# Federal Register 2026-19173 — effective 2026-10-29 — Establishment of United States Area Navigation Route T-581 in the Vicinity of Missoula, Montana — Federal Aviation Administration

For Federal Register 2026-19173, effective date is 2026-10-29; agency is Federal Aviation Administration; published is 2026-09-18; cfr parts amended is 14 CFR 71, recorded from its source on 2026-09-21; source re-checked 2026-11-03.

- **FR document number:** 2026-19173 _(verified: appears in the quote below)_
- **Rule:** Establishment of United States Area Navigation Route T-581 in the Vicinity of Missoula, Montana _(verified: appears in the quote below)_
- **Agency:** Federal Aviation Administration _(verified: appears in the quote below)_
- **Effective date:** 2026-10-29 _(verified: appears in the quote below)_
- **DATES, as printed:** The effective date of the final rule published in the Federal Register on August 3, 2026, remains 0901 UTC, October 29, 2026. The Director of the Federal Register approves this incorporation by reference action under 14 CFR part 71, subject to the annual revision of FAA Order JO 7400.11 and publication of conforming amendments. _(verified: appears in the quote below)_
- **CFR parts amended:** 14 CFR 71 _(our reading, not quoted from the source)_
- **Published:** 2026-09-18 _(verified: appears in the quote below)_

## What the source says

> {"document_number":"2026-19173","title":"Establishment of United States Area Navigation Route T-581 in the Vicinity of Missoula, Montana","agency_names":["Transportation Department","Federal Aviation Administration"],"effective_on":"2026-10-29","dates":"The effective date of the final rule published in the Federal Register on August 3, 2026, remains 0901 UTC, October 29, 2026. The Director of the Federal Register approves this incorporation by reference action under 14 CFR part 71, subject to the annual revision of FAA Order JO 7400.11 and publication of conforming amendments.","cfr_references":[{"chapter":null,"citation_url":null,"part":"71","title":14}],"publication_date":"2026-09-18","html_url":"https://www.federalregister.gov/documents/2026/09/18/2026-19173/establishment-of-united-states-area-navigation-route-t-581-in-the-vicinity-of-missoula-montana"}

## Source

- https://www.federalregister.gov/api/v1/documents.json?per_page=1000&order=oldest&conditions%5Btype%5D%5B%5D=RULE&conditions%5Beffective_date%5D%5Bgte%5D=2026-08-31&conditions%5Beffective_date%5D%5Blte%5D=2026-12-31&fields%5B%5D=document_number&fields%5B%5D=title&fields%5B%5D=agency_names&fields%5B%5D=effective_on&fields%5B%5D=dates&fields%5B%5D=cfr_references&fields%5B%5D=publication_date&fields%5B%5D=html_url

Last verified: 2026-11-03. Review by: 2026-11-16.
Part of [Federal rules taking effect: every US final rule in the Federal Register, by effective date](https://referencesource.org/federal-rules-taking-effect/).