Low speed was likely a factor in a fatal plane crash that killed three people in Chilliwack, according to the Transportation Safety Board of Canada report released June 25.
A pilot and two occupants were "fatally injured" on Oct. 6, 2023, during a training manoeuvre when the Piper PA-34-200 (Seneca) aircraft "rolled to the right and continued to roll" until it crashed into some bushes near the Chilliwack Airport.
The SkyQuest Aviation plane had taken off from Langley Airport. The flight school instructor and two students were on board, executing a second training exercise toward a multi-engine rating.
"After conducting some manoeuvring exercises and a circuit at Chilliwack Airport, B.C., the aircraft initiated a missed approach exercise," according to the TSB report. "During the manoeuvre, the airplane rolled to the right and continued to roll until it struck trees and terrain in a nose-down and inverted attitude."
The word "attitude" in this context is an aviation term referring to the nose-down pitch of the aircraft relative to the horizon.
The plane went into "a minimum control speed (VMC)3 roll before the collision," the TSB report said.
"A VMC roll occurs when there is an asymmetrical power situation and the aircraft’s speed falls below VMC," the report said, which makes it clear the speed was likely a factor.
The TSB's investigation was "unable to determine" what the instructor’s intentions were upon arrival at the airport; "however, the aircraft was observed completing one circuit and then lining up for an approach to Runway 07."
There was no flight-path data available, and no radar information recorded at the airport. But a dashcam video camera from a vehicle passing near the airport recorded the last moments of the flight.
The aircraft was "substantially damaged" after it touched down, but there was no post-impact fire despite a fuel leak.
"The aircraft levelled off below 100 feet above ground level (AGL) while aligned with the runway; then, before reaching the runway threshold, it banked and turned right.
"The bank angle continued to increase past 90 degrees while the aircraft’s heading changed toward a southerly direction, and the pitch decreased toward a nose-down attitude.
The aircraft "impacted the ground" near the casino in "a close-to-inverted and nose-low attitude."
The aircraft was examined at the accident site. The wing flaps were in the up position and the landing gear was extended.
"Because of the nature of the impact, damage to the aircraft, and work by first responders, the investigation was unable to assess the position of the engine controls or ancillary controls at the time of the occurrence."
At the accident site, first responders noted a strong odour of fuel and saw leaking fuel, suggesting there was fuel in the aircraft at the time of impact.
The fuel delivery system and ignition system were tested by a third party using diagnostic equipment and no anomalies were noted.
The light bulb for the stall warning system and the light bulbs for the turbocharger system were sent to an engineering lab in Ottawa, for analysis.
"It was determined that the stall and left-hand overboost lights were likely off at the time of the impact, but the right-hand overboost bulb exhibited some deformation that indicates that the bulb could have been illuminated at the time of impact," the report stated.
"The investigation could not reconcile this observation given that the turbochargers’ waste gates were fully open and not providing additive boost to the intake manifold.
"Notwithstanding the extent of the damage, the investigation did not discover any issues with the flight controls that would have led to the loss of control or anything mechanical that would have prevented either engine from producing power."
Weather was not considered a factor.
The investigation report did not assign fault.
The TSB clarified that it investigated the crash incident: "for the purpose of advancing transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability."
The TSB report included safety messages for flight instructors in the wake of the fatal collision:
"Instructors are reminded that during multi-engine training, any asymmetric thrust exercises should be performed at a safe altitude and airspeed given the significant altitude losses that can occur in the event of a VMC roll," the report concluded, which also addresses the speed issue.
"Pilots of multi-engine aircraft are reminded that should a loss of yaw control occur during an asymmetric thrust situation, it is imperative that power be reduced on the operating engine and recovery of airspeed be attained by reducing the pitch attitude.
"At lower altitudes this may result in a forced landing, which offers greater survivability than a VMC roll."
