Establishment of United States Area Navigation Route T-581 in the Vicinity of Missoula, Montana

DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 71</CFR> <DEPDOC>[Docket No. FAA-2025-3288; Airspace Docket No. 25-ANM-158]</DEPDOC> <RIN>RIN 2120-AA66</RIN> <SUBJECT>Establishment of United States Area Navigation Route T-581 in the Vicinity of Missoula, Montana</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), DOT. <HD SOURCE="HED">ACTION:</HD> Notice of proposed rulemaking (NPRM). <SUM> <HD SOURCE="HED">SUMMARY:</HD> 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. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> Comments must be received on or before January 26, 2026. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> Send comments identified by FAA Docket No. FAA-2025-3288 and Airspace Docket No. 25-ANM-158 using any of the following methods: * <E T="03">Federal eRulemaking Portal:</E> Go to <E T="03">www.regulations.gov</E> and follow the online instructions for sending your comments electronically. * <E T="03">Mail:</E> 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. * <E T="03">Hand Delivery or Courier:</E> 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. * <E T="03">Fax:</E> Fax comments to Docket Operations at (202) 493-2251. <E T="03">Docket:</E> Background documents or comments received may be read at <E T="03">www.regulations.gov</E> 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 <E T="03">www.faa.gov/air_traffic/publications/.</E> 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. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Steven Roff, Rules and Regulations Group, Policy Directorate, Federal Aviation Administration, 600 Independence Avenue SW, Washington, DC 20597; telephone: (202) 267-8783. </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">Authority for This Rulemaking</HD> 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. <HD SOURCE="HD1">Comments Invited</HD> 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. <E T="03">Privacy:</E> 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 <E T="03">www.regulations.gov,</E> as described in the system of records notice (DOT/ALL-14 FDMS), which can be reviewed at <E T="03">www.dot.gov/privacy.</E> <HD SOURCE="HD1">Availability of Rulemaking Documents</HD> An electronic copy of this document may be downloaded through the internet at <E T="03">www.regulations.gov.</E> Recently published rulemaking documents can also be accessed through the FAA's web page at <E T="03">www.faa.gov/air_traffic/publications/airspace_amendments/.</E> You may review the public docket containing the proposal, any comments received and any final disposition in person in the Dockets Operations office (see <E T="02">ADDRESSES</E> 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. <HD SOURCE="HD1">Incorporation by Reference</HD> 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 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 <E T="02">ADDRESSES</E> section of this document. <HD SOURCE="HD1">Background</HD> 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. <HD SOURCE="HD1">The Proposal</HD> The FAA is proposing an amendment to 14 CFR part 71 to establish RNAV Route T-581 in the vicinity of Missoula, Montana. <E T="03">T-581:</E> T-581 would extend between the Missoula, MT, VOR/DME and the Kalispell, MT, VOR/DME. <HD SOURCE="HD1">Regulatory Notices and Analyses</HD> 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. <HD SOURCE="HD1">Environmental Review</HD> 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. <LSTSUB> <HD SOURCE="HED">List of Subjects in 14 CFR Part 71</HD> Airspace, Incorporation by reference, Navigation (air). </LSTSUB> <HD SOURCE="HD1">The Proposed Amendment</HD> In consideration of the foregoing, the Federal Aviation Administration proposes to amend 14 CFR part 71 as follows: <HD SOURCE="HED">PART 71—DESIGNATION OF CLASS A, B, C, D, AND E AIRSPACE AREAS; AIR TRAFFIC SERVICE ROUTES; AND REPORTING POINTS</HD> 1. The authority citation for 14 CFR part 71 continues to read as follows: <HD SOURCE="HED">Authority: </HD> 49 U.S.C. 106(f), 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. <SECTION> <SECTNO>§ 71.1 </SECTNO> <SUBJECT>[Amended]</SUBJECT> </SECTION> 2. The incorporation by reference in 14 CFR 71.1 of FAA Order JO 7400.11K, Airspace Designations and Repo ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 11k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━