FAA Tells Pilots To Go Analogue As GNSS ‘Spoofing’ Incidents Increase

schmookeeg said:
Has anyone done some sort of celestial navigation computer? I've always thought that would be an amusing use of a raspberry pi, but never researched it deeply enough.

Obviously no good in IMC or with high overcast :)
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Actually yes. It was used by the US airforce in the 70's and into the 90's. I saw the celestial nav process on a F-111 in 1981 and got tour of how it worked.

From Wikipedia on Cestrial Navigation:
The US Air Force and US Navy continued instructing military aviators on celestial navigation use until 1997.
 
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Half Fast said:
I doubt truck drivers are using SAASM M-Code receivers, unless they’re military trucks. Classified technology to circumvent spoofing.
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Yeah but the good ole days of interference free JDAMs hitting their targets, seems to be over. Then again, even reverting to INS only, a typical MK-84 will still have an acceptable kill radius. One things for certain though, I wouldn’t want to be flying over there.

www.rusi.org

Jamming JDAM: The Threat to US Munitions from Russian Electronic Warfare

Leaked US documents show that Russian electronic warfare may be having a negative effect on US-supplied Joint Direct Attack Munitions.
www.rusi.org www.rusi.org
 
tsts4 said:
Not all VORs are being taken off line— they are going to maintain the Minimum Operating Network (MON) that will insure a ground based nav capability for the foreseeable future.
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I think more accurate to say:

they are going to try to keep a "Minimum Operating Network (MON)" running, that in theory will provide a ground based nav capability for airlines to use to navigate to most major airports, if they can afford it and find the spare parts.
 
The practical problem with MON is that the VOR network is already getting so sparse in the Northeast (between decommissioning and the many out-of-service VORs) that it can be difficult to find usable airways to get you where you want to go without going way out of your way. This is already showing up in IFR clearances. For example, at my airport (VGC) the usual clearance was 12 mi to the west to GGT VOR then on your way (usually west or south). Now with MON, my clearance starts with SYR VOR which is 35 mi to the northwest. I usually get sent on my way before I get there, but this is almost always opposite the direction I need to go. If you want to fly to Pittsburgh from Central New York, good luck finding a Victor airway that is viable, as ULW is permanently out of service, and CIP has frequently been down.

I wonder if eLORAN (or similar) would be a reasonable solution to an alternative ground based nav system. It's probably not accurate enough for military targeting, but suitable enough for enroute nav and non-precision approaches in the event that GPS is wonky. LORAN requires far fewer stations to complete a nav network than VORs. When I had LORAN-C in my plane, it performed very impressively. The only issue I had was that the master station was about 50-100 miles west of my airport on the old Seneca air base. When you fly too close to the master station, the position solution blows up for a few miles.
 
For approaches, I know we have GBAS being experimented with, but why not change the A to P for a Ground Based Positioning System? GPS minus the satellites, but otherwise the same thing. Better even since you no longer need to constantly calculate and update ephemeris, just minor updates for geological movement, and ionospheric conditions shouldn't have as much of an effect. A set of ground based transmitters around an airport should be able to have much higher power levels and be a bit more resistant to jamming by Joe Schmo trying to cheat his vehicle miles or whatever. If the biggest concern is approaches where accuracy down to the meter is critical, we don't need nationwide coverage, just around airports. Cell towers might make ideal existing sites.
 
tsts4 said:
There’s the MON plus ILS/LOCs. It will be a bit before it’s all taken offline. Not perfect but still a viable IFR environment. So my recommendation still stands.
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Except to receive MON stations at the 100 nm service volume the aircraft assumes the aircraft above 5000 ft AGL and a weather hazard called ice in the northern states starting about mid October.

Things are also going to get fun with SIDs and STARs during an outage.
 
Clip4 said:
Except to receive MON stations at the 100 nm service volume the aircraft assumes the aircraft above 5000 ft AGL and a weather hazard called ice in the northern states starting about mid October.
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Didn't say it was perfect and what you state still doesn't change my position or recommendation to maintain a VOR/ILS/LOC capability in the panel. If they come up with a better mouse trap at some point and we can ditch VOR completely I'm all for it, but until then........
 
MattCW said:
why not change the A to P for a Ground Based Positioning System? GPS minus the satellites, but otherwise the same thing.
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That's actually how business jets and airliners used to navigate before GPS - by using two DME stations (DME/DME NAV). That was not that long ago, and it still exists as a backup in pretty much every FMS today. Works great for enroute and terminal, not so much for approaches or oceanic, of course. It's nowhere near as accurate as GPS/GNSS.

