Incident at CYR518 (vicinity of Niagara Falls)

1996-04-11: The helicopter pilot reported a white, low-wing aircraft crossing through CYR518 in a non-standard pattern at no more than 500 feet above the helicopter (which was at 2,500 feet). The helicopter pilot attempted to contact the aircraft pilot on 122.05 without any response. The aircraft pilot confirmed (with St. Catharines FSS) that he had just been in the Niagara Falls pattern and had seen the helicopter but stated that he had been at 3,500 feet. The pilot stated that he had switched over to 122.05 but was unsure why he hadn't heard the helicopter pilot's call. On initial contact (inbound to the Falls) with St. Catharines FSS, the pilot reported at 3,500 feet but on leaving the Falls area, the pilot reported "three (3) south St. Catharines at 2,500 returning to London." Ops. impact -- unknown.