A DC-3 aircraft approached Penticton Airport during an instrument approach, requiring a rapid descent to a minimum altitude of 6,500 feet. Upon passing the Greata fan marker, the aircraft experienced a rapid descent, resulting in a collision with trees on the Okanagan Mountain. The port tail plane and elevator were severely damaged, and the port wing was severed. The wreckage rotated to the left and landed approximately 400 feet from the initial contact with the trees. Both the co-pilot and pilot-in-command sustained fatal injuries. The incident was likely caused by the aircraft being below the minimum altitude permissible when passing through the Greata fan marker during an instrument approach on the Penticton Radio Range.A DC-3 aircraft approached Penticton Airport during an instrument approach, requiring a rapid descent to a minimum altitude of 6,500 feet. Upon passing the Greata fan marker, the aircraft experienced a rapid descent, resulting in a collision with trees on the Okanagan Mountain. The port tail plane and elevator were severely damaged, and the port wing was severed. The wreckage rotated to the left and landed approximately 400 feet from the initial contact with the trees. Both the co-pilot and pilot-in-command sustained fatal injuries. The incident was likely caused by the aircraft being below the minimum altitude permissible when passing through the Greata fan marker during an instrument approach on the Penticton Radio Range.