Not those kind of Osprey! LOL!
The kind with propellers.
Also they are now flying at treetop level, or "under the radar".
I can look up and see the pilots as they go overhead.
I would say less than 300 feet above ground.
Will start to worry when black helicopters start flying over.
We had them flying over my neck of the woods last summer twice a day for a couple of weeks. I've got a buddy who is an aircraft mechanic, he said they were doing some specific altitude testing. Don't know what's going on in the Carolinas, but it probably doesn't have a lot to do with high altitude terrain. Get the camo nets out!
My son is an Air Force air traffic controller at SMJ AFB in Goldsboro NC. Talked to him Sunday. Seemed to be business as usual, but then if there is something going on he wouldn't be able to tell anyone.
Air Force spec ops trains in the Ospreys out of Kirtland AFB here in Albuquerque. The sound from tilt rotors is not as pronounced a regular helicopters. It's a bit more muffled with a faster blade count, very distinctive. It would be interesting to know if what you're seeing is Marine or AF. If they're AF, they're spec ops.
I live next to fort campbell and they fly around here all of the time. Training takes air crews all over the country. As long as they are not hunting you i would not worry about them, you may never know if it for a spec ops mission, but be happy they are there training because they are training to defend us.