Narrative:

Operating an air carrier X, B757-200 from jfk to sju. I served as first officer and flew this segment. Uneventful flight until near condo OM (FAF for ILS runway 10). We sequenced behind a falcon jet. A twin cessna on a right downwind and the local tower controller had the following exchange as we descended on the GS inside condo: twin cessna inquired 'confirm we are #1 for the airport.' tower responded, 'roger twin cessna..., you are #1 behind an air carrier Y.' twin cessna answered, 'ok, we'll keep it in close then.' the controller's non-standard phraseology and twin cessna's response instantly had us looking for a traffic conflict, but before this ambiguity could be resolved, the falcon pilot got on the frequency to report he could not find the taxiway to exit the runway. As an intensive visual search for the twin ensued, it became clear we had several problems. Though VFR conditions prevailed, traffic was difficult to acquire due to being lost in the lights of san juan. At 700-800 ft AGL we simultaneously acquired a visual on the traffic, now on a base leg on a perfect collision course. We initiated a go around and received instruction from tower to go around. Ironically, the tower gave the go around because of the falcon on the runway and not because of the twin cessna conflict. At this point, tower controller was unaware of the traffic conflict. We estimate missing the twin by zero ft in the horizontal plane and 100-200 ft vertically. TCASII RA was inhibited in this phase of flight.

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Original NASA ASRS Text

Title: ON APCH TO SJU ARPT, A B757 HAS AN NMAC WITH A TWIN CESSNA THAT TURNED ONTO FINAL IN FRONT OF THE FLT.

Narrative: OPERATING AN ACR X, B757-200 FROM JFK TO SJU. I SERVED AS FO AND FLEW THIS SEGMENT. UNEVENTFUL FLT UNTIL NEAR CONDO OM (FAF FOR ILS RWY 10). WE SEQUENCED BEHIND A FALCON JET. A TWIN CESSNA ON A R DOWNWIND AND THE LCL TWR CTLR HAD THE FOLLOWING EXCHANGE AS WE DSNDED ON THE GS INSIDE CONDO: TWIN CESSNA INQUIRED 'CONFIRM WE ARE #1 FOR THE ARPT.' TWR RESPONDED, 'ROGER TWIN CESSNA..., YOU ARE #1 BEHIND AN ACR Y.' TWIN CESSNA ANSWERED, 'OK, WE'LL KEEP IT IN CLOSE THEN.' THE CTLR'S NON-STANDARD PHRASEOLOGY AND TWIN CESSNA'S RESPONSE INSTANTLY HAD US LOOKING FOR A TFC CONFLICT, BUT BEFORE THIS AMBIGUITY COULD BE RESOLVED, THE FALCON PLT GOT ON THE FREQ TO RPT HE COULD NOT FIND THE TXWY TO EXIT THE RWY. AS AN INTENSIVE VISUAL SEARCH FOR THE TWIN ENSUED, IT BECAME CLR WE HAD SEVERAL PROBS. THOUGH VFR CONDITIONS PREVAILED, TFC WAS DIFFICULT TO ACQUIRE DUE TO BEING LOST IN THE LIGHTS OF SAN JUAN. AT 700-800 FT AGL WE SIMULTANEOUSLY ACQUIRED A VISUAL ON THE TFC, NOW ON A BASE LEG ON A PERFECT COLLISION COURSE. WE INITIATED A GAR AND RECEIVED INSTRUCTION FROM TWR TO GO AROUND. IRONICALLY, THE TWR GAVE THE GAR BECAUSE OF THE FALCON ON THE RWY AND NOT BECAUSE OF THE TWIN CESSNA CONFLICT. AT THIS POINT, TWR CTLR WAS UNAWARE OF THE TFC CONFLICT. WE ESTIMATE MISSING THE TWIN BY ZERO FT IN THE HORIZ PLANE AND 100-200 FT VERTLY. TCASII RA WAS INHIBITED IN THIS PHASE OF FLT.

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.