# Establishment of United States Area Navigation Route T-581 in the Vicinity of Missoula, Montana
> **Rule** · Final rule. · Published 2026-08-03 · Effective 2026-10-29 · 91 FR 48756
## Document
- **Document number:** 2026-15675
- **Category:** other
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 91 FR 48756
- **Publication date:** 2026-08-03
- **Effective date:** 2026-10-29
- **FAA docket:** Docket No. FAA-2025-3288
## Abstract

This action establishes United States Area Navigation (RNAV) Route T-581 in the vicinity of Missoula, Montana. The FAA is taking this action to increase navigational flexibility and safety margins for the users and to expand Air Traffic Control operational capabilities.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2026/08/03/2026-15675/establishment-of-united-states-area-navigation-route-t-581-in-the-vicinity-of-missoula-montana)
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