/apl/research/aircraft_technology/cleen/.
    \7\ Based on an average of approach and takeoff certificated 
noise levels as defined in 14 CFR part 36.
    \8\ See Section 213, ``Acceleration of NextGen Technologies,'' 
of the FAA Modernization and Reform Act of 2012, Public Law 112-95, 
213, 126 Stat. 11, 46-50 (2012), 49 U.S.C. 40101 note (PBN 
implementation required at key airports by statutory deadline).
---------------------------------------------------------------------------

Overview of FAA Research on Aircraft Noise

    Recognizing that aircraft noise remains a primary concern of many 
stakeholders, the FAA is actively working to understand, manage, and 
reduce the environmental impacts of global aviation through research, 
technological innovation, policy, and outreach to benefit the public.
    With the vision of removing environmental constraints on aviation 
growth by achieving quieter, cleaner, and more efficient air 
transportation, the FAA has worked closely with a number of industry, 
academic, and governmental stakeholders to assemble a comprehensive 
portfolio of research activities (including leveraging research 
undertaken by others) aimed at guiding investments in scientific 
studies, analytical tools, and innovative technologies to better 
understand and manage aircraft noise. However, due to the complex 
nature of aircraft noise and the varied priorities and concerns of 
stakeholders, no single set of findings can completely guide decision 
making. A broad understanding of aircraft noise and any potential 
impacts, from many different perspectives, is therefore needed. 
Summaries of the FAA's key

[[Page 2724]]

research, tools, and technology programs designed to potentially inform 
aircraft noise policy are provided below.

(1) Effects of Aircraft Noise on Individuals and Communities

Speech Interference and Children's Learning

    Much of our current understanding on speech interference due to 
noise was established by the Environmental Protection Agency (EPA) in 
the 1970s.\9\ The findings from these early research assessments are 
still relevant for today's considerations on the impacts from aircraft 
noise. However, the FAA is also investigating whether there are related 
considerations warranting more detailed studies. One area in particular 
is the potential effects of aviation noise on reading comprehension and 
learning motivation in children. Initial research in this area has 
shown there are challenges in designing effective studies, and this 
continues to be an area of interest to better inform noise mitigation 
and abatement strategies for schools and other noise-sensitive 
facilities. While additional research in this area is still being 
explored, the FAA has invested more than $440 million in sound 
insulation treatments at schools around the country \10\ in order to 
mitigate any potential issues related to aircraft noise.
---------------------------------------------------------------------------

    \9\ EPA, 1973, Public Health and Welfare Criteria For Noise, 
https://nepis.epa.gov/.
    \10\ Provided through Airport Improvement Program funding since 
1994.
---------------------------------------------------------------------------

Health and Human Impacts Research

    While community annoyance due to aircraft noise exposure provides a 
useful summary measure that captures public perceptions of noise, a 
full understanding of the impact of noise on communities requires a 
careful consideration of the potential physiological impacts as well. 
Knowledge of physiological impacts could also help the FAA develop 
targeted measures to address aircraft noise. Emerging research 
capabilities are providing new opportunities to examine specific 
impacts of noise on humans. When these are examined in a holistic 
manner with research on community annoyance, they could further inform 
aircraft noise policy considerations. The FAA is conducting research on 
the potential impacts of aircraft noise on cardiovascular health and 
sleep disturbance, as described below.

Impacts to Cardiovascular Health

    In partnership with academic researchers that are being led by the 
Boston University School of Public Health, the FAA is working to 
understand the relationship between aircraft noise exposure and 
cardiovascular health. The researchers are doing this by leveraging 
existing national longitudinal health cohorts wherein statistically 
large numbers of people provide data about their health on a periodic 
basis over the course of many years. These studies are typically used 
to understand the relative risk of different factors like diet on 
different health outcomes like heart disease. The Boston University 
team is expanding the list of factors to include aircraft noise 
exposure such that it can be placed in context with other factors that 
could increase one's risk of cardiovascular disease. The team is 
leveraging existing collaborations with well-recognized and respected 
health cohorts including the Nurses' Health Studies and the Health 
Professionals Follow-Up Study, as well as a complementary study at 
Boston University that is examining the Women' Heath Initiative cohort 
through funding from the National Institutes of Health.

