Aviation and the Environment: FAA's and NASA's Research and	 
Development Plans for Noise Reduction Are Aligned but the	 
Prospects of Achieving Noise Reduction Goals Are Uncertain	 
(15-FEB-08, GAO-08-384).					 
                                                                 
Reducing aviation noise is important to the efficient operation  
and expansion of the National Airspace System because community  
opposition to aviation noise is a major obstacle to airport and  
runway development. Such development is needed to help address	 
congestion and meet the nation's rapidly growing demand for air  
travel. The Federal Aviation Administration (FAA) and the	 
National Aeronautics and Space Administration (NASA) have the	 
primary federal responsibility for research and development (R&D)
on aviation noise. FAA focuses on the impacts of aviation noise  
on communities, while NASA focuses on noise at its		 
source--aircraft engines and airframes. Both FAA and NASA have	 
set noise reduction goals. This congressionally requested report 
on aviation noise addresses (1) FAA's and NASA's R&D plans for	 
addressing aviation noise and the extent to which they are	 
aligned and (2) FAA's and NASA's noise reduction goals and the	 
likelihood that these goals will be achieved. To conduct its	 
work, GAO reviewed FAA's and NASA's R&D planning documents,	 
coordinating mechanisms, and research plans and interviewed	 
agency officials. In addition, aviation industry representatives 
reviewed and commented on a draft of this report. A draft was	 
provided to FAA and NASA. Both agencies had no comment. 	 
-------------------------Indexing Terms------------------------- 
REPORTNUM:   GAO-08-384 					        
    ACCNO:   A80850						        
  TITLE:     Aviation and the Environment: FAA's and NASA's Research  
and Development Plans for Noise Reduction Are Aligned but the	 
Prospects of Achieving Noise Reduction Goals Are Uncertain	 
     DATE:   02/15/2008 
  SUBJECT:   Aircraft engines					 
	     Aircraft research					 
	     Aviation						 
	     Commercial aviation				 
	     Interagency relations				 
	     Noise pollution					 
	     Noise pollution control				 
	     Program evaluation 				 
	     Research and development				 
	     Strategic planning 				 
	     Program goals or objectives			 
	     Next Generation Air Transportation 		 
	     System						 
                                                                 

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**                                                              **
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GAO-08-384

   

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material separately. 

Report to Congressional Committees: 

GAO: 

February 2008: 

Aviation And The Environment: 

FAA's and NASA's Research and Development Plans for Noise Reduction Are 
Aligned but the Prospects of Achieving Noise Reduction Goals Are 
Uncertain: 

GAO-08-384: 

GAO Highlights: 

Highlights of GAO-08-384, a report to congressional committees. 

Why GAO Did This Study: 

Reducing aviation noise is important to the efficient operation and 
expansion of the National Airspace System because community opposition 
to aviation noise is a major obstacle to airport and runway 
development. Such development is needed to help address congestion and 
meet the nationï¿½s rapidly growing demand for air travel. The Federal 
Aviation Administration (FAA) and the National Aeronautics and Space 
Administration (NASA) have the primary federal responsibility for 
research and development (R&D) on aviation noise. FAA focuses on the 
impacts of aviation noise on communities, while NASA focuses on noise 
at its sourceï¿½aircraft engines and airframes. Both FAA and NASA have 
set noise reduction goals. This congressionally requested report on 
aviation noise addresses (1) FAAï¿½s and NASAï¿½s R&D plans for addressing 
aviation noise and the extent to which they are aligned and (2) FAAï¿½s 
and NASAï¿½s noise reduction goals and the likelihood that these goals 
will be achieved. To conduct its work, GAO reviewed FAAï¿½s and NASAï¿½s 
R&D planning documents, coordinating mechanisms, and research plans and 
interviewed agency officials. In addition, aviation industry 
representatives reviewed and commented on a draft of this report. A 
draft was provided to FAA and NASA. Both agencies had no comment. 

What GAO Found: 

FAAï¿½s and NASAï¿½s R&D plans include a wide range of projects for 
addressing aviation noise, and these plans are aligned through 
partnerships and planning and coordinating mechanisms. FAA sponsors 
aviation noise R&D in areas such as aviation noise measurement, 
aviation noise effects, aviation noise and emissions 
interrelationships, and flight procedures and technologies to mitigate 
the impact of noise on communities. FAA sponsors much of this research 
through partnerships with universities; other federal agencies, 
including NASA; and industry. NASA conducts R&D that can eventually 
lead to new technologies for making substantially quieter aircraft 
provided that the technologies are further developed by industry and 
integrated into production-ready aircraft designs. FAA and NASA have 
aligned their aviation noise R&D activities by working with interagency 
planning and coordinating groups to establish objectives for the 
nationï¿½s aeronautical research and for specific research on the 
environmental impacts of next generation aviation technologies. Both 
agencies also serve on the same aviation research advisory groups, and 
the alignment of their aviation noise R&D activities is reflected in 
strategic plans for the National Airspace System that indicates how 
each agencyï¿½s R&D efforts will contribute to meeting goals for reducing 
noise and thereby help reduce community opposition to increasing 
aviation system capacity. FAAï¿½s and NASAï¿½s noise reduction goals are 
designed, together, to reduce peopleï¿½s exposure to aviation noise 
primarily by reducing such noise at its source, but the likelihood of 
achieving these goals is uncertain. Under FAAï¿½s targets, the number of 
people exposed to significant aviation noiseï¿½estimated at 500,000 
nationwideï¿½would be reduced by 4 percent a year through fiscal year 
2012. NASAï¿½s targets, established for the next three generations of 
aircraft, would lead to the entry into service of successively quieter 
aircraft by 2015, 2020-2025, and 2030-2035, respectively. The 
likelihood of meeting these targets depends on a number of 
uncertainties. First, federal funding will be needed not only for 
NASAï¿½s research but also for later-stage R&D, which NASA expects others 
to perform. The administration has proposed a 10-year program to 
support later-stage R&D to demonstrate technologies for industry 
acceptance. But even if funded, the development of noise reduction 
technologies may be limited by concerns about global warming, since 
advances in these technologies could make it more difficult to also 
achieve reductions in aircraft emissions of greenhouse gases. Also 
uncertain is the extent to which manufacturers will integrate newly 
developed technologies into aircraft and engine designs. Finally, it is 
uncertain whether airlines will purchase new aircraft or retrofit 
existing aircraft with the new technologies in sufficient numbers to 
achieve targeted reductions in exposure to aviation noise. Failure to 
achieve FAAï¿½s and NASAï¿½s noise reduction goals could constrain efforts 
to expand the National Airspace Systemï¿½s capacity and reduce 
congestion. 

To view the full product, including the scope and methodology, click on 
[hyperlink, http://www.GAO-08-384]. For more information, contact 
Gerald L. Dillingham at (202) 512-2834 or [email protected]. 

