The Royal Canadian Air Force (RCAF) has concluded an investigation into the crash of a CH-147F Chinook that tragically killed two Canadian Armed Forces (CAF) members during a training flight over the Ottawa River near Petawawa, Ont., in June 2023.
The four-person helicopter crew, known by callsign Hammer 31, was conducting a nighttime training flight when the Chinook struck the river. The two pilots, Capt Marc Larouche and Capt David Domagala, were fatally injured. The two flight engineers egressed with minor injuries.
The Directorate of Flight Safety, the CAF airworthiness investigative authority, determined “the aircraft entered a constant but imperceptible descent” as the crew initiated a turning maneuver over the river.
“None of the crew realized the aircraft’s altitude and/or rate of descent until impact, resulting in a Controlled Flight into Terrain accident,” according to the investigation. The unrecognized downward acceleration, “along with environmental conditions that night, were significant contributors to the accident, causing spatial disorientation among the crew.”
“This accident was not caused by a single factor, instead, multiple elements contributed to the unrecognized spatial disorientation of all crew members of Hammer 31, leading to the continued descent until water impact,” Col Jean-François Gauvin, director of RCAF Flight Safety, said in a statement.
“Over 16 months, we thoroughly analyzed a large amount of data and collaborated closely with partners to identify additional contributing factors. Several recommendations are provided to help prevent similar accidents in the future.”
According to the report, the Chinook, CH147310, was scheduled to conduct two advanced night tests as part of the Tactical First Officer Course on the evening of June 19. Each test was expected to take two hours, with a crew change of student pilots at the halfway point.
The accident occurred during the second portion of the mission, shortly after the change of student pilot crews. The instructor pilot and the two flight engineers remained in the aircraft for the duration of the mission, and were on board at the time of the accident.
The aircrew was flying from Final Approach and Take-Off Area 17 to a confined area known as T40. The investigation found that the incident occurred following a simulated engine chip emergency, for which the aircraft was required 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 [T40], the aircraft started to descend. While descending and still established in the left turn, the helicopter impacted the Ottawa River with high energy.”
According to the investigation report, the aircraft entered a constant descent as the crew initiated the turn.
“None of the crew members realized the height and/or rate of descent of the aircraft before impact. … 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.
Among the investigation’s recommendations is the mandatory use of automation Level-3 (Native Mode Digital Automatic Flight Control System) when operating below 200 feet above water at night. Additional preventative measures to enhance safety and mitigate the risks associated with over-water missions were recommended at the base, squadron, wing, division and strategic levels.
“We continue to grieve alongside all those affected, and our thoughts remain with the loved ones of Capt Marc Larouche and Capt David Domagala,” said RCAF commander LGen Eric Kenny. “The results of the Flight Safety investigation provide us details and recommendations surrounding this tragic accident. We are committed to learning from this heartbreaking loss, and providing safety for our aviators as we continue our mission in service of Canada.”
The Flight Safety Investigation was shared with the family members of deceased, the RCAF stated.
The RCAF took delivery of the fleet of 15 Boeing CH-147F Chinooks starting in 2013. CH147310 was destroyed on impact. The RCAF has not indicated if the aircraft will be replaced.
