August 30, 1996
Incident at SAULT STE. MARIE ON (CYAM) (ATS operating irregularity)
CDR1957 was five miles final on approach to runway 29 (at Sault Ste. Marie, Ontario) when the crew called to enquire where the aircraft was going that was cutting underneath them. No other aircraft were on the frequency or cleared into the zone. A Cessna was observed northbound right under CDR1957. The controller called up on the Sault Ste. Marie/Sanderson Field (Michigan, U.S.A.) frequency and contacted N20355, advising that pilot of the situation and procedures. The controller was not positive that the aircraft contacted was the aircraft in question. Ops. impact -- unknown.