[End of section] 

United States Government Accountability Office: 

Contents: 

Letter: 

Results in Brief: 

FAA and NASA Use Partnerships and Planning and Coordinating Mechanisms 
to Align R&D on Noise Reduction: 

FAA and NASA Have Established Noise Reduction Technology Goals, but R&D 
Funding Issues and Other Factors Make the Achievement of Noise 
Reduction Goals Uncertain: 

Agency Comments: 

Appendix I: PARTNER Participants and Projects: 

Appendix II: NASA Letter to GAO: 

Appendix III: GAO Contact and Staff Acknowledgments: 

Tables: 

Table 1: AIP and PFC Investments for Noise-Related Purposes for Fiscal 
Years 1982-2007: 

Table 2: FAA Funds for R&D Efforts in Fiscal Years 1997-2007: 

Table 3: NASA's N+X Generation Aircraft Program: 

Figure: 

Figure 1: NASA's Research Approach Triangle: 

Abbreviations: 

ADS-B: Automatic Dependent Surveillance-Broadcast: 

AIP: Airport Improvement Program: 

CDA: Continuous Descent Arrival: 

CLEEN: Continuous Lower Energy, Emissions and Noise: 

dB: decibel: 

DNL: day-night level: 

EPN: effective perceived noise: 

FAA: Federal Aviation Administration: 

ICAO: International Civil Aviation Organization: 

JPDO: Joint Planning and Development Office: 

MOU: memorandum of understanding: 

NAS: National Airspace System: 

NASA: National Aeronautics and Space Administration: 

NextGen: Next Generation Air Transportation System: 

NRA: NASA Research Announcement: 

OSTP: Office of Science and Technology Policy: 

PARTNER: Partnership for Air Transportation Noise and Emissions 
Reductions: 

PFC: passenger facility charge: 

R&D: research and development: 

REDAC: Research, Engineering, and Development Advisory Committee: 

United States Government Accountability Office: 

Washington, DC 20548: 

February 15, 2008: 

The Honorable Mark Udall: 
Chairman: 
The Honorable Tom Feeney: 
Ranking Member: 
Subcommittee on Space and Aeronautics: 
Committee on Science and Technology: 
House of Representatives: 

The Honorable Jerry Costello: 
Chairman: 
The Honorable Thomas Petri: 
Ranking Republican Member: 
Subcommittee on Aviation: 
Committee on Transportation and Infrastructure: 
House of Representatives: 

Aviation noise continues to be a challenge to the operation and 
expansion of the National Airspace System (NAS). Air traffic has grown 
steadily over the past 5 years and is expected to continue growing as 
more flights are required to carry the 1 billion passengers anticipated 
by 2015. To handle the forecasted growth, the Joint Planning and 
Development Office (JPDO), an interagency organization within the 
Department of Transportation's Federal Aviation Administration (FAA), 
is working to plan a new air traffic management system, the Next 
Generation Air Transportation System (NextGen). Critical objectives for 
NextGen are to improve the overall safety and increase the efficiency 
of the NAS. Achieving these objectives will involve the implementation 
of new technologies and air traffic control procedures; airspace 
redesigns; and infrastructure developments, including new or expanded 
runways and airports. However, community opposition to these 
developments is a major challenge, largely because of concerns about 
aviation noise. According to JPDO's 2007 Concept of Operations 
document, current operational trends show that environmental impacts 
will be the primary constraint on the capacity and flexibility of the 
NAS unless these impacts are managed and mitigated. Legislative 
proposals to reauthorize FAA[Footnote 1] include a number of provisions 
designed to address aviation noise issues. 

To address aviation noise and its impacts, the federal government 
follows a "balanced approach" recommended by the International Civil 
Aviation Organization (ICAO).[Footnote 2] This balanced approach 
recognizes that short-term opportunities to mitigate the impacts of 
noise on communities through noise abatement programs, the 
soundproofing of residences and public buildings, and operational 
restrictions on aircraft should be combined with longer-term efforts to 
reduce aviation noise. Such longer-term efforts include reducing noise 
at its source through more stringent noise standards and supporting 
research and development (R&D) to make aircraft quieter, developing and 
implementing NextGen technologies and procedures, and encouraging 
compatible land use. As part of this balanced approach, FAA and the 
National Aeronautics and Space Administration (NASA) have the principal 
federal responsibility for R&D to address aviation noise. FAA, through 
its partnerships with universities and through JPDO, supports a broad 
range of research on measuring and reducing the impacts of noise on 
communities, while NASA's research program focuses on reducing noise at 
its source--in aircraft engines and airframes. NASA, in partnership 
with the aircraft and engine manufacturing industry, has contributed to 
a number of advancements in aircraft engine and airframe technology 
that have substantially reduced the amount of noise produced by 
aircraft and may lead to further reductions, depending on the extent to 
which current research leads to noise-reducing aircraft engine and 
airframe designs and other factors. FAA and NASA have set technology 
goals for reducing aviation noise. For example, FAA has set a system- 
level goal of a 4 percent yearly reduction in the number of people 
exposed to significant aviation noise. 

You requested that we study noise and other environmental impacts of 
aviation that may fundamentally constrain air transportation in the 
21st century. In October 2007, we testified before the Subcommittee on 
Aviation, House Transportation and Infrastructure Committee, on the 
impacts of aviation noise on efforts to expand the capacity of airports 
and the NAS.[Footnote 3] This report provides additional information on 
aviation noise, focusing particularly on FAA's and NASA's R&D related 
to this issue and on the ability of the two agencies to achieve their 
respective noise reduction goals through their R&D on aviation noise. 
Specifically, we addressed the following questions: 

1. What are FAA's and NASA's R&D plans for addressing aviation noise 
and to what extent are these plans aligned? 

2. What are FAA's and NASA's noise reduction goals, and what is the 
likelihood that the established goals will be achieved? 

To determine FAA's and NASA's aviation noise R&D plans, we reviewed FAA 
and NASA R&D planning documents and other information provided by these 
agencies on their near-term and long-term goals. To determine the 
extent to which FAA's and NASA's aviation noise-related activities are 
aligned to meet noise reduction goals, we obtained and analyzed 
information on mechanisms in place to coordinate noise R&D activities, 
such as JPDO's Environmental Working Group and FAA's Research, 
Engineering, and Development Advisory Committee (REDAC). We also 
compared FAA's and NASA's R&D plans to determine whether they are 
complementary and in line with JPDO's and the Executive Office of the 
President's Office of Science and Technology Policy's (OSTP) plans. We 
also analyzed how the agencies periodically assess the potential for 
synergies or gaps in research activities. In addition, we interviewed 
agency officials on the results of our analyses. To determine FAA's and 
NASA's noise reduction goals and the likelihood of meeting those goals, 
we reviewed FAA and NASA R&D planning documents and other information 
provided by the agencies. We also interviewed agency officials to 
obtain their views on the likelihood of meeting noise reduction goals 
within the established time frames. Three external aviation experts 
reviewed a draft of this report for accuracy and balance. We conducted 
this performance audit from November 2007 through February 2008 in 
accordance with generally accepted government auditing standards. Those 
standards require that we plan and perform the audit to obtain 
sufficient, appropriate evidence to provide a reasonable basis for our 
findings and conclusions based on our audit objectives. We believe that 
the evidence obtained provides a reasonable basis for our findings and 
conclusions based on our audit objectives. 

Results in Brief: 

FAA's and NASA's R&D plans include a wide range of projects for 
addressing aviation noise, and these activities are aligned through 
partnerships and planning and coordinating mechanisms. FAA sponsors 
aviation noise R&D in a number of areas, including aviation noise 
measurement, the effects of aviation noise, the interrelationships 
between aviation noise and emissions, and flight procedures and 
technologies that can mitigate the impacts of noise on communities. FAA 
sponsors much of this research through partnerships with universities; 
other federal agencies, including NASA; and industry as part of its 
Partnership for Air Transportation Noise and Emissions Reduction 
(PARTNER) Center of Excellence.[Footnote 4] NASA is the federal agency 
primarily responsible for conducting R&D to reduce the amount of noise 
produced by aircraft engines and airframes. NASA's aviation noise 
efforts focus on what NASA refers to as "fundamental research", a stage 
of the R&D process that takes a technology to a point where it can be 
further matured by manufacturers and eventually incorporated into new 
aircraft or engine designs. These technologies have the potential to 
make the next generations of aircraft substantially quieter than 
today's aircraft--provided that industry further develop the 
technologies and manufacturers integrate them into production-ready 
aircraft. FAA and NASA have aligned their aviation noise R&D plans 
through a number of planning and coordinating mechanisms in order to 
ensure that these plans are complementary and contribute to goals for 
addressing the environmental impacts of aviation, particularly as these 
impacts relate to the implementation of NextGen. FAA and NASA have 
participated in planning and establishing objectives for the nation's 
aeronautical research through OSTP, within the Executive Office of the 
President, as well as for specific research to address the 
environmental impacts of NextGen as part of JPDO's Environmental 
Working Group. In addition, FAA and NASA sit on the advisory board of 
PARTNER, which also includes representatives from the aircraft 
manufacturing industry, airlines, airports, and communities. 
Furthermore, NASA is a member of FAA's REDAC, and FAA participates in 
reviews of NASA's aviation noise research program. FAA's and NASA's 
alignment of their aviation noise R&D activities is reflected in JPDO's 
strategic plans for NextGen, which indicate how each agency's R&D 
efforts will contribute to meeting goals for reducing noise and thereby 
help to address an impediment to increasing the aviation system's 
safety and efficiency. 

