Narrative:

We were on the 223 degree right inbound to cri at 4000'. While I was making a required call to company, the controller cleared us for a visibility approach to jfk 13L to follow an large transport in our 2 O'clock position. The flying first officer acknowledged the transmission and idented an aircraft at the 2 O'clock position. (Later it turned out not to be an large transport.) I returned to the radio in time to hear him acknowledge the visibility approach. He pointed out the 'traffic' now going to our 1 O'clock position, and started a descent out of 4000'. (As altitude IAF, crossing altitude is 3000'.) we wanted to confirm the visibility clearance because it is very unusual into 13L, but the radio was busy. I shortly looked out the right side window and saw an large transport approaching us from the rear about 500' below us and closing. The large transport pilot asked our altitude (to the controller). The controller asked us if we had the large transport. I replied we did. The controller then issued a traffic alert and had us climb to 4000' and turn to 310 degrees. We had already started a turn by the time the controller gave us instructions. After the traffic conflict was resolved, we made an uneventful landing at jfk. The controller gave an erroneous clock position for the traffic which we were to follow. The PF idented an aircraft in the correct clock position but did not question the discrepancy of type. The whole routing for phl to jfk was a series of unusual rtings, changes in rtes and vectors. This put an unusual workload on the crew, causing me to be off the primary radio (with a required company call) in a critical phase of flight.

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Original NASA ASRS Text

Title: ACR SIGHTS TRAFFIC, BUT IT IS NOT THE ACFT ASSIGNED TO FOLLOW. EVASIVE ACTION TAKEN WHEN SIGHTING CORRECT ACFT.

Narrative: WE WERE ON THE 223 DEG R INBND TO CRI AT 4000'. WHILE I WAS MAKING A REQUIRED CALL TO COMPANY, THE CTLR CLRED US FOR A VIS APCH TO JFK 13L TO FOLLOW AN LGT IN OUR 2 O'CLOCK POS. THE FLYING F/O ACKNOWLEDGED THE XMISSION AND IDENTED AN ACFT AT THE 2 O'CLOCK POS. (LATER IT TURNED OUT NOT TO BE AN LGT.) I RETURNED TO THE RADIO IN TIME TO HEAR HIM ACKNOWLEDGE THE VIS APCH. HE POINTED OUT THE 'TFC' NOW GOING TO OUR 1 O'CLOCK POS, AND STARTED A DSCNT OUT OF 4000'. (AS ALT IAF, XING ALT IS 3000'.) WE WANTED TO CONFIRM THE VIS CLRNC BECAUSE IT IS VERY UNUSUAL INTO 13L, BUT THE RADIO WAS BUSY. I SHORTLY LOOKED OUT THE RIGHT SIDE WINDOW AND SAW AN LGT APCHING US FROM THE REAR ABOUT 500' BELOW US AND CLOSING. THE LGT PLT ASKED OUR ALT (TO THE CTLR). THE CTLR ASKED US IF WE HAD THE LGT. I REPLIED WE DID. THE CTLR THEN ISSUED A TFC ALERT AND HAD US CLB TO 4000' AND TURN TO 310 DEGS. WE HAD ALREADY STARTED A TURN BY THE TIME THE CTLR GAVE US INSTRUCTIONS. AFTER THE TFC CONFLICT WAS RESOLVED, WE MADE AN UNEVENTFUL LNDG AT JFK. THE CTLR GAVE AN ERRONEOUS CLOCK POS FOR THE TFC WHICH WE WERE TO FOLLOW. THE PF IDENTED AN ACFT IN THE CORRECT CLOCK POS BUT DID NOT QUESTION THE DISCREPANCY OF TYPE. THE WHOLE RTING FOR PHL TO JFK WAS A SERIES OF UNUSUAL RTINGS, CHANGES IN RTES AND VECTORS. THIS PUT AN UNUSUAL WORKLOAD ON THE CREW, CAUSING ME TO BE OFF THE PRIMARY RADIO (WITH A REQUIRED COMPANY CALL) IN A CRITICAL 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.