The Royal Canadian Air Force (RCAF) has concluded its investigation into the crash of a CH-147F Chinook helicopter that killed two Canadian Armed Forces (CAF) members during a training exercise over the Ottawa River in June 2023.
The investigation found that the accident was caused by a combination of spatial disorientation and environmental factors, which led to the helicopter’s fatal crash.
On the night of June 19, 2023, the four-person crew of the helicopter, operating under the callsign Hammer 31, was carrying out a nighttime training flight as part of the Tactical First Officer Course.
The mission involved two advanced night tests and began with a crew change at the halfway point. The incident occurred during the mission’s second phase, shortly after the new student pilots took over.
The flight crew initially departed from Final Approach and Take-Off Area 17, heading toward confined area T40 in training area “E.” Shortly after departure, the Instructor Pilot simulated an engine chip emergency, necessitating a return to base for landing.
Once the emergency scenario was completed, the crew took off again from Final Approach and Take-Off Area 17, this time heading directly for confined area T40. However, the aircraft began to descend during the turn towards the area.
While still in the left turn and continuing its descent, the helicopter crashed into the Ottawa River with high energy.
According to the Directorate of Flight Safety, which leads CAF airworthiness investigations, the Chinook entered a “constant but imperceptible descent” as the crew began a turning maneuver over the river.
But, the crew did not realize the aircraft’s altitude or descent rate until it was too late. The investigation concluded that this unrecognized downward acceleration and environmental conditions, such as darkness and weather, led to the crash.
“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,” stated the investigation report.
The report pointed out that spatial disorientation, caused by a mix of factors, led to the crew’s continued descent until the helicopter crashed into the Ottawa River at high speed.
The crash killed two pilots, Capt. Marc Larouche and Capt. David Domagala. The two flight engineers managed to egress from the wreckage with minor injuries. The RCAF has confirmed that the CH147310 helicopter was destroyed on impact.
Col. Jean-François Gauvin, director of RCAF Flight Safety, explained that the accident resulted from multiple contributing factors rather than a single cause.
“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,” Col. Gauvin stated in a formal statement.
Spatial Disorientation: A Silent Threat To Aviation?
Spatial disorientation (Spatial-D) is a phenomenon where an individual cannot determine their position, location, or motion relative to their environment. This disorientation poses a substantial risk in aviation as it impacts pilots operating all types of aircraft.
Alongside hypoxia and G-induced loss of consciousness (G-LOC), Spatial-D is one of the leading causes of human factor-related fatalities in aviation.
Unlike G-LOC, which is typically confined to military or acrobatic pilots in high-performance aircraft, Spatial-D is a universal challenge, impacting both civilian and military aviation sectors.
Spatial disorientation has a considerable economic and human cost, especially in defense operations. It accounts for hundreds of millions of dollars in wasted defense capabilities annually and continues to result in fatal accidents.
The issue arises from the limitations of human visual and vestibular systems in the flying environment, exacerbated by factors like task saturation and distraction.
The US Federal Aviation Administration (FAA) has previously highlighted the impact of spatial-D, particularly in the US Air Force (USAF). Between 1990 and 1999, the USAF experienced 36 spatial-D-related Class A mishaps, which resulted in the loss of 44 aircrew members and financial damages totaling US$557 million.
According to the FAA, Spatial-D often stems from discrepancies among the visual, vestibular, somatosensory, and cognitive systems, which creates a mismatch between a pilot’s perceived and actual orientation.
While pilots can sometimes override these mismatches by relying on aircraft instrumentation, incidents occur when pilots either fail to identify the disorientation or are unable to reconcile sensory inputs.
The dangers of Spatial-D extend to even the most advanced aviation technologies. In 2019, a Japan Air Self-Defense Force F-35A crashed into the ocean during a nighttime training flight, killing the pilot, Maj. Akinori Hosomi.
The investigation concluded that the crash resulted from spatial disorientation, highlighting how this phenomenon can impact even highly trained pilots and state-of-the-art aircraft.
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