In conjunction with their aligned R&D plans, FAA and NASA have set 
noise reduction goals, although the likelihood that these goals will be 
achieved depends on the implementation of noise reduction technologies 
developed through the agencies' research and other factors. FAA 
estimates that about 500,000 people in the United States are 
significantly impacted by aviation noise, and, under FAA's goal, the 
number of people exposed to aviation noise would decrease by 4 percent 
a year through fiscal year 2012.[Footnote 5] NASA's noise goals, 
established for the next three generations of aircraft, could lead to 
the entry into service of successively quieter aircraft. NASA's goals 
include a cumulative reduction[Footnote 6] in the effective perceived 
noise (EPN)[Footnote 7] of 32 decibels (dB)--expressed as a noise 
reduction of 32 EPN dB--relative to the current most stringent noise 
standard, for the next generation of aircraft expected to enter service 
in 2015. More aggressive NASA goals for the generations of aircraft 
entering service from 2020 through 2025 and from 2030 through 2035 are 
cumulative reductions of 42 EPN dB and 71 EPN dB, respectively, 
relative to the standard. NASA's goals would be achieved if noise 
reduction is the only aim; however, when other factors are considered, 
such as the need to reduce aircraft emissions, the noise reductions 
could be lower. 

NASA officials stress that when NASA's research ends, it is up to 
industry to develop the technologies further. Thus, aircraft and engine 
manufacturers will then need to integrate the technologies into 
aircraft and engine designs, and there are no guarantees that these 
additional steps will be taken. According to FAA, additional funding is 
needed to ensure the continued development and use of near-term 
technologies to meet noise reduction goals for NextGen. To move noise 
reduction technologies beyond NASA's stage of development, the House 
fiscal year 2007 reauthorization proposal for FAA includes the 
Continuous Lower Energy, Emissions and Noise (CLEEN) initiative, which 
would create a program for the development, maturation, and 
certification of airframe technologies for aircraft over the next 10 
years to reduce aviation noise and emissions.[Footnote 8] According to 
FAA, the program, in which NASA will participate as an adviser, is 
intended to accelerate near-term technology maturation and to 
demonstrate to aircraft and engine manufacturers the readiness of these 
technologies for incorporation into new aircraft and engine designs. 
Concern about other environmental problems, such as global warming and 
air quality, may also limit the likelihood of achieving FAA's and 
NASA's noise reduction goals, since it will be technologically 
challenging to design aircraft with reduced noise while, at the same 
time, achieving the significant reductions in greenhouse gases and 
other emissions that will be required. Furthermore, even if R&D efforts 
do lead to next generation aircraft that meet NASA's noise reduction 
goals, integrating these quieter aircraft into the fleet to the extent 
that they have a significant impact on noise reduction will be a 
challenge. Aircraft have a lifespan of about 30 years, and many of the 
aircraft in the current fleet are expected to be in operation for many 
years to come. In addition, the financial pressures facing many 
airlines will make it difficult for them to upgrade their fleets with 
new, quieter aircraft. Failure to achieve FAA's and NASA's noise 
reduction goals could have implications for the implementation of 
NextGen, because continued noise problems at airports could constrain 
efforts to increase the safety and efficiency of the NAS--a key 
component of the NextGen strategy. 

We provided a draft of this report to the Department of Transportation 
and NASA for review and comment and neither had comments. 

FAA and NASA Use Partnerships and Planning and Coordinating Mechanisms 
to Align R&D on Noise Reduction: 

FAA presently supports aviation noise R&D primarily in the areas of 
measuring and mitigating the impacts of aviation noise, while NASA 
focuses its efforts on technologies for reducing noise from aircraft 
engines and airframes, and the two agencies align their activities 
through partnerships and planning and coordinating mechanisms. 

FAA Supports Aviation Noise R&D Primarily through Partnerships with 
NASA, Academic Institutions, and the Aviation Industry: 

FAA's support of aviation noise R&D is part of its overall 
responsibility for reducing the impacts of aviation noise. In addition 
to R&D activities, FAA supports airports' efforts to mitigate aviation 
noise mainly through its voluntary noise compatibility program, known 
as the Part 150 Noise Compatibility Program,[Footnote 9] which provides 
guidance to airports on how to develop noise compatibility plans to 
mitigate noise on and around airports.[Footnote 10] FAA also 
administers grants through the Part 150 program that airports can use 
for noise mitigation efforts in areas exposed to significant aviation 
noise, defined as a 65 decibel day- night level (DNL 65 dB).[Footnote 
11] 

Airports that participate in the Part 150 program can receive noise set-
aside funds from the Airport Improvement Program (AIP),[Footnote 12] 
which they must match to varying degrees, depending on their 
size.[Footnote 13] These funds can be used to, among other things, 
develop plans for noise mitigation, soundproof buildings, and support 
relocation by acquiring homes in areas with significant noise. 
According to FAA, it has provided about $5 billion in AIP grants, and 
airports have used about $2.8 billion in passenger facilities charges 
(PFC)[Footnote 14] for Part 150 noise mitigation studies and projects. 
In total, this funding amounts to nearly $8 billion for fiscal years 
1982 through 2007 (see table 1). 

Table 1: AIP and PFC Investments for Noise-Related Purposes for Fiscal 
Years 1982-2007: 

Dollars in millions. 

AIP Funds: Mitigation measures for residences; 
Funding: $1,903. 

AIP Funds: Land acquisition; 
Funding: 2,170. 

AIP Funds: Noise monitoring system; 
Funding: 170. 

AIP Funds: Mitigation measures for public buildings; 
Funding: 703. 

AIP Funds: Noise compatibility plan; 
Funding: 87. 

Total AIP funds; 
Funding: $5,033. 

PFC funds: Multiphase; 
Funding: $1,283. 

PFC funds: Land acquisition; 
Funding: 481. 

PFC funds: Soundproofing; 
Funding: 1,018. 

PFC funds: Monitoring; 
Funding: 31. 

PFC funds: Planning; 
Funding: 15. 

Total PFC funds; 
Funding: $2,828. 

Grand total; 
Funding: $7,861. 

Source: FAA. 

[End of table] 

FAA sponsors aviation noise R&D in a number of areas, including 
aviation noise measurement, the effects of aviation noise, the 
interrelationships between aviation noise and emissions, and flight 
procedures and technologies that can mitigate the impacts of noise on 
communities. FAA sponsors much of this research through partnerships 
with universities, other federal agencies, and industry. University 
research is generally part of FAA's Air Transportation Centers of 
Excellence program. One of these Centers of Excellence, PARTNER, has 
conducted numerous noise-related R&D projects. See appendix I for a 
list of PARTNER participants and projects. PARTNER is a cooperative 
research organization that includes 10 collaborating universities and 
approximately 50 advisory board members who represent aerospace 
manufacturers, airlines, airports, state and local governments, and 
professional and community groups. NASA, along with FAA and Transport 
Canada,[Footnote 15] is a sponsor of PARTNER. The collaborating 
universities and organizations represented on the advisory board 
provide equal matches for federal funds for research and other 
activities. 

