Indian government reveals GPS spoofing at eight major airports

India’s Civil Aviation Minister has revealed that local authorities have detected GPS spoofing and jamming at eight major airports. In an written answer presented to India’s parliament, Minister Ram Mohan Naidu Kinjarapu said his department is aware of “recent” spoofing incidents in Delhi and other incidents since 2023. His …

[An_Old_Dog]

No Silver Bullet

I believe there is no technological navigation system which depends upon radio which cannot be jammed (possibly, and/or spoofed).

In this age of techno-assholes, you are going to have to, for the sake of flight safety, accept a return to navigation by manual methods (if inertial navigation systems are too expensive and/or are too inaccurate) and takeoffs and landings via the Mark I human eyeball.

This in turn means some takeoffs will have to be delayed, and some landings prohibited/re-routed to alternate airports under excessively rainy, foggy, snowy, or smokey conditions.

[Owain 1]

Re: No Silver Bullet

At least the air around Delhi is as clear as glass ;)

[DS999]

Re: No Silver Bullet

You can set up GPS base stations where the location is known/fixed which are able to broadcast at a much higher power than is received from the satellites. If you detect any attempt at jamming or spoofing those fixed points at the airport can crank up their power even higher to compensate.

Obviously it is possible that someone really intent on jamming could overwhelm even those, but they'd make themselves pretty vulnerable to discovery by doing so.

[Don Bannister]

Re: No Silver Bullet

"You can set up GPS base stations where the location is known/fixed which are able to broadcast at a much higher power than is received from the satellites".

Can someone explain how that works ? Normal GNS operation requires several signals from different directions so the the position equation can be solved. Or have I misunderstood something ?

[Fruit and Nutcase]

Differential GPS

See

https://en.wikipedia.org/wiki/Differential_GPS

It does however require the GPS receiver to be able to take the differential signal.

I have no Idea if aircraft GPS receivers are suitably equipped

[vtcodger]

Re: Differential GPS

Unless I misunderstand differential GPS, it probably won't help with jamming. The problem differential GPS is trying to solve is that the Earth's ionosphere slows the signal a bit making the satellite seem further away than it is. Unfortunately ionospheric delays vary somewhat unpredictably over time. That's a problem if you're trying to survey boundary lines or something else requiring precise position resolution.

What differential GPS does is send a correction to positions currently being obtained from GPS satellites. e.g. It's just a radio station whose location is precisely known squeaking continuously "GPS currently has me 7216mm at 37 degrees from true North of my true position ... 7214 at 36 ... 7221 at 37 ...".

Which is to say. it probably won't help if the aircraft trying to use it isn't hearing the satellites due to jamming.

[Fruit and Nutcase]

Re: Differential GPS

Thanks for the correction/understood

[herman]

Re: No Silver Bullet

A GPS test set can simulate multiple satellites at the same time. One can use it to make a UAV/missile go off course or fly in a circle. All you need to add to the test set is a linear amplifier and antenna. That is why the better UAVs use optical navigation systems. I used to build UAVs, so been there, done that.

[Headley_Grange]

Re: No Silver Bullet

There are US GPS miltary systems with null-steering antennas that can point nulls in the direction of the jamming which are practically jam-proof. The US GPS P(Y) mode makes the system very spoof resistant but it's military only.

[Anonymous Coward]

Re: No Silver Bullet

Hooray for the concept of phase angle. A military non-secret.

[herman]

Re: No Silver Bullet

Using marine GPS antennas that look up more than general purpose antennas is a much simpler solution since you only need to catch 3 satellites.

[ChrisC]

Re: No Silver Bullet

Number of visible satellites is a hard constraint on achieving a position fix, sure, and 3 is indeed the bare minimum if all you care about is lat/lon. But once you've achieved a fix at all, then *where* those satellites are relative to the receiver can then have a significant impact on the quality of that fix.

So realistically, unless you can guarantee that your initial "yeah, you're roughly here, give or take a hundred metres or so" fix can then be refined via other techniques such as DGPS, or unless your application is able to make use of such vague fixes, then intentionally restricting your receiver's ability to see as many satellites as possible isn't necessarily a simpler solution, nor one that would necessarily still guarantee the required level of performance under all potential threat (whether caused naturally/accidentally - e.g. weather related - or maliciously) scenarios which might still prevent even your more tightly focussed receiver from being able to reliably see at least those 3 bare minimum satellites at all times.

[Nik 2]

Re: No Silver Bullet

Solid state inertial systems are cheap enough to be used in cars, so multiple redundant systems won't affect the cost of an aeroplane. I know they are accurate enough to hold a Segway so still you can't see it move and robust enough to be attached to artillery shells, but I don't know how much error would creep in over the course of a long flight.

The mk 1 eyeball and existing radar approach control systems may be better.

[Caver_Dave]

Re: No Silver Bullet

They used to be used on commercial airlines

[Headley_Grange]

Re: No Silver Bullet

Most large aircraft use a combination of navaids and combine them using a Kalman filter. Over short periods of time (longer than a typical flight) these systems can cope with GPS* jamming provided that the GPS system provides a valid Figure of Merit, which gives a measure of the likely accuracy of the GPS. I'm not sure how they deal with spoofing. The fact that there is now more than one satellite-based system makes jamming and spoofing less of a probelm provided, of course, that the aircraft are equipped to use them all.

One problem is that many airports are going over to navaid-based approaches and I suspect that they rely more heavily on GPS than other sources.

This is always worth a watch.

https://www.youtube.com/watch?v=7mxmFCw-Dig

Loss of navaids here would certainly be brown-trouser territory.

*by GPS I mean general satellite-based location, not just the US version.

[stiine]

Re: No Silver Bullet

I would suggest that a silver bullet is the correct and the best answer to this problem.

[Fruit and Nutcase]

Re: No Silver Bullet

Lead bullets are cheaper

[Anonymous Coward]

Old News?

Link: https://www.theregister.com/2024/01/29/satellite_navigation_jamming_now_a/

[frankvw]

So what's the fallback?

GPS is the God of Navigation these days. Before the days of GPS it was all VHF and HF omnidirectional beacons, ranging systems, distance-measuring transponders, automatic radio direction finders, runway beams for ILS to center on, and what not. It wasn't as luxurious as GPS and the pilots had to work harder, but it did get us there.

Now with GPS based computer navigation being so incredibly convenient these days, many of these systems have been scrapped for cost saving reasons, and what little is left can be used as the absolute bare minimum emergecy fallback in a pinch, up to a point, but not much more. Also, the skills of pilots to use these more basic systems have atrophied somewhat over the years.

Perhaps it's time to look at reinstating some of the old school systems and train pilots to use them, just in case a major fecal missile hits the rotating blades and GPS becomes too unreliable or unavailable for safe air traffic.

Just a thought...

[herman]

Re: So what's the fallback?

There are multiple satellite based navigation systems, LEO and GEO. There are also multiple land based systems and land optical navigation systems, as well as star observation navigation systems. So many. The problem is the cost of it all.

[herman]

Spoofing themselves

GPS spoofing is probably done by their own military in an effort to protect their bases next to said airports.

[vtcodger]

One thing though

The report seems credible. But what's the point of jamming GPS at airports? In a conflict or other crisis? Sure, shut down air travel. But during routine operation? Seems to me that all that does is encourage the development and deployment of work-arounds.

[herman]

Re: One thing though

Airports in poorer countries frequently have a military air force base next to it sharing the runways.