Proposed Rule2025-22635
Establishment of United States Area Navigation Route T-581 in the Vicinity of Missoula, Montana
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
December 12, 2025
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
This action proposes to establish United States Area Navigation (RNAV) Route T-581 in the vicinity of Missoula, Montana. The FAA is proposing this action to increase navigational flexibility and safety margins for the users and to expand Air Traffic Control operational capabilities.
Full Text
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<title>Federal Register, Volume 90 Issue 237 (Friday, December 12, 2025)</title>
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[Federal Register Volume 90, Number 237 (Friday, December 12, 2025)]
[Proposed Rules]
[Pages 57721-57722]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-22635]
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Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
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Federal Register / Vol. 90, No. 237 / Friday, December 12, 2025 /
Proposed Rules
[[Page 57721]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 71
[Docket No. FAA-2025-3288; Airspace Docket No. 25-ANM-158]
RIN 2120-AA66
Establishment of United States Area Navigation Route T-581 in the
Vicinity of Missoula, Montana
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This action proposes to establish United States Area
Navigation (RNAV) Route T-581 in the vicinity of Missoula, Montana. The
FAA is proposing this action to increase navigational flexibility and
safety margins for the users and to expand Air Traffic Control
operational capabilities.
DATES: Comments must be received on or before January 26, 2026.
ADDRESSES: Send comments identified by FAA Docket No. FAA-2025-3288 and
Airspace Docket No. 25-ANM-158 using any of the following methods:
* Federal eRulemaking Portal: Go to <a href="http://www.regulations.gov">www.regulations.gov</a> and follow
the online instructions for sending your comments electronically.
* Mail: Send comments to Docket Operations, M-30; U.S. Department
of Transportation, 1200 New Jersey Avenue SE, Room W12-140, West
Building Ground Floor, Washington, DC 20590-0001.
* Hand Delivery or Courier: Take comments to Docket Operations in
Room W12-140 of the West Building Ground Floor at 1200 New Jersey
Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday through
Friday, except Federal holidays.
* Fax: Fax comments to Docket Operations at (202) 493-2251.
Docket: Background documents or comments received may be read at
<a href="http://www.regulations.gov">www.regulations.gov</a> at any time. Follow the online instructions for
accessing the docket or go to the Docket Operations in Room W12-140 of
the West Building Ground Floor at 1200 New Jersey Avenue SE,
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays.
FAA Order JO 7400.11K, Airspace Designations and Reporting Points,
and subsequent amendments can be viewed online at <a href="http://www.faa.gov/air_traffic/publications/">www.faa.gov/air_traffic/publications/</a>. You may also contact the Rules and
Regulations Group, Policy Directorate, Federal Aviation Administration,
600 Independence Avenue SW, Washington, DC 20597; telephone: (202) 267-
8783.
FOR FURTHER INFORMATION CONTACT: Steven Roff, Rules and Regulations
Group, Policy Directorate, Federal Aviation Administration, 600
Independence Avenue SW, Washington, DC 20597; telephone: (202) 267-
8783.
SUPPLEMENTARY INFORMATION:
Authority for This Rulemaking
The FAA's authority to issue rules regarding aviation safety is
found in Title 49 of the United States Code. Subtitle I, Section 106
describes the authority of the FAA Administrator. Subtitle VII,
Aviation Programs, describes in more detail the scope of the agency's
authority. This rulemaking is promulgated under the authority described
in Subtitle VII, Part A, Subpart I, Section 40103. Under that section,
the FAA is charged with prescribing regulations to assign the use of
the airspace necessary to ensure the safety of aircraft and the
efficient use of airspace. This regulation is within the scope of that
authority as it would amend the airway structure as necessary to
preserve the safe and efficient flow of air traffic within the National
Airspace System.
Comments Invited
The FAA invites interested persons to participate in this
rulemaking by submitting written comments, data, or views. Comments are
specifically invited on the overall regulatory, aeronautical, economic,
environmental, and energy-related aspects of the proposal. The most
helpful comments reference a specific portion of the proposal, explain
the reason for any recommended change, and include supporting data. To
ensure the docket does not contain duplicate comments, commenters
should submit only one time if comments are filed electronically, or
commenters should send only one copy of written comments if comments
are filed in writing.
The FAA will file in the docket all comments it receives, as well
as a report summarizing each substantive public contact with FAA
personnel concerning this proposed rulemaking. Before acting on this
proposal, the FAA will consider all comments it receives on or before
the closing date for comments. The FAA will consider comments filed
after the comment period has closed if it is possible to do so without
incurring expense or delay. The FAA may change this proposal in light
of the comments it receives.
Privacy: In accordance with 5 U.S.C. 553(c), DOT solicits comments
from the public to better inform its rulemaking process. DOT posts
these comments, without edit, including any personal information the
commenter provides, to <a href="http://www.regulations.gov">www.regulations.gov</a>, as described in the system
of records notice (DOT/ALL-14 FDMS), which can be reviewed at
<a href="http://www.dot.gov/privacy">www.dot.gov/privacy</a>.
