GPSJam: Daily maps of possible GPS interference(gpsjam.org) |
GPSJam: Daily maps of possible GPS interference(gpsjam.org) |
I'm curious about HN's take on a couple things:
1. Why haven't FlightRadar24, FlightAware, or any of the other flight trackers done this? Not enough people actually interested? I know there are companies that use GPSJAM to help brief their pilots.
2. Monetization! I can't really justify spending more time to work on projects like this one when they don't make money, and do cost (a little) money. But I absolutely do not want to turn these projects into another another job--I don't want contracts, obligations, deadlines. Do I try to get (very niche, but I bet they exist) advertisers to cover site costs and some of my time? Do I crowdfund for general development? Let me know your thoughts. And this isn't just for GPSJAM; I have other projects. For example...
A couple other aviation related projects I've done recently:
1. The Global Aircraft Event Viewer: https://aircraft.social/events/ A near real-time map of higher level aircraft behaviors around planet Earth: Circling, "near misses" (RAs), takeoffs, landings, emergency squawks, and other stuff. A very early experiment, but I think it's kind of neat (especially the RAs!).
2. Closest Points of Approach: https://skycircl.es/cpa/ An analysis tool for checking to see just how close two (or more) aircraft got. For example, if you saw the New York Times Story "How a Series of Air Traffic Control Lapses Nearly Killed 131 People"[1], here's a link that visualizes and animates the scenario that happened in Austin, where a Fedex jet almost landed on a Southwest passenger jet: http://skycircl.es/cpa/?kmlurl=https://gist.githubuserconten... My tool estimates they got within about 150 feet (assuming idealized point aircraft without volume!)–The NTSB said they got "within 200 feet".
1. https://www.nytimes.com/2023/10/11/business/air-traffic-cont...
Also, I'd just add ads and some recurrent donations and see how it goes - it looks to me that you're the perfect person to run projects like these. It would make no sense if money was the only problem that stops you.
Since planes tend to default to INS navigation with use GPS, GLONASS, Galileo or other systems to supplement the drift, it may be subject to certain data skew (e.g. if there's an area on the world where most planes aren't equipped with GPS navigation system, have poor quality navigation tech or you might be seeing "jamming" where there might just be a common place on airline route where INS drifts).
Since this data is reported by airplanes I wonder if they experience more jamming because the jamming signals distribute easier upwards than through the jungle of buildings in the city.
However, since the map actually shows the percentage of flights reporting low-navigation accuracy, what it really means is that there are no normal air traffic over Ukraine.
Mapbox's pricing for this would be insane (for a hobby site) if you got a lot of attention... $1 per 200 page loads once you breach the free tier -- though I'll admit the free tier looks generous for a small hobby site.
That is to say: could I establish a fixed ground station that measured these events and somehow augment this data from airplanes?
I think Galmon.eu may collect it along with all the other receiver-status data, but it isn't exposed in the main dashboard. You'd have to figure out how to extract it from the data, and I don't think anyone's done that yet, but we're in #galileo on OFTC IRC.
The main problem with this approach is that it's hyper-local. Ground stations aren't moving so they don't cover a very broad area, and they're not evenly distributed or even necessarily in interesting locations. Quite the contrary; regimes that employ GPS jamming are likely also hostile to citizens reporting on same.
1. directly observe signal integrity with your own GPS receiver
2. compare the location your receiver reports with the actual known location
3. compare the location your receiver reports on GPS with the location a different GNSS network reports.
US bases are in Jaen and Sevilla
Its support planes are in the area [1], and it was sighted on Sep 28 near Italy [2], and if I understand it correctly, has been tasked to this area.
1 - https://twitter.com/wipljw/status/1712780646530118125
2 - https://www.marinevesseltraffic.com/vessels/USS-Gerald-R.-Fo...
Snarky jokes aside, in my experience GPS works okay in Cyprus, so the jamming must be localised somehow.
Might be some interesting locations to cross check.
For Example, US Prisons want to jam Cell Phones but the FCC says no way.
Obviously, stuff like this is made some how: https://www.rtx.com/raytheon/what-we-do/sea/ngj
The caveats of that tweet still apply to higher resolutions: Specifically that you start to see the effects of individual aircraft, which can be harder to interpret.
You need to have one nerdy geek to record the data per ~500 mile circle of the globe.
Thats why ocean coverage is bad too.
Map showing the possible interference overlaid on an FAA sectional chart showing the MOAs: https://i.imgur.com/vieGhgN.png
And how many people looking at maps on the internet really perform (globe-scale) navigation where it would even matter?
Getting a sense for distances and/or proportions is arguably the most common use case, with “a sense for the precise bearing” a distant follower.
I hope this doesn't confuse the issue, because I don't think it's actually related to what you're talking about, but recently there have been reports of inertial nav systems being "corrupted", essentially, by spoofed GNSS. The hypothesis is that the INS/IRS is corrected using spoofed GNSS data after which the INS/IRS reports bad info: https://ops.group/blog/faa-warning-navigation-failures/
This actually makes spoofing attacks very difficult, since you'd need to target each receiver individually and in a very precise way (e.g. a reasonably filtered system would reject a GPS signal indicating that the plane just by a couple of kilometers and changed direction by 90 degrees without any measurable acceleration).
