New VOR Service Volumes Published

The October 7, 2021 edition of the Aeronautical Chart Users’ Guide notes that IFR en route charts now show expanded VOR standard service volumes that are being implemented to support the minimum operational network (MON). That network is a key part of the FAA plan to reduce the number of ground-based navigation aids (for more information see Latest on VOR Decommissioning and related posts here at BruceAir).

The new ACUG includes the following note:

IFR ENROUTE CHARTS

Two new VHF Omnidirectional Radio Range (VOR) standard service volumes (SSV) have been implemented in order to achieve VOR service within 70 nautical miles above 5,000 feet above ground level (AGL). The new NAVAID codes are VOR Low (VL) and VOR High (VH). Along with that effort, two new distance measuring equipment (DME) SSVs of DME Low (DL) and DME High (DH) have been implemented to support DME-DME RNAV service. Legacy SSVs of Terminal (T), Low (L), and High (H) will continue to be maintained.

In the past, NAVAIDs at one location typically all had the same SSV. For example, a VORTAC typically had a High (H) SSV for the VOR, the TACAN azimuth, and the TACAN DME, or a Low (L) or Terminal (T) SSV for all three. A VOR/DME typically had a High (H), Low (L), or Terminal (T) for both the VOR and the DME. A common SSV may no longer be the case at all locations. A VOR/DME, for example, could have an SSV of VL for the VOR and DH for the DME, or other combinations.

See Charting Notice ENR_21-01_CN_SSV_Codes for more information.

Sample VOR/DME NAVAID box with two SSVs:

Next Round of VOR Shutdowns

At the April 24-25, 2019 session of the Aeronautical Charting Meeting, FAA noted that the following VORs will be decommissioned in 2019 (to see each VOR on a VFR chart at SkyVector.com, click the links below):

1. [ASP] Au Sable, in Oscoda, MI – June 20, 2019
2. [CSX] Cardinal, in St. Louis, MO – June 20, 2019
3. [LSE] La Crosse, in La Crosse, WI – June 20, 2019
4. [MTO] Mattoon, in Mattoon/Charleston, IL – June 20, 2019
5. [BQM] Bowman, in Louisville, KY – Aug. 15, 2019
6. [CZQ] Clovis, in Fresno, CA – Aug. 15, 2019
7. [FRM] Fairmont, in Fairmont, MN – Aug. 15, 2019
8. [GRV] Grantsville, in Grantsville, MD – Aug. 15, 2019
9. [GTH] Guthrie, in Guthrie, TX – Aug. 15, 2019
10. [HUB] Hobby, in Houston, TX – Aug. 15, 2019
11. [IKK] Kankakee, in Kankakee, IL – Aug. 15, 2019
12. [ISQ] Schoolcraft County, in Manistique, MI – Aug. 15, 2019
13. [TPL] Temple, in Temple, TX – Aug. 15, 2019

These shutdowns are part of FAA’s Minimum Operational Network (MON) plan to decommission 311 (about 35%) of the existing VOR network by 2025, leaving some 585 VORs in operation. As of early June 2019, 42 VORs have been shut down.

You can review the latest update from the MON program office here (PDF) and find general information in AIM 1−1−3. VHF Omni−directional Range (VOR), paragraph f. The VOR Minimum Operational Network (MON).

More details about the FAAs plans are available at BruceAir: VOR Status–Another Update

A key part of the MON program is increasing the service volume of remaining VORs to 70 nm at 5000 AGL, as described in the program update.

 

Update on VOR Decommissioning

The FAA has updated its plans to shut down about 311 VORs (about 30% of the existing network of 873 navaids) by 2025. About 585 VORs will remain in the minimum operational network (MON).

I went through the list of VORs that have been shut down and those scheduled to be decommissioned through September 2018. This PDF includes links to each navaid at SkyVector so that you can see them on a chart.

Note that in all cases, several nearby VORs remain active. Some of the VORs retain the DME feature and remain named fixes that you can file and use (with GPS–or DME).

The primary impact of the shutdowns would seem to be VOR-based approaches and perhaps departure procedures. Low altitude Victor airways, where necessary, are being supplanted with T-routes.

As the slide below shows, most of the VORs set to be decommissioned are in the Eastern and Central regions; only 15 navaids in the Western region are on the list.

To see the full list of VORs on the shutdown list, visit this entry at BruceAir. For more information about the process that FAA follows, see this explanation at AOPA. More information is available in the FAA Navigation Programs Strategy (PDF).

