Study asks: Can cell phone signals help land a plane?

> Another problem, she said, is spoofing, which involves using a fake signal to mislead receivers into believing they are in a different location. The technique is no secret, as gaming communities use it to cheat in location-based games like Pokémon Go.

> “There are actual apps you can download that allow you to spoof your location, and entire subreddits dedicated to showing you how to use it for various games,” Sanderson said.

Not judging the research itself, but this is kind of a dumb statement. The type of "spoofing" that you can do by just installing an app, which merely causes the OS to return fake coordinates, has virtually nothing in common with the type of "spoofing" that would threaten an aircraft by actually transmitting fake radio signals.

> pioneering a backup system to keep an airplane on course when it cannot rely on global positioning system satellites.

So like the already existing VOR/DME network?

> The idea is to use these alternative signals to calculate a vehicle’s position and velocity.

All commercial planes have an IMU/ADIRU in them. Most are doubly if not triply redundant.

> There is no question GPS is still the gold standard for navigation

Not for flight. There are plenty of areas in Europe where it is compromised to the point of being useless.

> Scientists refer to it as “signals of opportunity”

Way back in the day pilots would use FM radio stations in the same way. If you were really lost out somewhere over a dark patch.

> If these signals are clean enough for navigation,

The bigger problem you have is while these are "fixed location" services our database of the locations isn't exactly awesome or well maintained in the face of maintenance or physical changes.

"Signals of opportunity" for flight is a bizarre regime to even consider.

Before commenting on this, please read "Final Report of the GPS Spoofing Group", from Ops Group.[1] This is a group for international pilots and flight planners who have to deal with GPS spoofing routinely. They are not happy about it, for multiple reasons. Newer avionics trusts GPS too much. Bad GPS data can affect other flight systems, mis-calibrate the inertial reference systems, and even change the aircraft clock.

GPS spoofing confuses the Ground Collision Avoidance System, which uses GPS position and elevation maps to report nearness to the ground. The false alarm rate is now so high that such systems are useless in parts of the world.

There's a lot of this spoofing going on. Look at the maps in the report.

[1] https://ops.group/blog/gps-spoofing-final-report/

Loran-C used to be available until it got shutdown in the 2010s because GPS was thought to be ubiquitous enough that other systems weren't needed:

* https://en.wikipedia.org/wiki/Loran-C

Turns out having a more resilient backup is useful.

China has built out an eLoran system (as well as a fibre-based precise-timing infrastructure):

* https://www.gpsworld.com/china-completes-national-eloran-net...

* https://www.mdpi.com/2076-3417/13/23/12703

* https://www.gpsworld.com/china-finishing-high-precision-grou...

I don't think Loran-c gives enough accuracy to land a plane all by itself, but it should get you to the airport, after which local beacons (VOR) will align you with the runway, and ILS will get you safely on the ground in IFR conditions.

For a start, "landing a plane" is a solved problem since long before GPS came along. They don't need "help".

As others have said, this seems to be a contrived "problem" to be solving. VOR, ADF, DME/DME and ILS already exist and work without GNSS. There's also LORAN if we were to need a ground based equivalent to GNSS.

Perhaps they should also ask: if GPS is down in an area, do the cell towers continue to operate?

This seems hand wavy. Nothing that demonstrates that they have any understanding of how aircraft currently navigate with GPS, WAAS, levels of accuracy that enable or rule out certain procedures. It’s like they decided to just co-opt aviation because it’s mission critical and has money. “Like one day maybe we’ll be able to do the fancy airplane stuff with the radio stuff and math stuff.”