PARTNER projects related to aviation noise involve identifying a means 
to reduce aircraft landing noise, assessing the human health and 
welfare risks of aviation noise, developing online resources to better 
inform the public about aviation noise issues, and testing alternative 
aircraft descent patterns. For example, researchers are developing an 
integrated suite of three analytical tools--the Environmental Design 
Space, the Aviation Environmental Design Tool, and the Aviation 
Environmental Portfolio Management Tool--that can be used to identify 
interrelationships between noise and emissions. Data from these three 
tools will allow for assessing the costs and benefits of aviation 
environmental policy options. PARTNER has also designed and flight 
tested a nighttime Continuous Descent Arrival (CDA) procedure for the 
Louisville International Airport.[Footnote 16] This procedure is 
expected to allow aircraft to remain at cruise altitudes longer as they 
approach destination airports, use lower power levels, and thereby 
lower noise and emissions during landings. United Parcel Service plans 
to begin using the CDA procedure for its operations at Louisville 
International Airport in the near future. Other PARTNER projects 
include an effort to assess sonic booms from a new supersonic business 
aircraft and studies to better understand land use, development, and 
aviation noise around airports. 

FAA also supports research efforts at the Department of 
Transportation's Volpe National Transportation Systems Center. The 
Volpe Center provides research and support for the Integrated Noise 
Model, which airports use to model aviation noise at airports. Noise 
mitigation measures, such as residential soundproofing, are based on 
the noise contour maps generated by this model. The Volpe Center also 
conducts noise modeling studies. For example, it has conducted studies 
of aviation noise over the Grand Canyon in Arizona and over Bryce 
Canyon in Utah. FAA also has contracts with other entities such as Wyle 
Labs and Aerodyne Research to improve noise measurement through 
modeling. For example, Wyle Labs performs work on the Model for 
Assessing Global Exposure to the Noise of Transport Aircraft, which 
estimates the global population exposed to noise and the effects of 
different mitigation scenarios. During the last decade, FAA has spent 
about $43 million to support aviation noise R&D (see table 2). 

Table 2: FAA Funds for R&D Efforts in Fiscal Years 1997-2007: 

Fiscal Year: 1997; 
Volpe Center: $770,000; 
PARTNER: [Empty]; 
Other: $1,121,150. 

Fiscal Year: 1998; 
Volpe Center: 841,000; 
PARTNER: [Empty]; 
Other: 1,654,000. 

Fiscal Year: 1999; 
Volpe Center: 737,500; 
PARTNER: [Empty]; 
Other: 473,817. 

Fiscal Year: 2000; 
Volpe Center: 1,040,000; 
PARTNER: [Empty]; 
Other: 577,000. 

Fiscal Year: 2001; 
Volpe Center: 1,100,000; 
PARTNER: [Empty]; 
Other: 430,000. 

Fiscal Year: 2002; 
Volpe Center: 889,000; 
PARTNER: [Empty]; 
Other: 869,000. 

Fiscal Year: 2003; 
Volpe Center: 1,560,000; 
PARTNER: $1,775,000; 
Other: 1,002,000. 

Fiscal Year: 2004; 
Volpe Center: 1,231,000; 
PARTNER: 1,200,000; 
Other: 1,740,000. 

Fiscal Year: 2005; 
Volpe Center: 1,962,750; 
PARTNER: 1,651,250; 
Other: 3,134,527. 

Fiscal Year: 2006; 
Volpe Center: 2,349,750; 
PARTNER: 3,378,657; 
Other: 2,875,750. 

Fiscal Year: 2007; 
Volpe Center: 2,432,750; 
PARTNER: 3,361,500; 
Other: 2,819,859. 

Fiscal Year: Total; 
Volpe Center: $14,913,750; 
PARTNER: $11,366,407; 
Other: $16,697,103. 

Source: FAA. 

[End of table] 

NASA's R&D Efforts Focus on Reducing Noise from Aircraft Engines and 
Airframes: 

NASA's efforts in the area of aviation noise are part of its overall 
aeronautical R&D program. NASA reorganized its aeronautical research 
plan in 2005 to focus on what it calls "fundamental research," which 
takes a technology to a point where it can be further matured by 
manufacturers and eventually integrated into new aircraft or engine 
designs. According to NASA, fundamental research includes (1) 
foundational research, which is the lowest level of the research 
pyramid on which advanced noise reduction technologies can be built; 
(2) discipline-level fundamental research, which includes the 
development of noise prediction methods that can be used to understand 
the noise reduction potential of various concepts; (3) multidiscipline- 
level fundamental research, which includes studying the trade-offs 
between noise, emissions, and performance that must be understood in 
order to determine the performance characteristics of a new aircraft; 
and (4) system-level fundamental research, which includes exploring 
research issues of interest to manufacturers when noise reduction 
technologies are integrated into a new aircraft and can include major 
wind-tunnel and flight tests. Figure 1 illustrates NASA's research 
approach and shows that foundational research serves as the basis for 
the development of technologies and tools that can later be integrated 
into aviation subsystems and systems. 

Figure 1: NASA's Research Approach Triangle: 

This figure is a triangle showing NASA's research approach triangle. 
From top to bottom, the text is: 

Multi-Disciplinary Analysis and Optimization Development,Validation and 
Application: System Level; 

Subsystem Integration, Test and Validation: Multi-Discipline; 

Technologies and Tool Development: Single-Discipline; 

Foundational Research: Basic Research. 

The arrow pointing up reads: 

NASA In-house Research: Knowledge and Capabilities. 

The arrow pointing down reads: 

Industry and Other Government Agency Cooperative Agreements: NASA 
Research Announcement Funded Research: Requirements and Needs. 

[See PDF for image] 

Source: GAO and NASA. 

[End of figure] 

NASA's research on aviation noise focuses on noise emitted by aircraft 
and emphasizes the development of noise prediction methods, diagnostic 
methods for determining noise sources, and noise reduction methods that 
are applicable across a range of aircraft. NASA's R&D plan is 
structured around reducing noise from three generations of aircraft, or 
vehicles, categorized as "N+1,"[Footnote 17] to be implemented by 2015; 
"N+2," to be implemented between 2020 and 2025;[Footnote 18] and "N+3," 
to be implemented between 2030 and 2035. N+1 R&D focuses on one of the 
main sources of aviation noise--aircraft engines--by addressing fan 
noise as well as parts of the airframe that produce noise, such as 
landing gear and flap sides. For the N+2 generation of aircraft, NASA 
intends to develop tools and technologies that more closely integrate 
the airframe with the propulsion system through such means as the 
blended wing body concept. This concept, which calls for mounting the 
engines above the wings, would allow the airframe to shield and thereby 
reduce the effects of engine noise. The N+3 generation of aircraft, 
according to NASA, will have further dramatic reductions in noise and 
emissions and improvements in performance. A request for proposal for 
N+3 is expected in the spring of 2008, with the objective of soliciting 
potential aircraft solutions and identifying key driving technologies 
for fundamental research investments. NASA states that noise reductions 
for N+2 and N+3 aircraft will depend strongly on the fundamental 
research that is carried out today. These NASA research efforts are 
also aimed at reducing emissions and fuel consumption, which in 
combination with noise reductions would help mitigate the environmental 
effects of future increases in air traffic. 

NASA is also working with others in the aeronautics research community 
on other advanced designs, such as the "silent aircraft" concept that 
was created by researchers from Cambridge University in Great Britain 
and the Massachusetts Institute of Technology. According to NASA, about 
$58 million of the fiscal year 2007 subsonic fixed-wing research budget 
was directed toward noise-related research. 