Sleep Disturbance

    The FAA is working with a team led by the University of 
Pennsylvania School of Medicine to conduct a national sleep study that 
will quantify the impact of aircraft noise exposure on sleep. The study 
will collect nationally representative information on the probability 
of being awoken by aircraft noise exposure. The study will start with 
input being requested from approximately 25,000 respondents through a 
mail survey. These surveys will be used to determine the eligibility of 
respondents for a detailed field study that will involve roughly 400 
volunteers. The volunteers in the detailed field study will use 
equipment provided by the research team to collect both noise and 
electrocardiography data in their homes while they sleep. The 
electrocardiography data combined with information on the level of 
aircraft noise exposure will advance our understanding of the 
physiological effects of aircraft noise on sleep.

Economic Impacts

    In addition to the aforementioned community and physiological 
impacts, the FAA is also working with researchers at Massachusetts 
Institute of Technology (MIT) to conduct an empirical assessment of the 
economic impacts to businesses located underneath aircraft flight 
paths. This assessment will take into account the economic benefits 
from aviation activities, as well as potential environmental and health 
impacts that might reduce economic productivity. The FAA is also in the 
developmental stage of a research project that would build on existing 
work done by MIT that has used housing value data to reveal the 
willingness of people to pay to avoid aircraft noise exposure. This 
research is intended to serve as a follow on to the Neighborhood 
Environmental Survey (described in the next section), to determine 
whether the findings of that survey on residents' sensitivity to 
aviation noise is also reflected in their ``revealed preferences'' when 
making housing location decisions.

Neighborhood Environmental Survey

    To review and improve the agency's understanding of community 
response to aircraft noise, the FAA initiated the Neighborhood 
Environmental Survey (NES) to help inform ongoing research and policy 
priorities on aviation noise. Section 187 of the FAA Reauthorization 
Act of 2018 \11\ requires the Administrator of the FAA to ``conclude 
the Administrator's ongoing review of the relationship between aircraft 
noise exposure and its effects on communities around airports . . . 
[and] submit to Congress a report containing the results of the 
review.''
---------------------------------------------------------------------------

    \11\ Public Law 115-254.
---------------------------------------------------------------------------

    Due to the interest from Congress and other stakeholders in the 
findings of this research, an expanded summary is provided in this 
notice below. The full text of the NES report, including a detailed 
description of the methodology and findings, as well as additional 
background material to help inform readers, is available on the FAA's 
website at: www.faa.gov/go/aviationnoise.
Overview of the Survey
    Working with statisticians and noise experts,\12\ the FAA worked 
with other Federal agencies that have statutory, regulatory, or other 
policy interests in aviation noise, to conduct a nationwide survey to 
update the scientific evidence on the relationship between aircraft 
noise exposure and its annoyance effects on communities around 
airports, based on today's aircraft fleet and operations. The NES 
included a range of questions on a variety of environmental concerns, 
including aviation noise exposure.
---------------------------------------------------------------------------

    \12\ The FAA contracted with Westat, a leading statistics firm, 
and HMMH, a leading noise consultancy, to conduct the survey.
---------------------------------------------------------------------------

    The team of expert consultants, under direction from the FAA, 
surveyed residents living around representative U.S. airports, drawing 
upon well-established research methods in order to

[[Page 2725]]

ensure scientific integrity and historical continuity with prior 
studies, while also employing advancements in techniques for noise 
modeling and social surveys. The NES consisted of over 10,000 mail 
responses from residents in communities around 20 statistically 
representative airports across the Nation, making it the single largest 
survey of this type undertaken at one time. In addition to the mail 
responses, the consultants also conducted a follow-up phone survey, 
which included over 2,000 responses to a series of more detailed 
questions. The FAA is now considering the full NES results, in 
conjunction with additional research findings as they become available, 
to determine how they may inform its noise policy considerations.
Overview of Community Response to Noise
    Historically, two of the main types of information considered by 
the FAA and other Federal agencies in relating noise exposure to 
community response have been: (1) Case studies analyzing individual and 
group actions (e.g., complaints or legal action) taken by residents of 
communities in response to noise; and (2) social surveys (such as the 
NES) that elicit information from community residents regarding their 
level of noise-induced annoyance. Annoyance is defined as a ``summary 
measure of the general adverse reaction of people to noise that causes 
interference with speech, sleep, the desire for a tranquil environment, 
and the ability to use the telephone, radio, or television 
satisfactorily.'' \13\ The results of social surveys of noise-induced 
annoyance are typically plotted as ``dose-response curves'' on a graph 
showing the relationship between the level of DNL \14\ cumulative noise 
exposure and the percentage of the population that is ``highly 
annoyed.''
---------------------------------------------------------------------------

