While supporting Ex ARCTIC RAM, Griffon CH146453 was conducting a night area of operations familiarization in the approved Temporary Tactical Low Flying Area. All three aircrew were qualified, current and authorized for the mission. They were all wearing night vision goggles.
The crew departed YZF, proceeded into the approved exercise area and conducted their planned landings and take offs at two Forward Operating Bases. On the return to YZF, while conducting low level flying training, the aircraft contacted three high power transmission lines approximately 6.5 NMnorth westof YZF. The three wires were guided through the wire strike protection system and were severed, which removed electrical power to the city ofYellowknife.
Post-impact, windshield plexiglas and other debris entered the cockpit and entangled the Aircraft Captain’s helmet. Shortly thereafter, the First Officer initiated a 180-degree turn to return to YZF and then overflew the same high-tension power line. The aircraft then approached YZF from the north, overflew several taxiways, ramps, and the main runway before turning onto the Golf taxiway and hover-taxing to the ramp for landing and shut down.
The aircraft sustained B category damage. Severe damage was found to the left pilot windshield, top window and adjacent fuselage structure. Electrical burn marks were found on the left tail pylon and the left and right fuselage, which indicate electrical discharge exit points. The aircraft was returned to third line contractor for further damage assessment.
The investigation is focussing on aircrew supervision, pre-flight preparations and briefings, aircrew human factors, in-flight decision making, low level flying in the wires environment and the wire strike protection system.