Occurrence
On the morning of the accident, flight THU890 departed Thunder Bay Airport (CYQT) at approximately 0653 during darkness, destined for Sault Ste. Marie Airport (CYAM) with a planned stop at Wawa Aerodrome (CYXZ) to pick up a patient. The aircraft carried two flight crew members and a paramedic. The cruise portion of the flight was uneventful.
Pre-flight and Approach
During pre-flight preparations, a flight crew member contacted Wawa Aerodrome at 0549 and spoke with an aerodrome employee on duty for after-hour inquiries. The crew member learned of ongoing light snowfall and understood the runway would be plowed by about 0730. The approach to CYXZ occurred during civil twilight, before sunrise. The flight crew activated the runway lights using the aircraft radio control of the aerodrome lighting system and performed the RNAV (GNSS) approach to Runway 03. They visually spotted the runway about 10 nautical miles out on final approach and observed that it was covered in snow.
Accident Sequence
The aircraft touched down on Runway 03 at 0739. Shortly after touchdown, it suddenly began sliding to the right. The flight crew attempted to correct using rudder pedals, differential propeller control, and power adjustments, but were unsuccessful. The aircraft rotated nearly 180 degrees while on the runway and slid off the right side, coming to rest on its left side in a drainage ditch about 78 feet from the runway edge. The aircraft was extensively damaged; the right engine propeller blades penetrated the cabin before the engines were shut down.
Post-accident Actions
After engine shutdown, occupants evacuated through the aircraft’s main door located at the rear left side, as the right emergency exit was damaged and would not open. A significant fuel leak was noted. The occupants walked a short distance to the runway, where snow depth was between 6 and 8 inches. They called 911 and the London Flight Information Centre to report the accident. Aerodrome staff observed the landing and slide; they drove a snow removal vehicle to check on the occupants, then continued plowing the runway. Another vehicle transported the occupants to the terminal building, where they were assessed by emergency medical services and taken to a local hospital for examination. There were only minor injuries.
Investigation and Findings
The investigation was unable to determine the aircraft’s exact touchdown point because the runway was plowed immediately after the occurrence. Based on available data, it was estimated that the aircraft touched down between 1000 and 1400 feet beyond the runway threshold and began sliding shortly after. The aircraft continued sliding to the right, rotated nearly 180 degrees, and exited the side of the runway at an angle of about 45 degrees to the runway edge. Following the accident, Thunder Airlines Limited issued an operations bulletin to all flight crews, stating that no flight crew shall depart until there is confirmation of suitable runway conditions (maximum ½ inch wet snow or 2 inches dry snow) from reliable sources on the ground. The bulletin also noted that if communicated information includes a plan to clear the runway, confirmation of a cleared runway must be obtained before landing. This bulletin will be incorporated into Thunder Airlines Limited standard operating procedures in the next revision.