    \13\ Federal Agency Review of Selected Airport Noise Analysis 
Issues (FICON), 1992.
    \14\ The Day-Night Average Sound Level (DNL or Ldn) is the 24-
hour average sound level, in decibels, for the period from midnight 
to midnight, obtained after the addition of ten decibels to sound 
levels for the periods between midnight and 7 a.m., and between 10 
p.m., and midnight, local time. See 14 CFR 150.7.
---------------------------------------------------------------------------

    Current FAA noise policy is informed by a dose-response curve 
initially created in the 1970s known as the Schultz Curve.\15\ This 
dose-response curve is generally accepted as a representation of noise 
impacts and has been revalidated by subsequent analyses over the 
years.\16\ The dose-response relationship it depicts has provided the 
best tool available to predict noise-induced annoyance for several 
decades. In 1992, the Federal Interagency Committee on Noise (FICON) 
reviewed the use of the Schultz Curve, and created an updated version 
of the curve using additional social survey data.\17\ The updated dose 
response curve was found to agree within one to two percent of the 
original curve, leading FICON to conclude that ``the updated Schultz 
Curve remains the best available source of empirical dosage-effect to 
predict community response to transportation noise.'' \18\ According to 
the 1992 FICON Report, the DNL-annoyance relationship depicted on the 
Schultz Curve ``is an invaluable aid in assessing community response as 
it relates the response to increases in both sound intensity and 
frequency of occurrence.'' Although the predicted annoyance, in terms 
of absolute levels, may vary among different communities, the Schultz 
Curve can reliably indicate changes in the level of annoyance for 
defined ranges of sound exposure for any given community.\19\ While the 
validity of the dose-response methodology used to create the Schultz 
Curve remains well supported, its underlying social survey data, 
including the additional data used by FICON to update the curve, is now 
on average more than 40 years old and warrants an update. The NES was 
conducted to create a new nationally representative dose-response curve 
to understand how community response to aircraft noise may have 
changed.
---------------------------------------------------------------------------

    \15\ See Schultz, T.J. 1978, ``Synthesis of Social Surveys on 
Noise Annoyance,'' Journal of the Acoustical Society of America 
64(2): 377-405.
    \16\ See Fidell, S., D. Barber, ``Updating a Dosage-Effect 
Relationship for the Prevalence of Annoyance Due to General 
Transportation Noise,'' Journal of the Acoustical Society of 
America, 89, January 1991, pp. 221-233; also see Finegold, L.S., 
C.S. Harris, and H.E. von Gierke, 1992, Applied Acoustical Report: 
Criteria for Assessment of Noise Impacts on People, Journal of the 
Acoustical Society of America, June 1992; also see Finegold, L.S., 
C.S. Harris, and H.E. von Gierke, 1994, Community Annoyance and 
Sleep Disturbance: Updated Criteria for Assessing the Impacts of 
General Transportation Noise on People, Noise Control Engineering 
Journal, Volume 42, Number 1, January-February 1994, pp. 25-30.
    \17\ The FICON 1992 analysis added to the Schultz Curve's 
original database of 161 survey data points and calculated an 
updated dose-response curve using the same methodology but with a 
total of 400 survey data points.
    \18\ FICON, 1992.
    \19\ Ibid., vol. 1, p. 2-6.
---------------------------------------------------------------------------

    The NES's collection of a nationally representative dataset on 
community annoyance in response to aircraft noise provides a 
contemporary update to the Schultz Curve, including technical 
refinements to improve its reliability. As with the Schultz Curve, the 
NES describes community annoyance in terms of the percentage of people 
who are ``highly annoyed'' and describes aircraft noise exposure in 
terms of the DNL noise metric. Based on the 1992 FICON Report, 
discussed previously, both the percentage of population highly annoyed 
and the DNL noise metric have continued to be recognized for this 
purpose including by FICON's successor, the Federal Interagency 
Committee on Aviation Noise in its 2018 report.\20\
---------------------------------------------------------------------------

