90 FR 139 pgs. 34593-34596 - Establishment of Restricted Area R-4601 in the Vicinity of Townsend, MT
Type: RULEVolume: 90Number: 139Pages: 34593 - 34596
Pages: 34593, 34594, 34595, 34596Docket number: [Docket No. FAA-2023-2371; Airspace Docket No. 22-ANM-42]
FR document: [FR Doc. 2025-13863 Filed 7-22-25; 8:45 am]
Agency: Transportation Department
Sub Agency: Federal Aviation Administration
Official PDF Version: PDF Version
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 73
[Docket No. FAA-2023-2371; Airspace Docket No. 22-ANM-42]
RIN 2120-AA66
Establishment of Restricted Area R-4601 in the Vicinity of Townsend, MT
AGENCY:
Federal Aviation Administration (FAA), DOT.
ACTION:
Final rule.
SUMMARY:
This action establishes restricted area R-4601 in the vicinity of Townsend, MT. The new restricted area will provide the Montana Army National Guard (MTARNG) and the 40th Helicopter Squadron with the ability to conduct aerial gunnery training in the Limestone Hills Training Area (LHTA).
DATES:
Effective date 0901 UTC, October 2, 2025.
ADDRESSES:
A copy of the Notice of Proposed Rulemaking (NPRM), all comments received, this final rule, and all background material may be viewed online at www.regulations.gov using the FAA Docket number. Electronic retrieval help and guidelines are available on the website. It is available 24 hours each day, 365 days each year.
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 increases the safety of aircraft by segregating non-participants from hazardous activities.
History
The FAA published a NPRM for Docket No. FAA 2023-2371 in the Federal Register (88 FR 88288; December 21, 2023), proposing to establish special use airspace (SUA) near Townsend, MT. The FAA received 18 comments that addressed several areas of concern. Multiple commenters expressed concern that the restricted area would impose a significant adverse impact on local flying especially during periods of inclement weather. Additionally, they contend that there is other airspace within the state of Montana that can be used in lieu of establishing new restricted airspace. They specifically mentioned the Powder and Hays Military Operations Areas (MOA) in the state of Montana.
As reported by a local pilot and airport manager, the majority of the visual flight rules (VFR) traffic moving through the Townsend area fly down the middle of the valley (over the river and/or over U.S. Route 287 and the railroad tracks). The proposed R-4601 does not overlie the river, highway, or railroad tracks. The Limestone Hills Training Area is easily identifiable west of U.S. Route 287, leaving adequate space to navigate through the valley.
The use of R-4601 during inclement weather would be highly unlikely as the type of training to be conducted requires visual meteorological conditions (VMC). Flight crews will not risk flying and training during marginal weather. Also, flight crews are precluded from conducting training in instrument meteorological conditions (IMC).
The location of the proposed R-4601 is adjacent to the very southern tip of Canyon Ferry Lake. At the narrowest point, there is approximately 1.5 nautical miles (NM) between the restricted area and the lake, leaving adequate airspace for aircraft that want to avoid flying over any portion of the lake. If an aircraft elected to fly further east around Broadwater County Airport (8U8), it would fly over a small portion of what is a large but very narrow lake. Very High Frequency Omnidirectional Range (VOR) Federal airways V-365, V-536, V-2, and United States Area Navigation (RNAV) Route T-268 all exist over the top of Canyon Ferry Lake.
Traffic counts at the Canyon Ferry Airport (8U9) are extremely low, and VFR traffic can easily circumnavigate both the 8U9 traffic pattern and the proposed R-4601. VFR transient aircraft should utilize the common traffic advisory frequencies (CTAF) of both 8U9 and 8U8 when in the vicinity.
The best practice for VFR traffic transiting the Townsend, MT area would be to fly above the 8U8 and 8U9 traffic patterns. The standard pattern altitude at a non-towered airport is 1,000 feet above ground level (AGL). The airport elevation at both 8U8 and 8U9 is just under 4,000 feet, mean sea level (MSL). Therefore, the standard pattern altitude at both airports would be approximately 5,000 feet MSL. It is reasonable to believe that most VFR aircraft transiting the area would commonly be operating at 5,500 feet or higher. If an aircraft plans to fly at lower altitudes through either traffic pattern (for weather or otherwise), operators are required to broadcast on the CTAF and determine if there is any traffic in the pattern. Also, most aircraft could circumnavigate R-4601 to the west.
The establishment of R-4601 will require pilots to be more aware of potential surrounding air traffic as they avoid the restricted area when active. While several of the Helena Regional Airport (HLN) Runway (RWY) 27 instrument approach procedures (IAP) are in the vicinity of R-4601, none of the IAPs begin over R-4601.
