Garmin PC Trainer Suite Update

Garmin has updated the free the PC Trainer Suite for GTN, G500/G600 TXi, GDU 620, GNX 375, GNC 355/355A, and GPS 175. You can find the new download here.

Note that the date on the web page is January 4, 2020; it should be 2021.

The PC Trainer Suite is a great tool for learning about, teaching, and practicing with Garmin’s latest panel-mount avionics for light GA aircraft. The key display elements and logic for navigating, flying procedures, etc. is essentially the same across the Garmin line, so this trainer can also help you teach about and learn the G1000, G5, and various panel-mount GPS navigators.

The web page shows the updates and system requirements for this version, which includes navigation/procedure/chart databases from May 2020.

New T-Routes in Las Vegas

FAA will establish several new T-routes (and high-altitude Q-routes) in the Las Vegas area on February 25, 2021 (notice in the Federal Register here). The final rule explains:

These Q and T routes facilitate the movement of aircraft to, from, and through the Las Vegas terminal area. Additionally, the routes promote operational efficiencies for users and provide connectivity to RNAV enroute procedures while enhancing capacity for adjacent airports.

Below are some details about the new low-altitude T-routes (T-338, T-357, T-359, T-361, and T-363) from the FAA announcement. I have plotted the LAT/LON coordinates on VFR and low-altitude IFR charts to help you visualize the routes. The notice, however, does not include the minimum IFR altitudes for the routes (MEAs). Note also that I converted the coordinates to show them on the charts, and those conversions may not accurately show the waypoints and courses as they will appear on the official charts to be published in February. To see how these routes connect to IFR departures, arrivals, and approaches, check the new procedure charts when they are published.

For more information about T-Routes, see AIM 5-3-4 Airways and Route Systems.

T-338 is established between the DSIRE, NV, WP to the BOEGY, AZ, WP. T-338 provides a lateral path for arrivals and departures to the North Las Vegas Airport (KVGT), Boulder City Municipal Airport (KBVU) and KLAS. Additionally, it serves propeller aircraft arriving at KVGT and KLAS from points east or that are departing from KVGT and KLAS to points east.

T338 Route on VFR Chart
T338 Route on IFR Chart

T-357 is established between the KONNG, NV, WP to the DSIRE, NV, WP. T-357 provides a predictable and repeatable path for overflights through the Las Vegas TRACON airspace and serves as an arrival/departure airway for KVGT, Henderson Executive Airport (KHND), KBVU, and KLAS aircraft.

T357 Route on VFR Chart
T357 Route on IFR Chart

T-359 is established from the DANBY, CA, WP to the DSIRE, NV, WP. T-359 provides a predictable and repeatable path for overflights through the Las Vegas TRACON airspace and serve as an arrival/departure airway for KVGT, KHND, KBVU, and KLAS aircraft. T-359 reduces the current requirement for air traffic control facilities to issue radar vectors or itinerant routing for KVGT arrivals/departures or overflights.

T359 Route on VFR Chart
T359 Route on IFR Chart

T-361 is established from the BOEGY, AZ, WP to the Mormon Mesa, NV, VORTAC (MMM). T-361 provides a predictable and repeatable flight path for aircraft flying through the Las Vegas TRACON airspace and to serve as an arrival/departure airway for KLAS, KVGT, KBVU, and KHND. T-361 reduces the current requirement for air traffic control facilities to issue radar vectors or itinerant routing for KLAS and KHND.

T361 Route on VFR Chart

T-363 is established from the DICSA, NV, FIX to the Mormon Mesa, NV, VORTAC (MMM). T-363 provides a predictable and repeatable path for propeller-driven arrivals and departures to and from KHND, KBVU, and KLAS to and from points north and northeast.

T363 Route on VFR Chart
T363 Route on IFR Chart

AIM Updates Navaid Service Volumes

The December 31, 2020 edition of the AIM is out. This edition includes only a few updates, but section 1−1−8 NAVAID Service Volumes, provides a detailed explanation of new navaid standard service volumes (SSV) for VORs and DME, largely to support the change to performance based navigation (PBN).

