I'm working on writing a book about a dragon and this one question keeps popping in my head: How high must he fly to be out of sight of humans? The answer isn't super important to my story, as I don't get that specific in it and I just assume he can do that, but the question still bugs me. I couldn't find anything in google, so I thought I'd ask here and hope someone has at least a rough suggestion. He's about twenty feet tall with a wingspan I haven't specified (I'm not scientific enough to figure that kind of thing out). His body frame is about like a typical dog, not too long or short and not too thick or thin. If anyone can give me a rough estimate, I'd really appreciate it.