[bri3d]

Most major airports will already have a counter-UAS system, it's a huge industry.

One big issue with radar is that it has the same problem pilots and human observers do: it struggles to distinguish drones from anything else in the sky (birds, balloons, planes, etc.). This is an active and improving research space, but by and large with radar, when your pilots report a drone, you still don't know how to figure out if it's the typical mis-identification or something real.

[ck2]

I'm reading about pilots spotting drones during takeoff/landing that the airport didn't know about

And I've read about airport shutdowns in UK and US without a single arrest which is why it keeps happening

So whatever system exists, apparently not good enough

[bri3d]

Right, there are two problems there:

* Pilots are very concerned about life and safety and are heavily exposed to drone “incident” related anecdotes, so they err far on the side of caution with drone sightings. Which is to say a very low percentage of them are real.

* Poorly implemented cUAS systems, especially ones based on passive or active RF locating (radar) can actually make the problem worse: they hallucinate everything into drones, pilots hallucinate everything into drones, and now everything is a drone. This also happens frequently when people try to repurpose military systems (which are usually designed to operate in significantly less crowded environments and trigger at the slightest hint of an issue, due to mostly orthogonal-to-airports threat models people discuss at length on this thread like “dark drones”) into urban use.

This type of array based directionfinding system is cool and it could work as a small ingredient in a drone detection system, but it’s not anywhere near the state of the art in the space and most airports are probably already ahead of this to some extent.