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.

FAA Publishes List of Instrument Approaches Set for Cancellation

FAA has published the latest list of 736 VOR and NDB approaches that it wants to cancel. You can download a Microsoft Excel worksheet that includes all of the procedures here.

According to the April 13, 2015 announcement in the Federal Register:

This action proposes to remove certain redundant or underutilized ground-based non-directional beacon and very high frequency, omnidirectional radio range Standard Instrument Approach Procedures based on the criteria established by the FAA’s Policy for Discontinuance of Certain Instrument Approach Procedures.

The announcement offers additional details as background:

On June 27, 2014, the FAA published a policy establishing criteria for cancelling instrument approach procedures (79 FR 36576). Cancelling certain ground-based non-directional beacon (NDB), and very high frequency (VHF), omnidirectional radio range (VOR) SIAPs is one integral part of right-sizing the quantity and type of procedures in the National Airspace System (NAS). As new technology facilitates the introduction of area navigation (RNAV) instrument approach procedures, the number of procedures available in the National Airspace System has nearly doubled over the past decade. The complexity and cost to the FAA of maintaining the existing ground based navigational infrastructure while expanding the new RNAV capability is not sustainable. Therefore, the FAA is proposing the following list of SIAPs for cancellation based on the criteria established in the Policy.

The proposal is open for comments until May 28, 2015.

You can find details about the current inventory of instrument approaches and related procedures at the Instrument Flight Procedures (IFP) Inventory Summary website.

To learn more about specific procedures and procedures in development, visit the Instrument Flight Procedures Information Gateway.

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.