The C-46 Commando had been cleared for a runway 3L ILS approach at Detroit in poor weather (sky obscured, visibility 1 mile, light drizzle). During the approach, at 1,5 miles right of the ILS course and 1 mile NE of the Outer Marker, the aircraft suddenly entered a 45-degree banked left turn. The bank angle exceeded 60 deg as the plane crossed the localizer course from left to right. The aircraft struck several 84 feet tall trees in an 8deg nose down and 30deg right bank attitude, struck the ground and disintegrated. In the investigation an incapacitation of the captain was considered, but not supported by post-mortem examination. PROBABLE CAUSE: “Loss of control during night instrument approach in adverse weather for an undetermined reason.”