Paragraph (a) of the section explains that:

The FAA publishes Standard Service Volumes (SSVs) for most NAVAIDs. The SSV is a three−dimensional volume within which the FAA ensures that a signal can be received with adequate signal strength and course quality, and is free from interference from other NAVAIDs on similar frequencies (e.g., co−channel or adjacent−channel interference). However, the SSV signal protection does not include potential blockage from terrain or obstructions. The SSV is principally intended for off−route navigation, such as proceeding direct to or from a VOR when not on a published instrument procedure or route. Navigation on published instrument procedures (e.g., approaches or departures) or routes (e.g., Victor routes) may use NAVAIDs outside of the SSV, when Extended Service Volume (ESV) is approved, since adequate signal strength, course quality, and freedom from interference are verified by the FAA prior to the publishing of the instrument procedure or route.

Details follow in paragraph (2):

With the progression of navigation capabilities to Performance Based Navigation (PBN), additional capabilities for off−route navigation are necessary. For example, the VOR MON (See paragraph 1−1−3 f.) requires the use of VORs at 5,000 feet AGL, which is beyond the original SSV ranges. Additionally, PBN procedures using DME require extended ranges. As a result, the FAA created four additional SSVs. Two of the new SSVs are associated with VORs: VOR Low (VL) and VOR High (VH), as shown in FIG 1−1−4. The other two new SSVs are associated with DME: DME Low (DL) and DME High (DH), as shown in FIG 1−1−5. The SSV at altitudes below 1,000 feet for the VL and VH are the same as FIG 1−1−3. The SSVs at altitudes below 12,900 feet for the DL and DH SSVs correspond to a conservative estimate of the DME radio line of sight (RLOS) coverage at each altitude (not including possible terrain blockage).

TBL 1−1−1, SSV Designator Altitude and Range Boundaries, and a couple of figures provide the details. ATH=Above Transmitter Height.

SSV DesignatorAltitude and Range Boundaries
T (Terminal)From 1,000 feet ATH up to and including 12,000 feet ATH at radial distances out to 25 NM.
L (Low Altitude)From 1,000 feet ATH up to and including 18,000 feet ATH at radial distances out to 40 NM.
H (High Altitude)From 1,000 feet ATH up to and including 14,500 feet ATH at radial distances out to 40 NM. From 14,500 ATH up to and including 60,000 feet at radial distances out to 100 NM. From 18,000 feet ATH up to and including 45,000 feet ATH at radial distances out to 130 NM.
VL (VOR Low)From 1,000 feet ATH up to but not including 5,000 feet ATH at radial distances out to 40 NM. From 5,000 feet ATH up to but not including 18,000 feet ATH at radial distances out to 70 NM.
VH (VOR High)From 1,000 feet ATH up to but not including 5,000 feet ATH at radial distances out to 40 NM. From 5,000 feet ATH up to but not including 14,500 feet ATH at radial distances out to 70 NM. From 14,500 ATH up to and including 60,000 feet at radial distances out to 100 NM. From 18,000 feet ATH up to and including 45,000 feet ATH at radial distances out to 130 NM.
DL (DME Low)For altitudes up to 12,900 feet ATH at a radial distance corresponding to the LOS to the NAVAID. From 12,900 feet ATH up to but not including 18,000 feet ATH at radial distances out to 130 NM
DH (DME High)For altitudes up to 12,900 feet ATH at a radial distance corresponding to the LOS to the NAVAID. From 12,900 ATH up to and including 60,000 feet at radial distances out to 100 NM. From 12,900 feet ATH up to and including 45,000 feet ATH at radial distances out to 130 NM.

Standard-Rate Turns

Here’s my latest Tip of the Week for Pilot Workshops:

Standard-Rate Turn Secret.

Theories of Lift

I just completed giving two end-of-course checks to flight instructor applicants during which the candidates explained lift, at least in part, by presenting the so-called equal transit time theory. That is, when a pair of air molecules encounters the leading edge of an airfoil, the molecule flowing over the curved top of the wing must travel a longer distance than its companion moving beneath the wing. The molecule on top must therefore move faster to meet its companion at the trailing edge. Pressure drops as a fluid’s speed increases, Bernoulli’s principle, and so forth.

Unfortunately, the equal transit time explanation is wrong, and has long been recognized as an error (see, e.g., Babinsky’s Demonstration: The Theory of Flight and Its Historical Background [PDF]). There’s no physical process that would require the two molecules to meet (we’re not talking quantum entanglement here). In fact, numerous wind tunnel studies and other demonstrations confirm that, while the air flowing over the top of the wing does indeed speed up, and its pressure does in fact drop, particles that start together at the leading edge don’t meet. A molecule taking the (typically slightly) longer upper path in fact ends up far ahead of its cohort that follows the shorter path below. The video below shows the physical reality.

