What happened
On a night flight under visual flight rules, a Beechcraft F33A operated by Seneca College of Applied Arts and Technology departed Toronto/Buttonville Municipal Airport for Kingston Airport. The flight crew, consisting of an instructor and two students, intended to practice instrument approaches. However, after encountering worsening weather conditions approximately 11 nautical miles east of Oshawa Airport, the crew decided to return to Buttonville.
During the return leg, the aircraft, registered C–GSCZ, contacted the tower to request a simulated RNAV approach. Following this communication, radar tracked the aircraft performing a climbing right turn. During this maneuver, the aircraft's airspeed decreased significantly. The aircraft then entered a steep left turn and a rapid descent. The aircraft struck a ploughed field roughly 10 nautical miles east of the airport, resulting in three fatalities. There was no fire at the crash site, and the emergency locator transmitter failed to activate.
The investigation
Investigators examined the flight path and environmental conditions at the time of the accident. Radar data indicated that as the aircraft climbed, the airspeed dropped to approximately 90 knots. The investigation focused on the sequence of events leading to the loss of control, specifically looking at the aircraft's aerodynamic state during the turn.
Analysis of the flight path suggested that the aircraft experienced a left wing stall followed by an abrupt wing drop. The investigation also considered the impact of local weather, which included rain, snow, and freezing rain, and how these conditions might have affected visibility and airframe icing. Furthermore, the physical layout of the cockpit was examined, specifically the placement of flight instruments which could have hindered the instructor's ability to monitor the aircraft's attitude from the right seat.
Findings
- The flight crew initiated a climbing right turn following the encounter with adverse weather.
- During this climb, engine power was likely not increased, causing the airspeed to decay.
- The angle of attack on the left wing increased until a stall occurred, leading to an unexpected wing drop.
- The instructor's ability to react and recover was likely hampered by the position of the flight instruments and the lack of visual references due to darkness and precipitation.
- Potential airframe icing may have contributed to the abruptness of the wing stall.