Data:
Date % w/ poss. interference # Good # Bad
--------- ----------------------- ------- -----
2023-10-04 2.82% 1172 33
2023-10-05 0.00% 1204 0
2023-10-06 2.55% 1253 32
2023-10-07 0.42% 1184 5
2023-10-08 0.00% 1261 0
2023-10-09 4.03% 1216 49
2023-10-10 2.21% 1178 26
2023-10-11 0.00% 1176 0
2023-10-12 0.00% 1203 0
My list of the most common things that make an aircraft report low GNSS accuracy:
1. Intentional GPS jamming.
2. Unintentional GPS interference.
3. Aerobatics that cause the aircraft's GPS antennae to be masked from satellites by the body of the aircraft.
4. On-board equipment issues.
I think the data suggests it's not #4. #3 is typically seen in military operating areas (MOAs) in the U.S.; I don't know if there might be fighters practicing in the skies west of London.
Edit to add: FWIW I've gotten one report from a person in the yellow hex that they weren't able to get a GPS fix. That's all I know.
As others have said, more likely dodgy methodology by gpsjam than anything sinister.
For example:
- As well as being an active airfield, Heathrow also houses a small number of maintenance bases (e.g. BA have one, United are currently upgrading an ex-Virgin one etc.). I'm not familiar with aircraft maintenance, but I suppose there could easily be scope for RF signals related to test procedures to be leaky and be picked up by geeks.
- There is also Farnborough. Whilst Farnborough is predominantly a GA (General Aviation, i.e. private jet) airfield, it is also on of the many homes of QinetiQ in the UK. QinetiQ being a defence contractor. So again, one could speculate about leaky test signals.Both unlikely otherwise (a) you would see similar around other active royal sites (b) same around other military installations.
I discovered GPSJam a few months ago, and have enjoyed some of your content on Twitter, and really enjoyed your work on the longer form article from a few years ago (the FBI one; "Secrets of the Sky") [0].
Best wishes for your endeavors!
[0] - for anyone curious: https://twitter.com/lemonodor/status/1250581745935593472 or https://docs.google.com/presentation/d/1sowJrQQfgxnLCErb-CvU...
https://apnews.com/article/russia-ukraine-war-riding-the-rai...
https://apnews.com/article/poland-railway-disruptions-arrest...
Also: you can double dip. When the free tier of mapbox runs out, swap over to MapTiler/StadiaMaps or any other provider of vector tiles.
I believe it's now usually a combination of multiple sources (e.g. ground-based navaids like VORs and DMEs, GNSSs/GPS, and INS to reject most spoofed signals or in case everything else fails).
But, as it always was, it is regularly corrected with GNSS or navaid corrections. As far as I know most airliners still don't automatically enter corrections for INS and require manual input (basically retyping of GNSS data from a screen into a keypad) to put human into the loop which can verify if GNSS is being spoofed. The pilots can alternatively do the correction using VOR/DME navaids or even their eyes if they feel like it.
As far as I know, it's becoming much more common to have INS with ability to automatically correct drift from GNSS in smaller planes (and I'm sure that will make it to airliners sooner than later).
However the autopilots inner loop and Flight Direction Indicator (artificial horizon) are going to be driven almost entirely by INS. This is because GPS positions can't update fast enough, are noisy, and don't provide velocity, acceleration, or orientation (outside of even slower position integration). Also those systems are not particularly involved in where the aircraft is, rather they care about where it is going.
I haven't looked into what the requirements of ADSB position information is, I don't suspect that they mandate GNSS but they may mandate a degree of accuracy. From an ATC perspective within crowded airspaces ADSB would be augmented by primary surveillance radar to prevent mishaps, spoofing, and errors.
For what it's worth my day job is aircraft avionics, navigation equipment is pretty much daily for me.
Ps. Hi HN, Reddit refugee and my first post here.
That being said, it seems like London only has interference recorded today and every other day is green. I would imagine it's more likely to be a quirk of how the data is recorded rather than geniune jamming.
This gpsjam site doesnt have much info on methodolgy. Seeing the data would probably show what is causing this issue.
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I suspect much or all of the data boradcast is GPS derived. Would be nice to have some hard data there.
For almost all general aviation aircraft in the USA the data source for ADS-B Out is GPS. All the GA STCs I've seen are GPS only position sources. Many modern GA aircraft will have AHRS but not a full INS, and so INS is not an option for them. Even on larger business jets that may have INS with GPS integration I am not clear any actually use it to drive ADS-B Out, the few installations I've looked at were all GPS.
Boeing was an early advocate for GNSS alone driving ADS-B Out. I think their argument was simplicity, everybody has the same data, and not dependent on erroneous INS or INS settings. I'm not sure what they ended up doing with all their actual installations. If the intent is to send more exotic data such as roll-angle they'll need some INS or at least AHRS integration, but there is no requirement to broadcast that data. The few early third party STCs I saw for ADS-B Out installations in Boeing aircraft only used GPS data sources.
In terms of airport systems, Atlanta isn't even the top in the USA.