In addition, NASA funds noise research conducted by outside 
organizations. According to NASA, it sponsors research by universities 
and companies for its Fundamental Aeronautics Program through NASA 
Research Announcements (NRA). NASA officials note that the agency has 
made 215 NRA awards ranging from $100,000 a year to $1.5 million a year 
since December 2007, and that many of these awards were directed toward 
noise generation, propagation, and mitigation. 

Participation in Advisory, Planning, and Coordinating Bodies Helps FAA 
and NASA Align and Monitor Their Aviation Noise R&D Plans: 

FAA and NASA have taken advantage of a number of mechanisms to align 
their aviation noise R&D plans. According to officials from both 
agencies, their collaboration in PARTNER is one of the ways they align 
their aviation noise R&D activities. Both FAA and NASA are members of 
the advisory board for PARTNER, along with representatives from 
aerospace manufacturers; airlines; airports; national, state, and local 
governments; professional associations; and community groups. The 
advisory board participates in strategic planning for PARTNER and 
semiannual reviews of the center's research plan to ensure, among other 
things, that the plan addresses national and international issues, 
including those related to aviation noise. 

FAA and NASA also seek to align their aviation noise research plans 
through participation in formal reviews of each other's aviation noise 
research efforts. FAA representatives participate on NASA review panels 
to assess the technical quality, performance, and relevance of NASA 
research programs. In return, NASA participates in FAA's REDAC, which 
is responsible for coordinating FAA's research, engineering, and 
development activities with those of industry and other government 
agencies. REDAC was established in 1989 to advise the FAA Administrator 
on R&D needs in air traffic services; airport technology; aircraft 
safety; human factors; and environmental issues, including aviation 
noise. NASA's Associate Administrator for Aeronautics Research is a 
member of REDAC, as are representatives from NASA's research programs 
in aeronautics who serve on the committee's subcommittees.[Footnote 19] 
FAA's Director of the Office of Aviation Research is currently the 
Executive Director of REDAC. 

Another key component of FAA's and NASA's efforts to align their 
aviation noise R&D plans, according to officials from both agencies, is 
their participation in JPDO's planning for NextGen. Both agencies are 
members of JPDO's Environmental Working Group,[Footnote 20] which is 
headed by the FAA Director of the Office of Environment and Energy. 
NASA chairs the Environmental Working Group's Technology Standing 
Committee, which focuses on the development of technologies to lessen 
NextGen's environmental impacts. 

According to FAA and NASA officials, the mechanisms in place to align 
their agencies' aviation noise R&D plans enable the two agencies and 
other stakeholders to periodically assess the potential for synergies 
or gaps in the agencies' research activities. FAA's and NASA's aviation 
noise plans focus on different aspects of aviation noise. As we have 
previously noted, most of FAA's R&D activities are presently 
concentrated on measuring and mitigating the impacts of aviation noise, 
whereas NASA's R&D centers on developing technologies to reduce noise 
from aircraft engines and airframes. Both agencies' participation in 
JPDO's Environmental Working Group and in REDAC and FAA's participation 
in NASA program reviews create opportunities for FAA and NASA to 
determine what adjustments in aviation noise R&D are needed to meet 
goals for reducing or mitigating the impacts of aviation noise. For 
example, the Environmental Working Group's analysis determined that 
more near-term demonstration of noise reduction technologies on 
aircraft was needed. According to FAA, the CLEEN proposal in the 
administration's reauthorization bill, which will be discussed later in 
this report, addresses this gap. 

The extent to which FAA's and NASA's aviation noise R&D plans are 
aligned is indicated in JPDO's strategic plans for NextGen, which serve 
as a blueprint for improving the nation's aviation system. These plans 
show how each agency's R&D efforts will contribute toward meeting goals 
for reducing noise. Meeting these goals is critical for the success of 
NextGen because aviation noise is a major impediment to increasing the 
capacity of the NAS. JPDO's goal is to reduce the impacts of 
significant aviation noise (defined as DNL 65 dB) on communities 
despite the predicted growth in air traffic. Specifically, the 
Technology Standing Committee of the Environmental Working Group seeks 
to ensure the development of technologies to contribute to reducing the 
impact of aviation noise on communities. According to NASA, the 
technologies it is developing under its current aviation noise R&D 
program, if implemented in new generations of aircraft, would 
significantly contribute toward meeting this goal. 

The alignment of FAA's and NASA's aviation noise research plans is also 
reflected in the national aeronautics research plan issued by OSTP in 
December 2007.[Footnote 21] This plan, to which FAA and NASA 
contributed, outlines environmental goals that are aligned with JPDO's. 
In line with the JPDO Environmental Working Group's goal, the national 
plan states that the "environmental footprint of aviation must continue 
to shrink, even while accounting for an anticipated two to three times 
growth in capacity of the U.S. aviation system by 2025." The national 
plan includes FAA and NASA goals for aviation noise research. For 
example, the plan's near-term goals include researching and developing 
air traffic control procedures to reduce noise and developing improved 
tools and metrics to quantify and characterize aviation's environmental 
impacts. Long-term goals include developing new approaches and models 
for optimizing ground and air operational procedures. In addition, the 
technologies under development or planned for NASA's N+1, N+2, and N+3 
programs are included in the national plan. 

FAA and NASA have formalized their efforts to align their aviation 
noise R&D plans through memorandums of understanding (MOU) on R&D since 
October 9, 1998, with the latest dated May 2006.[Footnote 22] The most 
recent MOU describes how the agencies will coordinate their R&D efforts 
through the FAA/NASA Executive Research Steering Committee, which is co-
chaired by the agencies, with selected members from FAA and NASA 
offices involved with research programs. According to the MOU, this 
committee ensures that complementary aviation and space transportation 
goals are defined for FAA and NASA and reflect each agency's mission. 
The MOU further states that the two agencies will acknowledge and 
support their goals, coordinate their planning and resources to achieve 
the goals when appropriate, and monitor progress toward the goals and 
propose changes on the basis of changing requirements. 

FAA and NASA Have Established Noise Reduction Technology Goals, but R&D 
Funding Issues and Other Factors Make the Achievement of Noise 
Reduction Goals Uncertain: 

FAA has established a goal for reducing the number of people exposed to 
significant noise from aircraft, while FAA and NASA have set goals for 
reducing noise from aircraft through technology development. However, 
questions about the sufficiency of federal funding for these efforts, 
the extent of government and industry participation in the later-stage 
development of noise reduction technologies, and airlines' ability to 
incorporate the technologies in the near term make the achievement of 
FAA's and NASA's noise goals uncertain. Failing to achieve these goals 
could stall the implementation of NextGen, because continued noise 
problems at airports could constrain its expansion. 

FAA and NASA Have Set Goals for Reducing Aviation Noise through New 
Technologies: 

FAA has established a target for reducing the number of people exposed 
to significant noise from aircraft, while FAA and NASA have set targets 
for noise reductions in aircraft to be achieved through technology 
development. FAA estimates that about 500,000 people in the United 
States are currently affected by significant aviation noise, defined as 
DNL 65 dB or greater, and has set a goal of reducing this number by 4 
percent for each year through fiscal year 2012. The annual 4 percent 
reduction goal is an increase over FAA's previous goal of an annual 1 
percent reduction in the population exposed to significant aviation 
noise. According to FAA, the 1 percent goal was exceeded in fiscal year 
2006 when the percentage of people exposed to significant noise 
decreased by 28 percent relative to the 3-year average for calendar 
years 2000 through 2002. FAA stated that the main contributor to the 
decrease in population exposed to significant noise is the early 
retirement of older, noisier aircraft primarily as the result of the 
air traffic downturn in the aftermath of the events of September 11, 
2001, and fuel inefficiency reasons. 