The HLN RNAV Global Positioning System (GPS) X RWY 27 initial approach fix is at SWEDD, MT, Fix with a crossing restriction of 10,000 feet MSL; the procedure path then proceeds north along the shore of Canyon Ferry Lake to GASBE, MT, Waypoint (WP), before turning west to HLN.
The HLN RNAV Required Navigation Performance (RNP) Y RWY 27 and RNAV RNP Z RWY 27 both have a crossing restriction of 10,000 feet MSL at SWEDD, MT, Fix before proceeding north along the shore of Canyon Ferry Lake to BOSCA, MT, WP, then turning west to HLN.
[top] SWEDD, MT, Fix is 6.9 NM north of the farthest-most point of the proposed
The southern arc of the HLN Instrument Landing System (ILS) Z or Localizer (LOC) Z RWY 27 comes closest to R-4601 and has an altitude of, at or above 11,000 feet MSL until KEDEC, MT, Fix (approximately the same location as SWEDD, MT, Fix) and, therefore, has less of an impact than the aforementioned IAPs.
The flight track of the HLN ILS Y or LOC Y is more than 12 NM north of the proposed R-4601 and is not considered a factor.
The HLN STAKK FIVE departure procedure (DP) includes a Bozeman transition that proceeds east over SWEDD, MT, Fix before turning to Bozeman. The required climb rates for both HLN runways place departing aircraft at or above 11,000 feet MSL before crossing SWEDD, MT, Fix, meaning that other aircraft in this area will have sufficient airspace to circumnavigate R-4601 and avoid aircraft on the DP. The remaining HLN instrument procedures are even further away and did not require additional evaluation.
Aircraft transiting from Bozeman to Helena should maintain awareness of other air traffic in the Helena area, including traffic utilizing any of the HLN instrument procedures. When R-4601 is active, there will be less space to maneuver and pilots will need to monitor their route of flight near R-4601, surrounding traffic, and the status of R-4601.
There are 1.5 miles of airspace between Canyon Ferry Lake and R-4601, which is considered adequate space to transit the area without being forced to fly over the lake. As noted above, aircraft can also circumnavigate R-4601 to the west.
The types of activities proposed for R-4601 are considered hazardous activities and require restricted airspace to separate nonparticipating aircraft from the hazardous activities. Although there are several MOAs in Montana, they are not restricted airspace and are inadequate/inappropriate for the proposed training activities. R-4601 will be the first restricted airspace in Montana.
The establishment of R-4601 at Limestone Hills Training Area combines two training activities in an already established area and is compatible with current land use. The establishment of a new restricted area requires control of the ground/property beneath the airspace, either by owning or agreement with the property owner. The DoD does not own or control any other suitable land in Montana that would support the establishment of restricted airspace. MTARNG has operated a firing range in the Limestone Hills Training Area responsibly since the 1950s and already manages the land in the area. Creating a new restricted area in another location would require the acquisition of additional Montana acreage/lands. The existing Limestone Hills Training Area was partially selected to capitalize on already-held state land and infrastructure assets and to avoid the need to acquire additional land for DoD use.
The R-4601 using agency will not activate R-4601 for training activities that do not require restricted airspace. If the training is non-hazardous and can be accomplished in a MOA, then they will use an existing MOA.
Multiple commenters believe that a transmitter should be installed within the Limestone Hills Training Area prior to establishing a restricted area to broadcast if the airspace is active or not. While a transmitter could aid pilots in determining the status of R-4601, there is no FAA requirement that such equipment be installed when establishing SUA. The status of R-4601 will be published in a Notice to Airmen (NOTAM), which is the current industry standard for publishing the times of use for special use airspace. In addition, air traffic control (ATC) frequencies are published on the VFR sectional charts, which pilots can utilize as another way to ascertain the status of R-4601. Pilots can also contact MTARNG Flight Operations at (406) 324-5779 to find out the status of the range.
Several commenters asserted that the Air Force's environmental analysis for this area was inadequate, and they disagreed with the determination that there are no suitable alternative sites in Montana to establish a restricted area. The Air Force prepared an environmental assessment (EA), which was adopted by the FAA. Public involvement as part of that process was conducted in accordance with the National Environmental Policy Act of 1969 (NEPA) (42 U.S.C. 4321, et seq. ) implementing regulations issued by the President's Council on Environmental Quality (CEQ), 40 CFR parts 1500 through 1508;? 1 and agency regulations, policies, and procedures for implementing CEQ Regulations and NEPA, including 32 CFR part 989, the Environmental Impact Analysis Process of the Department of Air Force; 32 CFR part 651, Environmental Analysis of Army Actions, Final Rule and the 2011 Army National Guard NEPA Handbook; FAA Order 1050.1F, Environmental Impacts: Policies and Procedures, 2 and FAA Order JO 7400.2R, Procedures for Handling Airspace Matters, which sets forth the FAA's procedures for considering and changing the NAS.
