Date: 201509
Local time of day: 1801-2400
Location: BOI.Airport, ID
Light: Daylight
Aircraft: Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Flight phase: Final Approach; Initial Approach
Airspace: Class C BOI
ATC / advisory: Tower BOI
Second aircraft: Medium Transport; High Wing; 2 Turboprop Eng
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Confusion; Situational Awareness
Anomaly: Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance
Contributing factors: Procedure; Human Factors
Primary problem: Human Factors

Narrative: Aircraft X was inbound from the North West and was showing SS in his data block meaning landing runway 28L parking south side. I told Aircraft X to continue for runway 28L traffic will be holding in position. The pilot acknowledged; 'Continue for the left'. I cleared Aircraft Y for takeoff from runway 28R and told Aircraft Z to line up and wait runway 28L traffic [Aircraft X] in the north downwind. I was busy scanning strips to radar and looking at the separation for my departures and right before I started to clear Aircraft Z; Aircraft X says I am turning final for runway 28L. I looked and saw Aircraft X on a very close in final for runway 10L well below the departing Aircraft Y. I told Aircraft X 'NEGATIVE YOU ARE ON FINAL FOR RUNWAY 10 TURN LEFT AND REJOIN THE DOWNWIND'. Aircraft X then said something about it being his fault and I saw him climbing and turning. Aircraft Y then said he passed the traffic off the departure end and I switched Aircraft Y to departure and explained the pilot was confused on the runway configuration. Aircraft Y switched and didn't say any more. I cleared Aircraft Z for takeoff and when the second [aircraft in flight of 2] rolled I cleared Aircraft X to land on runway 28L. He turned a very tight base and ended up having to break out to the south side and make a 270 degree turn to eventually land without incident. Pilot situational awareness training could help this pilot. There were many opportunities for the pilot to break the chain of events in this situation. I believe that the pilot came in to fast and was behind his airplane. When told to continue traffic in position he should have questioned why he didn't see this traffic. Why would he fly such a tight close in base without a landing clearance? When I told Aircraft Z flight that his traffic was in a north downwind why didn't the pilot think; no I am not; I am on a half mile base leg. My window to notice that he didn't turn downwind was fairly short but catching that in my scan was my only opportunity to break this chain.




Synopsis: BOI Tower Controller reported of an aircraft lining up for the incorrect runway requiring the Controller to intervene and reissue instructions. The Controller indicated that the pilot should have noticed the discrepancy due to issued traffic alerts.