FAA has also set a goal that would more directly indicate the 
contribution of R&D to reducing aviation noise. FAA's 2007 National 
Aviation Research Plan qualitatively spells out R&D goals up to 2015. 
According to this plan, FAA's goal is to demonstrate that aviation 
noise can be significantly reduced to cost-effectively expand up to 
three times the current capacity of the air traffic system. FAA R&D 
activities from 2009 through 2013 to achieve these goals include (1) 
measuring current levels of aviation-related noise and emissions, (2) 
determining acceptable levels of noise and emissions, (3) developing 
models to predict the impact and benefits of changes, and (4) 
developing noise-and emission-reduction methods. Current activities are 
being conducted by PARTNER and the Volpe Center in collaboration with 
various industry stakeholders. 

NASA has established what it considers to be aggressive technology 
goals for its aviation noise R&D program that could be incorporated 
into aircraft. Under these goals, new technologies would be developed 
and incorporated in three succeeding generations of new aircraft, as we 
discussed in the preceding section of this report, thereby increasingly 
reducing what is known as EPN. NASA's goals include a cumulative noise 
reduction of 32 EPN dB relative to the most current Chapter 4 noise 
standard[Footnote 23] for the next generation of aircraft, the N+1 
generation,[Footnote 24] and this goal would be achieved by 2015. Next, 
noise from the N+2 generation of aircraft would be reduced to 42 EPN dB 
below the Chapter 4 standard, and this goal would be met between 2020 
and 2025. Finally, noise from the N+3 generation of aircraft would 
decline to 71 EPN dB below the Chapter 4 standard during the period 
from about 2030 through 2035, thereby achieving NASA's third noise 
reduction goal. Aviation noise would be reduced to the extent NASA 
predicts through the technologies it is researching if noise reduction 
were the only goal. However, when efforts are also made to achieve 
other goals, such as to reduce greenhouse gas emissions, noise 
reductions may be lower. FAA and the other members of JPDO's 
Environmental Working Group have incorporated NASA's aviation noise 
reduction goals in NextGen plans for reducing the environmental impacts 
of aviation. Table 3 identifies the time frames, goals, and research 
projects planned for NASA's N+X generation aircraft program. 

Table 3: NASA's N+X Generation Aircraft Program: 

Program name: Time frame; 
N+1 generation: By 2015; 
N+2 generation: Between 2020 and 2025; 
N+3 generation: Between 2030 and 2035. 

Program name: Noise level[A]; 
N+1 generation: -32 EPN dB; 
N+2 generation: -42 EPN dB; 
N+3 generation: -71 EPN dB or greater. 

Program name: Research projects; 
N+1 generation: Engine noise reduction technologies; 
Airframe noise source; 
Investigation and mitigation study; 
N+2 generation: SAX-40 aircraft concept; 
Aerodynamics and acoustic testing; 
Predictive capabilities for subsonic aircraft; 
Pulsed circulation control; 
Plasma actuators for landing gear and high-lift side edges; 
N+3 generation: NASA to solicit proposals in spring 2008. 

Sources: GAO and NASA. 

[A] Cumulative reduction below Chapter 4 standards. 

[End of table] 

Meeting Noise Reduction Goals Is Uncertain Because of Questions about 
Federal R&D Funding, Government and Industry Participation, and Airline 
Investment Resources: 

Despite efforts by FAA and NASA, to align aviation noise and other 
environmentally related R&D, concerns have arisen about whether the 
resources devoted to near-term R&D will be sufficient to achieve noise 
reduction goals for aircraft engines and airframes within the NextGen 
time frame. According to FAA, more funding is needed to mature noise 
reduction technologies beyond NASA's research efforts. FAA is 
attempting to address this funding need through its proposed CLEEN 
consortium. 

Federal funding for aviation noise research has declined over the past 
decade, particularly for NASA, which provides most of the federal 
funding for aeronautics research, the category that includes aviation 
noise research. NASA's budget for aeronautics research has dropped by 
about one-half over the past decade and is about $717 million for 
fiscal year 2007. According to NASA, about $58 million of this funding 
goes toward noise-related research for subsonic fixed-wing aircraft. 
This downward trend contributed to NASA's decision, previously 
discussed in this report, to refocus its aeronautical research plan on 
the earlier stages of the R&D process. 

According to FAA, most of the federal funding available for mitigating 
aviation noise is targeted to the Part 150 Noise Compatibility Program 
for soundproofing buildings around airports and acquiring or relocating 
properties that are exposed to high levels of aviation noise. In a 2002 
report on reducing the environmental impacts of aviation, the National 
Research Council's Committee on Aeronautics Research and Technology for 
Environmental Compatibility[Footnote 25] noted that the vast majority 
of federal expenditures on aviation noise is allocated to noise 
abatement at individual airports rather than to research on quieter 
aircraft and engines, which could ultimately lead to reductions in 
aviation noise nationally and internationally. The report concluded 
that the funding for federal research programs was too low to remove 
noise as an impediment to the growth of aviation--a conclusion that FAA 
reiterated in a 2004 report to Congress on aviation and the 
environment.[Footnote 26] 

According to FAA, the administration is attempting to address the 
shortfall in aviation noise R&D spending in its proposal for 
reauthorizing FAA programs by seeking funding for programs to mature 
technologies that NASA and others originally developed. FAA officials 
stated that the proposed CLEEN Engine and Airframe Technology 
Partnership, for which the administration is seeking $111 million 
through fiscal year 2011, is intended to provide earlier maturation of 
aviation noise and emission reduction technologies while NASA focuses 
on longer-term fundamental research on noise and emissions. The CLEEN 
partnership, which is also in the House reauthorization bill, would 
create a program for the development, maturation, and certification of 
engine and airframe technologies for aircraft over the next 10 years to 
reduce aviation noise and emissions. The proposals would require the 
FAA Administrator to establish an objective of developing aircraft 
technology that would be certified for incorporation into current 
aircraft models, resulting in a cumulative noise reduction of 32 EPN dB 
below ICAO's Chapter 4 standards, which is the same as the goal NASA 
has set for its N+1 aviation noise R&D program. CLEEN would establish a 
research consortium of government, industry, and academic participants 
that would allow for the maturation of aviation noise technologies via 
demonstration projects for further refinement by the aviation industry 
and eventual incorporation into new aircraft designs. The proposal 
would also require the Administrator to set objectives for developing 
certifiable aircraft engine technologies for substantially reducing 
emissions. Because NASA's current focus is on fundamental research to 
develop system-level technologies, the CLEEN proposal would not overlap 
with NASA's R&D efforts. According to FAA, if the proposed program is 
authorized and funded at the requested level, FAA has reasonable 
confidence that noise goals will be achieved. 

NASA and FAA officials said they are making progress in meeting their 
noise reduction goals. NASA officials stated that NASA is progressing 
toward developing technologies that can be implemented in next 
generation aircraft engines and can meet the noise reduction goals set 
for N+1. For example, NASA has established a partnership with Pratt & 
Whitney to demonstrate the benefits of a technology that would reduce 
noise. NASA and FAA have also worked with Boeing to demonstrate 
airframe and engine noise reduction technologies on a Boeing 777. FAA 
stated, and we have confirmed, that FAA has met its 2007 noise 
reduction goals through September 2007. 

