Planes are having their GPS hacked. Could new clocks keep them safe?
58 comments
·March 7, 2025bArray
mapt
Chip-scale atomic clocks based on cesium were demonstrated in 2003 with DARPA/NIST funding, and entered commercial production in 2011.
https://en.wikipedia.org/wiki/Chip-scale_atomic_clock
Apparently they're not even export-protected, despite their obvious use in GPS validation schemes and in RTK.
> The SA.45s CSAC has an Export Commodity Control Number (ECCN) of EAR99. This means it is not ITAR-controlled and does not require a special license to ship to most nations. The SA.45s CSAC classification is controlled by the Bureau of Industrial Security (BIS) within the US Department of Commerce.
The article talks about quantum "optical clocks" but doesn't really explain the concept.
Which appears to be this:
https://en.wikipedia.org/wiki/Quantum_logic_clock
Which, like many things named "Quantum", still doesn't really explain how you get an IMU out of it.
pclmulqdq
You can do about 5x worse (in accuracy terms) than a Cesium clock in a smaller package using a rubidium atomic clock. Average ~4 of these and you get to the same accuracy as a cesium clock. They aren't export controlled because they aren't that special in terms of what you get.
freddie_mercury
> Now imagine if your plane loses power momentarily, and suddenly your GPS stops working entirely.
Now imagine your plane loses power momentarily and switches to a backup system... The exact same GPS every plane is using today.
SkyPuncher
Even further, you can loose your super accurate special crystal and simply fall back to “normal” GPS.
Cthulhu_
I don't really understand why the plane was diverted because GPS was jammed; I get that it's important for navigation, but not how it's required for landing when they're that close. There's (iirc) close range guidance systems, and of course visual ones (lamps, stripes, etc).
macguillicuddy
My understanding is it depends on the amount of visibility, plus what type of approach they were on. One type of approach, an ILS, has big radio transmitters pointing from the runway into the air and allows the plane (either pilots or autopilot) to get close enough to the runway without visibility, and with enough precision, to land. In many circumstances ILS isn't available and an alternative is Required Navigation Performance (RNP) which uses GPS plus a ton of other inputs to give some amount of precision to the same end. If they're on an RNP approach but suffer a reduction in navigation accuracy then I imagine it's a policy 'go-around'. Even if there's enough visibility it allows the pilots to brief a 'visual' approach before attempting it.
Gathering6678
Considering it's below 1000 feet, losing GPS could indicate an "unstablized" approach and require a go-around, as opposed to losing it at a higher altitude where the pilot could have more time to safely switch to alternatives (other navigating aids or go to visual?).
Source: my guess after watching a lot of aviation YouTube videos......
mapt
Commercial air travel is very risk-averse. Best practice is that if something unexpected occurs, and you have plenty of fuel to spare, you go and and find someplace else to land.
Iolaum
Before the GPS era (military) planes had inertial navigation systems, why can't civilian planes have something like that as a backup until you get in range of a terrestrial navigation radio tower - those are still in use, right?
secondcoming
They still have this system. This video gives great insights into how GPS jamming affects planes:
KaiserPro
GPS and other navigation systems are well worth the time to look into.
something like Decca or LORAN are really simple to understand: two or more base stations in a known location emitting phase locked signals. By counting the nodes/antinodes of the harmonics, you can work out how far away you are from the base stations. The downside is that you need a initial fix to work out absolute location.
The thing thats kinda touched on here is that GPS uses clocks to allow the receiver to work out how long the signal has been in flight (simplification) If you know where the satellites are (using the Almanac of satellite positions) you can get your location by fairly simple triangulation.
Now, you don't have an atomic clock on your receiver, so how can you accurately measure the time difference between signals?
for GPS you only need to know the relative time difference between each satellite, and even thought quartz clocks are only accurate to seconds a year, in the ~20-50ms it takes for the signal to arrive, its more than accurate enough.
However that means you are open to spoofing, because you sync your local clock to a satellite, you have no real way of detecting if the clock has skipped.
