The attack happened at the Cleveland Street station in Cypress Hills on Thursday, November 29, around 10:30 p.m.
Investigators say the man was on the platform and punched the J train conductor in the face as he stuck his head out of the train's window.
The conductor wasn't seriously hurt.
The individual is described as a black man last seen wearing a black knit cap, black gloves, a black jacket, black pants, black sneakers and he had on a black backpack.
Anyone with information in regard to this incident is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).
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