Narrative:

Cruising in cloud at 12000 ft with dtw approach control vectoring to dtw. Received TCASII 'traffic' warning followed by 'climb' warning. PF immediately began climb, and I advised ATC. Controller responded with altitude '13000' and 'left turn to 360 degrees.' traffic passed from 5 NM at 10 O'clock on initial warning, 900 ft below climbing at 500+ FPM to 3 O'clock, 400 ft below, and 2 NM while we were in our left turn. Warning ceased from TCASII after traffic passed 4 O'clock. We would have expected to receive traffic information from our controller on possible conflicting traffic, especially traffic with altitude squawking transponder. We are guessing that a turbojet departure out of dtw may have caused the conflict. At any rate, TCASII saved us, I believe. We never got visual contact. On a later flight, same day, same aircraft, 900 NM southwest of dtw, we got another very brief 'traffic' and then 'climb' warning from our TCASII on a conflicting aircraft which we did see through broken clouds and the information presented by TCASII was confirmed. TCASII traffic and RA's appeared reliable where they could be confirmed throughout the day. Supplemental information from acn 196729: initial TCASII target was approximately 6 mi at 12 O'clock position, opposite direction and climbing through altitude 900 ft below us. At approximately 2.5 NM TCASII target passed off the right side of our aircraft approximately 400 ft below us as we were in a left turn for avoidance while IMC. Visual contact with target was never made. Recommendation: ATC controller to advise us of traffic prior to TCASII interrogation and advisories.

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Original NASA ASRS Text

Title: MLG GOT TCASII ON UNKNOWN ACFT AND STARTED A CLB AND TURN PRIOR TO ATC ACTION. ACFT PASSED IN CLOSE PROX ACCORDING TO THE TCASII.

Narrative: CRUISING IN CLOUD AT 12000 FT WITH DTW APCH CTL VECTORING TO DTW. RECEIVED TCASII 'TFC' WARNING FOLLOWED BY 'CLB' WARNING. PF IMMEDIATELY BEGAN CLB, AND I ADVISED ATC. CTLR RESPONDED WITH ALT '13000' AND 'L TURN TO 360 DEGS.' TFC PASSED FROM 5 NM AT 10 O'CLOCK ON INITIAL WARNING, 900 FT BELOW CLBING AT 500+ FPM TO 3 O'CLOCK, 400 FT BELOW, AND 2 NM WHILE WE WERE IN OUR L TURN. WARNING CEASED FROM TCASII AFTER TFC PASSED 4 O'CLOCK. WE WOULD HAVE EXPECTED TO RECEIVE TFC INFO FROM OUR CTLR ON POSSIBLE CONFLICTING TFC, ESPECIALLY TFC WITH ALT SQUAWKING TRANSPONDER. WE ARE GUESSING THAT A TURBOJET DEP OUT OF DTW MAY HAVE CAUSED THE CONFLICT. AT ANY RATE, TCASII SAVED US, I BELIEVE. WE NEVER GOT VISUAL CONTACT. ON A LATER FLT, SAME DAY, SAME ACFT, 900 NM SW OF DTW, WE GOT ANOTHER VERY BRIEF 'TFC' AND THEN 'CLB' WARNING FROM OUR TCASII ON A CONFLICTING ACFT WHICH WE DID SEE THROUGH BROKEN CLOUDS AND THE INFO PRESENTED BY TCASII WAS CONFIRMED. TCASII TFC AND RA'S APPEARED RELIABLE WHERE THEY COULD BE CONFIRMED THROUGHOUT THE DAY. SUPPLEMENTAL INFO FROM ACN 196729: INITIAL TCASII TARGET WAS APPROX 6 MI AT 12 O'CLOCK POS, OPPOSITE DIRECTION AND CLBING THROUGH ALT 900 FT BELOW US. AT APPROX 2.5 NM TCASII TARGET PASSED OFF THE R SIDE OF OUR ACFT APPROX 400 FT BELOW US AS WE WERE IN A L TURN FOR AVOIDANCE WHILE IMC. VISUAL CONTACT WITH TARGET WAS NEVER MADE. RECOMMENDATION: ATC CTLR TO ADVISE US OF TFC PRIOR TO TCASII INTERROGATION AND ADVISORIES.

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.