Footnotes:
1 ?The CEQ NEPA-implementing regulations have since been rescinded, effective April 11, 2025. 90 FR 10610 (Feb. 25, 2025). However, at the time the EA was prepared, the regulations were operative.
2 ?FAA Order 1050.1F has recently been cancelled and replace by FAA Order 1050.1G. However, at the time the EA was prepared, Order 1050.1F was the operative version in effect.
Several commenters believe that the data used for the analysis of air traffic in the environmental analysis was out of date or incomplete. They contend that there is considerably more traffic in the area than the analysis reviewed. IFR traffic volumes, as well as impacts on IFR procedures in the vicinity of the Limestone Hills Training Area were discoverable/verifiable. The aeronautical study identified two potential impacts to HLN IAPs, and mitigation measures have been determined. One mitigation is to reduce the proposed altitude of R-4601 from 10,000 feet MSL to 9,000 feet MSL, which is reflected in the IAP, and the other is to amend one of the IAPs with a crossing restriction. With these mitigations, no IFR traffic will be impacted by R-4601.
VFR aviation traffic exists below 9,000 feet MSL in the Limestone Hills Training Area, and R-4601 will impact this traffic. However, the actual volume of VFR traffic is neither discoverable nor verifiable by existing technology. As a commenter pointed out, some VFR aircraft operate in the area without an operating transponder, etc., and many are well below surveillance coverage. However, information received indicates the route of flights for most VFR transient aircraft around the Limestone Hills Training Area is to overfly U.S. Route 287 or the railroad tracks; such a route is clear of R-4601.
[top] The use of R-4601 is restricted to 140 days of the year due to seasonal restrictions for wildfire and wildlife mitigations, leaving air traffic unincumbered for 225 days of the year. Of the 140 days available for activation of R-4601, the maximum estimated usage is up to 50 events that may occur during the day or night. During each day or night of usage, R-4601 would typically be used for a 2 to 3-hour block for a maximum total of 150 hours per year. Assuming most air traffic flies through the area between 0800 and 2000 (14 hours per day), the airspace in the Limestone Hills Training Area is used
One commenter questioned why the results of an electronically distributed pilot survey seeking information on general aviation operations that may be impacted by the restricted area was not distributed to the public. Concerns raised by the Montana Department of Transportation, Aeronautics Division, resulted in a pilot survey aimed at gathering more information on the number of VFR flights in and around the proposed restricted airspace since there is not adequate radar information. 3 The information gathered supported the environmental analysis. Parties interested in the survey results should contact Katie Rediske at 341ces.ceie.nepaworkflow@us.af.mil.
Footnotes:
3 ?The Montana Department of Transportation, Aeronautics Division submitted a comment on the NPRM criticizing the proposal and claiming that inadequate coordination was conducted with the agency as part of the EA process. Subsequent to submitting the comment, further coordination occurred, including the pilot survey mentioned here.
Two commenters had concerns regarding the future expansion of the size or utilization of R-4601 once it is established. Currently, the DoD has no intent or ability to segment the LHTA into any broader airspace utilization. This project was intended to make use of already held assets, namely the LHTA, an artillery range for the MTARNG, and to add restricted airspace to execute aerial gunnery for USAF and MTARNG readiness training. It does not segment or connect to any other project. The information analyzed for the number of training events in the EA was the highest use case scenario for USAF training and based on stated USAF training requirements. Table 2-2 in the EA lists the number of proposed training events by USAF and MTARNG, which are all based on range availability and other factors such as seasonal limitations, weather, and supply of ammunition. Therefore, the potential to expand the LHTA and/or R-4601 in the future is limited and would require additional analysis and public input.
Differences From the NPRM
After publishing the NPRM, the name of the proposed restricted area changed from "R-4601 Townsend, MT" to "R-4601 Limestone Hills Training Area, MT." Additionally, the FAA slightly modified the dimensions of the airspace from what was published in the NPRM. The shape of the airspace is relatively the same, however, portions have been removed on the southwest corner and to the northeast because [reason(s)]. Overall, the final size of the restricted area is smaller than what was published in the NPRM. This action makes both changes. The FAA has determined that good cause exists for not re-circulating the proposal for public comment given that the changes are either ministerial in nature or result in a reduction of the impacted airspace.
