Public Notice: Clarifying the Definition Of “Substantial Restoration of Natural Quiet” at Grand Canyon National Park, Arizona, 19246-19248 [E8-7410]

Download as PDF 19246 Federal Register / Vol. 73, No. 69 / Wednesday, April 9, 2008 / Notices RESPONDENTS’ ESTIMATED ANNUAL BURDEN HOURS—Continued Citation 30 CFR Reporting and recordkeeping requirement Total Burden ........................ Hour burden ......................................................................................................... Average number of annual responses .................... Annual burden hours 1,212 1,969 mstockstill on PROD1PC66 with NOTICES Note: The ORA determined that the audit process is not covered by the PRA because MMS staff asks non-standard questions to resolve exceptions. * Rounded up from 0.25. Estimated Annual Reporting and Recordkeeping ‘‘Non-hour’’ Cost Burden: We have identified no ‘‘nonhour’’ cost burdens. 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Comments: Before submitting an ICR to OMB, PRA Section 3506(c)(2)(A) requires each agency ‘‘* * * to provide notice * * * and otherwise consult with members of the public and affected agencies concerning each proposed collection of information * * *.’’ Agencies must specifically solicit comments to: (a) Evaluate whether the proposed collection of information is necessary for the agency to perform its duties, including whether the information is useful; (b) evaluate the accuracy of the agency’s estimate of the burden of the proposed collection of information; (c) enhance the quality, usefulness, and clarity of the information to be collected; and (d) minimize the burden on the respondents, including the use of automated collection techniques or other forms of information technology. The PRA also requires agencies to estimate the total annual reporting ‘‘non-hour cost’’ burden to respondents or recordkeepers resulting from the collection of information. If you have costs to generate, maintain, and disclose this information, you should comment and provide your total capital and startup cost components or annual operation, maintenance, and purchase of service components. You should describe the methods you use to estimate major cost factors, including system and technology acquisition, expected useful life of capital equipment, discount rate(s), and the period over which you incur costs. Capital and startup costs include, among other items, computers and software you purchase to prepare for collecting information; monitoring, sampling, and testing equipment; and record storage facilities. Generally, your estimates should not include equipment VerDate Aug<31>2005 18:06 Apr 08, 2008 Jkt 214001 or services purchased: (i) Before October 1, 1995; (ii) to comply with requirements not associated with the information collection; (iii) for reasons other than to provide information or keep records for the Federal Government; or (iv) as part of customary and usual business or private practices. We will summarize written responses to this notice and address them in our ICR submission for OMB approval, including appropriate adjustments to the estimated burden. We will provide a copy of the ICR to you without charge upon request. The ICR also will be posted on our Web site at http:// www.mrm.mms.gov/Laws_R_D/ FRNotices/FRInfColl.htm. Public Comment Policy: We will post all comments in response to this notice on our website at http:// www.mrm.mms.gov/Laws_R_D/InfoColl/ InfoColCom.htm. We will also make copies of the comments available for public review, including names and addresses of respondents, during regular business hours at our offices in Lakewood, Colorado. Before including your address, phone number, e-mail address, or other personal identifying information in your comment, you should be aware that your entire comment—including your personal identifying information—may be made publicly available at any time. While you can ask us in your comment to withhold your personal identifying information from public view, we cannot guarantee that we will be able to do so. MMS Information Collection Clearance Officer: Arlene Bajusz (202) 208 7744. Dated: April 2, 2008. Walter D. Cruickshank, Acting Associate Director for Minerals Revenue Management. [FR Doc. E8–7448 Filed 4–8–08; 8:45 am] BILLING CODE 4310–MR–P PO 00000 DEPARTMENT OF THE INTERIOR National Park Service Public Notice: Clarifying the Definition Of ‘‘Substantial Restoration of Natural Quiet’’ at Grand Canyon National Park, Arizona National Park Service, Department of the Interior. ACTION: Public Notice: Clarifying the definition of ‘‘substantial restoration of natural quiet’’ at Grand Canyon National Park. AGENCY: SUMMARY: This notice clarifies the definition used by Grand Canyon National Park (GCNP) for achieving substantial restoration of natural quiet as mandated by the 1987 Overflights Act (Pub. L. 100–91) (Overflights Act). This clarification of the definition is necessary to address current acoustic conditions to comply with the intent of recommendations provided in the 1995 Report to Congress,1 and respond to a 2002 U.S. Court of Appeals decision. The provisions of the Special Flight Aviation Regulation (SFAR) 50–2 have not resulted in substantial restoration of natural quiet of GCNP. Given the volume of high altitude commercial jet and general aviation traffic overflying the Grand Canyon above 