[Federal Register Volume 68, Number 216 (Friday, November 7, 2003)]
[Notices]
[Pages 63129-63130]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-28113]


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DEPARTMENT OF THE INTERIOR

National Park Service


Clarification of the Term the day in the Definition of 
Substantial Restoration of Natural Quiet for Grand Canyon NP

AGENCY: National Park Service, Department of the Interior.

ACTION: Notice.

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SUMMARY: This notice clarifies the meaning of the term the day as it is 
used in the National Park Service (NPS) definition of substantial 
restoration of natural quiet at Grand Canyon National Park (GCNP) 
pursuant to Public Law 100-91, the National Parks Overflights Act of 
1987. It also helps to clarify the definition of substantial 
restoration of natural quiet recently the subject of litigation before 
the United States Court of Appeals, District of Columbia Circuit, in 
the case United States Air Tour Association v. Federal Aviation 
Administration (Grand Canyon Trust, Interveners). In this case, the 
Court declared that ``* * * the Park Service is entitled to deference 
for its interpretation of its own definitions'' (p. 19). The Court 
concluded ``* * * the FAA's use of an ``average annual day'' for 
measuring ``substantial restoration of

[[Page 63130]]

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'' (p. 22).
    Several interpretations of the meaning of the term the day have 
been advanced by various parties over the past few years, and the 
different interpretations have major implications for calculating the 
percentage of substantial restoration of natural quiet achieved at 
GCNP. This notice clarifies that the term the day in the definition of 
substantial restoration of natural quiet means any given day, every 
day, and provides guidance to the Federal Aviation Administration (FAA) 
concerning the appropriate definition of the day as used in the 
measurement of substantial restoration of natural quiet at GCNP. 
Clarification of this term will provide a benchmark for the future 
alternative dispute resolution process between the FAA and NPS. This 
clarification does not change the definition of substantial restoration 
of natural quiet.

ADDRESSES: You may view a copy of this definition through the Internet 
at: http://www.nps.gov/grca/overflights.

FOR FURTHER INFORMATION CONTACT: Ken McMullen, Overflights and Natural 
Soundscape Program Manager, National Park Service, Grand Canyon NP, 823 
N. San Francisco St., Suite B, Flagstaff, Arizona 86001. Telephone: 
(928) 779-2095, or by e-mail at [email protected].

SUPPLEMENTARY INFORMATION:

Background

    Public Law 100-91 called for the ``substantial restoration of 
natural quiet and experience of the park'' at GCNP. The NPS in its 
``Report on Effects of Aircraft Overflights on the National Park 
System'' (submitted to Congress in September, 1994, and published in 
July, 1995) determined that ``* * * substantial restoration requires 
that 50% or more of the Park achieve `natural quiet' (i.e., no aircraft 
audible) for 75-100 percent of the day'' (p. 182). Although the context 
of this definition suggested that the day implied each day, every day, 
or any given day (terms considered to mean the same thing in this 
context), the term was not further clarified in this report. However, 
the NPS analysis in the report was consistent with any given day.
    In its ``Review of Scientific Basis for Change in Noise Impact 
Assessment Method Used at Grand Canyon National Park'' (2000), the NPS 
provided definitions of terms used, as well as rationale, for its noise 
impact assessment methods. In this review the NPS defined substantial 
restoration of natural quiet to be ``* * * a threshold not to be 
exceeded on any given day. * * *'' (p. 16).
    The term the day in the definition of substantial restoration of 
natural quiet was recently the subject of litigation before the United 
States Court of Appeals, District of Columbia Circuit, in the case, 
United States Air Tour Association v. Federal Aviation Administration 
(Grand Canyon Trust, Intervenors). In this case, the Court declared 
that ``* * * the Park Service is entitled to deference for its 
interpretation of its own definitions'' (p. 19). 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'' (p. 22).

Clarification of the Term

    When used in the definition of substantial restoration of natural 
quiet, the day means any given day; that is, following the mandate of 
Public Law 100-91, natural quiet must be substantially restored at GCNP 
on any given day of the year. As further clarification, to achieve 
substantial restoration of natural quiet, 50% or more of the park must 
achieve ``natural quiet'' (i.e., no aircraft audible) for 75-100 
percent of any given day.
    Clarification also provides the FAA the guidance from the NPS 
concerning the appropriate definition of this term and assists in the 
determination of how to address aircraft noise as discussed in the 
Department of Transportation/FAA Federal Register Notice of February 
27, 2003, Modification of the Dimensions of the Grand Canyon National 
Park Special Flight Rules Area and Flight Free Zones (Federal Register/
Vol. 68, No. 39, pgs. 9496-9498). Clarification of this term will 
provide a benchmark for the future alternative dispute resolution 
process between the FAA and NPS.
    Significance of using any given day vs. other possible 
interpretations: Computer modeling of substantial restoration of 
natural quiet for previous FAA regulations followed FAA procedures and 
was based upon the number of air tour operations on an ``average annual 
day,'' as determined by dividing the year's total operations by 365 
days. The most recent computer modeling was done as a part of the 
Supplemental Environmental Assessment (Feb. 2000) accompanying the FAA 
final rule, ``Commercial Air Tour Limitations in the Grand Canyon 
National Park Special Flight Rules Area'' (65 FR 17,708). The modeling 
used the FAA's Integrated Noise Model (INM) and was based on air tour 
operations reported for the 12-month period May 1, 1997 through April 
30, 1998. The model indicated that using the ``peak day'' (any given 
day) definition, substantial restoration would not occur during the 
high visitation season, and that restoration of natural quiet would 
occur in 19% of the park. In contrast, modeling on the ``average annual 
day'' indicated that substantial restoration of natural quiet would 
occur in 44 % of the park. Thus, when using an ``average annual day'' 
standard, substantial restoration of natural quiet would not be 
achieved during the five summer months and portions of the shoulder 
seasons'times when the majority of the people visit the park. As the 
Court observed, ``* * * the use of an annual average does not 
correspond to the experience of the Park's actual visitors. People do 
not visit the Park on `average days', nor do they stay long enough to 
benefit from averaging noise over an entire year. For the typical 
visitor, who visits the Grand Canyon for just a few days during the 
peak summer season, the fact that the Park is quiet `on average' is 
cold comfort'' (p. 21).
    In summary, the National Parks Overflights Act of 1987 made clear 
that the visitors to GCNP are entitled to have the opportunity to 
experience substantial restoration of natural quiet. The Act did not 
limit that opportunity to only a portion of the park visitors or a 
portion of the year. The NPS, in its report to Congress, stated that 
such restoration would be for the day and, in its ``Review of 
Scientific Basis for Change in Noise Impact Assessment Method * * *'', 
the NPS further stated that it intended this to be ``a threshold not to 
be exceeded on any given day.'' Thus, as suggested by the United States 
Court of Appeals, District of Columbia Circuit, the NPS clarifies the 
day to mean any given day. On each and every day, visitors to GCNP will 
have the opportunity to experience natural quiet, that is, 50% of the 
park naturally quiet 75-100% of the time.

    Dated: May 15, 2003.
Michael D. Sunder,
Acting IMR-Regional Director.
[FR Doc. 03-28113 Filed 11-6-03; 8:45 am]
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