Narrative:

Approaching gdm on the gardner 2 arrival bos center pointed out VFR traffic at approximately 12 O'clock. Our clearance was to cross bronc at 11000. Bos mentioned that our traffic was wbound and would level at 14500. We thought the controller would plan our descent below 14500 before the passing point. Bos center never stopped our descent nor did they stop the other aircraft's climb. We realized a potential problem for the first time when TCASII issued an RA. TCASII said 'reduce your descent' and so I did. I reduced the descent to 0 FPM as we leveled at 14300 and that is when the aircraft passed abeam on our port side. We had the traffic in sight during the entire episode, but found it difficult to judge just where he was in relation to our position. After passing, we questioned bos as to his position and altitude. The response was defensive and the controller stated that he told us we could level at 15000 until traffic passed if we wished to! No one in my crew heard that transmission. This incident could have been prevented in many different ways. The VFR traffic should not have been allowed to fly against gardener-2 arrival traffic and climbing through our descent altitude. Avoidance turns could have been issued, altitude changes could have been applied. More and better communication could have been used to make each of us more fully aware of the situation. The controller must have watched the 2 of us come together on his radar screen at the same altitude, he must have been able to see the scenario developing -- yet, he sat there watching all this develop and said nothing! Supplemental information from acn 209780: at 16000 ft and 5 mi west of gardner, the captain pulled out the spdbrakes to increase our rate of descent in order to make the crossing restriction. At some point, I heard the controller say something about '15000,' but did not catch the whole transmission and assumed that he was telling us that the traffic was at 15000 ft. Our first officer did not acknowledge that call. I thought that the VFR traffic might be getting close to us so I kept my eye on him. At approximately 15000 ft our TCASII gave us a verbal RA of 'reduce descent, reduce descent.' this certainly caught my attention so I glanced at the TCASII instrument which showed a red arc on the lower half of the case. I did not focus my eyes on the instrument because I wanted to clear for the traffic. The captain started to stop our descent at this point. At approximately 14500 ft I saw the traffic pass off our left wing within 1/4 mi and what appeared to be the same altitude. Being that it was night, I can only guess at the horizontal distance. Our captain had not made any evasive turn, and I noticed that our altitude bottomed out at 14300 ft as we passed over gardner VOR. The controller never issued us any turns or altitude changes. The VFR traffic did not say anything about the conflict. A few mi later, our first officer told the center that we had seen the traffic pass us and asked what altitude he was at. The controller said he was at 14500 ft. At this point, the VFR traffic said he though we were told that 'it was suggested that we maintain 15000 ft.' the controller said nothing. My airplane's crew members never heard the 'suggestion' and certainly did not acknowledge any such transmission at the time. In my mind, throughout this whole situation, I thought that the VFR traffic was maintaining 15000 ft and that we would be descending well in front of him. I feel that the ATC controller's lack of aggressiveness, failure to control his airspace, and overall nonchalance was the cause of the traffic conflict. It is beyond belief that bos center would allow a VFR airplane to fly outbound on the arrival route to bos.

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Original NASA ASRS Text

Title: ACR X TCASII TA RA STOP DSCNT HAD CONFLICT WITH VFR ACR Y. SEE AND AVOID CONCEPT.