The Rule
This action amends 14 CFR part 73 by establishing restricted area R-4601 in the vicinity of Townsend, MT. This new restricted area will provide a new training capability to the MTARNG in preparation for combat deployments and the 40th Helicopter Squadron located at Malmstrom Air Force Base (AFB) in support of security operations. The new restricted area is described below.
R-4601: Restricted area R-4601 extends upward from the surface of the ground to 9,000 feet MSL. The restricted area is located approximately four miles west of Broadwater County Airport, MT (8U8) and extends approximately eight miles to the southwest. The restricted area will be activated by a NOTAM to inform nonparticipants when the restricted area is active. During periods when the restricted area airspace is not needed by the using agency for its designated purpose, the airspace will be returned to the controlling agency for access by other National Airspace System users. The controlling agency for this proposed restricted area is the Salt Lake City Air Route Traffic Control Center.
Regulatory Notices and Analyses
The FAA has determined that this 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 only affects air traffic procedures and air navigation, it is certified that this rule, when promulgated, does not have a significant economic impact on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
Environmental Review
The FAA's establishment of restricted area R-4601 in the vicinity of Townsend, MT, for the MTARNG's and the 40th Helicopter Squadron's conduct of aerial gunnery training, was evaluated and documented in accordance with the National Environmental Policy Act (NEPA) (42 U.S.C. 4321, et seq. ) in the United States Air Force's (USAF) Final Environmental Assessment (FEA) for the Establishment and Operation of a Helicopter Aerial Gunnery Range and Establishment of Special Use Airspace Restricted Area R-4601 at the Limestone Hills Training Area, in Broadwater County, MT, signed November 2024. The USAF's FEA analyzes the FAA's modification of SUA, including the FAA's establishment of the new restricted area, R-4601, at LHTA which will be used for military flight training by the Air Force Global Strike Command (AFGSC) and the National Guard Bureau (NGB) operator for the Montana Army National Guard (MTARNG). The FAA, in fulfilling its mandated role as Cooperating Agency for this USAF proposed action, has adopted the USAF's FEA in a separate FAA NEPA adoption document and Record of Decision (ROD), drafted in accordance with Section 107 of NEPA, NEPA's implementing regulations concerning the roles and responsibilities of Cooperating Agencies, and other applicable authorities, including FAA's NEPA implementing guidance, FAA Order 1050.1F, Environmental Impacts: Policies and Procedures, which sets forth the FAA's policies and procedures for considering the environmental impacts of its actions including the process for Adoption of Other Agencies' NEPA Documents; and FAA Order JO 7400.2R, Procedures for Handling Airspace Matters, which sets forth the FAA's procedures for evaluating and changing the National Airspace System (NAS), including SUA.
Lists of Subjects in 14 CFR Part 73
Airspace, Prohibited areas, Restricted areas.
The Amendment
In consideration of the foregoing, the Federal Aviation Administration amends 14 CFR part 73 as follows:
PART 73-SPECIAL USE AIRSPACE
1. The authority citation for part 73 continues to read as follows:
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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.
§?73.46 Montana (MT) [New]
2. Section 73.46 is amended as follows:
R-4601 Limestone Hills, MT [New]
Boundaries. Beginning at lat. 46°19'22? N, long. 111°37'20? W; to lat. 46°20'08? N, long. 111°33'57? W; to lat. 46°19'18? N, long. 111°33'24? W; to lat. 46°18'43? N, long. 111°33'24? W; to lat. 46°18'43? N, long. 111°33'43? W; to lat. 46°18'22? N, long. 111°34'02? W; to lat. 46°18'00? N, long. 111°34'02? W; to lat. 46°17'30? N, long. 111°33'10? W; to lat. 46°17'30? N, long. 111°32'11? W; to lat. 46°14'33? N, long. 111°32'11? W; to lat. 46°13'30? N, long. 111°33'38? W; to lat. 46°13'31? N, long. 111°36'31? W; to lat. 46°14'19? N, long. 111°36'31? W; to lat. 46°14'33? N, long. 111°37'10? W; to lat. 46°14'33? N, long. 111°38'00? W; to lat. 46°17'21? N, long. 111°38'00? W; to lat. 46°17'21? N, long. 111°37'47? W; to lat. 46°19'04? N, long. 111°37'46? W; to the point of beginning.
Designated altitudes: Surface to 9,000 feet MSL.
Time of designation: By NOTAM.
Controlling agency: FAA, Salt Lake City ARTCC.
Using agency: U.S. Army, Montana Army National Guard, Joint Forces Headquarters, Fort Harrison, MT.
Issued in Washington, DC, July 21, 2025.
Brian Eric Konie,
Manager (A), Rules and Regulations Group.
[FR Doc. 2025-13863 Filed 7-22-25; 8:45 am]
BILLING CODE 4910-13-P