Narrative:

We were level at 10000 ft on bunkr 7 arrival to msp. Msp center issued traffic at 11 O'clock indicating 10500 non-verified. Approximately 3 mi in front of us, we got a TCASII TA and the target showed 300 ft higher than us. Very shortly thereafter, we got a TCASII RA to descend at 2500 FPM. We descended to 9500, leveled at the 'monitor vertical speed' then climbed back to 10000 at the 'clear of conflict.' the 500 ft deviation was never mentioned by the controller. The VFR target did not meet VFR cloud separation distances as we were barely on top of the broken layer which had many clouds above 10000 ft. The ATC controller was good about issuing the traffic initially, but he never gave us an update. Score 1 for TCASII. Supplemental information from acn 218705: although first officer flying I reduced power to idle and applied more down elevator sufficient to get rate of descent into green. I offered no further control or power inputs and first officer keeps flying. Our TCASII instruction manual says to start a descent or climb promptly and smoothly, but I think that when the traffic is called at such short distance and altitude (2 mi and 300 ft) immediate and aggressive action is required. I.e., a quicker descent maneuver than the autoplt would perform. We were heading approximately 075 degrees and traffic was called at 10 to 11 and even in clear WX above the clouds with the sun at our back, none of the 3 of us ever saw traffic. Supplemental information from acn 219207: the TCASII really did the job for us this time. Without it, the consequences could have been tragic.

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Original NASA ASRS Text

Title: POTENTIAL CONFLICT.

Narrative: WE WERE LEVEL AT 10000 FT ON BUNKR 7 ARR TO MSP. MSP CTR ISSUED TFC AT 11 O'CLOCK INDICATING 10500 NON-VERIFIED. APPROX 3 MI IN FRONT OF US, WE GOT A TCASII TA AND THE TARGET SHOWED 300 FT HIGHER THAN US. VERY SHORTLY THEREAFTER, WE GOT A TCASII RA TO DSND AT 2500 FPM. WE DSNDED TO 9500, LEVELED AT THE 'MONITOR VERT SPD' THEN CLBED BACK TO 10000 AT THE 'CLR OF CONFLICT.' THE 500 FT DEV WAS NEVER MENTIONED BY THE CTLR. THE VFR TARGET DID NOT MEET VFR CLOUD SEPARATION DISTANCES AS WE WERE BARELY ON TOP OF THE BROKEN LAYER WHICH HAD MANY CLOUDS ABOVE 10000 FT. THE ATC CTLR WAS GOOD ABOUT ISSUING THE TFC INITIALLY, BUT HE NEVER GAVE US AN UPDATE. SCORE 1 FOR TCASII. SUPPLEMENTAL INFO FROM ACN 218705: ALTHOUGH FO FLYING I REDUCED PWR TO IDLE AND APPLIED MORE DOWN ELEVATOR SUFFICIENT TO GET RATE OF DSCNT INTO GREEN. I OFFERED NO FURTHER CTL OR PWR INPUTS AND FO KEEPS FLYING. OUR TCASII INSTRUCTION MANUAL SAYS TO START A DSCNT OR CLB PROMPTLY AND SMOOTHLY, BUT I THINK THAT WHEN THE TFC IS CALLED AT SUCH SHORT DISTANCE AND ALT (2 MI AND 300 FT) IMMEDIATE AND AGGRESSIVE ACTION IS REQUIRED. I.E., A QUICKER DSCNT MANEUVER THAN THE AUTOPLT WOULD PERFORM. WE WERE HDG APPROX 075 DEGS AND TFC WAS CALLED AT 10 TO 11 AND EVEN IN CLR WX ABOVE THE CLOUDS WITH THE SUN AT OUR BACK, NONE OF THE 3 OF US EVER SAW TFC. SUPPLEMENTAL INFO FROM ACN 219207: THE TCASII REALLY DID THE JOB FOR US THIS TIME. WITHOUT IT, THE CONSEQUENCES COULD HAVE BEEN TRAGIC.

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.