This longer video provides additional details. This one’s good, too.

Indeed, as Doug MacLean (see below) explains, the typical difference in the length of the pathways above and below an airfoil is about an order of magnitude too small to produce the actual observed lift. Moreover, symmetrical airfoils, and even flat planes, provided they meet a stream at an angle of attack, produce lift (more or less efficiently, to be sure) despite the fact that the distances the molecules must travel are effectively equal.

Clearly something (or somethings) else is (are) going on.

Doug MacLean, a retired Boeing aerodynamicist, quotes a former colleague, Philipe Spalart, who said: “It’s easy to explain how a rocket works, but explaining how a wing works takes a rocket scientist.”

(See MacLean in this YouTube video. Warning: There’s math late in the presentation. Triple integrals…)

Here’s a recent, accessible article from Scientific American about various theories of how airfoils create lift. It’s a good read that explains several key points. A teaser:

…Adding to the confusion is the fact that accounts of lift exist on two separate levels of abstraction: the technical and the nontechnical. They are complementary rather than contradictory, but they differ in their aims. One exists as a strictly mathematical theory, a realm in which the analysis medium consists of equations, symbols, computer simulations and numbers. There is little, if any, serious disagreement as to what the appropriate equations or their solutions are. The objective of technical mathematical theory is to make accurate predictions and to project results that are useful to aeronautical engineers engaged in the complex business of designing aircraft.

But by themselves, equations are not explanations, and neither are their solutions. There is a second, nontechnical level of analysis that is intended to provide us with a physical, commonsense explanation of lift. The objective of the nontechnical approach is to give us an intuitive understanding of the actual forces and factors that are at work in holding an airplane aloft. This approach exists not on the level of numbers and equations but rather on the level of concepts and principles that are familiar and intelligible to nonspecialists.

It is on this second, nontechnical level where the controversies lie. Two different theories are commonly proposed to explain lift, and advocates on both sides argue their viewpoints in articles, in books and online. The problem is that each of these two nontechnical theories is correct in itself. But neither produces a complete explanation of lift, one that provides a full accounting of all the basic forces, factors and physical conditions governing aerodynamic lift, with no issues left dangling, unexplained or unknown. Does such a theory even exist?

Read the article for a more complete discussion. You can also find excellent visualizations and explanations via the Lippisch videos, discussed in The Secret of Flight–Dr. Alexander Lippisch.

In the meantime, it seems the best we can do as flight instructors is explain that airfoils are shapes that efficiently produce lift as they move through the air (or the air moves over them). Pressure does in fact drop above an airfoil at a positive AoA resulting in an upward force. The air around an airfoil also is deflected and therefore accelerated (it has a change in velocity, by definition an acceleration), and, as MacLean argues, Newton’s Second Law (F=ma), not so much the Third Law (equal and opposite forces) applies. Lift and drag are the results, and we as pilots can control lift and drag by using the elevator control to change AoA, extending flaps, etc.

But the smart people who try to understand what causes these phenomena still can’t agree on complete theory of lift. As the Scientific American article concludes:

“One apparent problem is that there is no explanation that will be universally accepted,” [Drela] says. So where does that leave us? In effect, right where we started: with John D. Anderson, who stated, “There is no simple one-liner answer to this.”

Redefining Designated Mountainous Areas

FAA is working on a long-term project to redefine Designated Mountainous Areas, a change that could allow lower IFR altitudes in many parts of the western U.S. and in sections of higher terrain in the East. The project was a topic at the October 2020 session of the Aeronautical Charting Meeting; the images below come from an FAA presentation at that meeting.

First, some background. The current Designated Mountainous Areas (DMA) are described in 14 CFR Part 95 Subpart B (originally published in 1963). The references that apply to the continental U.S. are:

  • §95.13   Eastern United States Mountainous Area.
  • §95.15   Western United States Mountainous Area.

Figure 5-6-3 from the AIM shows these areas highlighted in blue. In general, the western third of the U.S., with a couple of exceptions in the Central Valley of California and part of the Puget Sound region near Seattle, is designated as a mountainous area. Another swath covers the high terrain from Alabama to New England, with exceptions in New York and Maine.