    \20\ Federal Interagency Committee on Aviation Noise Research 
Review of Selected Aviation Noise Issues (FICAN), 2018.
---------------------------------------------------------------------------

NES Results
    Compared with the Schultz Curve representing transportation noise, 
the NES results show a substantially higher percentage of people highly 
annoyed over the entire range of aircraft noise levels (i.e., from DNL 
50 to 75 dB) at which the NES was conducted. This includes an increase 
in annoyance at lower noise levels. The NES results also show 
proportionally less change in annoyance from the lower noise levels to 
the higher noise levels.
    Comparing the percent of population highly annoyed due to noise 
exposure between the updated Schultz Curve for transportation noise in 
the 1992 FICON Report and the NES:
     At a noise exposure level of DNL 65 dB, the updated 
Schultz Curve from the 1992 FICON Report indicated that 12.3 percent of 
people were highly annoyed, compared to between 60.1 percent and 70.9 
percent within a 95 percent confidence limit from the NES.
     At a noise exposure level of DNL 60 dB, the updated 
Schultz Curve from the 1992 FICON Report indicated that 6.5 percent of 
people were highly annoyed, compared to between 43.8 percent and 53.7 
percent within a 95 percent confidence limit from the NES.
     At a noise exposure level of DNL 55 dB, the updated 
Schultz Curve from the 1992 FICON Report indicated that 3.3 percent of 
people were highly annoyed, compared to between 27.8 percent and 36.8 
percent within a 95 percent confidence limit from the NES.
     At a noise exposure level of DNL 50 dB, the updated 
Schultz Curve from the 1992 FICON Report indicated that 1.7 percent of 
people were highly annoyed, compared to between 15.4 percent and 23.4 
percent within a 95 percent confidence limit from the NES.
    Graphics comparing the updated Schultz Curve from the 1992 FICON 
Report and the curve from the NES are provided on the FAA website at 
www.faa.gov/go/aviationnoise.

[[Page 2726]]

Advancements in Survey Methodology
    Earlier work to understand community response to noise, including 
Schultz's dose-response analysis, was based on the premise that the 
annoyance from any source of noise would be the same for a given DNL 
noise level. However, more recent work has shown that aircraft noise 
often results in higher levels of annoyance compared to the same level 
of noise from ground transportation sources.\21\ There have been 
relatively few surveys of communities in the United States about 
aircraft noise undertaken over the last four decades. However, other 
countries around the world have conducted aircraft noise surveys during 
this time considering aircraft noise separately from noise from other 
modes of transportation. The results of these surveys, as reflected in 
a dose-response relationship published by the International 
Organization for Standardization,\22\ have consistently shown higher 
levels of annoyance than exhibited by the Schultz Curve. Informed by 
these results, the national dose-response curve in the NES report 
reflects only responses to the question about aircraft noise exposure.
---------------------------------------------------------------------------

    \21\ See, for example: Janssen, S., &, Vos, H. (2011). Dose-
Response Relationship between DNL and Aircraft Noise Annoyance: 
Contribution of TNO. Retrieved from TNO Report TNO-060-UT-2011-
00207.
    \22\ International Organization for Standardization. (2016, 
March 1, 2016). International Standard 1996-1, Acoustics--
Description Measurement and Assessment of Environmental Noise--Part 
1: Basic Quantities and Assessment Procedures, 3rd edition.
---------------------------------------------------------------------------

Other Factors
    In addition to enhancements in survey techniques and changes to the 
way aircraft operate, there are likely other factors contributing to a 
change in the way communities respond to aircraft noise. Future work is 
needed to fully understand the specific drivers behind these reasons, 
but several possibilities include:
     Changes to where people are choosing to live, including 
societal migration to increasingly urban environments.\23\ 
Additionally, growth and changes to the makeup of suburban communities 
and their proximity to urban hubs may also be influencing factors on 
community expectations for aircraft noise exposure.
---------------------------------------------------------------------------

    \23\ The U.S. Census Bureau indicates that the percentage of the 
population living in urban areas has increased from 73.6 percent in 
1970 to 80.7 percent in 2010, an increase of 7.1 percent.
---------------------------------------------------------------------------

     How people work and live, including influencing factors 
such as increased in-home business and teleworking in today's 
economy.\24\ Changes in expectations for spending time outdoors versus 
indoors and the associated aircraft noise exposure may also be a 
factor.
---------------------------------------------------------------------------