17,999 feet Mean Sea Level (MSL) and a recent court decision, the substantial restoration goal as currently defined cannot be attained. This clarification of the restoration definition, while focusing on air tour and air tour related and general aviation aircraft that are conducting overflights of GCNP at altitudes at or below 17,999 MSL, also incorporates measures to address noise from all aircraft. The 1995 definition of substantial restoration of natural quiet is being clarified to distinguish between aircraft noise generated above and below 17,999 feet MSL. The Special Flight Rules Area (SFRA) ceiling was set at 17,999 MSL to avoid additional requirements, restrictions and 1 National Park Service, (1995) Report of Effects of Aircraft Overflights on the National Park System, Report to Congress, July 1995. Frm 00061 Fmt 4703 Sfmt 4703 E:\FR\FM\09APN1.SGM 09APN1 Federal Register / Vol. 73, No. 69 / Wednesday, April 9, 2008 / Notices regulations that occur at or above 18,000 MSL. GCNP and the Federal Aviation Administration (FAA) are currently engaged in the preparation of an environmental impact statement (EIS) entitled ‘‘Special Flight Rules Area in the Vicinity of Grand Canyon National Park.’’ GCNP, in consultation with the FAA, has determined in the noise methodology section of the EIS that aviation noise above 17,999 feet MSL will be considered as a cumulative impact for purposes of the EIS, and aircraft noise generated at or below 17,999 feet MSL, within the Special Flights Rules Area (SFRA) will be managed to attain the NPS recommendations and meet restoration management objectives consistent with GCNP management direction, 2006 NPS Management Policies, and the 1995 Report to Congress. The NPS proposes the following clarification to the definition of substantial restoration of natural quiet. mstockstill on PROD1PC66 with NOTICES (a) Substantial restoration of natural quiet at GCNP will be achieved when the reduction of noise from aircraft operations at or below 17,999 feet MSL results in 50% or more of the park achieving restoration of the natural quiet (i.e., no aircraft audible) for 75% to 100% of the day, each and every day; and (b) The NPS defines the substantial restoration of natural quiet from all aircraft above 17,999 feet MSL, to mean that there will be an overall reduction in aviation noise generated above 17,999 feet MSL above the park over time through the implementation of measures in accordance with FAA commitments. The NPS also clarifies that 50% of GCNP is a minimum in the restoration goal. This includes not only the impacts of aircraft noise on the soundscape but the impact of noise on the visitor experience and natural, cultural and historic resources for the entire park. The analysis of noise impacts in the overflights EIS will be based on the defined substantial restoration goal, park values and purposes, and the GCNP General Management Plan land zoning objectives and overall park management objectives.2 NPS has deferred the assessment of aviation safety to FAA’s jurisdiction. Both agencies have agreed to consider the noise from all aircraft in the ongoing ETS and planning process. Further, both agencies have agreed to consider reducing aircraft noise over the park in the future from aircraft operating above 17,999 feet MSL over the SFRA, while removing aircraft operations above 17,999 MSL from direct regulation in this action. This notice seeks public 2 National Park Service (1995) General Management Plan for Grand Canyon National Park. VerDate Aug<31>2005 18:06 Apr 08, 2008 Jkt 214001 comment on the clarification of the NPS definition of substantial restoration. DATES: This notice will be on public review for 30 days, May 9, 2008. ADDRESSES: If you wish to comment, you may mail or hand deliver comments to the name and address below or comment online via http:// parkplanning.nps.gov/grca (select ‘‘Substantial Restoration Clarification’’). Comments must be received within 30 days from the date of this printing. You may also view a copy of this clarification through the Internet at: http://www.nps.gov/grca/naturescience/ soundscape.htm. FOR FURTHER INFORMATION CONTACT: Ken McMullen, Overflights and Natural Soundscape Program Manager, Grand Canyon National Park, 823 N. San Francisco St., Suite B, Flagstaff, Arizona 8600l National Park Service, Grand Canyon NP, Telephone: (928) 779–2095. SUPPLEMENTARY INFORMATION: Background This notice is one of several steps being taken by the Secretary of the Interior (SOI), through the NPS, and the FAA to fulfill the mandate established by Congress in PL 100–91, the Overflights Act, to provide for the substantial restoration of natural quiet in Grand Canyon National Park. Section 3 of the Overflights Act mandated the SOI to submit to the Administrator of the FAA recommendations ‘‘regarding actions necessary for the protection of resources in the Grand Canyon from adverse impacts associated with aircraft overflights.’’ The express statutory goal for these recommendations is the ‘‘substantial restoration of natural quiet and experience of the park and protection of public health and safety from adverse affects associated with aircraft overflight.’’ The Overflights Act requires the FAA Administrator to adopt the recommendations of the SOI ‘‘without change unless the Administrator determines that implementing the recommendations would adversely affect aviation safety.’’ Congress did not define natural quiet or substantial restoration of natural quiet and, instead, delegated the interpretation of the statute to the Secretary. Under well established rules of statutory construction, the agency’s interpretation is given deference so long as it is based on a reasonable construction of the statute. The D.C. Circuit Court of Appeals found that the NPS had reasonable justification for its interpretations of natural quiet and substantial restoration of natural quiet, as set forth in the 1995 Report to Congress. (See Grand Canyon Air Tour PO 00000 Frm 00062 Fmt 4703 Sfmt 4703 19247 Coalition v. FAA, 154 F.3d 455 (D.C. Cir. 1998)). In its 1995 Report to Congress the policy decision of the NPS was that substantial restoration requires that 50% or more of the park achieve natural quiet (i.e. no aircraft audible) for 75– 100% of the day. The NPS provided definitions of terms used, as well as rationale for its noise impact assessment methods in ‘‘Review of Scientific Basis for Change in Noise Impact Assessment Method Used at Grand Canyon National Park,’’ 2000.3 In the review, the NPS defined one parameter of substantial restoration of natural quiet to be ‘‘* * * a threshold not to be exceeded on any given day * * * .’’ In 2002, the definition of substantial restoration of natural quiet and the FAA’s noise methodology in the 2000 Final Supplemental Environmental Assessment was addressed in litigation before the D.C. Circuit Court of Appeals, in the case United States Air Tour Association v. FAA, 298 F.3d 997 (D.C. Cir. 2002). In this case, the Court declared that ‘‘ * * * the Park Service is entitled to deference for its interpretation of its own definitions.’’ The Court concluded ‘‘* * * the FAA’s use of an ‘‘average annual day’’ for measuring ‘substantial restoration of natural quiet’ appears inconsistent with both the Park Service’s definition of the term and with the premise upon which that definition was based. * * * We must therefore remand this issue for further consideration.’’ In response to the court decision, the term ‘‘the day’’ was clarified by the NPS in the November 7, 2003 Federal Register Notice (68 FR 63129–63130) to mean ‘‘each and every day.’’ The D.C. Circuit Court of Appeals also found that the FAA’s noise methodology was flawed because it only accounted for noise from commercial air tours, while ignoring noise from other types of aircraft (commercial jets, general aviation, and military flights). The court further stated that the Overflights Act did not provide any basis for ignoring noise caused by such aircraft and in the absence of any reasonable justification for excluding non-tour aircraft from its noise model, the court concluded that this aspect of the FAA’s methodology was arbitrary and capricious and required reconsideration by the agency. Reasons for the Clarification Based on the 2002 D.C. Circuit Court of Appeals decision, as well as review 3 National Park Service, (2000) Review of Scientific Basis For Change in Noise Impact Assessment Method Used at Grand Canyon National Park. January 2000. E:\FR\FM\09APN1.SGM 09APN1 mstockstill on PROD1PC66 with NOTICES 19248 Federal Register / Vol. 73, No. 69 / Wednesday, April 9, 2008 / Notices of Congressional intent, aircraft noise levels, and national airspace safety and efficiency, this clarification of the restoration definition is necessary to address the noise of all aircraft while distinguishing how the substantial restoration of natural quiet will be achieved at and below 17,999 feet MSL within the Special Flight Rules Area (SFRA) and above the SFRA. The NPS recognizes that due to the impacts of aviation noise on park resources and the visitor experience, even with implementation of quiet technology aircraft, restoration of the natural quiet as defined in the 1995 Report to Congress will not be achieved without reduction of the sounds produced by jet traffic above 17,999. The 1995 Report to Congress concluded that SFAR 50–2 had not resulted in substantial restoration of natural quiet in Grand Canyon National Park and continued growth in air traffic may diminish or negate progress to date. The report looked at air tour, military, general aviation and high altitude commercial overflights and found that the major aircraft noise impacts on natural quiet came from air tour activity and high flying commercial jet traffic. Low flying general aviation and military overflights were thought to contribute little to the overall aircraft noise impacts. As discussed in the Report to Congress, high altitude jets were known to be a noise issue that the FAA needed to address. In particular it was recommended in the report that (1) FAA not authorize any deviations from normal high altitude routes for sightseeing purposes; (2) FAA not authorize deviations from normal flight plans and cruising altitudes over the Grand Canyon for other than safety reasons; and (3) that FAA conduct a study on high altitude commercial jet routes that may also have impacts on natural quiet in the park. Consequently, subsequent regulations focused on the regulation of air tour and related operations. In 2005 and 2006, the GCNP initiated a soundscape monitoring and data collection effort to verify the accuracy of the earlier acoustic science and methodologies used since the early 1980’s (see discussion in 64 FR 38006– 