In a DMA, the minimum altitudes for IFR flight (explicitly defined in 14 CFR §91.177) must be 2,000 feet above the highest obstacle within a horizontal distance of 4 nautical miles from the course to be flown. Because the current DMA, especially in the West, covers such a large area, the MEAs for airways and minimum IFR altitudes that ATC must use can be unnecessarily high in regions such as central Washington and Oregon and similar wide valleys and basins in other states. This issue has become more important as we evolve to GPS navigation that supports direct RNAV routes and as ATC applies ADSB to its surveillance capabilities.

The FAA project seeks to redefine mountainous areas more specifically as:

Designated mountainous areas include those areas having a terrain elevation differential exceeding 3,000 feet within 10 nautical miles within those one arc-second quadrangles overlying terrain or U.S. territorial waters.

This new definition would also align with that used by ICAO.

Illustrations from the presentation at the ACM meeting help clarify the proposed change. These images (not to scale) show how the terrain in each quadrangle is evaluated.

For example, here’s a depiction of how the DMA in the West would change under the new rule. The shaded blue area shows the current DMA. The new definition would require the designation only for the orange-brown areas.

The DMA in the East would also shrink.

The practical effects of the change would alter the requirements for different phases of IFR flight. For example, pilots of piston-powered aircraft could have more flexibility in choosing IFR routes at comfortable altitudes, whether flying airways or RNAV direct. The new DMA could also provide more options when avoiding icing and allow new IFR departure procedures.

For example, when planning an off-airways route under IFR, you must consider the OROCA (although an OROCA is not, in itself, a legal minimum IFR altitude; see 14 CFR §91.177). The AIM defines OROCA thus:

OROCA is an off−route altitude which provides obstruction clearance with a 1,000 foot buffer in non-mountainous terrain areas and a 2,000 foot buffer in designated mountainous areas within the U.S. This altitude may not provide signal coverage from ground−based navigational aids, air traffic control radar, or communications coverage.

ATC must also apply minimum IFR altitudes when clearing you direct off-airways and other published route segments. As the AIM explains:

The minimum vectoring altitude [or minimum IFR altitude (MIA)] in each sector provides 1,000 feet above the highest obstacle in non-mountainous areas and 2,000 feet above the highest obstacle in designated mountainous areas. Where lower MVAs are required in designated mountainous areas to achieve compatibility with terminal routes or to permit vectoring to an IAP, 1,000 feet of obstacle clearance may be authorized with the use of Airport Surveillance Radar (ASR). The minimum vectoring altitude will provide at least 300 feet above the floor of controlled airspace.

Departure procedures are also constrained by DMA. When FAA develops ODPs and SIDs, the AIM explains, planners must evaluate obstacles around an airport:

The 40:1 obstacle identification surface (OIS) begins at the departure end of runway (DER) and slopes upward at 152 FPNM until reaching the minimum IFR altitude or entering the en route structure. This assessment area is limited to 25 NM from the airport in non-mountainous areas and 46 NM in designated mountainous areas.

The expanded OIS required in current DMA can result in steep climb gradients, course changes, and other requirements that can make IFR departures challenging, even when an airport is located in a broad valley or basin.

The effort to redefine DMA is a long project. The timeline below shows that work began in 2017.

A draft NPRM is scheduled for publication in February 2021, but the date may slip due to COVID. And at present, there’s no date for implementation. Changing the DMA would require extensive coordination and updates to legally defined routes, all types of IFR charts, databases, ATC resources and procedures, and FAA publications, including IFR training handbooks. Nevertheless, the effort is a welcome sign of progress as we adopt new navigation technologies and avionics.

A Busy, Blustery Day at Boeing Field

Even on a windy, bumpy Sunday afternoon, Boeing Field (KBFI) in Seattle can be a busy place.

I wanted to get some practice wrestling with crosswinds, so I took a short hop to nearby Bremerton, WA (KPWT) and then back to KBFI. Bremerton wasn’t busy. The wind there was 20-30 degrees off the runway heading and gusting to about 30 knots.

I was surprised on the return to KBFI, however, to find that the tower frequency was hopping. As you can hear in the first video above, one controller was working the two parallel runways on separate frequencies, herding a mix of VFR and IFR traffic, single-engine pistons and jets, helicopters and amphibs.

The wind at KBFI wasn’t quite as strong and it was more closely aligned with the runway, but Boeing Field lies in a valley, and the wind strength and direction often change dramatically as you descend to traffic pattern altitude and then to the runway.

