What happened
On the early morning of October 6, 2005, a Morningstar Air Express Inc. Cessna 208B Caravan, registered C-FEXS, departed Winnipeg International Airport for a scheduled freight flight to Thunder Bay, Ontario. The flight, operating as MAL8060, began its climb following an instrument flight rules clearance. Shortly after reaching an altitude of approximately 1,300 feet, the aircraft began a gradual descent. The pilot subsequently requested an immediate return to the Winnipeg airport. During the turn toward a southwesterly heading, the aircraft entered a steep descent and moved below radar coverage. The aircraft ultimately crashed onto railway tracks near the intersection of Donald Street and Corydon Avenue in Winnipeg. The impact and a subsequent intense fire destroyed the aircraft and resulted in one fatality.
The investigation
The investigation focused on the aircraft's weight, balance, and the environmental conditions at the time of departure. Investigators examined the pilot's flight planning, maintenance records, and the cargo loading process. While the pilot had significant experience on the type, the investigation scrutinized the accuracy of the weight and balance computations performed prior to takeoff. Technical reviews of the aircraft's records also revealed an error in the recorded basic weight of the airframe due to a mistake made during a previous battery replacement. Furthermore, investigators analyzed the cargo manifest and the physical loading of the aircraft, noting that the cargo was placed in the cabin and an external pod without being secured by tie-downs.
Findings
Several critical factors contributed to the accident. The investigation established that the aircraft was over its maximum allowable takeoff weight. Specifically, the calculated takeoff weight was 9,038 pounds, which exceeded the maximum limit of 8,750 pounds. This weight exceeded the even more restrictive limit of 8,550 pounds required for flight in known icing conditions.
Several errors led to this overweight condition:
- An error in the aircraft's recorded basic weight, where a weight difference from a battery change was added rather than subtracted.
- Inaccuracies in the cargo weight calculations, including an incorrect tare weight for a Winnipeg container and an arithmetic error regarding a Toronto container.
- The use of estimated rather than precise weights for cargo distributed across different zones in the cabin and cargo pod.
Additionally, the flight occurred during a period of instrument meteorological conditions involving light snow and freezing levels at the surface, which necessitated stricter weight limitations that the aircraft failed to meet.