38007) and to determine the natural ambient conditions for most of the park area. NPS noise modeling results predicted that over 96% of the park area had aircraft noise audible for over 25% of the 12-hour day; however, there were notable differences between air tour aircraft flying at lower altitudes within the SFRA and high altitude (primarily commercial) aircraft flying above the SFRA. Low flying air tour aircraft generated more noise at ground level, VerDate Aug<31>2005 18:06 Apr 08, 2008 Jkt 214001 but could meet the threshold of the substantial restoration goal. Higher altitude aircraft generated lower levels of noise at ground level, but produced broader areas of audibility. The broader geographic coverage of audibility of high altitude aircraft noise made achieving the NPS percentage goals of substantially restoring natural quiet to the Grand Canyon unattainable from a practical standpoint, no matter how few air tour and general aviation operations occurred within the SFAR and over the park. GCNP noise monitoring results in 2005 supported the model predictions. The time jet aircraft (above 17,999 feet MSL) were audible ranged between 22% and 35% of the day at four sites in remote backcountry locations.4 These results are similar to those reported by Harris Miller Miller and Hanson, Inc. in 2004 where the average percentages of time high altitude jet traffic were audible was 34.4%.5 In 2006, the FAA retained MITRE Corporation CAASD to conduct a study on the feasibility of implementing a flight free zone over the heart of GCNP for flights above 17,999 feet MSL, and adjusting traffic routes that would avoid a large and very important portion of the Grand Canyon. The unpublished study titled ‘‘Impact from Restricting Flights From Grand Canyon Airspace’’ 6 determined that ‘‘routing of commercial aviation would have a significant impact on the users of the airspace, would add thousands of extra miles and flying minutes to the routes, and safety of the airspace and operation would be negatively impacted through increased complexity and risks.’’ From the results of the MITRE study, the FAA determined that a flight free zone for high altitude aircraft over the Grand Canyon would adversely affect the safety and efficiency of the national airspace system. Based on the data provided through the various NPS studies and the MITRE report, the NPS acknowledges that the definition of substantial restoration of natural quiet needs clarification to distinguish the goals within and above the SFRA, while at the same time considering the noise from all aircraft in 4 National Park Service (2007) Report on Winter Ambient Sound Levels in Grand Canyon National Park, Report No.GRCA–07–02. 5 Ross, J., Menge, C., and Miller. N.P. (2004) Percentage of time jet aircraft are audible in Grand Canyon National Park. Harris Miller Miller and Hanson, Inc., For NPS–HMMH Job No. 295860.044). 6 Abrahamsen, T.R., Marani. G.F., and Bearer, R., (2006) Impact on Restricting Flights From Grand Canyon Airspace. The MITRE Corporation CAASD for the Federal Aviation Administration and National Park Service, Report No. F063–B06–050, Presented to the Grand Canyon Working Group, September 2006. PO 00000 Frm 00063 Fmt 4703 Sfmt 4703 order to comply with the Overflights Act and the 2002 D.C. Circuit Court of Appeals decision. This notice clarifies that through the application of law and policy, the NPS is clarifying that ‘‘(a) Substantial restoration of natural quiet at GCNP is achieved when the reduction of noise from aircraft operations at or below 17,999 feet MSL results in 50% or more of the park achieving restoration of the natural quiet (i.e., no aircraft audible) for 75% to 100% of the day, each and every day; and (b) the NPS defines the substantial restoration of natural quiet, from all aircraft above 17,999 feet MSL, to mean that there will be an overall reduction in aviation noise generated above 17,999 feet MSL above the park over time through the implementation of specific measures in accordance with commitments made by FAA to the NPS. The NPS also clarifies that 50% of the park is a minimum in the restoration goal. Dated: January 16, 2008. Hal J. Grovert, Acting Regional Director, Intermountain Region, National Park Service. [FR Doc. E8–7410 Filed 4–8–08; 8:45 am] BILLING CODE 4312–ED–M DEPARTMENT OF THE INTERIOR National Park Service General Management Plan Amendment, Environmental Impact Statement, Petrified Forest National Park, Arizona National Park Service, Department of the Interior. ACTION: Notice of Intent to prepare an Environmental Impact Statement for a General Management Plan amendment, Petrified Forest National Park. AGENCY: SUMMARY: Under the provisions of the National Environmental Policy Act of 1969, 42 U.S.C. 4332(2)(C), the National Park Service is preparing an Environmental Impact Statement (EIS) for a General Management Plan (GMP) amendment for Petrified Forest National Park. The park is currently managed under a GMP that was completed in 1993. This plan describes a proposed boundary expansion for the park of approximately 93,000 acres. However, the 1993 GMP does not prescribe management for the proposed addition lands. The GMP was revised in 2004 to address specific aspects of the park’s management; this GMP Revision also does not address management activities for proposed addition lands. E:\FR\FM\09APN1.SGM 09APN1

