NTSB Probable Cause

A LOSS OF DIRECTIONAL CONTROL FOLLOWING AN UNDETERMINED AUTOPILOT FAILURE, DURING WHICH THE PILOT FAILED TO PERFORM THE EMERGENCY PROCEDURE TO CORRECT A MIS-TRIM CONDITION. CONTRIBUTING TO THE ACCIDENT WAS A PERCEIVED ELEVATOR CONTROL PROBLEM; THE INABILITY OF THE PILOT TO OVERPOWER THE MIS-TRIM CONDITION; AND A LACK OF UNDERSTANDING AND TRAINING IN AUTOPILOT SYSTEMS AND FAILURES.