National Transportation Safety Board (NTSB) investigators are examining the flight recorders in a laboratory.
The plane clipped trees at the end of a runway and slammed into a hillside, killing the two crewmembers onboard.
The NTSB says the findings are only preliminary and investigators are hoping to learn more details from the evidence gathered from data and voice recorders.
The twin-engine A300 bound for Birmingham from Louisville, Ky., was attempting to land on a 7,000-foot-long runway at Birmingham Shuttlesworth International Airport when it crashed before dawn Wednesday. Sumwalt said the airport's other, 12,000-foot runway was shut down for repair work on its lights at the time.
The Associated Press contributed to this report.
