A sudden, unexpected drop in seat height instigated a series of events that led to a crash that destroyed a CH-149 Cormorant helicopter on a training flight in 2022, according to a report from the Canadian Department of National Defence (DND)’s Airworthiness Investigative Authority.
“The investigation determined that a combination of factors, including seat non-conformances and the horizontal position that was maladjusted, allowed the seat to be in a false lock condition,” the report said.
“When the seat dropped, the loss of outside visual references in combination with the severe vertical vibration resulted in an unrecognized spatial disorientation of the pilot flying."
“This caused the pilot flying to incorrectly perceive a right yaw and apply full left pedal input; this led to a severe left yaw and contributed to the change in roll attitude that likely rendered the helicopter unrecoverable.”
Multiple special inspections and aircrew information files have been issued to address seat non-conformances and avoid false lock conditions, according to the report.
