CH147310 Chinook – Epilogue

On the evening of 19 Jun 2023, the crew of Hammer 31, on board aircraft CH147310, was scheduled to conduct two Advanced Night Tests as part of the Tactical First Officer Course. The flight was planned for a total of four hours, with each test taking two hours to complete. The two Student Pilots undergoing training conducted a crew change at the halfway point of the four-hour mission. The Instructor Pilot and the two Flight Engineers remained on board for the complete duration of the mission. The accident occurred during the second portion of the mission, shortly after the two Student Pilots’ crew change. Two pilots and two Flight Engineers were on board the aircraft at the time of the accident.

The accident crew departed from Final Approach and Take-Off Area 17 to fly to confined area T40 in training area “E”. Shortly after departure the Instructor Pilot simulated an engine chip emergency, which required the aircraft to return for landing. After the emergency scenario was completed, the crew departed again from Final Approach and Take Off Area 17 to fly to confined area T40. During the turn towards confined area T40, the aircraft started to descend. While descending and still established in the left turn, the helicopter impacted the Ottawa River with high energy.

The helicopter was destroyed. The two pilots were fatally injured in the accident while the two Flight Engineers successfully egressed the helicopter, receiving only minor injuries.

The investigation determined that when the crew initiated the turn towards area T40, the aircraft entered a constant descent. None of the crew members realized the height and/or rate of descent of the aircraft before impact, resulting in a Controlled Flight into Terrain (CFIT) accident. It was concluded that the unperceived acceleration and the environmental conditions that night were key factors that played a role in this accident, contributing to the spatial disorientation experienced by the crew.

The investigation made numerous recommendations to amend the CH147F publications, including a recommendation to mandate the use of automation Level-3 (Native Mode Digital Automatic Flight Control System) when operating below 200 ft above water at night. Additional recommendations were made to improve emergency response preparedness.