Good news! radars are working :)

[Rattlehead]

Yeah, it does work for sure, although it does pick up aircraft that fly below 500m.
It detected Heinkels flying at 300m, but what's interesting is that the information you receive seems to differ depending on the altitude of the incoming aircraft. (Such as the number of aircraft detected.)

It also detects them way out to sea. All in all, a nifty little feature.