Narrative:

Air carrier X departed bos climbing to 4000 ft on a 340 degree heading. VFR small aircraft Y orbiting 10 northwest bos at 3500 VFR. Air carrier Z at 5000 ft 15 northwest swbound, level flight (not on frequency). Air carrier X was in climb to 4000 ft (out of 3000 ft 4 northwest) received TCASII RA and climbed above 4000 ft. When his altitude was questioned he advised about the TCASII RA and replied descending from 4300 ft to 4000 ft. I advised air carrier X to maintain 4000 ft and reissued the 3500 ft traffic and additional traffic at 5000 ft, 1 mi. Air carrier X advised was receiving another RA from TCASII and was climbing. I again stated maintain 4000 ft and issued the 5000 ft traffic. Air carrier X advised he did not see any traffic and was climbing regardless of ATC instructions. I turned air carrier X 090 degrees to maintain separation. Air carrier X complied. I believe the reason for erroneous TCASII RA was due to the fact that the VFR small aircraft Y at 3500 ft was circling. The fact that air carrier X climbed into known traffic because of a TCASII RA, regardless of ATC instructions is in this case a potentially dangerous situation.

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Original NASA ASRS Text

Title: ACR X TCASII RA WITH VFR SMA NON ADHERENCE TO ATC CLRNC UNAUTH CLB FROM ASSIGNED ALT HAD LTSS FROM ACR Z. PLTDEV.

Narrative: ACR X DEPARTED BOS CLBING TO 4000 FT ON A 340 DEG HDG. VFR SMA Y ORBITING 10 NW BOS AT 3500 VFR. ACR Z AT 5000 FT 15 NW SWBOUND, LEVEL FLT (NOT ON FREQ). ACR X WAS IN CLB TO 4000 FT (OUT OF 3000 FT 4 NW) RECEIVED TCASII RA AND CLBED ABOVE 4000 FT. WHEN HIS ALT WAS QUESTIONED HE ADVISED ABOUT THE TCASII RA AND REPLIED DSNDING FROM 4300 FT TO 4000 FT. I ADVISED ACR X TO MAINTAIN 4000 FT AND REISSUED THE 3500 FT TFC AND ADDITIONAL TFC AT 5000 FT, 1 MI. ACR X ADVISED WAS RECEIVING ANOTHER RA FROM TCASII AND WAS CLBING. I AGAIN STATED MAINTAIN 4000 FT AND ISSUED THE 5000 FT TFC. ACR X ADVISED HE DID NOT SEE ANY TFC AND WAS CLBING REGARDLESS OF ATC INSTRUCTIONS. I TURNED ACR X 090 DEGS TO MAINTAIN SEPARATION. ACR X COMPLIED. I BELIEVE THE REASON FOR ERRONEOUS TCASII RA WAS DUE TO THE FACT THAT THE VFR SMA Y AT 3500 FT WAS CIRCLING. THE FACT THAT ACR X CLBED INTO KNOWN TFC BECAUSE OF A TCASII RA, REGARDLESS OF ATC INSTRUCTIONS IS IN THIS CASE A POTENTIALLY DANGEROUS SIT.

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.