Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 7.5
Situational Awareness; Communication Breakdown; Confusion
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Separated Traffic; Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Human Factors; Airspace Structure; Airport; Procedure
I was working arrival/final radar.  Aircraft X was turned to the airport and cleared for a visual approach to Runway XX right about 6 miles south of the field and switched to the local controller.  Aircraft Y was turned about 3 miles west of Aircraft X on a base for Runway XX Left.  Aircraft Y advised the field in sight and was turned on a heading to join and cleared for the visual approach to Runway XX Left.  Shortly after I observed Aircraft X going through the Runway XX Right final approach course and encroaching on Aircraft Y.  Local then called and told me that Aircraft X said he was cleared for the visual approach to Runway XX Left.  After reviewing the tapes Aircraft X was cleared for visual approach to Runway XX Right and read it back.  However when Aircraft X originally checked on he was told to expect Runway XX Left.I would probably have to say that expectation both on my part and the pilots part led to the event.  The pilot expected the left runway because that's what he was told when checking in.  I expected him to fly the visual approach for the right runway because that's what he was cleared for and what he read back.  Not sure that I have any recommendations other than to be more aware and expect the aircraft to do what you think they won't do.
An aircraft checked on frequency and was told to expect the left runway. When the aircraft reported the airport in sight the Controller cleared the aircraft for a visual approach to the right runway. The aircraft read back the clearance that he was cleared for the right runway. The aircraft intercepted the left runway final approach course. The aircraft thought they were cleared for an approach to the left runway. There was traffic slightly ahead lined up for Left Runway.