What happened
While performing external load operations near Bella Bella, a Canadian Coast Guard Messerschmitt-Bolkow-Blohm BO 105 helicopter, registration C-GCHX, crashed into the water. The aircraft, operated by Transport Canada, was returning to the CCGS Bartlett from Dryad Point Lighthouse Station after completing 27 external loads. The helicopter was carrying an empty cargo bonnet attached to a 33-metre synthetic longline.
At an altitude of approximately 200 feet, the cargo bonnet moved upward and behind the tail rotor. This movement caused the longline to snag the rear of the helicopter. The aircraft subsequently lost speed, began a descent, and entered a right turn before impacting the water. The helicopter sank immediately at a depth of 26 metres. The pilot managed to exit the submerged wreckage but was found face down in the water. Despite being in critical condition, the pilot was rescued within three minutes.
The investigation
Investigators examined the configuration of the sling equipment, which consisted of a 33-metre synthetic rope line attached to the aircraft's belly hook. The load included a bonnet containing rope gear and slings, secured with a polypropylene rope. The investigation also looked into the pilot's safety equipment and the cabin interior, noting that the pilot's helmet was fractured due to upper-body movement during the impact. Furthermore, the investigation assessed the visibility of the pilot in the water, noting that the grey and navy blue colors of the flight suit and helmet made detection difficult.
Findings
- The primary cause of the accident was that the polypropylene rope used to secure the bonnet slid up the becket, allowing the bonnet to open during flight.
- The resulting asymmetric shape and high drag of the light, empty bonnet caused it to fly into the helicopter's flight path, bringing the longline into contact with the tail rotor and disabling it.
- The lack of an upper-body restraint device allowed the pilot's torso to move violently within the cabin during impact, increasing the risk of injury and drowning.
- The pilot's flight suit and helmet colors reduced the likelihood of rapid detection during the rescue operation.
- Even when properly secured, the cabin configuration posed a risk of the pilot striking their head on a liferaft fixture during impact.