A lot of people are thinking about how to augment GNSS with an independent system, similar enough to provide the same or better performance but dissimilar enough to not be jammed and spoofed in the same way. Not just for aviation... the whole world has become addicted to GNSS, it seems.

- Martin
 
As has been highlighted already, non-GPS RNAV already existed via DME/DME FMS, radial/dme(KNS-80), and LORAN. It's just a matter of cost. We used to even do it no-ish manually in the USAF, via "fix to fix pencil method" and the like, until the FAA outlawed the practice in the NAS and we got told to KIO.

There's not enough economies of scale to make non-GNSS RNAV commercially viable in light piston. The KNS suffered from hardware reliability due to old timey board/display complexity and heat/form factor problems, but it was an excellent capability given the lack of affordability of big boy INS/FMS in light piston. Loran was even better (imo); both got axed with the advent of GPS moving map avionics. The only way these avenues (VOR/DME RNAV, as LORAN is not coming back) become prolific in spam can land is if the GPS reliability starts becoming visibly problematic to start boning up the IFR system. Until then, there won't be enough economies of scale to install non-GNSS RNAV affordably in small fry aviation.

I used to view MON derisively, then I realized the new service volumes are adequate for a robust non-GPS rnav box that can make the enroute presentation on a moving map with modern software and solid state hardware/displays. It's not meant to replace WAAS, it's called not looking at gift horse in the mouth when you're in the soup and GPS ain't working for ya, and center is swamped. VORTACs are not that bad. So I'm still a fan, especially now that solid state CDI/HSI/converters are economically available (self-install, screw fac built labor). My main complaint with vhf nav has always been the hardware cost of analog, and its uneconomical upkeep. I do concede a bit of bias in that I make a living in primary/intermediate flight training, so I'm constantly practice bleeding with vhf nav, whereas most people's atrophied inability to mentally navigate absent "ownship moving map" these days would prob freak out the FAA.
 
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schmookeeg said:
Has anyone done some sort of celestial navigation computer? :)
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Yes, and the capability has been around for a long time. Extremely low duty cycle but very effective.
schmookeeg said:
Obviously no good in IMC or with high overcast :)
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Weather isn't really an issue for the system I'm thinking of.

Nauga,
and Mirv Griffin
 
Martin Pauly said:
That's actually how business jets and airliners used to navigate before GPS - by using two DME stations (DME/DME NAV). That was not that long ago, and it still exists as a backup in pretty much every FMS today. Works great for enroute and terminal, not so much for approaches or oceanic, of course. It's nowhere near as accurate as GPS/GNSS.

A lot of people are thinking about how to augment GNSS with an independent system, similar enough to provide the same or better performance but dissimilar enough to not be jammed and spoofed in the same way. Not just for aviation... the whole world has become addicted to GNSS, it seems.

- Martin
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Our old system tracked 6 DME and 2 VOR stations. I cannot remember how many we needed to get an accurate position, but I think it was more than 2.
 
Plano Pilot said:
Our old system tracked 6 DME and 2 VOR stations. I cannot remember how many we needed to get an accurate position, but I think it was more than 2.
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DME/DME systems need 3 to give a specific positon. Two stations give you 2 possible positions.
 
Pinecone said:
DME/DME systems need 3 to give a specific positon. Two stations give you 2 possible positions.
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That's mathematically correct.

But airplanes don't jump around in space randomly. With a known approximate starting position and Kalman filter etc., navigating while in contact with two DME stations works just fine in FMS-equipped airplanes.

- Martin
 
I like the idea of a nav box that uses GPS, GLONASS, DME/DME, DME/VOR, VOR/VOR, and a solid-state INS to provide navigation in most any circumstance.
 
schmookeeg said:
Has anyone done some sort of celestial navigation computer? I've always thought that would be an amusing use of a raspberry pi, but never researched it deeply enough.

Obviously no good in IMC or with high overcast :)
Click to expand...
I am pretty sure that was designed and flown in the 60’s for a certain famous high flying spy plane.

theaviationgeekclub.com

SR-71 Astroinertial Navigation System was crucial in Blackbird mission.

The SR-71 Astroinertial Navigation System, aka R2-D2, was crucial in Blackbird reconnaissance mission. Here’s why.
theaviationgeekclub.com theaviationgeekclub.com
 
I'll toss out a software challenge... It should be possible to do this based on FM radio stations. They're all over the place, their location is known, they're VHF, and they're powerful. Four little antennas and some simple hardware can give you a DF fix within a few degrees of all the local stations. From there I bet it's possible to discern a location, especially if you start tracking from a known starting point.
 
