What happened
On 19 June 2008, a Eurocopter EC 1ob helicopter, registration C-GHNI, departed Lac des Neiges, Quebec, for a private flight under visual flight rules. During the flight, the pilot encountered intensifying rain showers and low cloud layers, prompting a decision to find a safe landing spot at Lac à l'Épaule to wait for better weather.
While flying at approximately 100 feet above ground level over the lake, the pilot attempted to clear condensation from the front windshield by activating the demist hot air system. This action caused the windshield and side windows to fog up instantly, obscuring all outside visual references. Consequently, the pilot did not realize the aircraft was descending and struck the water surface at a speed of 20 to 30 knots.
Both the pilot and the passenger sustained minor injuries and managed to evacuate the aircraft before it sank in 25 feet of water. Although the pilot assisted the passenger toward the shore, the passenger later died from cardiac arrhythmia caused by the stress of the event and exposure to the cold water.
The investigation
Investigators examined the wreckage of the EC 120B and found that the cabin's ventilation and demisting systems were functioning as designed. The investigation focused on why the activation of the demist system resulted in a sudden loss of visibility. It was determined that the warm air from the ventilation ducts cooled rapidly upon hitting the cold windshield, causing immediate condensation.
Technical analysis revealed that the pilot's approach over the water, while intended to avoid obstacles, placed the aircraft beyond gliding distance from the shore, increasing the risk to the occupants. Additionally, investigators noted that the pilot had not checked the weather forecast for the route prior to departure.