Narrative:

Laguardia was on the expressway visual to runway 31 approach. Departing runway 04. I was in the process of relieving a controller on the local control position. The previous controller needed space for a departure and told aircraft X to join a two mile left base and square it off (this is a routine procedure to accommodate departures on this configuration). Aircraft X extended his downwind and had to be prompted by the previous controller to turn his base. Aircraft X wound up joining three mile left base. The previous controller told aircraft Y that aircraft X extended and suggested that he do the same.I took the position at this time and told aircraft Y where aircraft X was and asked the pilot if he had him in sight. Aircraft Y confirmed that he had aircraft X in sight and began a turn to fall in behind him. I observed both aircraft out the window and saw that aircraft Y was in fact behind aircraft X. Very soon after I noticed on radar that aircraft Y continued a turn towards the runway cutting aircraft X off. I questioned the pilot and he turned to the right. Due to the aircraft altitude and position. I felt that he would not be able to continue the approach. Because he was on a visual. I asked the pilot if he would be able to continue or if he would like to go around. The pilot chose to go around.because the aircraft was below the MVA and the pilot need a heading as to not leave my airspace. I instructed the pilot for fly a heading of 010 and climb to 2000 ft. This would have kept the aircraft clear of any terrain. I handed the aircraft back to approach control on a heading 040 climbing to 3000 ft. This was at TRACON's request.both aircraft landed without incident.due to lgas configuration. The expressway visual to runway 31 can be very challenging. I suggest that we use the RNAV approach to this runway. Because each pilot flies the visual differently. We have to use several techniques to make it work and still accommodate departure. The RNAV approach would keep the aircraft more on a consistence path.

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Original NASA ASRS Text

Title: LGA Tower Controller and a CRJ-900 Captain reported a traffic alert and go-around during a visual approach at night.

Narrative: LaGuardia was on the expressway visual to runway 31 approach. Departing runway 04. I was in the process of relieving a controller on the local control position. The previous controller needed space for a departure and told Aircraft X to join a two mile left base and square it off (this is a routine procedure to accommodate departures on this configuration). Aircraft X extended his downwind and had to be prompted by the previous controller to turn his base. Aircraft X wound up joining three mile left base. The previous controller told Aircraft Y that Aircraft X extended and suggested that he do the same.I took the position at this time and told Aircraft Y where Aircraft X was and asked the pilot if he had him in sight. Aircraft Y confirmed that he had Aircraft X in sight and began a turn to fall in behind him. I observed both aircraft out the window and saw that Aircraft Y was in fact behind Aircraft X. Very soon after I noticed on radar that Aircraft Y continued a turn towards the runway cutting Aircraft X off. I questioned the pilot and he turned to the right. Due to the aircraft altitude and position. I felt that he would not be able to continue the approach. Because he was on a visual. I asked the pilot if he would be able to continue or if he would like to go around. The pilot chose to go around.Because the aircraft was below the MVA and the pilot need a heading as to not leave my airspace. I instructed the pilot for fly a heading of 010 and climb to 2000 ft. This would have kept the aircraft clear of any terrain. I handed the aircraft back to approach control on a heading 040 climbing to 3000 ft. This was at TRACON's request.Both aircraft landed without incident.Due to LGAs configuration. The expressway visual to runway 31 can be very challenging. I suggest that we use the RNAV approach to this runway. Because each pilot flies the visual differently. We have to use several techniques to make it work and still accommodate departure. The RNAV approach would keep the aircraft more on a consistence path.

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.