    \24\ Work to explore changes to how population distribution 
throughout the day are related to aircraft noise exposure is planned 
under Airport Cooperative Research Project (ACRP) 02-84 
[Anticipated] http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=4421.
---------------------------------------------------------------------------

     The rise of social media, the internet, and other national 
and global information sources, leading to an increased awareness and 
perception of local and national noise issues.
     Overall societal response to noise due to a combination of 
these or other factors.
    In addition to the NES, which focuses on annoyance, the FAA is also 
engaged in a range of research initiatives aimed at providing 
information on other impacts of aircraft noise, including effects on 
children's learning, sleep disturbance, and potential health effects. 
Each of these research initiatives focuses on a distinct type of 
potential adverse effect associated with aviation noise exposure. The 
potential adverse effects explored by these initiatives may also be 
factors influencing the annoyance reported by the NES. However, 
research in these areas is still ongoing and therefore was not 
specifically addressed by the NES. Additional details on these research 
programs is provided below.

(2) Noise Modeling, Noise Metrics, and Environmental Data Visualization

    As a core component of FAA's work to address aircraft noise, as 
well as a requirement of its environmental regulatory commitments, the 
FAA must maintain the ability to accurately quantify aircraft noise 
exposure around airports and throughout the National Airspace System. 
High-fidelity modeling is the only practical method to accomplish this 
objective, as aircraft noise needs to be quantified over relatively 
large scales in an efficient and consistent manner. For more than four 
decades, the FAA has worked closely with industry, academic, and 
governmental stakeholders to advance research and development in 
aircraft noise modeling. This effort advances the analytical tools, 
metrics, data, and standards required to provide high quality results 
to inform the public and other stakeholders about noise exposure 
levels. The FAA has also been actively exploring ways to use emerging 
technologies to visualize environmental data including noise exposure.

Aviation Environmental Design Tool

    The Aviation Environmental Design Tool (AEDT) is the FAA's required 
noise and environmental modeling application for all U.S. domestic 
regulatory analyses requiring FAA review. The AEDT also provides 
analysis support for the International Civil Aviation Organization--
Committee on Aviation Environmental Protection, and is used as a 
research and assessment tool by other Federal agencies, universities, 
and industry stakeholders.
    Through collaborations with government, university, and industry 
partners, the FAA actively manages AEDT to ensure that features and 
capabilities are developed to meet expanding environmental analysis 
needs, and to ensure that as new data and technologies become available 
they are incorporated in order to enhance modeling accuracy and 
efficiency. The AEDT builds on a legacy of noise modeling development, 
and is based on detailed aircraft-specific noise measurements and 
internationally accepted aircraft performance models and standards. A 
dynamic development process is used to create new versions of AEDT. 
This process allows for new features and capabilities to be added as 
needed, for example, when required by policy updates or informed by 
emerging research findings.

Noise Screening

    Building from the high-fidelity noise modeling capabilities 
available through AEDT, the FAA is also working to develop an updated 
noise screening tool. This updated noise screening tool will use a 
simplified noise modeling process to facilitate an expedited review of 
proposed Federal actions where significant noise impacts are not 
expected. Such an approach is beneficial where a proposed Federal 
Action is limited in scope and could qualify for a categorical 
exclusion under the FAA's procedures for implementing the National 
Environmental Policy Act (NEPA).\25\ The primary goal of updating the 
noise screening tool is to decrease the amount of time that an analyst 
will need to conduct an assessment while also ensuring a fully 
validated result that is readily understandable by the public. While 
the output from a noise screening tool cannot provide the same level of 
detail as a comprehensive modeling tool, the simplified process 
provides for an expedited initial view of

[[Page 2727]]

any potential changes in aircraft noise exposure.
---------------------------------------------------------------------------

    \25\ See FAA Order 1050.1F, Environmental Impacts: Policies and 
Procedures, Chapter 5 (``Categorical Exclusions'').
---------------------------------------------------------------------------

Environmental Data Visualization

    The FAA has been developing ways to utilize geospatial data to 
improve the agency's ability to communicate environmental data to the 
public. For example, the FAA has designed an Environmental 
Visualization Tool to take advantage of the availability of high 
quality geospatial data to deliver an agency-wide resource using a 
consistent, common visual language. Once fully implemented, this common 
visualization platform will serve the needs of multiple environmental 
programs within the FAA, including those presenting aircraft noise data 
to the public.