At the April 25-26, 2018 meeting of the Aeronautical Charting Forum (complete meeting minutes as PDF here), a representative of the VOR MON Program Office described progress on the plan (full presentation as PDF here). Here are some highlights:

• As of April 2018, 23 VORs have been decommissioned (see list below).
• 15 more VORs will be shut down by the fall of 2018 (see list below).
• FAA is upgrading the remaining VORs to support a standard service volume of 70 nm at 5000 AGL.

The FAA plans to increase the standard service volume (SSV) of the VORs that remain in the MON. Specifically, SSV at 5000 AGL will increase from the present 40 nm to 70 nm to support IFR navigation during a GPS outage. The following slides compare VOR coverage under the current standard with coverage using the new SSV.

Here’s the list of VORs that have been decommissioned so far:

Here’s the list of the VORs scheduled for shutdown by the fall of 2018:

FAA Releases List of VORs to be Shut Down

FAA has published a list of 308 VORs that it plans to shut down in phases by 2025. The notice in the Federal Register appeared on July 26, 2016. The notice includes a list of VORs that the FAA wants to decommission.

This document provides the discontinuance selection criteria and candidate list of VOR Navigational Aids (NAVAIDs) targeted for discontinuance as part of the VOR MON Implementation Program and United States (U.S.) National Airspace System (NAS) Efficient Streamline Services Initiative. Additionally, this policy addresses the regulatory processes the FAA plans to follow to discontinue VORs.

For background on the FAA’s plans, see Latest Info on VOR Shutdowns here at BruceAir. Note that under this plan, only about one-third of the existing network of VORs will be decommissioned.

According to the FAA notice:

The following criteria were used by the FAA to determine which VORs would be retained as a part of the MON:

— Retain VORs to perform Instrument Landing System (ILS), Localizer (LOC), or VOR approaches supporting MON airports at suitable destinations within 100 NM of any location within the CONUS. Selected approaches would not require Automatic Direction Finder (ADF), Distance Measuring Equipment (DME), Radar, or GPS.Show citation box

— Retain VORs to support international oceanic arrival routes.

— Retain VORs to provide coverage at and above 5,000 ft AGL.

— Retain most VORs in the Western U.S. Mountainous Area (WUSMA), specifically those anchoring Victor airways through high elevation terrain.

— Retain VORs required for military use.

— VORs outside of the CONUS were not considered for discontinuance under the VOR MON Implementation Program.

The following considerations were used to supplement the VOR MON criteria above:

— Only FAA owned/operated VORs were considered for discontinuance.

— Co-located DME and Tactical Air Navigation (TACAN) systems will generally be retained when the VOR service is terminated.

— Co-located communication services relocated or reconfigured to continue transmitting their services.

According to the FAA notice:

The FAA remains committed to the plan to retain an optimized network of VOR NAVAIDs. The MON will enable pilots to revert from Performance Based Navigation (PBN) to conventional navigation for approach, terminal and en route operations in the event of a GPS outage…

The VOR MON is designed to enable aircraft, having lost Global Navigation Satellite System (GNSS) service, to revert to conventional navigation procedures. The VOR MON is further designed to allow aircraft to proceed to a MON airport where an ILS or VOR approach procedure can be flown without the necessity of GPS, DME, ADF, or Surveillance. Of course, any airport with a suitable instrument approach may be used for landing, but the VOR MON assures that at least one airport will be within 100 NM.

How FAA Hopes to Change the Airway Structure

FAA has outlined a concept for overhauling the current network of low- and high-altitude airways. The plan is part of the FAA’s initiative to move toward performance-based navigation (PBN). At present, the proposal is just that—it isn’t a formal program with full funding.

The presentation, given at the FAA’s Aeronautical Charting Forum meeting on October 28-30, is available as a PDF in my  Aviation Documents folder at OneDrive.

The guiding principles of the proposal are:

• “Structure where structure is necessary and point-to-point where it is not.”
• Route structure requirements will be based on factors such as traffic demand, airspace utilization, ATC task complexity, airspace access, and user operational efficiencies.
• Ground based airways will be retained in areas of with poor radar coverage and in mountainous terrain.

Pilots of light aircraft are most concerned about low-altitude airways and routings, including the venerable victor airways and newer T-routes.

Regarding T-routes, FAA hopes to publish low-altitude PBN ATS routes “precisely where needed to”:

• Access rather than circumvent Class B/C airspace
• Lower minimum altitudes in areas of high terrain to improve access and avoid icing
• Circumvent Special Use Airspace in safe and optimal manner

The presentation includes an interesting slide that shows daily utilization of victor airways. The average for the top 81-100 low-altitude airways was just 3 operations (in FY2013).

