Narrative:

Air carrier X on an assigned of 320 degrees and cleared to descend to 4000 by buf approach. At approximately 4400', buf approach pointed out traffic at 10:00. I said we had him in sight. Approach then asked us to maintain visibility sep. I told them we may not be able to maintain visibility sep because of a solid cloud layer not far below us. At this time the TCAS gave an RA and it was clear we would have to take evasive action to avoid a possible collision. Air carrier Y appeared to be in level flight about 4000' on a northeast heading. At this point, the captain elected to deviate and follow a path under air carrier Y. We could see the clouds maybe 1000' below us now. By going under, we could keep air carrier Y in sight. The captain increased our rate of descent somewhat, and we descended to about 3500'. We passed under air carrier Y and climbed back to 4000'. The rest of approach and landing proceeded west/O event. We discussed the matter on the ground with air carrier Y crew and the approach controller supervisor. Supplemental information from acn 170220. I had the autoplt engaged. At approximately 4400' descending, ATC called out company air carrier Y traffic at our 10:30 position (range I don't recall) descending to 2500', and asked if we saw him. We saw him immediately and responded affirmative. He appeared to be at our altitude. The controller asked if we could maintain visibility sep to which my first officer replied that it might be difficult due to the cloud deck below. At this point we got a TCAS alert in addition to the controller advising us that the traffic was to follow us on the approach. The traffic had a nose high attitude. At this point I decided to descend as it appeared the other aircraft was in a climb. We descended to 3400' and the traffic passed overhead. We then climbed back to 4000'. The nose high attitude of air carrier Y gave the appearance that he was climbing rather than descending. This coupled with the controller's statement that he was to follow us made me think we should be at the lower altitude. At this point, I lost all confidence in the controller and believed that he had reversed our altitude assignments. I knew we could get under the aircraft and keep him in sight. It should be noted that I felt a tremendous sensory overload during the conflict the extent to which I have never experienced before. My cockpit was sterile, no unnecessary talking or other distrs were taking place. Then everything happened at once: the controller was talking, my first officer responding to him , my first officer and I looking at the traffic, and discussing it, the TCAS alert nd the largest sensory input looking at an aircraft with which we were on a collision course. In conclusion, I must mention the very repressive safety atmosphere that the FAA has created in this industry: with their aggresive 'enforcement' posture rather than 'all of us learning from an individual's mistakes.' supplemental information from acn 170236. I was captain of air carrier Y approaching buf on downwind for runway 23 descending to 2500'. Air carrier X approached at my 3 O'clock position and flew below us by about 800'.

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Original NASA ASRS Text

Title: ACR X HAD LESS THAN STANDARD SEPARATION FROM ACR Y. SYSTEM ERROR.

Narrative: ACR X ON AN ASSIGNED OF 320 DEGS AND CLRED TO DSND TO 4000 BY BUF APCH. AT APPROX 4400', BUF APCH POINTED OUT TFC AT 10:00. I SAID WE HAD HIM IN SIGHT. APCH THEN ASKED US TO MAINTAIN VIS SEP. I TOLD THEM WE MAY NOT BE ABLE TO MAINTAIN VIS SEP BECAUSE OF A SOLID CLOUD LAYER NOT FAR BELOW US. AT THIS TIME THE TCAS GAVE AN RA AND IT WAS CLR WE WOULD HAVE TO TAKE EVASIVE ACTION TO AVOID A POSSIBLE COLLISION. ACR Y APPEARED TO BE IN LEVEL FLT ABOUT 4000' ON A NE HDG. AT THIS POINT, THE CAPT ELECTED TO DEVIATE AND FOLLOW A PATH UNDER ACR Y. WE COULD SEE THE CLOUDS MAYBE 1000' BELOW US NOW. BY GOING UNDER, WE COULD KEEP ACR Y IN SIGHT. THE CAPT INCREASED OUR RATE OF DSNT SOMEWHAT, AND WE DSNDED TO ABOUT 3500'. WE PASSED UNDER ACR Y AND CLBED BACK TO 4000'. THE REST OF APCH AND LNDG PROCEEDED W/O EVENT. WE DISCUSSED THE MATTER ON THE GND WITH ACR Y CREW AND THE APCH CTLR SUPVR. SUPPLEMENTAL INFO FROM ACN 170220. I HAD THE AUTOPLT ENGAGED. AT APPROX 4400' DSNDING, ATC CALLED OUT COMPANY ACR Y TFC AT OUR 10:30 POS (RANGE I DON'T RECALL) DSNDING TO 2500', AND ASKED IF WE SAW HIM. WE SAW HIM IMMEDIATELY AND RESPONDED AFFIRMATIVE. HE APPEARED TO BE AT OUR ALT. THE CTLR ASKED IF WE COULD MAINTAIN VIS SEP TO WHICH MY F/O REPLIED THAT IT MIGHT BE DIFFICULT DUE TO THE CLOUD DECK BELOW. AT THIS POINT WE GOT A TCAS ALERT IN ADDITION TO THE CTLR ADVISING US THAT THE TFC WAS TO FOLLOW US ON THE APCH. THE TFC HAD A NOSE HIGH ATTITUDE. AT THIS POINT I DECIDED TO DSND AS IT APPEARED THE OTHER ACFT WAS IN A CLB. WE DSNDED TO 3400' AND THE TFC PASSED OVERHEAD. WE THEN CLBED BACK TO 4000'. THE NOSE HIGH ATTITUDE OF ACR Y GAVE THE APPEARANCE THAT HE WAS CLBING RATHER THAN DSNDING. THIS COUPLED WITH THE CTLR'S STATEMENT THAT HE WAS TO FOLLOW US MADE ME THINK WE SHOULD BE AT THE LOWER ALT. AT THIS POINT, I LOST ALL CONFIDENCE IN THE CTLR AND BELIEVED THAT HE HAD REVERSED OUR ALT ASSIGNMENTS. I KNEW WE COULD GET UNDER THE ACFT AND KEEP HIM IN SIGHT. IT SHOULD BE NOTED THAT I FELT A TREMENDOUS SENSORY OVERLOAD DURING THE CONFLICT THE EXTENT TO WHICH I HAVE NEVER EXPERIENCED BEFORE. MY COCKPIT WAS STERILE, NO UNNECESSARY TALKING OR OTHER DISTRS WERE TAKING PLACE. THEN EVERYTHING HAPPENED AT ONCE: THE CTLR WAS TALKING, MY F/O RESPONDING TO HIM , MY F/O AND I LOOKING AT THE TFC, AND DISCUSSING IT, THE TCAS ALERT ND THE LARGEST SENSORY INPUT LOOKING AT AN ACFT WITH WHICH WE WERE ON A COLLISION COURSE. IN CONCLUSION, I MUST MENTION THE VERY REPRESSIVE SAFETY ATMOSPHERE THAT THE FAA HAS CREATED IN THIS INDUSTRY: WITH THEIR AGGRESIVE 'ENFORCEMENT' POSTURE RATHER THAN 'ALL OF US LEARNING FROM AN INDIVIDUAL'S MISTAKES.' SUPPLEMENTAL INFO FROM ACN 170236. I WAS CAPT OF ACR Y APCHING BUF ON DOWNWIND FOR RWY 23 DSNDING TO 2500'. ACR X APCHED AT MY 3 O'CLOCK POS AND FLEW BELOW US BY ABOUT 800'.

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.