Another Update on VOR Decommissioning

At the October 26-27, 2016 meeting of the Aeronautical Charting Forum, FAA provided an update on its plans to decommission VORs as the aviation world transitions to performance based navigation (PBN) predicated on GPS.

The briefing on the topic included proposed new language for the AIM (PDF), scheduled for publication in 2017, to describe the minimum operational network (MON) of VORs that will remain in place as about one-third of the existing VORs are gradually shut down.

You can learn more about the plans to reduce the number of VORs at this blog, here.

The new text (still subject to final revision) will appear in AIM 1-1-3.VHF Omni-directional Range (VOR):

f. The VOR Minimum Operating Network (MON). As flight procedures and route structure based on VORs are gradually being replaced with Performance Based Navigation (PBN) procedures, the FAA is removing selected VORs from service. PBN procedures are primarily enabled by GPS and its augmentation systems, collectively referred to as Global Navigation Satellite System (GNSS). Aircraft that carry DME/DME equipment can also use RNAV which provides a backup to continue flying PBN during a GNSS disruption. For those aircraft that do not carry DME/DME. the FAA is retaining a limited network of VORs, called the VOR Minimum Operating Network (MON) to provide a basic conventional navigation service for operators to use if GNSS becomes unavailable. During a GNSS disruption, the MON will enable aircraft to navigate through the affected area or to a safe landing at a MON airport without reliance on GNSS. Navigation using the MON will not be as efficient as the new PBN route structure, but use of the MON will provide nearly continuous VOR signal coverage at 5,000 feet AGL across the NAS outside of the Western US Mountainous Area (WUSMA). (There is no plan to change the NAVAID and route structure in the WUSMA).

The VOR MON has been retained principally for IFR aircraft that are not equipped with
DME/DME avionics. However, VFR aircraft may use the MON as desired. Aircraft equipped with DME/DME navigation systems would, in most cases, use DME/DME to continue flight using RNAV to their destination. However, these aircraft may, of course, use the MON.

1. Distance to a MON airport. Within the contiguous United States (CONUS), the VOR MON is designed to ensure that an airport that has an instrument approach that is not dependent on GPS, ADF, DME or radar is within 100 nautical miles of any location. These airports are referred to as “MON airports” and will have an ILS approach or a VOR approach if an ILS is not available. VORs to support these approaches will be retained in the VOR MON. MON airports are charted on low-altitude enroute charts and are contained in the Chart Supplement and other appropriate publications.

It is important to note that any suitable airport can be used to land in the event of a VOR outage. For example, an airport with a DME-recquired ILS approach may be available and could be used by aircraft that are equipped with DME. The intent of the MON airport is to provide an approach that can be used by aircraft without ADF or DME when radar may not be available.

2. Navigating to an airport. The VOR MON will retain sufficient VORs and increase VOR service volume to ensure that pilots will have nearly continuous signal reception of a VOR when flying at 5,000 feet AGL. A key concept of the MON is to ensure that an aircraft will always be within 100 NM of airport with an instrument approach that is not dependent on GPS. (See 1-1-8.) If the pilot encounters a GPS outage, the pilot will be able to proceed via VOR-to-VOR navigation at 5,000 feet AGL through the GPS outage area or to a safe landing at a MON airport or another suitable airport, as appropriate. Nearly all VORs inside of the US Western Mountainous Area (WUSMA) and outside the CONUS are being retained. In these areas, pilots may use the existing (i.e., Victor and Jet) route structure and VORs to proceed through a CPS outage or to a landing.

3. Using the VOR MON. In the case of a planned GPS outage (e.g., contained in a published NOTAM), pilots may plan to fly through the outage using the MON as appropriate and as cleared by ATC. Similarly, aircraft not equipped with GPS may plan to fly and land using the MON, as appropriate and as cleared by ATC. Note that, in many cases, flying using the MON may involve a more circuitous route than flying GPS-enabled RNAV.

In the case of an unscheduled GPS outage, pilots and ATC will need to coordinate the best outcome for all aircraft. It is possible that a GPS outage could be disruptive, causing high workload and demand for ATC service. Generally, the VOR MON concept will enable pilots to navigate through the GPS outage or land at a MON airport or at another airport that may have an appropriate approach or may be in visual conditions.

The VOR MON is a reversionary service provided by the FAA for use by aircraft that are unable to continue RNAV during a GPS disruption. The FAA has not mandated that preflight or inflight planning include provisions for GPS- or WAAS-equipped aircraft to carry sufficient fuel to proceed to a MON airport in case of an unforeseen GPS outage. Specifically, flying to a MON airport as a filed alternate will not be explicitly required. Of course, consideration for the possibility of a GPS outage is prudent during flight planning as is maintaining proficiency with VOR navigation.

