Air Transportation Safety Investigation Report A18p0031

At 1121, the pilot called the Abbotsford air traffic control (ATC) tower to ask whether he could receive an early clearance while the aircraft was still in the hangar.2 The pilot was concerned that, with the heavy snowfall, the aircraft would be covered in snow if the flight experienced any delay in receiving the IFR clearance. [...] Once the aircraft came to rest, the pilot moved the FUEL CUTOFF & FEATHER levers to the FUEL CUTOFF & FEATHER position and ordered the passengers to evacuate the aircraft. [...] The TSB has previously identified the risks associated with operating above the maximum allowable gross weight, and the effect that it can have on aircraft performance.10 In general, as the C of G moves further aft, it results in less downforce on the tail and improved aircraft performance; however, moving the C of G aft also reduces the longitudinal stability of the aircraft.11 The aircraft fligh [...] The investigation was able to determine, using snowfall rate information from Abbotsford Airport, that the snowfall rate had increased to approximately 2 cm per hour during the half hour before the occurrence.16 At this rate, the amount of snow estimated to have fallen on the aircraft from the time it exited the hangar until it entered the runway was about 4 to 5 mm. [...] The runway surface condition information in the 1127 ATIS originated from a SNOWTAM/NOTAMJ observation at 1048.23 The runway surface condition information had not been updated to reflect the increase in snowfall between the 1048 SNOWTAM/NOTAMJ observation and the time of the occurrence.