Narrative:

Aircraft X checked in on a visual approach to runway 31L. I advised the aircraft of the wind; and the parallel runway traffic; and cleared aircraft X to land runway 31L shortened. I was busy working both finals; class B airspace; and departures and at some point; aircraft Y asked 'which runway [is] aircraft X going to?'.. (Sic). I observed aircraft X cutting across aircraft Y enroute to runway 31R. I called traffic; and ensured that aircraft Y had traffic and was able to maintain visual separation with aircraft X. I then asked aircraft X if he intended to land on runway 31R; he advised he was going back to runway 31L. Both aircraft landed their respective runways. All concerned notified. I retain the right to amend all or any of this statement as information and recall come forth.I have no recommendations; however; I am confused as to why the 'conflict alert' did not deploy.

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Original NASA ASRS Text

Title: JFK Controller reported being asked by a pilot which runway another aircraft was going to land. The pilot stated the runway as assigned but had cut through the other aircraft's path and looked as though it was going to land on the same runway. Controller insured visual separation was being applied and had preceding aircraft go to the correct runway. Both aircraft landed their assigned runways.

Narrative: Aircraft X checked in on a visual approach to runway 31L. I advised the aircraft of the wind; and the parallel runway traffic; and cleared Aircraft X to land runway 31L shortened. I was busy working both finals; Class B Airspace; and departures and at some point; Aircraft Y asked 'which runway [is] Aircraft X going to?'.. (SIC). I observed Aircraft X cutting across Aircraft Y enroute to runway 31R. I called traffic; and ensured that Aircraft Y had traffic and was able to maintain visual separation with Aircraft X. I then asked Aircraft X if he intended to land on runway 31R; he advised he was going back to runway 31L. Both aircraft landed their respective runways. All concerned notified. I retain the right to amend all or any of this statement as information and recall come forth.I have no recommendations; however; I am confused as to why the 'conflict alert' did not deploy.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.