However, even with additional funding for aviation noise R&D, such as 
the amounts included in the CLEEN proposal, achieving FAA's and NASA's 
aviation noise goals for reducing noise from aircraft engines and 
airframes will remain a challenge because of uncertainties about the 
ability of aircraft engine and aircraft manufacturers to incorporate 
new noise reduction technologies into new engine and aircraft designs, 
and the need to consider trade-offs between noise reductions and 
reductions in emissions of greenhouse gases. NASA officials stressed 
that when NASA's research ends, it will be up to engine and aircraft 
manufacturers to take the next steps to integrate the noise reduction 
technologies into engine and aircraft designs, and the manufacturers' 
willingness to do so is not guaranteed. In addition, an expert we 
consulted noted that if manufacturers do take the steps to integrate 
noise reduction technologies into new designs, the pace of noise 
reduction will also depend on the pace of development for new aircraft 
and aircraft engine designs. According to FAA, the CLEEN proposal is to 
demonstrate to manufacturers that technologies initially developed by 
NASA and others are ready to be incorporated into new aircraft and 
engine designs. However, it is uncertain whether the CLEEN proposal, if 
adopted, would be sufficient to achieve this objective. Concern about 
other environmental problems, such as global warming and air quality, 
may also limit the likelihood of achieving FAA's and NASA's noise 
reduction goals, since it may be technologically challenging to design 
aircraft with reduced noise while, at the same time, achieving the 
significant reductions in greenhouse gases and other emissions that 
will be required. Although it is possible to design engines that 
produce less noise and fewer greenhouse gas emissions, the reductions 
in greenhouse gases could be limited in engines that produce 
substantially less noise. Furthermore, engines that burn less fuel are 
less costly to operate. As a result, air carriers may not be inclined 
to buy jets with engines that reduce noise but may be more expensive to 
operate. 

If R&D efforts lead to advancements in noise reduction technologies 
that can be incorporated in new aircraft in the near future, it is 
uncertain whether these advancements will contribute toward meeting 
FAA's goals for reducing the number of people exposed to significant 
noise. As we noted in our recent testimony on aviation noise,[Footnote 
27] implementing new noise reduction technologies, whether by 
integrating new, quieter aircraft into the fleet or by retrofitting 
aircraft, poses financial challenges for the aviation industry. 
Aircraft have an average lifespan of about 30 years, and airlines can 
take almost that entire period to pay for an aircraft. The current 
fleet is, on average, about half as many years old--11 years for wide-
body aircraft and 14 years for narrow-body aircraft--and therefore, is 
expected to be in operation for many years to come. In addition, the 
financial pressures facing many airlines make it difficult for them to 
upgrade their fleets with new, state-of-the-art quieter aircraft, such 
as the Boeing 787 and Airbus A380. Currently, for example, U.S. 
carriers have placed a small proportion of the over 700 orders (40, or 
less than 6 percent) that Boeing officials say the company has received 
for its 787 model. Furthermore, no U.S. carriers have placed orders for 
the new Airbus A380, which is the world's largest passenger aircraft. 
According to Airbus, the A380 produces significantly less noise than 
other large passenger aircraft currently in service. 

Failure to meet the aviation noise reduction goals outlined in FAA's 
and NASA's R&D plans could have significant implications for the 
implementation of NextGen. According to FAA, it generally takes 12 to 
15 years to implement new technology on aircraft, and, therefore, 
NextGen technologies must be brought to maturity soon to meet the 2025 
goal for implementing NextGen. According to FAA, without additional 
funding such as that proposed for CLEEN, near-term noise reduction 
goals may not be attained. However, if the technologies are developed 
that allow the goals to be met, FAA may also need to consider how to 
encourage airlines to introduce quieter aircraft into their fleets as 
well as to retrofit existing aircraft with new equipment such as the 
satellite-based Automatic Dependent Surveillance-Broadcast (ADS-B) 
navigational system, which can allow aircraft to make more efficient, 
quieter approaches and descents. One way would be to offer operational 
advantages such as preferred takeoff and landing slots to quieter 
aircraft or aircraft equipped with ADS-B. Without significant noise 
reductions around the nation's airports, efforts to expand their 
capacity could be stalled and the implementation of NextGen delayed, 
thereby limiting FAA's ability to efficiently manage the forecasted 
growth in air traffic. 

Agency Comments: 

We provided copies of a draft of this report to the Department of 
Transportation and NASA for review and comment (see app. II). Both 
agencies had no comments. FAA and NASA did provide technical 
clarifications, which we incorporated into the report as appropriate. 

As agreed with your offices, unless you publicly announce the contents 
of the report earlier, we plan no further distribution until 30 days 
from the date of this letter. At that time, we will send copies of the 
report to interested congressional committees, the Secretary of 
Transportation, the Administrator of the FAA, and the Administrator of 
NASA. We will also make copies available to others upon request. In 
addition, the report will be made available at no charge on the GAO Web 
site at [hyperlink, http://www.gao.gov]. 

If you or your staffs have any questions about this report, please 
contact me at (202) 512-2834 or [email protected]. Contact points for 
our Offices of Congressional Relations and Public Affairs may be found 
on the last page of this report. Individuals making key contributions 
to this report are listed in appendix III. 

Signed by: 

Gerald L. Dillingham, Ph.D.: 

Director, Physical Infrastructure Issues: 

[End of section] 

Appendix I: PARTNER Participants and Projects: 

Collaborating Universities: 

Boise State University: 
Georgia Institute of Technology: 
Harvard University: 
Massachusetts Institute of Technology: 
Pennsylvania State University: 
Purdue University: 
Stanford University: 
University of Missouri at Rolla: 
University of North Carolina: 
York University: 

Advisory Board Members: 
Aerodyne Research Aerospace Industries Association: 
Airbus: 
Air Line Pilots Association: 
Air Transport Association of America: 
Airports Council International ï¿½ North America: 
American Institute of Aeronautics and Astronautics: 
Bay Area Air Quality Management District: 
Bell Helicopter Textron: 
Boeing: 
Bombardier Aerospace: 
Cessna Aircraft: 
Commercial Aviation Alternative Fuels Initiative: 
CSSI: 
Delta Airlines: 
Environmental Compatible Air Transport System: 
FAA Airports and Environmental Law Division: 
FAA Air Traffic Environmental Programs Division: 
FAA Airport Planning, Community and Environmental Needs Division: 
FAA Centers of Excellence: 
FAA Flight Standards: 
FAA Office of Environment and Energy: 
General Electric Aircraft Engines: 
Gulfstream Aerospace: 
Harris Miller Miller & Hanson: 
Indiana Department of Transportation: 
International Airline Passengers Association: 
Larry Finegold & Son, Consultants: 
Lockheed Martin Aeronautics: 
Logistics Management Institute: 
Massachusetts Port Authority: 
Metron Aviation: 
Metropolitan Washington Airport Authority: 
NASA Aeronautics Research Mission Directorate: 
NASA Science Mission Directorate: 
National Organization to Insure a Sound Controlled Environment: 
Oï¿½Hare Noise Compatibility Commission: 
Omega: 
Palisades Citizens Association: 
Pratt & Whitney: 
Raisbeck Engineering: 
Rannoch Corp.: 
Regional Airport Authority of Louisville and Jefferson County: 
Rolls Royce: 
San Francisco International Airport/Community Roundtable: 
Sikorsky Aircraft: 
SNECMA: 
Transport Canada: 
United Parcel Service: 
U.S. DOT Volpe National Transportation Systems Center: 
U.S. EPA National Risk Management Research Laboratory: 
Wyle Laboratories: 

PARTNER Projects: 
Airport Surface Movement Optimization: 
Alternative Fuels: 
Continuous Descent Arrival: 
En Route Traffic Optimization to Reduce Environmental Impact: 
Emissions Atmospheric Research: 
Emissions Characteristics of Alternative Aviation Fuels: 
Energy Policy Act Study: 
Environmental Design Space: 
Health Effects of Aircraft Noise: 
Health Impacts of Aviation-Related Air Pollutants: 
Investigation of Aviation Emissions Air Quality Impacts: 
Land Use Management and Airport Controls (project completed): 
Lateral Alignment in Complex Systems (project completed): 
Low Frequency Noise Study (project completed): 
Measurement of Emissions: 
Network Restructuring Scenarios for ATO Forecasts: 
NoiseQuest: 
Quantifying and Mitigating the Impact of Noise on People: 
Reduced Vertical Separation Minimums (project completed): 
Sonic Boom Mitigation: 
Valuation and Trade-offs of Policy Options: 

[End of section] 

Appendix II: NASA Letter to GAO: 

National Aeronautics and Space Administration: 
Headquarters: 
Washington, DC 20546-0001: 

February 5, 2008: 

Reply to Attn of: Aeronautics Research Mission Directorate: 

Gerald L. Dillingham, Ph. D.: 
Director, Physical Infrastructure Issues: 
Government Accountability Office: 
Washington, DC 20548: 

Dear Dr. Dillingham:   

Thank you for the opportunity to review your draft report entitled, 
"Aviation and the Environment," (GAO-08-384). This draft report 
contains no recommendation to NASA and we are not providing comments 
via separate correspondence.   

