Recently, I’ve noticed that drone aircraft are often referred to as “unmanned.” Aren’t all drone aircraft unmanned? Or is there a kind that does have a passenger?
For years, the aircraft in question were referred to as “Unmanned Aerial Vehicles”, or “UAVs”; recently, however, everyone has started calling them as “drones”. I don’t know why.
Anyway, “unmanned drone” probably comes from a conflation of the two terms. That doesn’t make it any less of a redundancy, of course.