Supplemental Noise Metrics

    The FAA's primary noise metric, DNL, was developed and validated to 
identify significant aviation noise exposure for land use and 
mitigation planning as well as for determining significant change in 
noise exposure under NEPA review. In some cases, however, it can be 
useful to supplement DNL with the use of other noise metrics. While 
other noise metrics may not provide as complete an understanding of the 
cumulative noise exposure from activity around an airport and its 
associated airspace, they often can provide opportunities to 
communicate the specific characteristics of noise changes due to the 
unique aspects of a proposed action. The FAA's NEPA procedures address 
the use of supplemental noise metrics.\26\ To assist the public in 
understanding noise impacts, and to better facilitate communication 
among communities interested in systematic departure flight track 
dispersion, the FAA is working to assess the use of potential 
supplemental metrics. For a supplemental metric to be effective in 
evaluating potential means of achieving flight track dispersion, and to 
ensure that communities understand the impacts of dispersion (i.e., 
that dispersion does not eliminate noise but rather it may move noise 
to other neighborhoods), the supplemental metric will need to 
effectively communicate the changes in noise exposure that will occur 
in all of the communities affected by the change, both those that would 
be exposed to less noise and those that would be exposed to more 
noise.\27\
---------------------------------------------------------------------------

    \26\ See FAA Order 1050.1F, Environmental Impacts: Policies and 
Procedures, Appendix B, paragraph B-1.6; 1050.1F Desk Reference, 
Section 11.4.
    \27\ FAA, 2020, Report to Congress: FAA Reauthorization Act of 
2018 (Pub. L. 115-254) Section 188 and Sec 173, https://www.faa.gov/about/plans_reports/congress/media/Day-Night_Average_Sound_Levels_COMPLETED_report_w_letters.pdf.
---------------------------------------------------------------------------

(3) Reduction, Abatement, and Mitigation of Aviation Noise

    To directly address noise concerns, the FAA sponsors multiple 
research programs to explore different concepts for aircraft noise 
reduction. As aircraft noise is a complex issue, no single concept is 
capable of providing a universal solution. However, by conducting 
research across different areas, the FAA is developing solutions to 
reduce noise at its source, abate noise through operations, and 
mitigate the effects of noise on communities. The intent of this 
approach is to have a variety of options to reduce the noise being 
experienced by those living near airports around the country and to 
have options that could be tailored to specific airports.

Aircraft Source Noise Reduction

    As noted previously, the single most influential factor in the 
historical decline in noise exposure was the phased transition to 
quieter aircraft. Through the public-private partnership of the 
Continuous Lower Energy, Emissions, and Noise (CLEEN) Program, the FAA 
and industry are working together to develop technologies that will 
enable manufacturers to create aircraft and engines with lower noise 
and emissions as well as improved fuel efficiency.\28\ The technologies 
being accelerated by the CLEEN Program have relatively large 
technological risk. Government resources help mitigate this risk and 
incentivize aviation manufacturers to invest and develop these 
technologies. By cost-sharing the development with the FAA, industry is 
willing to accept the greater risk and can better support the business 
case for this technological development. Once entered into service, the 
CLEEN technologies will provide societal benefits in terms of reduced 
noise, fuel burn, and emissions throughout the fleet for years to come. 
In addition to the benefits provided by technologies developed under 
the CLEEN, the program leads to advances in the analysis and design 
tools that are used on every aircraft or engine product being made by 
these companies; this extends the benefits of the CLEEN Program well 
beyond the individual technologies being matured.
---------------------------------------------------------------------------

    \28\ See, for example, information on the FAA's ``Continuous 
Lower Energy, Emissions, and Noise'' (CLEEN) Program at: https://www.faa.gov/about/office_org/headquarters_offices/apl/research/aircraft_technology/cleen/.
---------------------------------------------------------------------------

    As new aircraft and engine technologies lead to quieter aircraft 
over time, the FAA works to establish aircraft certification standards 
based on noise stringency requirements. These standards are a 
requirement of the airworthiness process and are described in 14 CFR 
part 36. These requirements do not force manufactures to develop new 
technology. However, as new noise reduction technologies emerge they do 
ensure that new aircraft continue to meet increasingly quieter 
standards within the bounds of what is technologically feasible and 
economically reasonable.

