Narrative:

Scheduled flight from stl to dsm, we were assigned 290 degrees heading and cleared to climb to FL230. When we were leaving 11000' approximately, the center told us we had helicopter traffic at 1 O'clock 11 mi at 13500'. First officer and I looked for traffic but we did not see to it. I returned to my normal scan but the first officer continued to look for the traffic. He spotted traffic and painted it out to me. It was an small aircraft type aircraft. He was above us. I judged that he was on a westerly heading because I could see both wings and his tail. I judged that I would miss the traffic but to be safe I started a left 20 degree bank turn and I disconnected the autoplt and trimmed nose down. I judged that by taking this action I would pass off the left wing and well below the traffic. About this time the ATC controller issued a traffic conflict in an urgent tone of voice. At this instant I realized the traffic was not changing position on the first officer's windshield. I immediately pushed forward on the yoke and pulled the throttles back. Almost immediately it became apparent that we would pass very close to the traffic. We leveled off at about 13000'. We continued in a left turn and descended about 300' before we continued on course and climb. The traffic was a single engine small aircraft with wing struts, maybe an small aircraft. He was probably on a heading of 150 degrees to 160 degrees. He was probably descending. He had his nose wheel light on. It was only visible as we passed in front of him. He did not appear to take evasive action. I clearly saw the circle of his propeller. It was all over very quickly. It was the closest call I have had in almost 31 yrs of airline flying.

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Original NASA ASRS Text

Title: NMAC BETWEEN ACR MLG IN CLIMB AND SMA IN CRUISE OR DESCENT.

Narrative: SCHEDULED FLT FROM STL TO DSM, WE WERE ASSIGNED 290 DEGS HDG AND CLRED TO CLB TO FL230. WHEN WE WERE LEAVING 11000' APPROX, THE CTR TOLD US WE HAD HELI TFC AT 1 O'CLOCK 11 MI AT 13500'. F/O AND I LOOKED FOR TFC BUT WE DID NOT SEE TO IT. I RETURNED TO MY NORMAL SCAN BUT THE F/O CONTINUED TO LOOK FOR THE TFC. HE SPOTTED TFC AND PAINTED IT OUT TO ME. IT WAS AN SMA TYPE ACFT. HE WAS ABOVE US. I JUDGED THAT HE WAS ON A WESTERLY HDG BECAUSE I COULD SEE BOTH WINGS AND HIS TAIL. I JUDGED THAT I WOULD MISS THE TFC BUT TO BE SAFE I STARTED A L 20 DEG BANK TURN AND I DISCONNECTED THE AUTOPLT AND TRIMMED NOSE DOWN. I JUDGED THAT BY TAKING THIS ACTION I WOULD PASS OFF THE L WING AND WELL BELOW THE TFC. ABOUT THIS TIME THE ATC CTLR ISSUED A TFC CONFLICT IN AN URGENT TONE OF VOICE. AT THIS INSTANT I REALIZED THE TFC WAS NOT CHANGING POS ON THE F/O'S WINDSHIELD. I IMMEDIATELY PUSHED FORWARD ON THE YOKE AND PULLED THE THROTTLES BACK. ALMOST IMMEDIATELY IT BECAME APPARENT THAT WE WOULD PASS VERY CLOSE TO THE TFC. WE LEVELED OFF AT ABOUT 13000'. WE CONTINUED IN A L TURN AND DSNDED ABOUT 300' BEFORE WE CONTINUED ON COURSE AND CLB. THE TFC WAS A SINGLE ENG SMA WITH WING STRUTS, MAYBE AN SMA. HE WAS PROBABLY ON A HDG OF 150 DEGS TO 160 DEGS. HE WAS PROBABLY DSNDING. HE HAD HIS NOSE WHEEL LIGHT ON. IT WAS ONLY VISIBLE AS WE PASSED IN FRONT OF HIM. HE DID NOT APPEAR TO TAKE EVASIVE ACTION. I CLRLY SAW THE CIRCLE OF HIS PROP. IT WAS ALL OVER VERY QUICKLY. IT WAS THE CLOSEST CALL I HAVE HAD IN ALMOST 31 YRS OF AIRLINE FLYING.

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.