Enjoy the ride. More flying videos at my YouTube channel: BruceAirFlying.

Traffic Pattern Calls: TMI

Lately, it seems that I hear many pilots at nontowered airports announcing their intentions like this:

Generic Traffic, Cessna 123A, 8 miles to the south, setting up for a 45 to the downwind, runway 27. Generic.


Generic Traffic, Cessna 123A on the downwind for base, runway 27. Generic.

Radio calls that include two or more legs of the traffic pattern grate on the ear (almost as much as “Any traffic in the area…“). More importantly, they could easily confuse other pilots, especially when the CTAF is busy and transmissions are cut off or lost in the static of multiple position reports:

Did that Cessna say, “On the 45” or “On downwind?”

Perhaps my noticing such CTAF calls is an example of the frequency illusion called the Baader-Meinhof phenomenon:

Baader-Meinhof phenomenon, or Baader-Meinhof effect, is when your awareness of something increases. This leads you to believe it’s actually happening more, even if that’s not the case.

Whatever the actual frequency of the announcements, they don’t help. When transmitting your position and intentions, provide the essential information, not a detailed description of your plan. For example, I teach this sequence of calls on the CTAF:

Podunk Traffic, Cessna 123A, one-zero miles south, planning left/right traffic runway 27. Podunk.

Podunk Traffic, Cessna 123A, on the 45, left/right traffic, runway 27. Podunk.

Podunk Traffic, Cessna 123A, [turning] left/right downwind runway 27 [full stop/touch and go]. Podunk.

Podunk Traffic, Cessna 123A, [turning] final runway 27 [full stop/touch and go]. Podunk.

Stating the direction of the traffic pattern (left or right) is especially important at airports with non-standard patterns or parallel or intersecting runways. It’s also helpful to tell other pilots that you’re planning a touch-and-go, full-stop, stop-and-go, or low approach.

AC 90-66B: Non-Towered Airport Flight Operations provides more details about this topic, and AIM 4-1-9, Traffic Advisory Practices at Airports Without Operating Control Towers includes additional specific examples such as:

Strawn traffic, Apache Two Two Five Zulu, (position), (altitude), (descending) or entering downwind/base/final (as appropriate) runway one seven full stop, touch−and−go, Strawn.

Note the forward slashes: downwind/base/final as in “downwind or base or final.”

And as for “Any traffic…please advise,” see both the AIM and the AC:

Pilots stating, “Traffic in the area, please advise” is not a recognized Self−Announce Position and/or Intention phrase and should not be used under any condition. (AIM)

Note: Pilots are reminded that the use of the phrase, “ANY TRAFFIC IN THE AREA, PLEASE ADVISE,” is not a recognized self-announce position and/or intention phrase and should not be used under any condition. Any traffic that is present at the time of your self-announcement that is capable of radio communications should reply without being prompted to do so. (AC 90-66B)

For more details, see Operations at Non-Towered Airports.

Unusable Airways, Routes, and Segments

Consider the following excerpt from the FAA low-altitude IFR enroute chart (L-33 / L-34) in upstate NY.

The light gray, EKG-like line that overlays V293/T295 is appearing more often as the FAA continues the MON program to decommission about one-third of the VORs in the continental U.S.

The zigzag line means that the underlying segment of an airway or route is unusable. That word, unusable, has a specific legal meaning in the FAA regulations. It also affects how you can operate under IFR in the area so depicted on a chart.

The combination of the symbol and its underlying meaning continues to confuse many pilots who fly RNAV-capable aircraft, typically using GPS to navigate even along VOR-based airways and routes.

The Aeronautical Chart User’s Guide describes the zigzag symbol thus:

For clarity, I’ve reproduced the caption below:

Pilots should not file a flight plan for or accept a clearance that includes navigation on any route or route segment depicted as unusable. Pilots using RNAV may request ATC clearance to fly point-to-point between valid waypoints or fixes, even those on routes depicted as unusable (refer to AC 90-108 for RNAV eligibility).

The AIM also addresses this issue, although somewhat obliquely.

For example, a note in AIM 1-2-3 Use of Suitable Area Navigation (RNAV) Systems on Conventional Procedures and Routes explains:

Unless otherwise specified, a suitable RNAV system cannot be used for navigation on procedures that are identified as not authorized (“NA”) without exception by a NOTAM. For example, an operator may not use a RNAV system to navigate on a procedure affected by an expired or unsatisfactory flight inspection, or a procedure that is based upon a recently decommissioned NAVAID.

