Narrative:

While flying from cak to cvg at 10000 ft MSL on V-5, 95 DME from cvg, our TCASII gave us a verbal 'traffic, traffic' and shortly thereafter verbally called 'climb, climb.' we smoothly pulled-up and the target passed underneath us. We climbed approximately 900-1000 ft and immediately descended back to 10000 ft. The 'target' indicated 'minus 200' in our 12 O'clock position and closing on us rapidly as we began the maneuvers and disappeared from the TCASII as we came back to our assigned altitude. We informed ATC of our deviation. The controller acknowledged, but said nothing else. Why didn't the controller advise of the traffic before it became a potential problem? He was busy on frequency, but does he have priorities? Was he overloaded? Tired? Did he have radar that warns of impending conflict? Was it working? It should be noted that we were between layers of clouds and never did get a visual contact on the other aircraft. Callback conversation with reporter revealed the following information: reporter stated that he did not realize that VFR aircraft squawking 1200 may not have an altitude readout for ATC, therefore, ATC does not furnish advisories for the numerous targets in a busy terminal area that may be at a lower altitude causing no traffic conflict to higher aircraft. TCASII in this incident was most useful in avoiding a collision. The reporter was operating a saab SF340B.

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Original NASA ASRS Text

Title: FLC OF AN LTT CLBED ABOVE ASSIGNED ALT IN RESPONSE TO A TCASII RA. NMAC.

Narrative: WHILE FLYING FROM CAK TO CVG AT 10000 FT MSL ON V-5, 95 DME FROM CVG, OUR TCASII GAVE US A VERBAL 'TFC, TFC' AND SHORTLY THEREAFTER VERBALLY CALLED 'CLB, CLB.' WE SMOOTHLY PULLED-UP AND THE TARGET PASSED UNDERNEATH US. WE CLBED APPROX 900-1000 FT AND IMMEDIATELY DSNDED BACK TO 10000 FT. THE 'TARGET' INDICATED 'MINUS 200' IN OUR 12 O'CLOCK POS AND CLOSING ON US RAPIDLY AS WE BEGAN THE MANEUVERS AND DISAPPEARED FROM THE TCASII AS WE CAME BACK TO OUR ASSIGNED ALT. WE INFORMED ATC OF OUR DEV. THE CTLR ACKNOWLEDGED, BUT SAID NOTHING ELSE. WHY DIDN'T THE CTLR ADVISE OF THE TFC BEFORE IT BECAME A POTENTIAL PROB? HE WAS BUSY ON FREQ, BUT DOES HE HAVE PRIORITIES? WAS HE OVERLOADED? TIRED? DID HE HAVE RADAR THAT WARNS OF IMPENDING CONFLICT? WAS IT WORKING? IT SHOULD BE NOTED THAT WE WERE BTWN LAYERS OF CLOUDS AND NEVER DID GET A VISUAL CONTACT ON THE OTHER ACFT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT HE DID NOT REALIZE THAT VFR ACFT SQUAWKING 1200 MAY NOT HAVE AN ALT READOUT FOR ATC, THEREFORE, ATC DOES NOT FURNISH ADVISORIES FOR THE NUMEROUS TARGETS IN A BUSY TERMINAL AREA THAT MAY BE AT A LOWER ALT CAUSING NO TFC CONFLICT TO HIGHER ACFT. TCASII IN THIS INCIDENT WAS MOST USEFUL IN AVOIDING A COLLISION. THE RPTR WAS OPERATING A SAAB SF340B.

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.