An RCMP plane that crashed at the Whitehorse airport in April 2023, destroying the aircraft and badly hurting the RCMP pilot, was the result of a faulty stall warning system sensor, according to a report by the Transportation Safety Board of Canada (TSB).
The investigation report indicates the sensor for the plane’s stall warning system failed. This caused a false stall signal to be emitted, sounded a warning and activated the stick shaker, a device the TSB report states is designed to improve aircraft handling at low speed and to prevent the plane from stalling. Both warnings persisted throughout the flight. While this was all happening, the pilot tried to focus on flying instead of locating the circuit breakers that could be used to suppress the stall warning and the shaker.
The incident involving the RCMP Pilatus PC-12/47E occurred on April 17, 2023, following an uneventful flight from Yellowknife, N.W.T., to Whitehorse with three RCMP members and a pilot onboard. The temperature was just below freezing, the winds were light from the northwest and snow was falling, with low visibility at the Erik Nielsen Whitehorse International Airport.
The pilot, now alone, prepared to make the return flight back to Yellowknife.
The pilot isn’t named in the report. Police previously said their identity won’t be released.
The plane was cleared to take off at 11:34 a.m. Shortly after lifting off, the continuous aural stall warning and the stick shaker activated. The pilot flew low, below the clouds, and tried to notify air traffic control of their intent to turn back to the runway.
The report states that radio congestion on the frequency prevented the message from being received.
The pilot pulled a 180-degree turn to land, without indicating which runway they were planning to land on, and there was a miscommunication with the air traffic controllers during the landing effort.
About four minutes after being cleared for takeoff, while trying to line up with the runway, the plane took a steep downward right turn at a low speed and the plane’s right wing hit the ground. Moments later, the left wing struck a pile of frozen asphalt millings, causing the wing to break off. The aircraft rolled over and slid about 130 feet before coming to a halt on an airport service road.
While the pilot was seriously injured, they exited the plane using an emergency exit, with the help of aircraft rescue and firefighting personnel minutes after the crash. The pilot went to the hospital and was released the next day, according to the report.
One thousand litres of fuel spilled, and was subsequently cleaned up.
The airport was temporarily closed due to the emergency situation.
The report notes the pilot had 8,700 flying hours under their belt, and there’s no indication that fatigue was a factor in the crash.
The plane was manufactured in 2008.
The stall system warning went off for the duration of the flight, distracting the pilot and increasing their workload, as noted in a TSB press release.
“While attempting to align the aircraft for landing, the pilot experienced attentional narrowing due to an intense stress reaction in response to the continuous stall warning,” reads the release.
“As a result, the pilot’s attention was focused outside the aircraft, and the pilot unknowingly placed the aircraft in a flight regime that likely resulted in an aerodynamic stall at a very low height above ground.”
The press release indicates the RCMP’s training around stall warning malfunctions was inadequate and the pilot operating handbook provided limited guidance, thus the pilot didn’t know a switch could be used to quickly stop the false aural stall warning that was distracting them throughout the flight.
RCMP has improved its related training on stall warning system-related scenarios and single-pilot operating procedures for its crews on this type of plane. Police also looked back at technical records of its fleet and consulted the manufacturer about new sensors, per the board’s release.
Contact Dana Hatherly at dana.hatherly@yukon-news.com