Noise Abatement

    The FAA is also supporting multiple efforts to identify means to 
abate noise through changes in how aircraft are operated in the 
airspace over communities. In the immediate vicinity of an airport, use 
of voluntary noise abatement departure procedures (NADP) has been a 
longstanding technique available to reduce noise. Recent research is 
examining the effectiveness of these procedures and identifying means 
of improving their use.
    As the FAA works to modernize the National Airspace System, new 
aircraft flight procedures have been designed to take advantage of PBN 
technologies. To better understand both the environmental benefits and 
challenges posed by PBN, the FAA is working to re-examine ways to 
routinely consider noise during flight procedure design. This effort 
includes an exploration of how PBN can better control flight paths and 
move them away from noise-sensitive areas, how changes in aircraft 
performance could be safely managed to reduce noise, and how systematic 
departure flight track dispersion can be implemented to abate noise 
concerns.
    In a recent partnership with the Massachusetts Port Authority 
(Massport) and MIT, the FAA jointly contributed to research considering 
how Area Navigation (RNAV) PBN procedures could be designed and 
implemented to reduce noise. Multiple concepts were explored that 
highlighted how collaborations between the FAA, airport operators, and 
community members can produce innovative noise abatement strategies.
    A recently completed analysis of operational procedures that 
resulted from the Massport-MIT-FAA partnership shows that for modern 
aircraft on departure, changes in aircraft climb speed have minimal 
impact on the overall aircraft departure noise. The current best 
practice for NADP, using International Civil Aviation Organization 
distant community or

[[Page 2728]]

``NADP-2'' departure procedure, has been shown to minimize modeled 
noise impacts. This analysis also shows that for modern aircraft on 
arrival, changes in approach airspeed could have a noticeable impact 
(reductions of 4-8 dBA) on the overall aircraft noise at relatively 
large distances from touching down (between 10 and 25 nautical miles 
from the runway). While NADP procedures have the potential to reduce 
community noise, they may also have implementation challenges that will 
need to be overcome. Research is ongoing at MIT to address these 
challenges.\29\
---------------------------------------------------------------------------

    \29\ https://ascent.aero/project/analytical-approach-for-quantifying-noise-from-advanced-operational-procedures/, https://ascent.aero/project/aircraft-noise-abatement-procedure-modeling-and-validation/.
---------------------------------------------------------------------------

    In addition to airplane operations, the FAA is also examining the 
potential for helicopter noise abatement through changes in operational 
procedures. The FAA has partnered with the Volpe Center, the National 
Aeronautics and Space Administration, the Pennsylvania State 
University, and operator organizations to explore new ways to safely 
fly rotorcraft while also reducing noise through the Fly Neighborly 
Program.\30\
---------------------------------------------------------------------------

    \30\ https://www.rotor.org/initiatives/fly-neighborly.
---------------------------------------------------------------------------

Noise Mitigation Research

    Noise mitigation is the effort to take actions to reduce the impact 
of aircraft noise exposure that occurs. The primary mitigation 
strategies involve encouraging responsible land use planning in airport 
communities and, where appropriate, the application of sound insulation 
treatments to eligible homes or other noise-sensitive public buildings 
(e.g., schools or hospitals). In extreme cases where sound insulation 
technologies cannot provide adequate mitigation, the acquisition of 
residential homes and conversion to non-residential land use is also an 
option.
    As sound insulation treatment costs have continued to rise and new 
research on the human impacts from noise becomes available, the FAA is 
exploring the cost-benefit calculus of existing noise mitigation 
strategies and technologies in order to better direct where and how 
limited mitigation resources should be applied. Recent academic 
research \31\ and internal assessments have raised questions about the 
benefits of sound insulation relative to the costs. While the relative 
benefits of sound insulation for noise exposures above DNL 65dB will 
depend on the individual home treatment costs, minimal benefit can be 
expected for sound insulation treatments applied for noise exposures 
below DNL 65dB.
---------------------------------------------------------------------------

    \31\ Wolfe, Malina, Barrett & Waitz 2016, Cost and benefits of 
US Aviation noise land-use policies, Transportation Research Part D.
---------------------------------------------------------------------------

