So I came across this… Sorry about the whiny kid’s in the background, siblings right?
I’ve heard it too, there are a couple small areas on the map that you can hear it…
It sounds like the airdrop plane to me, just very far away.
I’ve hear this too, it is very annoying. I believe it is a bug but I’m not too sure, it could be an easter egg when there are machines running in the rad towns or something and nobody knows about it.