Narrative: APCHING GDM ON THE GARDNER 2 ARR BOS CTR POINTED OUT VFR TFC AT APPROX 12 O'CLOCK. OUR CLRNC WAS TO CROSS BRONC AT 11000. BOS MENTIONED THAT OUR TFC WAS WBOUND AND WOULD LEVEL AT 14500. WE THOUGHT THE CTLR WOULD PLAN OUR DSCNT BELOW 14500 BEFORE THE PASSING POINT. BOS CTR NEVER STOPPED OUR DSCNT NOR DID THEY STOP THE OTHER ACFT'S CLB. WE REALIZED A POTENTIAL PROBLEM FOR THE FIRST TIME WHEN TCASII ISSUED AN RA. TCASII SAID 'REDUCE YOUR DSCNT' AND SO I DID. I REDUCED THE DSCNT TO 0 FPM AS WE LEVELED AT 14300 AND THAT IS WHEN THE ACFT PASSED ABEAM ON OUR PORT SIDE. WE HAD THE TFC IN SIGHT DURING THE ENTIRE EPISODE, BUT FOUND IT DIFFICULT TO JUDGE JUST WHERE HE WAS IN RELATION TO OUR POS. AFTER PASSING, WE QUESTIONED BOS AS TO HIS POS AND ALT. THE RESPONSE WAS DEFENSIVE AND THE CTLR STATED THAT HE TOLD US WE COULD LEVEL AT 15000 UNTIL TFC PASSED IF WE WISHED TO! NO ONE IN MY CREW HEARD THAT XMISSION. THIS INCIDENT COULD HAVE BEEN PREVENTED IN MANY DIFFERENT WAYS. THE VFR TFC SHOULD NOT HAVE BEEN ALLOWED TO FLY AGAINST GARDENER-2 ARR TFC AND CLBING THROUGH OUR DSCNT ALT. AVOIDANCE TURNS COULD HAVE BEEN ISSUED, ALT CHANGES COULD HAVE BEEN APPLIED. MORE AND BETTER COM COULD HAVE BEEN USED TO MAKE EACH OF US MORE FULLY AWARE OF THE SITUATION. THE CTLR MUST HAVE WATCHED THE 2 OF US COME TOGETHER ON HIS RADAR SCREEN AT THE SAME ALT, HE MUST HAVE BEEN ABLE TO SEE THE SCENARIO DEVELOPING -- YET, HE SAT THERE WATCHING ALL THIS DEVELOP AND SAID NOTHING! SUPPLEMENTAL INFO FROM ACN 209780: AT 16000 FT AND 5 MI W OF GARDNER, THE CAPT PULLED OUT THE SPDBRAKES TO INCREASE OUR RATE OF DSCNT IN ORDER TO MAKE THE XING RESTRICTION. AT SOME POINT, I HEARD THE CTLR SAY SOMETHING ABOUT '15000,' BUT DID NOT CATCH THE WHOLE XMISSION AND ASSUMED THAT HE WAS TELLING US THAT THE TFC WAS AT 15000 FT. OUR FO DID NOT ACKNOWLEDGE THAT CALL. I THOUGHT THAT THE VFR TFC MIGHT BE GETTING CLOSE TO US SO I KEPT MY EYE ON HIM. AT APPROX 15000 FT OUR TCASII GAVE US A VERBAL RA OF 'REDUCE DSCNT, REDUCE DSCNT.' THIS CERTAINLY CAUGHT MY ATTN SO I GLANCED AT THE TCASII INST WHICH SHOWED A RED ARC ON THE LOWER HALF OF THE CASE. I DID NOT FOCUS MY EYES ON THE INST BECAUSE I WANTED TO CLR FOR THE TFC. THE CAPT STARTED TO STOP OUR DSCNT AT THIS POINT. AT APPROX 14500 FT I SAW THE TFC PASS OFF OUR L WING WITHIN 1/4 MI AND WHAT APPEARED TO BE THE SAME ALT. BEING THAT IT WAS NIGHT, I CAN ONLY GUESS AT THE HORIZ DISTANCE. OUR CAPT HAD NOT MADE ANY EVASIVE TURN, AND I NOTICED THAT OUR ALT BOTTOMED OUT AT 14300 FT AS WE PASSED OVER GARDNER VOR. THE CTLR NEVER ISSUED US ANY TURNS OR ALT CHANGES. THE VFR TFC DID NOT SAY ANYTHING ABOUT THE CONFLICT. A FEW MI LATER, OUR FO TOLD THE CTR THAT WE HAD SEEN THE TFC PASS US AND ASKED WHAT ALT HE WAS AT. THE CTLR SAID HE WAS AT 14500 FT. AT THIS POINT, THE VFR TFC SAID HE THOUGH WE WERE TOLD THAT 'IT WAS SUGGESTED THAT WE MAINTAIN 15000 FT.' THE CTLR SAID NOTHING. MY AIRPLANE'S CREW MEMBERS NEVER HEARD THE 'SUGGESTION' AND CERTAINLY DID NOT ACKNOWLEDGE ANY SUCH XMISSION AT THE TIME. IN MY MIND, THROUGHOUT THIS WHOLE SITUATION, I THOUGHT THAT THE VFR TFC WAS MAINTAINING 15000 FT AND THAT WE WOULD BE DSNDING WELL IN FRONT OF HIM. I FEEL THAT THE ATC CTLR'S LACK OF AGGRESSIVENESS, FAILURE TO CTL HIS AIRSPACE, AND OVERALL NONCHALANCE WAS THE CAUSE OF THE TFC CONFLICT. IT IS BEYOND BELIEF THAT BOS CTR WOULD ALLOW A VFR AIRPLANE TO FLY OUTBOUND ON THE ARR RTE TO BOS.

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.