FAA Advises Using Analog NAVAIDS In Spoofing Areas


The FAA is telling pilots to brush up on their old-school instrument procedures and use analog NAVAIDs where possible if they’re headed to areas where GPS spoofing is going on. In a Jan. 25 Safety Alert for Operators, the agency said GPS and GNSS disruptions are on the rise, particularly around war zones but also near military operations areas and places where countermeasures against drones are being used. “When available, operators should plan to use conventional Navigational Aids (NAVAIDs) in these locations,” the SAFO says. “The FAA recommends that each operator follow the detailed guidance from their respective OEM.”

The agency also wants pilots who encounter satellite navigation problems to report it to a dedicated website to add to a disturbingly long list of failures that have occurred so far. Among the anomalies experienced so far are:

  • Inability to use GPS/GNSS for navigation;
  • Inability to use hybrid GPS/GNSS inertial systems for navigation;
  • Loss of area navigation (RNAV) capability, to include required navigation performance (RNP);
  • Unreliable triggering of Terrain Avoidance and Warning systems (TAWS);
  • Inaccurate aircraft position on navigation display (e.g., moving map and electronic flight bag);
  • Loss of or erroneous Automatic Dependent Surveillance-Broadcast (ADS-B) outputs;
  • Unanticipated effects to use of conventional navigation aids (e.g., inability to autotune);
  • Unanticipated position-dependent flight management system effects (e.g., insufficient fuel indication)
  • Failure or degradation of Air Traffic Management (ATM) infrastructure and its associated systems reliant on GPS/GNSS, resulting in potential airspace infringements and/or route deviations.
Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.


    • Got that right, Larry. ADS-B Out is GPS-based. ADS-B is a surveillance technology relies on GPS to determine an aircraft’s position.

    • “ So much for ADS-B”

      ADS-B may be the answer. There are thousands of new ADS-B ground stations whose locations are known and surveyed. Each of those ground stations transmit data along with a unique identifier.

      Triangulation of those stations with unique identifiers who’s position is well surveyed and you have a ground based navigation system.

      • Sounds like DME/DME which already exists and is in use. We just need a box in light GA airplanes which could provide that navigation solution to existing navigators.

        • The Garmin GI-275, Aspen, and other similar boxes could probably be programmed to take two VOR/DME sources to triangulate the aircraft position. So in theory, at least some aircraft wouldn’t even need additional hardware and would only need a software update.

          • They would need a DME receiver and antenna. But it seems it would be smart to do VOR/VOR position checking now, and maybe have an external box to add DME/DME and VOR/DME position. Later models would add the DME receiver internally

      • “There are thousands of new ADS-B ground stations whose locations are known and surveyed.”

        First off, there aren’t “thousands” of new ADS-B ground stations. As far as I know, the number hasn’t changed much AND I’m betting the FAA will ‘spring’ space based ADS-B on us in less than a decade. And there’s no way for an “in” box to somehow figure out where the signal it’s receiving are coming from.

        You ARE right that the poition of each remote ADS-B location is known but just how is an ADS-B ‘in’ unit gonna get present position off of a ADS-B remote location … the audience here would like to know. GPS units DO NOT get position from the ground stations … period.

        • Not to. Mention that if they aren’t already jamming or spoofing adsn out data.

          I’m sure someone is or there causing phantom conflicts or just jamming.
          Does airline ADDB indicate to crew when jammed? I know there is no authentication, so it seems trivial.

        • In case the moderators aren’t quick enough, do a google search for a white paper:

          “Techniques to Provide Resilient
          Alternative Positioning, Navigation, and Timing
          (APNT) Using Automatic Dependent
          Surveillance – Broadcast (ADS-B) Ground Stations”

          • I bit and read the paper. It’s interesting technically but it’s basically reinventing a DME system. In order to make his idea work, a massive overhaul of the ‘systems’ would be required. And the paper reiterates what I said … there are ~~680 ground stations … NOT thousands !!

          • “ And the paper reiterates what I said … there are ~~680 ground stations … NOT thousands !!”

            That’s 680 stations in the U.S. alone.

        • I can’t help but wonder if it wouldn’t really require any new aircraft equipment since ADS-B (both 978UAT and 1090ES) should be easily received by satellite. Imagine if Starlink’s satellites were collecting that data.

          As far as an ADS-B receiver figuring out where it’s at, it’s possible but I think the real problem would be the lack of synchronization of some signal. The idea reminds me of LORAN-C years ago. Also as you pointed out, there aren’t nearly enough to make it usable.

          I could see a simple software update using ground station reception or even reception of ground based navaids allowing a sanity check of position. I.E. If GPS position indicates you should be receiving XYZ and ABC VOR’s or receiving a particular ADS-B ground station but you’re not, then pop a caution about GPS position. That sure seems like something that could be implemented fairly quickly with a software update.

