Accident Overview
The pilot and a passenger departed Rockford in the early morning and conducted several flights throughout the day in the region. While cruising over Lake Michigan at night, the pilot lost control of the airplane, which then crashed into the lake off Manitou Beach. Both occupants were killed.
Flight History
The pilot had departed Rockford approximately 18 hours prior to the accident and had flown about 10 hours during the day. The pilot had attended a copilot picnic where he was observed with a can of beer. Toxicological results were not decisive.
Probable Cause and Contributing Factors
The official probable cause was loss of control in flight after the pilot became lost/disoriented. Contributing factors identified were physical impairment, pilot fatigue, the long duty day (departed 18 hours prior, flew 10 hours), and attendance at a picnic where beer was consumed.