Also, in case of a GPS outage, pilots may coordinate with ATC and elect to continue though the outage or land. The VOR MON is designed to ensure that an aircraft is within 100 nautical miles of an airport, but pilots may decide to proceed to any appropriate airport where a safe landing can be made. WAAS users flying under Part 91 are not required to carry VOR avionics. These users do not have the ability or requirement to use the VOR MON. Prudent flight planning by these WAAS-only aircraft should consider the possibility of a GPS outage.

The FAA recognizes that non-GPS-based approaches will be reduced as VORs are eliminated and that most airports with an instrument approach may only have GPS- or WAAS-based approaches. Pilots flying GPS or WAAS-eguipped aircraft that also have VOR/ILS avionics should be diligent to maintain proficiency in VOR and ILS approaches in the event of a GPS outage.

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Latest Update on VOR Decommissioning Program

The latest update from FAA on its plans to decommission VORs includes the following details:

  • Decommission approximately 30% (308) of the current 957 VORs by 2025
  • 74 VORs will be shut down during phase 1 (FY2016 through FY2020)
  • Another 234 VORs will be decommissioned during phase 2 (FY2021 – FY2025)
  • Of the 308 VORs to be shut down, 15 will be in the West, 162 in the central U.S., and 131 in the East.
  • 649 VORs will remain in operation after 2025, forming the minimum operational network (MON).

The goals established for the MON include allowing pilots to:

  • Revert from PBN to conventional navigation in the event of a Global Positioning System (GPS) outage;
  • Tune and identify a VOR at an altitude of 5,000 feet or higher;
  • Navigate using VOR procedures through a GPS outage area;
  • Navigate to a MON airport within 100 nautical miles to fly an Instrument Landing System (ILS) or VOR instrument approach without Distance Measuring Equipment (DME), Automatic Direction Finder (ADF), surveillance, or GPS; and
  • Navigate along VOR Airways especially in mountainous terrain where surveillance services are not available and Minimum En Route Altitudes (MEAs) offer lower altitude selection for options in icing conditions.

Progress will be slow initially. Only 5 VORs are to be shut down by September 2016. Another 4 navaids will be decommissioned by September 2017, followed by 4 more through September 2018. In 2019, FAA plans to shut down an additional 25 VORs, followed by 36 more in 2020.

Phase 2 begins in FY2021. A total of 234 VORs will be shut down through 2025.

You can read more details about the MON plan in the minutes of the 15-02 meeting of the Aeronautical Charting Forum.

 

VOR Decommissioning: Latest FAA Update

The latest meeting of the FAA’s Aeronautical Charting Forum included an update from FAA on its plans to decommission many VORs as the nation’s air navigation and air traffic control services transition to a GPS-based system. Here’s a summary of the briefing from the ACF meeting minutes:

Discontinuation of VOR Services

Leonixa Salcedo, AJM-324, briefed the issue. Leonixa gave an overview of the VOR MON program and a status report since the last ACF. She reviewed the progress made to date on identifying VORs that may be decommissioned. She pointed out to the audience a significant change in the number of VORs expected to be decommissioned. Previously, it had been reported that approximately 50% of all the VORs in the NAS would be decommissioned. That estimation has been readjusted to just over 33% (approximately 308).

Leonixa stated that since the last ACF, the criteria for decommissioning VORs has been developed by the FAA and MITRE. Discussions have also taken place between the FAA and the DoD, during which the military emphasized that their operational requirements within the NAS require that fewer VORs be decommissioned.

Leonixa explained that the VOR MON program will be on a 10 year timeline of three phases, with the decommissioning of approximately 100 VORs during each phase. The goal is for final transition to the VOR MON by 2025. In the short term, Leonixa stated that a list of VORs initially selected for decommissioning will be released to the public sometime in 2015.

You can review the PowerPoint presentation about the VOR decommissioning program from the ACF meeting here (PDF).

Update on VOR Decommissioning

The Aeronautical Charting Forum, a forum sponsored by FAA, met on April 29, 2014 outside Washington, DC. Among the items on the agenda was an update on FAA’s plans to reduce the number of VORs to a minimum operational network (MON). You can download and review a PDF version of the FAA’s PowerPoint presentation here. (Minutes from the full two-day meeting are available here.)

Key points:

  • FAA now plans to transition from a legacy network of 967 VORs to a MON of  approximately 500 VORs by FY2025. That’s a slip of five years from the previous goal of establishing the MON by 2020. For more background, see the FAA’s VOR Minimum Operational Network (MON) Information Paper (PDF).
  • The number of VORs comprising the MON may increase or decrease depending on the requirements for the Department of Defense and the Tactical Operations Committee.