          • Canada’s ADSB system is space-based. At the moment there is only ADSB-OUT.

            Implementation has been slow.

        • There are thousands and thousands of ADBS ground receivers out there. Many hobbyists, museums, amateur radio operators etc. have them hooked up to websites like Flightaware and others. I run two at the moment.

          They already use Multilateration to give the location to those who have a device that doesnt give their location. The coverage isnt 100% nor is it accurate enough actual navigation. But it would be enough to tell if their is spoofing or if a problem exists. This location is totally independent of the GPS signal the airplane receives. It is derived from a number (the more the more accurate it is) of receivers receiving the signal from the plane and the distance to each is derived by which one hears the plane first and how long until the second one hears the plane and so on and so on. This is similar to how Time Difference of Arrival (TDOA) works.

          Since the majority of these ADSB receivers are on internet connected Raspberry Pi’s or similar hardware, it wouldn’t take much to have the software notify the FAA or someone that the planes GPS coordinates are deviating from the MLAT derived coordinates. When 10-15 are saying the same thing, then chances are that plane has an issue with the location its sending.

          Another terrestrial option but one that would require hardware on the plane is using cell towers for triangulation. They are powerful enough and their positions dont vary. I believe the cell towers do broadcast an tower identification. Once again, not nearly as accurate or widespread as GPS, but it would be able to tell when the GPS is not accurate.

          This would be fairly easy to implement and would bring some good press and easily a few more thousand receivers scattered around the world. Flightaware is likely the biggest and their marketing could make use of this feature.

          • You present a VERY interesting idea, Mike. Using MLAT derived aircraft position and comparing it with the UAT or Mode S ES transmitted ADS-B position WOULD show an error. OK, the terrestrial network informs the FAA system it has detected an error. Now how do you get that up to the airplane? In the end, it’s about navigating the airplane from A to B. The beauty of your idea, however, is that there’s a reasonably cheap way to detect the problem … it’s just that it isn’t gonna help steer the airplane. The same thing could be done with the colocated transponder antenna systems comounted on the radars. A deviation is detected but we still have to steer the airplane.

      • The problem is that receiving unit would also have to know its distance and direction from the ground station, and I don’t think there are enough of them for an aircraft to always have more than 2 stations in range at once. At least, not outside of the dense metro areas.

      • And we are being told by NavCanada we must get antenna diversity because they are going straight satellite. Also Gary B is right: where I’m at near the northern border, there is no coverage below 5000′ and center radar is spotty below 4000. As long as we stick with a ground based system, but it is still far easier to block or adulterate a UHF and GHz frequency low powered RF signal than a comparable MF (200 kHz) signal.

    • Problem with VOR’s is that many ATP pilots trained in the last 10-15 years don’t know how to navigate with VOR only. NDB even worse. These pilot mills need to start doing a better job at teaching navigation other that GPS.

  1. According to FAA’s “Very High Frequency Omnidirectional Range (VOR) Minimum Operational Network (MON) Program Update” dated April 2021,objectives include “Discontinue approximately 34% (307) of VORs in the CONUS by FY30”. Is this timeline still active with the spoofing problem happening?

    • It doesn’t matter if it’s still active – there are so many VORs that are partially or fully-non-functional that they’re effectively already discontinued.

  2. Anyone remember LORAN? They were planning on upgrading it to compete with GPS before it was dismantled. I thought it was a dumb decision then and still do now.

    • You and everyone else who could see putting all of our navigation eggs in one basket would eventually come back to bite us.

    • Yep. I bought an airplane with a Northstar LORAN unit in it and loved it. Those units could triangulate so a 2-D position — like an intersection — could be determined. The only beef I had with ’em was that they were ‘slow’ to respond vs GPS but — still — woulda been a superb backup to GPS. I liked LORAN SO well I bought backup units … now worthless in a box in my hangar 🙁 .
      As others have said, it was an absolutely penny wise and dollar foolish move to do away with LORAN. The Gov’t … hard at work screwing things up.

  3. How many VORs have been de-commissioned or are mostly useless? Years ago, Phil Boyer warned about our growing dependency on GPS and suggested we keep the LORAN system active as a backup.

  4. The short-term answer to the problem, at least for the commercial guys, could be decoupling the inertial guidance systems (INS) from the GNSS. Inertial guidance systems, especially with the newer solid-state, laser, and fiber-optic gyros are accurate and independent of outside interference. While not as accurate as GNSS, they are accurate enough for point-to-point navigation. Current INS systems are updated periodically from the GNSS systems. Remove the GNSS update when spoofing or jamming is an issue and the problem disappears.

    Commercial carriers and the military relied heavily on INS systems before GNSS and seemed to get along OK. RNAV approaches would be an issue but that may be handled by other ground-based systems.

