In a report released Tuesday, the National Transportation Safety Board determined the probable cause of the Feb. 20, 2013, crash was the pilot's failure to follow procedures. It said his lack of knowledge about the aircraft and fatigue contributed to the accident near an airport in Thomson.
The report says that the pilot only slept five hours the night before and later slept for about four hours in a chair in a pilot lounge in Nashville, Tennessee.
The pilot and co-pilot survived, but were severely injured. All five passengers, seated in the back, were killed.