Agencies

[Federal Register Volume 73, Number 69 (Wednesday, April 9, 2008)]
[Notices]
[Pages 19246-19248]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E8-7410]


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DEPARTMENT OF THE INTERIOR

National Park Service


Public Notice: Clarifying the Definition Of ``Substantial 
Restoration of Natural Quiet'' at Grand Canyon National Park, Arizona

AGENCY: National Park Service, Department of the Interior.

ACTION: Public Notice: Clarifying the definition of ``substantial 
restoration of natural quiet'' at Grand Canyon National Park.

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

SUMMARY: This notice clarifies the definition used by Grand Canyon 
National Park (GCNP) for achieving substantial restoration of natural 
quiet as mandated by the 1987 Overflights Act (Pub. L. 100-91) 
(Overflights Act). This clarification of the definition is necessary to 
address current acoustic conditions to comply with the intent of 
recommendations provided in the 1995 Report to Congress,\1\ and respond 
to a 2002 U.S. Court of Appeals decision. The provisions of the Special 
Flight Aviation Regulation (SFAR) 50-2 have not resulted in substantial 
restoration of natural quiet of GCNP. Given the volume of high altitude 
commercial jet and general aviation traffic overflying the Grand Canyon 
above 17,999 feet Mean Sea Level (MSL) and a recent court decision, the 
substantial restoration goal as currently defined cannot be attained. 
This clarification of the restoration definition, while focusing on air 
tour and air tour related and general aviation aircraft that are 
conducting overflights of GCNP at altitudes at or below 17,999 MSL, 
also incorporates measures to address noise from all aircraft. The 1995 
definition of substantial restoration of natural quiet is being 
clarified to distinguish between aircraft noise generated above and 
below 17,999 feet MSL. The Special Flight Rules Area (SFRA) ceiling was 
set at 17,999 MSL to avoid additional requirements, restrictions and

[[Page 19247]]

regulations that occur at or above 18,000 MSL.
---------------------------------------------------------------------------

    \1\ National Park Service, (1995) Report of Effects of Aircraft 
Overflights on the National Park System, Report to Congress, July 
1995.
---------------------------------------------------------------------------

    GCNP and the Federal Aviation Administration (FAA) are currently 
engaged in the preparation of an environmental impact statement (EIS) 
entitled ``Special Flight Rules Area in the Vicinity of Grand Canyon 
National Park.'' GCNP, in consultation with the FAA, has determined in 
the noise methodology section of the EIS that aviation noise above 
17,999 feet MSL will be considered as a cumulative impact for purposes 
of the EIS, and aircraft noise generated at or below 17,999 feet MSL, 
within the Special Flights Rules Area (SFRA) will be managed to attain 
the NPS recommendations and meet restoration management objectives 
consistent with GCNP management direction, 2006 NPS Management 
Policies, and the 1995 Report to Congress.
    The NPS proposes the following clarification to the definition of 
substantial restoration of natural quiet.