Aircraft Noise Policy Background

    Community response to noise has historically been a primary factor 
underlying the FAA's noise-related policies, including the 
establishment of DNL 65 dB as the threshold of ``significant'' aircraft 
noise exposure. The FAA has been using a DNL of 65 dB as the basis for: 
(1) Setting the agency's policy goal of reducing the number of people 
exposed to significant aircraft noise; \32\ (2) the level of aircraft 
noise exposure below which residential land use is ``normally 
compatible,'' as defined in regulations implementing the Aviation 
Safety and Noise Abatement Act of 1979,\33\ and (3) the level of 
aircraft noise exposure below which noise impacts of FAA actions in 
residential areas are not considered ``significant'' under section 
102(2)(C) of the National Environmental Policy Act of 1969.\34\
---------------------------------------------------------------------------

    \32\ See ``Aviation Environmental and Energy Policy Statement,'' 
77 FR 43137, 43138 (July 23, 2012), available on the FAA website at 
[URL]. The ``noise goal'' identified in this document includes 
``[r]educ[ing] the number of people exposed to significant noise 
around U.S. airports.''
    \33\ 49 U.S.C. 47502. The regulations implementing this section 
are codified at 14 CFR part 150.
    \34\ 49 U.S.C. 4332(2)(C). See FAA Order 1050.1F, 
``Environmental Impacts: Policies and Procedures'' (2015), Exhibit 
4-1. The significance threshold for noise used for NEPA purposes in 
FAA Order 1050.1F is also used by the FAA for determining 
significant adverse noise effects under 49 U.S.C. 47106(c)(1)(B) for 
airport development projects involving the location of an airport or 
runway or a major runway extension. See 80 FR 44209, 44223 (July 24, 
2015) (preamble to FAA Order 1050.1F).
---------------------------------------------------------------------------

    Research results, as reflected in the programs and studies 
described in this notice, will provide new information on how aircraft 
noise in communities near airports may be effectively managed and will 
inform future decision making on the FAA's aircraft noise policies.
    However, as previously stated, the FAA will not make any 
determinations on implications from these emerging research results for 
FAA noise policies until it has carefully considered public and other 
stakeholder input, and assesses the factors behind any increases in 
community impacts from aircraft noise exposure. Unless and until any 
changes become effective, all existing FAA regulations, orders, and 
policies remain in effect. The FAA is committed to informing and 
involving the public, and to giving meaningful consideration to 
community concerns and views as the FAA makes aviation decisions that 
affect them.

Comments Invited

    The FAA recognizes that a range of factors may be driving concerns 
due to aircraft noise. However, as outlined in this notice, a broad 
understanding of aircraft noise and its potential impacts is needed in 
order to better manage and reduce concerns from aviation noise.
    The FAA is inviting comments on these concerns to assist the agency 
in assessing how resources should be directed to better understand and 
manage the factors underlying the concern from aircraft noise exposure.
    Comments that focus on the questions listed below will be most 
helpful. The more specific the comments, the more useful they will be 
in the FAA's considerations.
    (1) What, if any, additional investigation, analysis, or research 
should be undertaken in each of the following three categories as 
described in this notice:
     Effects of Aircraft Noise on Individuals and Communities;
     Noise Modeling, Noise Metrics, and Environmental Data 
Visualization; and
     Reduction, Abatement, and Mitigation of Aviation Noise?
    (2) As outlined in this notice, the FAA recognizes that a range of 
factors may be driving the increase in annoyance shown in the 
Neighborhood Environmental Survey results compared to earlier 
transportation noise annoyance surveys--including survey methodology, 
changes in how commercial aircraft operate, population distribution, 
how people live and work, and societal response to noise. The FAA 
requests input on the factors that may be contributing to the increase 
in annoyance shown in the survey results.
    (3) What, if any, additional categories of investigation, analysis, 
or research should be undertaken to inform FAA noise policy?

    Authority: National Environmental Policy Act (NEPA) 42 U.S.C. 
4321 et. seq., Aviation Safety and Noise Abatement Act (ASNA) 49 
U.S.C. 47501 et. seq., Federal Aviation Act, 49 U.S.C. 44715.

    Issued in Washington, DC.
Kevin Welsh,
Director, Office of Environment and Energy.
[FR Doc. 2021-00564 Filed 1-12-21; 8:45 am]
BILLING CODE 4910-13-P