What happened
The flight originated at Minneapolis-Wold Chamberlain with a destination of Seattle, including several intermediate stops. While approaching Fargo-Hector Field under nighttime conditions, the crew encountered significant icing. The aircraft exhibited unstable behavior, characterized by pitching up and down. As the airplane stalled, the captain applied full engine power. The aircraft subsequently crashed into a prairie in Moorhead, where it was destroyed by post-crash fire. One pilot survived the incident, while 14 other occupants were killed.
Findings
The investigation determined that the primary cause was the aircraft's failure to respond appropriately to full power application when the inboard wing sections were stalled. This response was inconsistent with expectations based on aeronautical knowledge available at the time. Several contributing factors were identified:
- Ice accumulation on wings and other surfaces increased stalling speed and drag.
- The captain lost confidence in the air-speed indicator, failing to recognize the proximity to a stall.
- The decision to descend for a landing at Fargo despite known icing and low ceiling conditions, rather than diverting to an alternate airport.
- The dispatcher failed to assess the severity of the weather near Fargo and did not instruct the pilot to proceed to the alternate.