I think it is time to print a picture of the plane on milk cartons to see if anyone in the public has seen it. That might turn up some leads.
I once picked up a girl in a bar. We went to her place and her walls were covered with pictures from milk cartons. One of them kinda’ looked like me. I called my parents and said “Now I know why you don’t have any pictures of me when I was younger than 5 years old.”