Narrative:

We were cruising at 11000 ft and ATC called traffic. We had traffic in sight. ATC told us to climb to 12000 ft which was our final altitude and to keep visual separation from the traffic. It appeared to us that the traffic was flying swbound which was parallel to our course. As we watched the traffic the target became larger, and at this point we realized that we were converging with the other aircraft. We made a bank and climb to our right to avoid the other aircraft, the other aircraft banked left to avoid us. This whole situation could have been avoided if ATC had not cleared 2 aircraft into the same airspace at once. Even though we had a visual on other aircraft, it was not apparent to us that our flight paths were converging. We appreciate direct clrncs from ATC but when 2 aircraft are at same altitude this can be dangerous because with the naked eye it is almost impossible to tell if 2 aircraft are converging until quick evasive action is required. Fortunately I did recognize that our paths were crossing and was able to make an appropriate correction.

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Original NASA ASRS Text

Title: FLC EXPERIENCED AN NMAC AFTER ACCEPTING A VISUAL SEPARATION CLRNC, CLB TO OCCUPIED ALT.

Narrative: WE WERE CRUISING AT 11000 FT AND ATC CALLED TFC. WE HAD TFC IN SIGHT. ATC TOLD US TO CLB TO 12000 FT WHICH WAS OUR FINAL ALT AND TO KEEP VISUAL SEPARATION FROM THE TFC. IT APPEARED TO US THAT THE TFC WAS FLYING SWBOUND WHICH WAS PARALLEL TO OUR COURSE. AS WE WATCHED THE TFC THE TARGET BECAME LARGER, AND AT THIS POINT WE REALIZED THAT WE WERE CONVERGING WITH THE OTHER ACFT. WE MADE A BANK AND CLB TO OUR R TO AVOID THE OTHER ACFT, THE OTHER ACFT BANKED L TO AVOID US. THIS WHOLE SIT COULD HAVE BEEN AVOIDED IF ATC HAD NOT CLRED 2 ACFT INTO THE SAME AIRSPACE AT ONCE. EVEN THOUGH WE HAD A VISUAL ON OTHER ACFT, IT WAS NOT APPARENT TO US THAT OUR FLT PATHS WERE CONVERGING. WE APPRECIATE DIRECT CLRNCS FROM ATC BUT WHEN 2 ACFT ARE AT SAME ALT THIS CAN BE DANGEROUS BECAUSE WITH THE NAKED EYE IT IS ALMOST IMPOSSIBLE TO TELL IF 2 ACFT ARE CONVERGING UNTIL QUICK EVASIVE ACTION IS REQUIRED. FORTUNATELY I DID RECOGNIZE THAT OUR PATHS WERE XING AND WAS ABLE TO MAKE AN APPROPRIATE CORRECTION.

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.