That’s the legal answer, tied to the legal description of a Victor airway, which is explicitly defined by VOR radials (see 14 CFR Part 71, 14 CFR §91.181 Course to be flown, and FAA Order 7400.11).

For example, if a VOR is decommissioned or temporarily out of service, or if a radial or range of radials that define one or more airways or route segments is unusable, then the Victor airway or route segments that those radials establish are also unusable. An airway or segment might also be rendered unusable for other reasons, including new obstacles.

In other words, even if you fly an RNAV-capable airplane and routinely fly Victor airways using GPS, according to the chart below, you can’t legally file or fly V292 between SAGES and WIGEN. ATC should not even issue a clearance that includes “V292” for that part of the route.

In this case, there’s an easy way around the dilemma. The unusable segment coincides with a T-route, T295. T-routes are designated for use by aircraft with an IFR-approved GPS. And a note below the unusable segment of the airway states: ONLY V292 UNUSABLE.

So you could fly along the black line beneath the zigzag on this segment, provided ATC cleared you via T295.

Another option, point-to-point RNAV navigation, is also legal. ATC could clear you to fly (for example, west-to-east) along this segment via SAGES -> WIGAN.

Sometimes a segment marked as unusable does not have a charted MEA, or the only MEA is a GPS minimum altitude (in blue) associated with a coincident T-route. But ATC can still clear you by using its normal off-route or point-to-point procedures, including the minimum IFR altitudes (MIA) or minimum vectoring altitudes (MVA) established for that area.

This discussion may seem moot in the RNAV era. Most IFR pilots routinely fly victor airways using only GPS. As a practical matter, if you have a navigator that supports airways (for example, a GTN or newer G1000 system) and ATC clears you to fly the “unusable” segment via SAGES -> WIGAN, you would probably still load V292 into the box.

Or you could enter and fly that portion of T295. Either option saves you from having to enter the fixes individually.

As we’ve seen, the preceding example offers a couple of choices, because a T-route coincides with the Victor airway. But that’s not always the case if a Victor airway has been rendered unusable because a VOR has been decommissioned.

Consider this segment of V469:

The chart shows a GPS-based MEA (6900) for one segment marked unusable, but there is no coincident T-route. According to the AIM reference cited above, you can’t file or accept a clearance to fly V469 south of BRUCY. In this situation, legally, if you want to fly the course defined by the black line on the chart (and if the lack of a VOR signal is the only reason for the unusable segment), you must file, and ATC must clear you, via the fixes along that route: BRUCY -> EXRAS -> IFAVU -> BOOME

Again, you could save time and avoid potential errors by loading the airway into a navigator like a GTN. But technically, your clearance would be direct between the fixes at an altitude assigned by ATC for that portion of the route.

VOR Decommissioning: October 2020 Update

FAA continues its program to decommission about 307 (34%) of the VORs in the continental U.S. Some 589 VORs (with enhanced service volumes) will remain operational when the minimum operational network (MON) program is complete, now scheduled for FY2030.

At the October 2020 session of the Aeronautical Charting Meeting, Ernesto Etienne, VOR MON Lead Engineer at FAA, provided an update on the program to date.

For more information about the MON program, see: Updated VOR Retention List, Next Round of VOR Shutdowns, VOR Status–Another Update, Minimum Operational Network (MON) Airports.

As of September 20, 2020, FAA had shut down 82 VORs. In Phase 2 of the program, which runs through FY2030, another 225 navaids will be decommissioned.

The 82 VORs discontinued as of September 30, 2020 are in this list (PDF).

Through the end of calendar year 2020, the following navaids are scheduled to be shut down (to see these VORs on a chart at SkyVector, click the links).

Five (5) VORs planned for discontinuance – November 5, 2020:

  • (FAH) Falls, in Sheboygan, WI
  • (LNR) Lone Rock, in Lone Rock, WI
  • (MKG) Muskegon, in Muskegon, MI
  • (RBA) Robinson, in Robinson, KS
  • (UKN) Waukon, in Waukon, IA

Three (3) VORs planned for discontinuance – December 31, 2020:

  • (EWO) New Hope, in New Hope, KY
  • (ITH) Ithaca, in Ithaca, NY
  • (URH) Texoma, in Durant, OK