The problem is GPS market capture. Until GPS reliance starts showing actionable cracks in safety traffic flow, there won't be an economic incentive for the market to re-attack any ground nav FMS offering for sub-6k piston land. Things like the KNS80 and LORAN existed for a reason, and it was GPS which primarily killed them. But like every initial adoption of single point of failure solutions, opportunity costs are/were always viewed as "that's my grandkids' problem not mine". tEe-EHsS-oHH potato makes the entry to market more sclerotic than it has to be, but that's a Tuesday in this space and not worth rehashing, everybody on here already knows that memo.

Albany Tom said:
I'll toss out a software challenge... It should be possible to do this based on FM radio stations. They're all over the place, their location is known, they're VHF, and they're powerful. Four little antennas and some simple hardware can give you a DF fix within a few degrees of all the local stations. From there I bet it's possible to discern a location, especially if you start tracking from a known starting point.
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What you're describing is basically a "life-hacked" LORAN based off short-range pre-existing civilian infrastructure instead of "long" wave .mil controlled surplus naval transmitters. I like it. Make VHF Nav great again. :biggrin:
 
hindsight2020 said:
The problem is GPS market capture. Until GPS reliance starts showing actionable cracks in safety traffic flow, there won't be an economic incentive for the market to re-attack any ground nav FMS offering for sub-6k piston land. Things like the KNS80 and LORAN existed for a reason, and it was GPS which primarily killed them. But like every initial adoption of single point of failure solutions, opportunity costs are/were always viewed as "that's my grandkids' problem not mine". tEe-EHsS-oHH potato makes the entry to market more sclerotic than it has to be, but that's a Tuesday in this space and not worth rehashing, everybody on here already knows that memo.


What you're describing is basically a "life-hacked" LORAN based off short-range pre-existing civilian infrastructure instead of "long" wave .mil controlled surplus naval transmitters. I like it. Make VHF Nav great again. :biggrin:
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Yeap, until there is a problem, there will not be a solution.'

But I would think that with the addition of a DME receiver, you could easily implement DME/DME and rho/theta positions. And even VOR/VOR. Even with a single VOR and DME receiver, just switch from station to station. Use GPS for initial rough position to pick the stations, then track in the background to confirm GPS position.

The using commercial FM stations also has merit.

Several solutions to the problem. Just have to generate interest. I am in the middle of a major avionics upgrade. I would pay at least an additional $5000 to $10,000 to add such back up nav.
 
hindsight2020 said:
The problem is GPS market capture. Until GPS reliance starts showing actionable cracks in safety traffic flow, there won't be an economic incentive for the market to re-attack any ground nav FMS offering for sub-6k piston land. Things like the KNS80 and LORAN existed for a reason, and it was GPS which primarily killed them. But like every initial adoption of single point of failure solutions, opportunity costs are/were always viewed as "that's my grandkids' problem not mine". tEe-EHsS-oHH potato makes the entry to market more sclerotic than it has to be, but that's a Tuesday in this space and not worth rehashing, everybody on here already knows that memo.


What you're describing is basically a "life-hacked" LORAN based off short-range pre-existing civilian infrastructure instead of "long" wave .mil controlled surplus naval transmitters. I like it. Make VHF Nav great again. :biggrin:
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I think there's some fundamental technical differences: Loran had precision clock time info in what was transmitted (kinda sorta like what the GPS satellites do now) - but FM broadcast transmitters have nothing like that in what they put out. Without that timing info in the signals, using FM broadcast to navigate would have to work more like an ADF of some sort, as a VHF direction finder. Could be automated, probably, given today's electronic and software capabilities.
 
40YearDream said:
I think there's some fundamental technical differences: Loran had precision clock time info in what was transmitted (kinda sorta like what the GPS satellites do now) - but FM broadcast transmitters have nothing like that in what they put out. Without that timing info in the signals, using FM broadcast to navigate would have to work more like an ADF of some sort, as a VHF direction finder. Could be automated, probably, given today's electronic and software capabilities.
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I can see it working, you'd need to have an ADF-type receiver/antennas to determine the direction to the stations. SDR could easily scan quickly through frequencies and a reasonable position estimate could likely be determined.

But the devil is in the details. Radio signals (even VHF/FM) are subject to reflections and atmospheric effects, and these would have to be accounted for (my guess is just through receiving dozens of signals and error checking that way). Then there would be the issue of verifying station locations and updating if they move.

I'm curious as to what level of accuracy could be theoretically generated with such a system.
 