You can find additional details about the FAA’s program to decommission VORs here at BruceAir’s blog:

More Details about VOR Shutdowns

The latest edition of the FAA SatNavNews includes a discussion* of the agency’s plans to shut down many VORs as the aviation world shifts to GPS-based navigation. The article, on pages 5-8 of the Summer 2012 issue (PDF), includes graphics that show how shutting down many of the VORs in the eastern two-thirds of the continental U.S. will change the existing airway system.

*As noted in the newsletter:

The following is an abridged version of the information paper on the Very High Frequency Omnidirectional Range (VOR) Minimum Operational Network (MON) presented by the United States in May 2012 at a meeting of the Navigation Systems Panel of the International Civil Aviation Organization (ICAO) in Montreal, Canada.

FAA Provides More Details about Cutting VORs

The FAA recently published information about its plans to shut down VORs as it transitions to a GPS-based navigation system, an overhaul that’s part of the NextGen program.

Update: FAA Proposed Policy for Discontinuance of Certain Instrument Approach Procedures. Although this proposal is not directly related to the VOR Minimum Operational Network, it’s of interest to pilots who rely on ground-based navigation aids under IFR.

Now, at the behest of AOPA, FAA has released a few specifics about the proposal, including the map below that shows which VORs (green) will remain as others (red) are shut down, no later than 2020.

According to the FAA summary document:

FAA is planning on removing many of the 954 federally-owned and operated VORs and establishing a Minimum Operational Network (MON) of VORs not later than 2020…The purpose of the MON is to maintain a backup navigation capability to provide service for VOR-equipped aircraft in case of a GPS outage. In the MON, all VORs will be retained in Alaska, the Western U.S. Mountainous Area (WUSMA), and U.S. Islands and territories.

The FAA summary describes the “backup navigation capability” this way:

The MON will provide a safe landing for VOR-equipped aircraft flying under IFR in the case of a GPS outage. However, in general, the MON will not provide an efficient or useable navigation network for VOR-only aircraft (i.e., aircraft not equipped with GPS or Wide Area Augmentation System (WAAS) avionics). VOR-based navigation using only the MON would likely be circuitous, and not all airports will have instrument approaches that will be useable by VOR-only aircraft. The MON could be used by aircraft flying under Visual Flight Rules (VFR), but the primary purpose of the MON is to support safe landing of IFR aircraft during a GPS outage.

The document also notes that:

In considering VORs for discontinuance, each facility will be evaluated on its own merits. The FAA will convene a working group that will develop a candidate list of VORs for discontinuance using relevant operational, safety, cost, and economic criteria. As part of the process, this working group will engage aviation industry stakeholders and other members of the public for input.

For more details about the plan to shut down VORs, see the AOPA summary and the FAA white paper, which includes additional maps and tables, here. Comments on the FAA’s proposal are due March 7, 2012.

More on FAA Plans to Decommission VORs

Here’s a link to the latest proposal from FAA to change from a ground-based navigation network to a GPS-based system of airways and approaches. The long title of the document: Proposed Provision of Navigation Services for the Next Generation Air Transportation System (NextGen) Transition to Performance-Based Navigation (PBN).

You can read all of the details and learn how to submit comments (due March 7, 2012) at the preceding link.

Update: FAA has released a three-page summary that provides more details about which VORs would be decommissioned. Details and links available from AOPA here.

Here are some highlights from the proposal:

The FAA plans to transition from defining airways, routes and procedures using VHF Omni-directional Range (VOR) and other legacy navigation aids (NAVAIDs) towards a NAS based on Area Navigation (RNAV) everywhere and Required Navigation Performance (RNP) where beneficial. Such capabilities will be enabled largely by the Global Positioning System (GPS) and the Wide Area Augmentation System (WAAS). The FAA plans to retain an optimized network of Distance Measuring Equipment (DME) stations and a minimum operational network (MON) of VOR stations to ensure safety and continuous operations for high and low altitude en route airspace over the conterminous US (CONUS) and terminal operations at the Core 30 airports.

Currently, over 80% of the 967 VORs in the NAS inventory are past their economic service life and cost the FAA more than $110M per year to operate. Likewise, replacement parts are becoming increasingly difficult to obtain. The replacement of all of the VORs would cost over $1.0B. Therefore, the FAA is planning a gradual discontinuance (removal from service) of VOR facilities in CONUS to a minimum operational network (MON). The MON would enable aircraft anywhere in the CONUS to proceed safely to a destination with a GPS-independent approach within 100 nm. MON coverage is planned to be provided at altitudes above 5,000 feet above ground level (AGL). The FAA would also retain VORs to support international arrival airways from the Atlantic, Pacific, Caribbean, and at the Core 30 airports. The existing U.S. legacy navigation aids outside CONUS will be retained until a longer-term solution can be coordinated with users. The drawdown of VORs to a MON would be completed no later than January 1, 2020.

For more information about the FAA’s plans, see an earlier post here at BruceAir’s blog about the Federal Radionavigation Plan (PDF).