If you have an accurate clock source, you can then validate the clocks that are on the transmitters. I think, but can't confidently assert that calculating position becomes easier because you have an authoritative clock source, so don't need to piss about with clock sync using an unknown time offset.
I think the implication is that this provides a strong form of signal authentication.
However chipscale super-stable clock references also allow more autonomous styles of navigation. (ie celestial)
PinguTS
What I don't understand about this GPS spamming: we don't need to rely on GPS. We have Galileo, (GLONASS) and BAIDU. That is the reason we its now called GNSS.
Most of the chips and as such the receivers are supoorting all of these systems in parallel. While I understand that the Chinese use their own coordinate system, I don't if BAIDU is based on that or not. Galileo is available. Galileo is able to use authenticated signals. Galileo has much improved over GPS. I assume in (important) comercial applications like aircrafts, you could use the better Galileo service for which you have to pay for.
So how important is GPS spaming really?
ElectRabbit
> Galileo
Which has optional cryptographic signatures of its positioning data. It's not spoofable anymore (but still jam'able with strong transmitters).
Free for use.
(https://www.gsc-europa.eu/sites/default/files/sites/all/file...)
Same for the HAS (High Accuracy Service) which offers precision down to 30cm without additional correction data.
Also free for use. But requires a special receiver as it's using an additional band.
Galileo was the ugly duckling for a very long time - but it turned into a shining one after it aged a bit.
PinguTS
> Galileo was the ugly duckling for a very long time - but it turned into a shining one after it aged a bit.
Yeah, for some time I was also in the camp of "why we need our own expansive service". But the current development has shown, that it was a wise desicion to have our own system.
BTW: thanks for updating on some other details. I never followed up really, it was from the initial plans, that I was told there should be comercial service, that should pay. Also that for some emergency services there is a very limited possibility to have a back channel.
ElectRabbit
As far as I know all nav sats have emergency beacon payloads (Cospas-Sarsat). All providers (Beidou, GPS, Glonass, Galileo) joined this.
azernik
It has optional cryptographic signatures of the navigation message, i.e. the data indicating position of satellites.
Spoofing generally works not by altering the navigation message, but by altering the timing of arriving signals. I'd recommend this video for a publicly-available overview of the techniques: https://www.youtube.com/watch?v=sAjWJbZOq6I
tl;dr Galileo spoofers exist and work just fine.
azernik
"GPS" is being used as a genericism in these articles. All the GNSS constellations work the same way, and all of the military-grade spoofers are multi constellation.
sebzim4500
Authenticating signals for GNSS sound like an impossible cryptographic task. What stops a malicious actor from recording the signals coming off the satellites and replaying them louder with a delay?
If you pick the delay properly you can make the plane believe it is at an arbitrary point in space and time (although of course that time would always have to be at least a few `us` in the past).
ElectRabbit
Galileo offers optional cryptographic signatures for their positioning data.
It's a solved problem and free for use.
https://www.gsc-europa.eu/sites/default/files/sites/all/file...
anovikov
So this pertains to jamming so strong that traditional jam-proof GPS that uses signal phase shift to weed out GPS signals coming from "wrong" directions, are insufficient? 100db attenuation of jamming signal has been achieved around 15 years ago with those.
In the air, there are always more GPS satellites visible than necessary. So jam-proofing through signal processing methods is the way to go.
thesh4d0w
I don't understand this article. If the GPS signals are jammed, what purpose does it serve to have an atomic clock on board your plane? You still need accurate signals with time data to measure against.
Am I missing something?
touisteur
You can get a very accurate timestamp from GNSS. What lots of people do then is slave a PLL based on a local oscillator, to be able to get time between two GNSS captations. Or to be able to extrapolate when they have no GNSS signal.