Pinecone said:
I like the idea of a nav box that uses GPS, GLONASS, DME/DME, DME/VOR, VOR/VOR, and a solid-state INS to provide navigation in most any circumstance.
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Doppler nav works great if you lose satellites as well. Only drawback is you have to update it periodically with ground based references.
 
Velocity173 said:
Doppler nav works great if you lose satellites as well. Only drawback is you have to update it periodically with ground based references.
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Well, that and having to acquire a Doppler nav system for your Cherokee 140.

Nauga,
whose beam is sharp
 
Gilbert Buettner said:
We had it in our C-130s. Didn't trust it much because it would be way off on ocean crossings.
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Yeah if it wasn’t updated along the way, it’ll be way off. I remember reading the F-111 Libya raids in 86 with those guys being off course because of the problems of updating it with current position. I had the GPS fail only once in Iraq and flew about an hour without an update. She was probably a mile off on arrival.
 
nauga said:
Well, that and having to acquire a Doppler nav system for your Cherokee 140.

Nauga,
whose beam is sharp
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I’m not sure how jam proof Doppler is either. Like the issues we’re having with RADALTs and 5G. All it would take is knowing the right frequency of the Doppler.
 
RussR said:
I can see it working, you'd need to have an ADF-type receiver/antennas to determine the direction to the stations. SDR could easily scan quickly through frequencies and a reasonable position estimate could likely be determined.

But the devil is in the details. Radio signals (even VHF/FM) are subject to reflections and atmospheric effects, and these would have to be accounted for (my guess is just through receiving dozens of signals and error checking that way). Then there would be the issue of verifying station locations and updating if they move.

I'm curious as to what level of accuracy could be theoretically generated with such a system.
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Re VHF direction finding, there was a company in Rochester that made a kit ham version of technology that I think was developed for the USAF in Vietnam, and maybe top secret then. You use four antennas and measure the phase angle between the received signals. I think they did it with a single receiver, rotating through the antennas at the input with diode switching, and taking the output from the audio stage. It wasn't really Doppler, but that's what they called it, maybe as a cover. It was quick enough it could get a DF fix from someone just keying up the radio for less than a second.

They used it with 2 or maybe more planes in the air, so they could locate any pop up ground stations pretty much instantly. I don't know if anyone's used it the other way around, that particular type of DF, but it ought to work. Having multiple physical stations transmitting on the same frequencies might be a pita, but then again FM capture should give you the strongest/closest ones...if that doesn't break the phase based DF system.

This site doesn't talk about the tech, but it sounds like the description of the friend of mine who was part of the program: https://6994th.com/history/mission/
 
Albany Tom said:
I'll toss out a software challenge... It should be possible to do this based on FM radio stations. They're all over the place, their location is known, they're VHF, and they're powerful. Four little antennas and some simple hardware can give you a DF fix within a few degrees of all the local stations. From there I bet it's possible to discern a location, especially if you start tracking from a known starting point.
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I'd heard about this a while ago when they flew too close to the sun with passive radar, but hadn't realized that they'd shrinkwrapped the DF bits:
https://www.krakenrf.com/
 
The FAA has to get a few convictions under there belt. Anyone doing this is also telegraphing their location. Given this activity has the potential to kill hundreds of people, a sentence of a few decades in jail would be a strong deterrence for wannabe spoofers. Also, a network of receivers looking for transmitters that are not where they are supposed to be would help in identifying these clowns.
 
If you read the FAA notice carefully, their main concern is overflights of conflict areas. The domestic threat is still constrained by cost, size, and power output. Commercial jammers have a maximum effective radius of a few hundred meters and would have no impact on aircraft at altitude. The only way to bother you would be to place it directly under a GPS final approach. Unless the Russians smuggle one of these into the US, your GPS NAV is not going to be obsolete any time soon.
R-330Zh_Zhitel_jammer.jpg
 
Ed Haywood said:
Unless the Russians smuggle one of these into the US, your GPS NAV is not going to be obsolete any time soon.
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And that would be a nearly impossible feat, given the US’s airtight border.

(Most of the necessary equipment can be bought inside the borders; don’t have to smuggle much.)
 
Ed Haywood said:
I have a buddy with one at Z Hills if you need practice. That's the nav station for a C-47.

View attachment 125274
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I actually learned how to navigate with a sextant back in the mid-60s when I was in the Civil Air Patrol. We spent a bunch of time flying around in USAF cargo planes and I would bring my sextant and they would let me navigate. Had a sailboat in the late 80s, and used it then, (mostly to show off). Alas, it hasn't been out of the case since. Maybe it's time to brush off the cobwebs.
 
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