Duluth, MN (KDAL) – At last check authorities were searching for the pilot of a single-engine plane that appears to have crashed in to Lake Superior. The Duluth Fire Department says debris was discovered, including the plane’s log book, about a mile off of Brighton Beach. Air traffic controllers at the Duluth airport were tracking the plane at an altitude of 6,000 feet when it plummeted to 2,500 feet and off of radar. It had left Duluth and was en route to Thunder Bay. Investigators believe there was only one occupant on board and they are now treating the search as a recovery operation. Dense fog appeared to be hampering search efforts.