Now suppose someone is spoofing your GNSS signals, it's pretty hard to replace a constellation with another one whilst maintaining time consistency for you. One way to detect spoofing is comparing what a local clock is saying to whatever the GNSS is giving. A local, unfudgeable, stable, accurate clock is a good reference for this.
thesh4d0w
Ahhhhh, that makes sense. Treating this as security mechanism rather than an anti-jamming one.
simne
As I read from book about gyroscopes, most sensitive achieve so fine accuracy, they detect daily Earth rotation and even yearly Earth rotation.
But when they speaking about near zero temperatures, looks like they talking about something like Rydberg atoms - extremely sensitive matter, which could be considered as nuclear scale gyroscopes, or quantum gyroscopes, or read more about quantum accelerometer.
And current inertial navigation could be used to calculate relative coordinates like automobile odometer, but from integrating accelerations. But classic accelerometer is just not fine enough, and at this place appear quantum accelerometer and quantum gyroscope.
And I agree, article is terrible. I don't know why they use so abstract language, when could just say, navy already tested quantum navigation.
RandomBacon
> daily Earth rotation and even yearly Earth rotation.
Minor FYI: the earth rotates daily, but it revolves around the sun yearly.
revolve /rĭ-vŏlv′/
intransitive verb
To orbit a central point.
"The planets revolve around the sun."simne
To be more concrete, space rockets nearly all fly with inertial navigation, but they are extreme case, because most use only inertial navigation just few minutes (so all those classic gyros/accelerometers integrated errors are small enough to successful enter stable orbit, and then using some sort of radio or optical fine measurements and making corrections with fine engines).
Planes flights are much more lengthy than rockets - I think, typical ~40 minutes or more (most long I hear 20 hours), so INS could integrate huge mistake.
p_l
INS essentially was expensive and AFAIK once GPS became available started to drop off in use outside of military. And with GPS availability coinciding with switching to more modern integrated Flight Management System/Computer, a lot of planes simply don't have INS installed.
foldr
I believe submarines navigate long distances using INS. I don’t know how accurate it is, or how often they have to make corrections using other data. But ballistic missile submarines can’t really use active sonar or surface with any frequency, so I’m not sure what other method they’d use.
magnetometer
> most sensitive achieve so fine accuracy, they detect daily Earth rotation and even yearly Earth rotation
Daily rotation is 360°/23.934h, so 0,25°/min, which is acutally quite a lot if you want to use a device to track your orientation.
simne
Unfortunately, these numbers considered state of art for modern classic gyroscopes.
Better are quantum navigation systems, using quantum matter as sensor, but they was too bulky to be used on planes, only last years appear more compact systems, sized like common home fridge.
BenjiWiebe
I didn't read the article, but: a GPS receiver must calculate/find both it's time and position to get a fix. So maybe by having the time already available really accurately it makes the job of finding position easier?
gorbypark
From my (very basic) understanding of GPS you need at minimum four satellites to calculate the time. If you had a local atomic clock in sync with the GPS satellites, you'd only need three satellites to get a position fix. It would (probably, maybe?) also speed up the time to first fix / time to a precise position fix.
looofooo0
Fun fact: optical mouse tech was developed for airplane navigation first. So it would not be very expensive to have this system as a backup.
Eduard
> optical mouse tech was developed for airplane navigation first
Citation needed.
bArray
I cannot tell you how infuriating it is as a UK tax payer on a UK-based ISP, that pays for this content to be made, to be blocked from viewing it.
Worse still, if I view the article in 'Private' browser mode then I can see it all.
harha_
Russia is like a kid playing with matches. I'm a noob when it comes to aviation, but AFAIK RNAV GPS approaches are quite common? Disrupting that is dangerous.
pjc50
Russia keep seeing what they can get away with and then push harder. Since nobody is willing to apply enough meaningful punishment due to fear of escalation, and they successfully propagandized/bought the US Republican party, they're winning on this axis.
More sanctions should have been imposed when they shot down a passenger plane and killed several hundred Dutch civilians.
looofooo0
True, the cheapest option was always to hid hard with sanction on Russia as early as the first Chechen war and establish backup for Russian energy. But instead, Germany still build Nordstream after Georgia.
pjc50
German politics was clearly heavily compromised as well, beyond the basic self interest of cheap gas. See Wirecard and Jan Marsalek.