    (a) Substantial restoration of natural quiet at GCNP will be 
achieved when the reduction of noise from aircraft operations at or 
below 17,999 feet MSL results in 50% or more of the park achieving 
restoration of the natural quiet (i.e., no aircraft audible) for 75% 
to 100% of the day, each and every day; and
    (b) The NPS defines the substantial restoration of natural quiet 
from all aircraft above 17,999 feet MSL, to mean that there will be 
an overall reduction in aviation noise generated above 17,999 feet 
MSL above the park over time through the implementation of measures 
in accordance with FAA commitments.

    The NPS also clarifies that 50% of GCNP is a minimum in the 
restoration goal. This includes not only the impacts of aircraft noise 
on the soundscape but the impact of noise on the visitor experience and 
natural, cultural and historic resources for the entire park. The 
analysis of noise impacts in the overflights EIS will be based on the 
defined substantial restoration goal, park values and purposes, and the 
GCNP General Management Plan land zoning objectives and overall park 
management objectives.\2\ NPS has deferred the assessment of aviation 
safety to FAA's jurisdiction. Both agencies have agreed to consider the 
noise from all aircraft in the ongoing ETS and planning process. 
Further, both agencies have agreed to consider reducing aircraft noise 
over the park in the future from aircraft operating above 17,999 feet 
MSL over the SFRA, while removing aircraft operations above 17,999 MSL 
from direct regulation in this action. This notice seeks public comment 
on the clarification of the NPS definition of substantial restoration.
---------------------------------------------------------------------------

    \2\ National Park Service (1995) General Management Plan for 
Grand Canyon National Park.

---------------------------------------------------------------------------
DATES: This notice will be on public review for 30 days, May 9, 2008.

ADDRESSES: If you wish to comment, you may mail or hand deliver 
comments to the name and address below or comment online via http://
parkplanning.nps.gov/grca (select ``Substantial Restoration 
Clarification''). Comments must be received within 30 days from the 
date of this printing. You may also view a copy of this clarification 
through the Internet at: http://www.nps.gov/grca/naturescience/
soundscape.htm.

FOR FURTHER INFORMATION CONTACT: Ken McMullen, Overflights and Natural 
Soundscape Program Manager, Grand Canyon National Park, 823 N. San 
Francisco St., Suite B, Flagstaff, Arizona 8600l National Park Service, 
Grand Canyon NP, Telephone: (928) 779-2095.

SUPPLEMENTARY INFORMATION:

