Narrative:

Air carrier X cruising at FL370, proceeding direct to alb. At approximately 200 NM west of alb, the controller told us to turn left to a 020 degree heading for traffic and to expect to be reclred direct to alb. The left turn to 020 degree required about an 80 degree heading change. I promptly initiated the turn to the assigned heading, at this point there were no traffic returns on our TCASII display. Near the end of the turn, (passing through about 040 degree heading) we got pop up traffic on our TCASII and an aural TA ('traffic, traffic'). Both the captain and I reduced our map scale to the 10 mi range and idented opposite direction traffic at FL370. Since we were established in the left turn and lined up with the conflicting traffic, I disconnected the autoplt and increased the bank angle to insure that the traffic would pass off to our right side. At this point, ATC realized the conflict and told us to descend to FL350 for traffic, and told air carrier Y to turn left for traffic. I immediately initiated the descent to FL350 and we simultaneously received an aural RA on the TCASII ('descend, descend'). Since I had already initiated the descent as per the ATC clearance, I complied with the TCASII commanded descent rate (about 1500 FPM). Passing through FL360, we received a 'clear of conflict' message on TCASII. We never visually saw the other traffic, but, based on TCASII, estimate that it passed off our right side 1-2 mi laterally and 800-1000 ft above us. As we leveled at FL350, ZOB cleared us direct to alb. The TCASII worked well as it gave us RA's in a timely manner to insure separation.

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Original NASA ASRS Text

Title: ACR X TCASII TA RA SAME ALT ASSIGNED, HAD LTSS FROM ACR Y. SYS ERROR.

Narrative: ACR X CRUISING AT FL370, PROCEEDING DIRECT TO ALB. AT APPROX 200 NM W OF ALB, THE CTLR TOLD US TO TURN L TO A 020 DEG HDG FOR TFC AND TO EXPECT TO BE RECLRED DIRECT TO ALB. THE L TURN TO 020 DEG REQUIRED ABOUT AN 80 DEG HDG CHANGE. I PROMPTLY INITIATED THE TURN TO THE ASSIGNED HDG, AT THIS POINT THERE WERE NO TFC RETURNS ON OUR TCASII DISPLAY. NEAR THE END OF THE TURN, (PASSING THROUGH ABOUT 040 DEG HDG) WE GOT POP UP TFC ON OUR TCASII AND AN AURAL TA ('TFC, TFC'). BOTH THE CAPT AND I REDUCED OUR MAP SCALE TO THE 10 MI RANGE AND IDENTED OPPOSITE DIRECTION TFC AT FL370. SINCE WE WERE ESTABLISHED IN THE L TURN AND LINED UP WITH THE CONFLICTING TFC, I DISCONNECTED THE AUTOPLT AND INCREASED THE BANK ANGLE TO INSURE THAT THE TFC WOULD PASS OFF TO OUR R SIDE. AT THIS POINT, ATC REALIZED THE CONFLICT AND TOLD US TO DSND TO FL350 FOR TFC, AND TOLD ACR Y TO TURN L FOR TFC. I IMMEDIATELY INITIATED THE DSCNT TO FL350 AND WE SIMULTANEOUSLY RECEIVED AN AURAL RA ON THE TCASII ('DSND, DSND'). SINCE I HAD ALREADY INITIATED THE DSCNT AS PER THE ATC CLRNC, I COMPLIED WITH THE TCASII COMMANDED DSCNT RATE (ABOUT 1500 FPM). PASSING THROUGH FL360, WE RECEIVED A 'CLR OF CONFLICT' MESSAGE ON TCASII. WE NEVER VISUALLY SAW THE OTHER TFC, BUT, BASED ON TCASII, ESTIMATE THAT IT PASSED OFF OUR R SIDE 1-2 MI LATERALLY AND 800-1000 FT ABOVE US. AS WE LEVELED AT FL350, ZOB CLRED US DIRECT TO ALB. THE TCASII WORKED WELL AS IT GAVE US RA'S IN A TIMELY MANNER TO INSURE SEPARATION.

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.