    However, having said all this, leaving functional ground-based systems in place such as VORs, TACAN, NDBs or some form of LORAN would be a good idea. Jamming and spoofing are not the only issues affecting GNSS, solar storms could also seriously affect spaced-based systems.

  5. If this GPS spoofing is going to happen at the alarming rate they are informing us, then its up to the FAA to do everything in its power to be sure that pilot’s know where, when and how long. A five or more day notice should be given of the area(s) to avoid. This notice should not be buried at the bottom of a list of NOTAMs, that no one reads. It should be graphically represented and available to pilots via a EFB. Secondly, those low altitude VORs and OMs need to come back on-line. They got plenty of money to send to Ukraine, but can’t keep a VOR or OM working. As for ADS-B, you can’t find out where someone is if you don’t know where you are. Without GPS it’s useless.

    • The decisions to dismantle VOR etc were made long before Putin’s most recent invasion of Ukraine.
      If you want to keep a KGB Colonel going with traditional Soviet ambitions, continue to advocate for not supporting Ukraine’s defense.
      If you don’t remember or are not old enough to remember why the Soviet Union was a bad idea then read defector accounts, read history.

  6. Loran would be spoofed if it was still in use.
    The answer is IRS operating in the background as in airliners.
    When GPS fails, IRS takes over till GPS comes back.
    It should be relatively simple to produce systems for lesser aircraft, given the wide availability of solid state equipment such as that found in phones and other equipment.

    • I worked the bomb/nav system in the B-58 ‘Hustler’ in the 60’s. IT had an inertial nav system and also had an astro tracker to provide corrections … worked very well. Problem is, celestial nav is never gonna happen in a 172. An affordable INS … maybe?

  7. The present advise of FAA is somehow strange to me.
    Yesterday, the FAA posted an YouTube video about the “Proposed Airspace Changes” in “Minneapolis St. Paul International Airport”, saying that it was needed to “update the technologies and procedures that support safe navigation”, the “need to eliminate outdate equipment … enhance safety … doing this by updating … procedures and replacing old equipment with modern technology, including satellite based navigation”, adding that that sort of navigation was “accurate and reliable” and it “enhances safety and efficiency”.
    On the other hand, a substancial part of “old fashion” navigation systems and equipment has been disabled, discontinued or discarded.
    Facing all this context, the advise of FAA is somewhat strange IMHO.

  8. Perhaps the FAA should consider more than the 100 VORs and associated DME in their proposed Minimum Operational Network of VORs.

  9. let’s see…will this be RR, RDF, ADF or that new VOR stuff??

    (1957 aviation cadet graduate of USAF pilot training)

  10. GNS430W best nav/comm boxes ever.
    100,000 units worldwide.

    About 1000 of combined VORs+VOR/DME+VORTACS in service. Plenty to have fun with and still get there-just like in the good ol’ days.

    • ADF, I say, RAF. Simple system except recent pilots would likely electrocute themselves 🙂 In rural WI, many of the small outlying airports had an ADF transmitter enabling finding the airport. Didn’t costs the airport sponsors much, most airplanes had ADF and life was good. All that went the way of the Dodo bird along with lots of the VOR system, sadly. Same thing with GPS. Everyone thought GPS was gonna be the cat’s meow and make everything else obsolete so they shut down much of the ‘old’ stuff. NOW we know that was a giant mistake.

      SO far, no one has mentioned the dependency of the ATC system upon the internet. Without the internet, the tie between much of the GPS and ADS-B infrastructure will not work.

      Translated … we’re screwed !

        • I also owned a 172 with a new panel and couldn’t bring myself to remove the ADF. Chuck Barker, a dear friend and a retired Captain from Frontier Airlines, scheduled every Monday night for several years what he affectionately called ‘the one with the ADF.’ He was like a kid in a candy store when flying the ADF around the Imperial Valley AM broadscast stations.

          • I did my instrument rating in a 172 at (then) Buckley ANGB in Denver. For the flight test, I had to do an ADF approach to the old Stapleton IAP. If somehow I could have been time transported to see today’s panels filled with TV sets, I’da thought I was on Mars.

  11. I just rebuilt my panel with the Dynon Skyview HDX, an older GNS430W and all the newest goodies. I cannot tell you how much grief I got when I said, I’m keeping the ADF and the antique King KX155 VOR/LOC/GS and the Stormscope. My reasoning: GPS is too easy to spoof or worse, block altogether. Phil Harbin and his Lightsquared and its phoenix Legato demonstrated that when ran tests in NV that rendered a 1500 mile radius GPS signals unusable during the Obama administration.

    As for ADS-B ground stations, fine. But I still have a perfectly functional ARNAV loran C sitting on the shelf in the hangar that served me very well for many 30 years, and MF radiation is hard to spoof, requires half a dozen transmitters, very redundant and close to foolproof. Probably could carry the ball game over its carrier too.