Background

    This notice is one of several steps being taken by the Secretary of 
the Interior (SOI), through the NPS, and the FAA to fulfill the mandate 
established by Congress in PL 100-91, the Overflights Act, to provide 
for the substantial restoration of natural quiet in Grand Canyon 
National Park. Section 3 of the Overflights Act mandated the SOI to 
submit to the Administrator of the FAA recommendations ``regarding 
actions necessary for the protection of resources in the Grand Canyon 
from adverse impacts associated with aircraft overflights.'' The 
express statutory goal for these recommendations is the ``substantial 
restoration of natural quiet and experience of the park and protection 
of public health and safety from adverse affects associated with 
aircraft overflight.'' The Overflights Act requires the FAA 
Administrator to adopt the recommendations of the SOI ``without change 
unless the Administrator determines that implementing the 
recommendations would adversely affect aviation safety.''
    Congress did not define natural quiet or substantial restoration of 
natural quiet and, instead, delegated the interpretation of the statute 
to the Secretary. Under well established rules of statutory 
construction, the agency's interpretation is given deference so long as 
it is based on a reasonable construction of the statute. The D.C. 
Circuit Court of Appeals found that the NPS had reasonable 
justification for its interpretations of natural quiet and substantial 
restoration of natural quiet, as set forth in the 1995 Report to 
Congress. (See Grand Canyon Air Tour Coalition v. FAA, 154 F.3d 455 
(D.C. Cir. 1998)).
    In its 1995 Report to Congress the policy decision of the NPS was 
that substantial restoration requires that 50% or more of the park 
achieve natural quiet (i.e. no aircraft audible) for 75-100% of the 
day. The NPS provided definitions of terms used, as well as rationale 
for its noise impact assessment methods in ``Review of Scientific Basis 
for Change in Noise Impact Assessment Method Used at Grand Canyon 
National Park,'' 2000.\3\ In the review, the NPS defined one parameter 
of substantial restoration of natural quiet to be ``* * * a threshold 
not to be exceeded on any given day * * * .'' In 2002, the definition 
of substantial restoration of natural quiet and the FAA's noise 
methodology in the 2000 Final Supplemental Environmental Assessment was 
addressed in litigation before the D.C. Circuit Court of Appeals, in 
the case United States Air Tour Association v. FAA, 298 F.3d 997 (D.C. 
Cir. 2002). In this case, the Court declared that `` * * * the Park 
Service is entitled to deference for its interpretation of its own 
definitions.'' The Court concluded ``* * * the FAA's use of an 
``average annual day'' for measuring `substantial restoration of 
natural quiet' appears inconsistent with both the Park Service's 
definition of the term and with the premise upon which that definition 
was based. * * * We must therefore remand this issue for further 
consideration.'' In response to the court decision, the term ``the 
day'' was clarified by the NPS in the November 7, 2003 Federal Register 
Notice (68 FR 63129-63130) to mean ``each and every day.''
---------------------------------------------------------------------------

    \3\ National Park Service, (2000) Review of Scientific Basis For 
Change in Noise Impact Assessment Method Used at Grand Canyon 
National Park. January 2000.
---------------------------------------------------------------------------

    The D.C. Circuit Court of Appeals also found that the FAA's noise 
methodology was flawed because it only accounted for noise from 
commercial air tours, while ignoring noise from other types of aircraft 
(commercial jets, general aviation, and military flights). The court 
further stated that the Overflights Act did not provide any basis for 
ignoring noise caused by such aircraft and in the absence of any 
reasonable justification for excluding non-tour aircraft from its noise 
model, the court concluded that this aspect of the FAA's methodology 
was arbitrary and capricious and required reconsideration by the 
agency.

Reasons for the Clarification

    Based on the 2002 D.C. Circuit Court of Appeals decision, as well 
as review

[[Page 19248]]

of Congressional intent, aircraft noise levels, and national airspace 
safety and efficiency, this clarification of the restoration definition 
is necessary to address the noise of all aircraft while distinguishing 
how the substantial restoration of natural quiet will be achieved at 
and below 17,999 feet MSL within the Special Flight Rules Area (SFRA) 
and above the SFRA. The NPS recognizes that due to the impacts of 
aviation noise on park resources and the visitor experience, even with 
implementation of quiet technology aircraft, restoration of the natural 
quiet as defined in the 1995 Report to Congress will not be achieved 
without reduction of the sounds produced by jet traffic above 17,999.
    The 1995 Report to Congress concluded that SFAR 50-2 had not 
resulted in substantial restoration of natural quiet in Grand Canyon 
National Park and continued growth in air traffic may diminish or 
negate progress to date. The report looked at air tour, military, 
general aviation and high altitude commercial overflights and found 
that the major aircraft noise impacts on natural quiet came from air 
tour activity and high flying commercial jet traffic. Low flying 
general aviation and military overflights were thought to contribute 
little to the overall aircraft noise impacts. As discussed in the 
Report to Congress, high altitude jets were known to be a noise issue 
that the FAA needed to address. In particular it was recommended in the 
report that (1) FAA not authorize any deviations from normal high 
altitude routes for sight-seeing purposes; (2) FAA not authorize 
deviations from normal flight plans and cruising altitudes over the 
Grand Canyon for other than safety reasons; and (3) that FAA conduct a 
study on high altitude commercial jet routes that may also have impacts 
on natural quiet in the park. Consequently, subsequent regulations 
focused on the regulation of air tour and related operations.
    In 2005 and 2006, the GCNP initiated a soundscape monitoring and 
data collection effort to verify the accuracy of the earlier acoustic 
science and methodologies used since the early 1980's (see discussion 
in 64 FR 38006-38007) and to determine the natural ambient conditions 
for most of the park area. NPS noise modeling results predicted that 
over 96% of the park area had aircraft noise audible for over 25% of 
the 12-hour day; however, there were notable differences between air 
tour aircraft flying at lower altitudes within the SFRA and high 
altitude (primarily commercial) aircraft flying above the SFRA. Low 
flying air tour aircraft generated more noise at ground level, but 
could meet the threshold of the substantial restoration goal. Higher 
altitude aircraft generated lower levels of noise at ground level, but 
produced broader areas of audibility. The broader geographic coverage 
of audibility of high altitude aircraft noise made achieving the NPS 
percentage goals of substantially restoring natural quiet to the Grand 
Canyon unattainable from a practical standpoint, no matter how few air 
tour and general aviation operations occurred within the SFAR and over 
the park. GCNP noise monitoring results in 2005 supported the model 
predictions. The time jet aircraft (above 17,999 feet MSL) were audible 
ranged between 22% and 35% of the day at four sites in remote 
backcountry locations.\4\ These results are similar to those reported 
by Harris Miller Miller and Hanson, Inc. in 2004 where the average 
percentages of time high altitude jet traffic were audible was 
34.4%.\5\
---------------------------------------------------------------------------