The interesting question is how compromised British politics has been. Lots of very suspicious things (secret Boris Johnson meeting against the advice of security services; appointment of Lord Lebedev), but UK support for the Ukraine war has been unwavering.
Cthulhu_
Yeah, and its leadership held to account; for some reason the results of the investigation was that a number of individuals were marked as suspect, while IMO the entire military leadership all the way up the chain should be held accountable.
I really hope this war ends, and ends up with Russia paying for repatriations, including this case.
pjc50
Unfortunately I don't see the reparations coming about without the war getting much, much larger first, like a EU-NATO ground invasion of Russia. Which violates a whole load of red lines and would get a lot of people killed. But maybe Russia will force it to happen regardless.
(what is happening is turning the asset freeze into asset seizure, but this is complicated - rightly - by human rights law, because most of the assets are nominally private)
miohtama
Since this year, the most likely reason to die in an consumer aviation accident is being hit by a Russian missile.
yetihehe
No, they are bullies trying to extort other kids. They fully know what they are doing, but they are trying to find what they can get away with.
Cthulhu_
And they have for years now. Invaded / occupied Crimea with a slap on the wrist at best. International cybercrime for at least 15 years now, probably longer, but they get plausible deniability because it's not officially state doing it (even though we know they are).
But outside of Ukraine, none of it crosses physical borders; the sabotage of undersea cabling is all done in international waters, the internet is some kind of free for all as well, etc.
What should have happened is that the international community stepped up and sent a clear message, like "Russia will be cut off from the internet if they do not stop their digital attacks". Boundaries mean nothing if there are no consequences to violating them.
p_l
RNAV are less common than people think, and given the limitations appear to mostly be used as secondary help in conditions where one could possibly go by vectoring.
Losing them however does drop capacity because now you need extra work to get planes to final.
piokoch
Russia is playing with matches since NATO allows for this. It would be sufficient if in Kaliningrad Oblast or in Petersburg NATO forces jammed GPS/Glonas/Beidou and, as a bonus, also VAR system (much more important than GPS for aviation) and next day Russia would apologize and never try stupid games again.
harha_
Pardon my ignorance, but do you mean VOR instead of VAR? Or what does VAR stand for in your example?
InDubioProRubio
But do planes not have these fancy laser gyroscopes- so accurate, they have to correct in software for earth and the solar system moving?
https://en.wikipedia.org/wiki/Ring_laser_gyroscope
Why is GPS relevant here?
h1fra
It's bad when Russia is doing it, but no mention of Israel jamming a big part of the land during the war
> The Boeing 737 MAX 8-200 had already descended to around 850ft (259m) when the disruption occurred. Instead of landing, the plane was forced to climb back into the sky and divert nearly 400km (250 miles) south to Warsaw, Poland. Lithuanian air authorities later confirmed the aircraft had been affected by "GPS signal interference".
GPS is incredibly flimsy. Normally it operates by taking the average of 1000 observations to generate a noisy signal. It's not that difficult to be louder than something shouting from space. You can pick up cheap GPS blockers easily about the size of a walkie-talkie (handheld radio).
> By carrying a group of atoms cooled to -273C on the plane itself, rather than relying on an external signal, the technology can't be interfered with by jamming.
Last year I was on a plane where if the engines were not running, it entirely went into darkness. They hooked the plane up to the airport and tripped the airport electrics too. Now imagine if your plane loses power momentarily, and suddenly your GPS stops working entirely.
> Henry White, part of the team from BAE Systems that worked on the test flight, told BBC News that he thought the first application could be aboard ships, "where there's a bit more space".
> Quantum clocks, gyroscopes and accelerometers are large, bulky and incredibly expensive, with an accurate quantum clock costing around £100,000. Yet military research is allowing the creation of smaller, better and cheaper systems.
Likely a minimum of 10 years from being viable. Mt White of BAE is politely saying as much.