Narrative:

While flying the expressway visual to runway 31 (clear skies, visibility 10+ mi), we were vectored behind a B757, who was in turn vectored wide by tower. We were vectored through the runway centerline and were slightly right of centerline on the VASI's descending through 700 ft with clearance to land. The B757 was about to touch down. Dash 8 was cleared for a visual landing behind us. First officer noticed dash 8, who was slightly behind us on a left base, turn sharply toward the runway. Dash 8 apparently thought the landing B757 was us and, with his right wing up, did not see us on final. With our aircraft fully configured and below 700 ft, our TCASII was inhibited, but dash 8's DOT was superimposed over our left wing and at our altitude on the TCASII display (we were displaying 5 mi scale). First officer pointed out that dash 8 was coming right at us. I took a quick glance to my left and immediately ordered a breakout to the right (north). First officer, who was flying, began a climbing right turn, it seemed like 10-15 seconds before I could get through tower frequency congestion to call the go around and declare a near miss with the tower. I estimate that we came within 300-500 ft of the dash 8 aircraft, but this is difficult to judge at night. We were both on short final, below 700 ft, landing on the same runway, side-by-side. Tower apparently did not observe the event, since no go around or breakout was directed by them. Additionally, they did not immediately respond to, or seem aware of our go around, until I notified them on the radio. We were vectored for another approach and landing without incident. I notified the passenger that 'we were vectored too close to another aircraft for a safe landing, and although we were in no danger, we elected to go around and set up for another approach for their safety.' first officer should be commended for his situational awareness and prompted and correct actions to avoid what could well have been a tragic event. He has been well trained and it showed.

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Original NASA ASRS Text

Title: MD80 CREW AND A DASH 8 HAD AN NMAC ON THE EXPRESSWAY VISUAL RWY 31 APCH TO LGA.

Narrative: WHILE FLYING THE EXPRESSWAY VISUAL TO RWY 31 (CLR SKIES, VISIBILITY 10+ MI), WE WERE VECTORED BEHIND A B757, WHO WAS IN TURN VECTORED WIDE BY TWR. WE WERE VECTORED THROUGH THE RWY CTRLINE AND WERE SLIGHTLY R OF CTRLINE ON THE VASI'S DSNDING THROUGH 700 FT WITH CLRNC TO LAND. THE B757 WAS ABOUT TO TOUCH DOWN. DASH 8 WAS CLRED FOR A VISUAL LNDG BEHIND US. FO NOTICED DASH 8, WHO WAS SLIGHTLY BEHIND US ON A L BASE, TURN SHARPLY TOWARD THE RWY. DASH 8 APPARENTLY THOUGHT THE LNDG B757 WAS US AND, WITH HIS R WING UP, DID NOT SEE US ON FINAL. WITH OUR ACFT FULLY CONFIGURED AND BELOW 700 FT, OUR TCASII WAS INHIBITED, BUT DASH 8'S DOT WAS SUPERIMPOSED OVER OUR L WING AND AT OUR ALT ON THE TCASII DISPLAY (WE WERE DISPLAYING 5 MI SCALE). FO POINTED OUT THAT DASH 8 WAS COMING RIGHT AT US. I TOOK A QUICK GLANCE TO MY L AND IMMEDIATELY ORDERED A BREAKOUT TO THE R (N). FO, WHO WAS FLYING, BEGAN A CLBING R TURN, IT SEEMED LIKE 10-15 SECONDS BEFORE I COULD GET THROUGH TWR FREQ CONGESTION TO CALL THE GAR AND DECLARE A NEAR MISS WITH THE TWR. I ESTIMATE THAT WE CAME WITHIN 300-500 FT OF THE DASH 8 ACFT, BUT THIS IS DIFFICULT TO JUDGE AT NIGHT. WE WERE BOTH ON SHORT FINAL, BELOW 700 FT, LNDG ON THE SAME RWY, SIDE-BY-SIDE. TWR APPARENTLY DID NOT OBSERVE THE EVENT, SINCE NO GAR OR BREAKOUT WAS DIRECTED BY THEM. ADDITIONALLY, THEY DID NOT IMMEDIATELY RESPOND TO, OR SEEM AWARE OF OUR GAR, UNTIL I NOTIFIED THEM ON THE RADIO. WE WERE VECTORED FOR ANOTHER APCH AND LNDG WITHOUT INCIDENT. I NOTIFIED THE PAX THAT 'WE WERE VECTORED TOO CLOSE TO ANOTHER ACFT FOR A SAFE LNDG, AND ALTHOUGH WE WERE IN NO DANGER, WE ELECTED TO GO AROUND AND SET UP FOR ANOTHER APCH FOR THEIR SAFETY.' FO SHOULD BE COMMENDED FOR HIS SITUATIONAL AWARENESS AND PROMPTED AND CORRECT ACTIONS TO AVOID WHAT COULD WELL HAVE BEEN A TRAGIC EVENT. HE HAS BEEN WELL TRAINED AND IT SHOWED.

Data retrieved from NASA's ASRS site as of July 2007 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.