If you have any questions, or require additional information, please 
contact Juan Alonso at (202) 358-1216.   

Sincerely, 

Signed by:  

Dr. Jaiwon Shin
Associate Administrator for Aeronautics Research: 

[End of section] 

Appendix III: GAO Contact and Staff Acknowledgements: 

GAO Contact: Gerald L. Dillingham, Ph.D., (202) 512-2834 or 
[email protected]: 

Staff Acknowledgements: In addition to the contact named above, Ed 
Laughlin (Assistant Director), Elizabeth Eisenstadt, Rosa Leung, and 
Maureen Luna-Long made key contributions to this report. 

[End of section] 

Footnotes: 

[1] H.R. 2881 and S. 1300. 

[2] ICAO is an advisory organization affiliated with the United Nations 
that aims to promote the establishment of international civil aviation 
standards and recommended practices and procedures.

[3] GAO, Aviation and the Environment: Impact of Aviation Noise on 
Communities Presents Challenges for Airport Operations and Future 
Growth of the National Airspace System, GAO-08-216T (Washington, D.C.: 
Oct. 24, 2007). 

[4] FAA Centers of Excellence are FAA partnerships with universities 
and affiliated industry associations and businesses throughout the 
country that conduct aviation research in a number of areas, including 
advanced materials, aircraft noise and emissions, and airworthiness. 

[5] This goal is measured by a 3-year moving average for calendar years 
2000 through 2002. In fiscal year 2007, the noise exposure goal was 
revised from a 1 percent to a 4 percent cumulative reduction per year 
in the number of people exposed to significant aviation noise. 

[6] The NASA goals are cumulative decreases that are obtained by adding 
together the decreases in an aircraftï¿½s maximum noise levels at take 
off, flyover, and approach.  

[7] EPN is the noise measure used to establish compliance with noise 
certification standards.

[8] A similar provision is in the Senate bill for FAA reauthorization. 
As of the date of this publication, the House and Senate are discussing 
the reauthorization bills.

[9] 14 CFR 150. 

[10] As part of its environmental responsibilities, FAA also works 
through ICAO to foster international environmental standards, including 
those for noise, as well as recommended practices and guidance 
materials. 

[11] The impact of aviation noise is usually analyzed in terms of the 
extent to which the noise annoys people by interfering with their 
normal activities, such as sleep, relaxation, speech, television 
viewing, and school and business operations. The generally accepted 
model for assessing the effects of long-term noise exposure is based on 
a correlation of the day-night average sound level, DNL, to the 
percentage of population highly annoyed by recurring noise sound 
events. DNL is a noise descriptor or metric that takes into account the 
magnitude of the sound levels of all individual events that occur 
during a 24-hour period, the number of events, and an increased 
sensitivity to noise during typical sleeping hours (between 10:00 p.m. 
and 7:00 a.m.). The correlation shows that the percentage of people 
highly annoyed by noise exposure increases significantly above DNL 65 
dB. Some aviation noise consultants have noted disadvantages of DNL as 
a metric to measure noise and suggest the use of supplemental metrics 
that measure the frequency and intensity of individual noise events 
that may provide a more adequate measure of aviation noise as 
experienced by people. Some airports have included supplemental 
analysis such as the Number of events Above and the Time Above, within 
their noise studies. FAA requires the use of DNL for airport analysis 
but also allows for the use of supplemental metrics. 

[12] The AIP program provides federal funds for development projects at 
the entire range of the nationï¿½s 3,400 airportsï¿½from small general 
aviation airports to the very largest airports that handle several 
million passengers per year. 

[13] According to FAA, noise projects are eligible for 80 percent 
funding under AIP for large- and medium-hub airports and 95 percent 
funding at small, nonhub, general aviation, and reliever airports. 

[14] PFCs are fees that airports can charge passengers to fund FAA-
approved projects. Not all airports charge these fees. 

[15] Transport Canada is the department within the government of Canada 
that is responsible for developing policies, regulations, and services 
for the Canadian transportation system.

[16] John-Paul Clarke, et al., Partnership for Air Transportation and 
Emissions Reduction Development, Design and Flight Test Evaluation of a 
Continuous Descent Approach Procedure for Nighttime Operation at 
Louisville International Airport (Cambridge, MA: Jan. 9, 2006). 

[17] ï¿½Nï¿½ refers to the current generation of tube-and-wing aircraft 
entering into service in 2008 such as the Boeing 787. 

[18] According to NASA estimates, the introduction of N+2 vehicles for 
Initial Operational Capability for military or cargo vehicles would be 
around 2020, and Entry Into Service for commercial vehicles would be 
around 2025. 

[19] The four NASA aeronautics research programs are the Fundamental 
Aeronautics Program, the Airspace Systems Program, the Aviation Safety 
Program, and the Aeronautics Test Program. 

[20] JPDO has restructured its Integrated Product Teams into Working 
Groups. Nevertheless, FAA and NASA continue to collaborate in the same 
roles and according to the Integrated Work Plan. 

[21] OSTPï¿½s charter is to advise the President on the effects of 
science and technology on domestic and international affairs and to 
lead interagency efforts to develop and implement science and 
technology policies and budgets. OSTPï¿½s plan, National Plan for 
Aeronautics Research and Development and Related Infrastructure by the 
National Science and Technology Council (December 2007), establishes 
national research priorities, objectives, and schedules to achieve the 
identified objectives by 2020. 

[22] Memorandum of Understanding Between Department of Transportation, 
Federal Aviation Administration and National Aeronautics and Space 
Administration Concerning A Partnership to Achieve Goals in Aviation 
and Space Transportation (May 15, 2006). 

[23] In July, 2005, FAA issued a Federal Aviation Regulation (14 CFR 
36.103 and 91.801-91.877) requiring that all new aircraft designs be 
subject to the current, more stringent ICAO noise standards, know as 
Chapter 4 (known as Stage 4 standards in the regulation). Specifically, 
any new aircraft whose design was submitted to FAA for approval on or 
after January 1, 2006, must meet these standards adopted by ICAO in 
2001. The less stringent Chapter 3 standard applies to most other 
aircraft. Under the Chapter 4 standards, none of an aircraftï¿½s maximum 
noise levels at takeoff, landing, and approach can exceed Chapter 3 
noise levels. Compliance with the standards is determined by 
subtracting an aircraftï¿½s maximum noise levels at takeoff, flyover, and 
approach from the maximum permitted noise levels. The differences 
obtained are the noise limit margins. When the three margins are added 
together, the total must be 10 EPN dB or greater; and when any of the 
two margins are added together, the sum must be 2 EPN dB or greater. 

[24] The reductions would occur in aircraft that would replace such 
current aircraft as the Boeing 737 and Airbus A320. Reductions would be 
different for larger aircraft and regional jets. 

[25] National Research Council, Committee on Aeronautics Research and 
Technology for Environmental Compatibility, National Academy of 
Sciences For Greener Skies: Reducing Environmental Impacts of Aviation 
(Washington, D.C.: 2002). 

[26] FAA, Aviation and the Environment: A National Vision Statement, 
Framework for Goals and Recommended Actions (Washington, D.C.: December 
2004). 

[27] GAO-08-216T. 

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