The graphic below shows how V2, which runs east-west across the northern part of the US, was used in the last two fiscal years. Very few aircraft flew most segments of the airway.

Note that the segment that crosses the Cascades east of Seattle (SEA-ELN) gets regular traffic. Other segments, such as MINNY-MKG across Lake Michigan, and legs near BUF, are also well-used, probably due to ATC requirements in these high-traffic areas.

The FAA notes that 80-90% of the aircraft flying the 20 most-used victor airways are already equipped to fly T-routes, which require an IFR-approved GPS.

Given that so many aircraft are RNAV-capable, FAA notes that “Users file any combination of route segments, NAVAIDs, and  waypoints when not route restricted by ATC and automation.”

The proposal advocates retiring existing point-to-point navigation programs to give pilots more flexibility in planning and filing direct routes. FAA says it will work with users to create a network of optimally placed waypoints. When specific routes are required, the plan would expand the network of ATC IFR preferred routes, which would not necessarily follow existing airways. Point-to-point navigation would available elsewhere.

The new routes outlines in the plan would also:

• Increase the number of parallel route options through high density airspace
• Reduce separation between centerlines of published routes to 8 nm
• Circumnavigate Special Activity Airspace

For example, the program noted that T-319 passes directly over KATL, giving controllers a straightforward way to route aircraft through the Atlanta Class B airspace.

Latest Update from FAA on Plans to Decommission VORs

Two representatives from the FAA recently provided an update on the agency’s plans to decommission VORs. The presentation, given at the FAA’s Aeronautical Charting Forum meeting on October 28-30, is available as a PDF in my Aviation Documents folder at OneDrive. The presentation largely recapped information described in briefings and white papers (described here, here, and here), but it did restate several key points and provide some new information.

Highlights from the latest presentation include:

• The VOR MON Program will implement the [minimum operational network of VORs] by decommissioning 30-50% of the VORs in the NAS by 2025 (although the current plan retains all VORs in the designated mountainous region of the U.S.—roughly the western third of the country).
• The reduction will begin gradually over the first five years during which time the bulk of the procedural/airway/airspace work will assessed. Then the plan is to accelerate the process, with 20-25 VORs shut down each year.
• Only FAA owned/operated VORs will be considered for shutdown.
• DMEs and TACANs will generally be retained.
• Many of the remaining VORs will be enhanced to supply increased service volume. VOR standard service volume (SSV) will become 77 NM radius at 5000 ft. AGL.
• Increase support for direct navigation between VORs without airways.
• Retain sufficient ILSs, LOCs, and VORs to support “safe-landing” at a suitable destination with a GPS-independent approach (ILS, LOC or VOR) within 100 NM of any location within CONUS.
• Provide seamless VOR coverage at and above 5000 ft AGL.
• More than 5,000 instrument approaches may be affected by the reduction in operational VORs.
• Nearly 1,300 SIDs, STARs, and ODPs may be affected by the reduction in operational VORs.
• FAA is considering how to refer to and chart DME-only facilities.

Graphics in the presentation include a pair of maps that show how the current airway structure will be changed when the MON is established.

When a VOR is Decommissioned

The recent shutdown of the Lake Henry VOR (LHY), which lies northeast of Wilkes-Barre PA (VFR chart at SkyVector here), is an example of how the FAA is handling the gradual decommissioning of VORs. (See also More Details about VOR Shutdowns)

As the latest IFR low-altitude en route charts show, the VOR (at present still depicted on the charts to help pilots become familiar with the new routes) has been replaced by a five-letter waypoint, LAAYK.

Note that the frequency for the VOR (110.8) is now shaded to indicate that the facility has been shut down, as described on p. 54 of the Aeronautical Chart User’s Guide.

A wider view of the area shows that several victor airways or segments of airways have been replaced with T-routes, depicted in blue on charts published by the FAA.

T-routes and their associated G (GPS-based) MEAs are described in AIM 5−3−4. Airways and Route Systems and in “Area Naviation (RNAV) ‘T’ Route System” on page 56 of the Aeronautical Chart User’s Guide (12th edition).

You can expect similar changes as more VORs are shut down over the next several years, leaving what the FAA calls the Minimum Operational Network. That plan at present calls for all VORs in the mountainous regions (essentially the western U.S.) to remain online, while many VORs elsewhere in the country are decommissioned.