    \4\ National Park Service (2007) Report on Winter Ambient Sound 
Levels in Grand Canyon National Park, Report No.GRCA-07-02.
    \5\ Ross, J., Menge, C., and Miller. N.P. (2004) Percentage of 
time jet aircraft are audible in Grand Canyon National Park. Harris 
Miller Miller and Hanson, Inc., For NPS-HMMH Job No. 295860.044).
---------------------------------------------------------------------------

    In 2006, the FAA retained MITRE Corporation CAASD to conduct a 
study on the feasibility of implementing a flight free zone over the 
heart of GCNP for flights above 17,999 feet MSL, and adjusting traffic 
routes that would avoid a large and very important portion of the Grand 
Canyon. The unpublished study titled ``Impact from Restricting Flights 
From Grand Canyon Airspace'' \6\ determined that ``routing of 
commercial aviation would have a significant impact on the users of the 
airspace, would add thousands of extra miles and flying minutes to the 
routes, and safety of the airspace and operation would be negatively 
impacted through increased complexity and risks.'' From the results of 
the MITRE study, the FAA determined that a flight free zone for high 
altitude aircraft over the Grand Canyon would adversely affect the 
safety and efficiency of the national airspace system.
---------------------------------------------------------------------------

    \6\ Abrahamsen, T.R., Marani. G.F., and Bearer, R., (2006) 
Impact on Restricting Flights From Grand Canyon Airspace. The MITRE 
Corporation CAASD for the Federal Aviation Administration and 
National Park Service, Report No. F063-B06-050, Presented to the 
Grand Canyon Working Group, September 2006.
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    Based on the data provided through the various NPS studies and the 
MITRE report, the NPS acknowledges that the definition of substantial 
restoration of natural quiet needs clarification to distinguish the 
goals within and above the SFRA, while at the same time considering the 
noise from all aircraft in order to comply with the Overflights Act and 
the 2002 D.C. Circuit Court of Appeals decision.
    This notice clarifies that through the application of law and 
policy, the NPS is clarifying that ``(a) Substantial restoration of 
natural quiet at GCNP is achieved when the reduction of noise from 
aircraft operations at or below 17,999 feet MSL results in 50% or more 
of the park achieving restoration of the natural quiet (i.e., no 
aircraft audible) for 75% to 100% of the day, each and every day; and 
(b) the NPS defines the substantial restoration of natural quiet, from 
all aircraft above 17,999 feet MSL, to mean that there will be an 
overall reduction in aviation noise generated above 17,999 feet MSL 
above the park over time through the implementation of specific 
measures in accordance with commitments made by FAA to the NPS. The NPS 
also clarifies that 50% of the park is a minimum in the restoration 
goal.

    Dated: January 16, 2008.
Hal J. Grovert,
Acting Regional Director, Intermountain Region, National Park Service.
 [FR Doc. E8-7410 Filed 4-8-08; 8:45 am]
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