Narrative:

On aug/xx/94, I was the captain in command of flight from dfw to bos. My aircraft was a boeing 767-232. Flight operation was normal until we received an 'RA' from our TCASII while on final approach to runway 4R at boston logan international airport, necessitating a climb from 3000 ft MSL to 3500 ft MSL. Approximately time of the 'RA' was XA09 local time. Not long after intercepting the runway 4R localizer at 3000 ft MSL and being cleared for the approach, approach control pointed out traffic to us at our 10 O'clock position heading southeast at 2800 ft and unconfirmed. No sooner than the time it took to acknowledge the transmission, we received a TCASII 'TA' showing a target at that position and 2800 ft. I was unable to find the traffic in the night lights of boston and returned my attention to flying the aircraft. Within a matter of seconds, we received the TCASII 'RA' to climb and both the first officer and I aggressively initiated a climb in response to the 'RA.' at 3500 ft MSL the TCASII advised us we were clear of traffic. We estimate our separation from the traffic to have been 500 ft. We were then reclred for the approach to runway 4R and completed the approach to a landing. I later called approach control by phone and spoke with the supervisor. He said the target popped up on the controller's screen at 2500 ft and then showed a climb to 2800 ft. At that time the controller advised us and we responded to the 'RA.' the supervisor said the target was outside the 10 mi arc and they had no radio contact with him.

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Original NASA ASRS Text

Title: WDB TAKES EVASIVE ACTION ON ILS FINAL IN RESPONSE TO A TCASII RA CAUSED BY AN INTRUDER IN CLASS B AIRSPACE.

Narrative: ON AUG/XX/94, I WAS THE CAPT IN COMMAND OF FLT FROM DFW TO BOS. MY ACFT WAS A BOEING 767-232. FLT OP WAS NORMAL UNTIL WE RECEIVED AN 'RA' FROM OUR TCASII WHILE ON FINAL APCH TO RWY 4R AT BOSTON LOGAN INTL ARPT, NECESSITATING A CLB FROM 3000 FT MSL TO 3500 FT MSL. APPROX TIME OF THE 'RA' WAS XA09 LCL TIME. NOT LONG AFTER INTERCEPTING THE RWY 4R LOC AT 3000 FT MSL AND BEING CLRED FOR THE APCH, APCH CTL POINTED OUT TFC TO US AT OUR 10 O'CLOCK POS HDG SE AT 2800 FT AND UNCONFIRMED. NO SOONER THAN THE TIME IT TOOK TO ACKNOWLEDGE THE XMISSION, WE RECEIVED A TCASII 'TA' SHOWING A TARGET AT THAT POS AND 2800 FT. I WAS UNABLE TO FIND THE TFC IN THE NIGHT LIGHTS OF BOSTON AND RETURNED MY ATTN TO FLYING THE ACFT. WITHIN A MATTER OF SECONDS, WE RECEIVED THE TCASII 'RA' TO CLB AND BOTH THE FO AND I AGGRESSIVELY INITIATED A CLB IN RESPONSE TO THE 'RA.' AT 3500 FT MSL THE TCASII ADVISED US WE WERE CLR OF TFC. WE ESTIMATE OUR SEPARATION FROM THE TFC TO HAVE BEEN 500 FT. WE WERE THEN RECLRED FOR THE APCH TO RWY 4R AND COMPLETED THE APCH TO A LNDG. I LATER CALLED APCH CTL BY PHONE AND SPOKE WITH THE SUPVR. HE SAID THE TARGET POPPED UP ON THE CTLR'S SCREEN AT 2500 FT AND THEN SHOWED A CLB TO 2800 FT. AT THAT TIME THE CTLR ADVISED US AND WE RESPONDED TO THE 'RA.' THE SUPVR SAID THE TARGET WAS OUTSIDE THE 10 MI ARC AND THEY HAD NO RADIO CONTACT WITH HIM.

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.