Availability of Rulemaking Documents
An electronic copy of this document may be downloaded through the
internet at <a href="http://www.regulations.gov">www.regulations.gov</a>. Recently published rulemaking
documents can also be accessed through the FAA's web page at
<a href="http://www.faa.gov/air_traffic/publications/airspace_amendments/">www.faa.gov/air_traffic/publications/airspace_amendments/</a>.
You may review the public docket containing the proposal, any
comments received and any final disposition in person in the Dockets
Operations office (see ADDRESSES section for address, phone number, and
hours of operations). An informal docket may also be examined during
normal business hours at the office of the Western Service Center,
Federal Aviation Administration, 2200 South 216th St., Des Moines, WA
98198.
Incorporation by Reference
United States Area Navigation Routes are published in paragraph
6011 of FAA Order JO 7400.11, Airspace Designations and Reporting
Points, which is incorporated by reference in 14 CFR 71.1 on an annual
basis. This document proposes to amend the current version of that
order, FAA Order JO 7400.11K, dated August 4, 2025, and
[[Page 57722]]
effective September 15, 2025. These updates would be published in the
next update to FAA Order JO 7400.11. FAA Order JO 7400.11K, which lists
Class A, B, C, D, and E airspace areas, air traffic service routes, and
reporting points, is publicly available as listed in the ADDRESSES
section of this document.
Background
The FAA is proposing to establish RNAV Route T-581 between the
Missoula, MT, Very High Frequency (VHF) Omni-directional Range (VOR)/
Distance Measuring Equipment (DME), and Kalispell, MT, VOR/DME. The new
route will directly overlay existing VOR Federal Airway V-231 between
the Missoula VOR/DME and the Kalispell VOR/DME. This area is within
mountainous terrain and because the existing V-231 relies on ground-
based VHF navigation signal coverage, the Minimum Enroute Altitudes
(MEA) are higher than what could be expected with a similar RNAV route
that is non-dependent of ground-based NAVAIDs.
RNAV Route T-581 will use the same points as V-231 between the
Missoula VOR/DME and the Kalispell VOR/DME and the MEAs will be
generally lower since there is no reliance on ground-based navigation
signals. These lower MEAs will provide greater navigational flexibility
and safety margins for the users and will expand ATC operational
capabilities.
The Proposal
The FAA is proposing an amendment to 14 CFR part 71 to establish
RNAV Route T-581 in the vicinity of Missoula, Montana.
T-581: T-581 would extend between the Missoula, MT, VOR/DME and the
Kalispell, MT, VOR/DME.
Regulatory Notices and Analyses
The FAA has determined that this proposed regulation only involves
an established body of technical regulations for which frequent and
routine amendments are necessary to keep them operationally current.
It, therefore: (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under DOT
Regulatory Policies and Procedures (44 FR 11034; February 26, 1979);
and (3) does not warrant preparation of a regulatory evaluation as the
anticipated impact is so minimal. Since this is a routine matter that
will only affect air traffic procedures and air navigation, it is
certified that this proposed rule, when promulgated, will not have a
significant economic impact on a substantial number of small entities
under the criteria of the Regulatory Flexibility Act.
Environmental Review
This proposal will be subject to an environmental analysis in
accordance with FAA Order 1050.1G, ``FAA National Environmental Policy
Act Implementing Procedures'' prior to any FAA final regulatory action.
List of Subjects in 14 CFR Part 71
Airspace, Incorporation by reference, Navigation (air).
The Proposed Amendment
In consideration of the foregoing, the Federal Aviation
Administration proposes to amend 14 CFR part 71 as follows:
PART 71--DESIGNATION OF CLASS A, B, C, D, AND E AIRSPACE AREAS; AIR
TRAFFIC SERVICE ROUTES; AND REPORTING POINTS
0
1. The authority citation for 14 CFR part 71 continues to read as
follows:
Authority: 49 U.S.C. 106(f), 106(g), 40103, 40113, 40120; E.O.
10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389.
Sec. 71.1 [Amended]
0
2. The incorporation by reference in 14 CFR 71.1 of FAA Order JO
7400.11K, Airspace Designations and Reporting Points, dated August 4,
2025, and effective September 15, 2025, is amended as follows:
Paragraph 6011 United States Area Navigation Routes.
* * * * *
T-581 Missoula, MT (MSO) to Kalispell, MT (FCA) [NEW]
Missoula, MT (MSO) VOR/DME (Lat. 46[deg]54'28.68'' N, long. 114[deg]05'01.15'' W)
SULFY, MT FIX (Lat. 47[deg]07'27.30'' N, long. 114[deg]06'00.88'' W)
ARLEE, MT FIX (Lat. 47[deg]08'27.42'' N, long. 114[deg]05'59.11'' W)
Kalispell, MT (FCA) VOR/DME (Lat. 48[deg]12'50.77'' N, long. 114[deg]10'33.21'' W)
* * * * *
Issued in Washington, DC, on December 9, 2025.
Alex W. Nelson,
Acting Manager, Rules and Regulations Group.
[FR Doc. 2025-22635 Filed 12-11-25; 8:45 am]
BILLING CODE 4910-13-P
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