Narrative:

Incident occurred on the kayuu 1 arrival route (kmci) in the vicinity of hairs intersection. Approach control advised medium large transport traffic at 10 O'clock position climbing from '3500 to 10000.' several mins later, I observed jet traffic at that position, low, and climbing. Traffic observed was wbound. When queried about the traffic a second time, I reported the traffic in sight. Shortly after that, we began a turn to a 190 degree heading (from 120 degrees) to follow the arrival route. At the same time, we were cleared from 11000 ft to 6000 ft (not sure) reference the traffic. My last sighting of the traffic was at about the 8 O'clock position and still wbound. Approach also advised the medium large transport crew of our position and was advised that they had us in sight. We slowed to 210 KTS and began our descent. Early into our descent, an medium large transport passed under us. That traffic approached from the 5:30 position, at about 10000 ft. Our altitude was about 10500 ft. I had either initially idented the wrong traffic or, the traffic I saw turned sbound after it passed behind me -- either way I should not have begun my descent. I am surprised that approach control and the medium large transport did not catch my mistake, it's hard to keep track of an aircraft at the 6 O'clock position! I believe that cockpit workload contributed to my error. Busy phase of flight, with checklists and programming for the approach.

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Original NASA ASRS Text

Title: AN LGT ACR ACFT HAD AN NMAC WITH AN ACR MLG. THE RPTING ACFT SLOWED EARLY AND THE INTRUDER ACFT FLEW UNDERNEATH.

Narrative: INCIDENT OCCURRED ON THE KAYUU 1 ARR RTE (KMCI) IN THE VICINITY OF HAIRS INTXN. APCH CTL ADVISED MLG TFC AT 10 O'CLOCK POS CLBING FROM '3500 TO 10000.' SEVERAL MINS LATER, I OBSERVED JET TFC AT THAT POS, LOW, AND CLBING. TFC OBSERVED WAS WBOUND. WHEN QUERIED ABOUT THE TFC A SECOND TIME, I RPTED THE TFC IN SIGHT. SHORTLY AFTER THAT, WE BEGAN A TURN TO A 190 DEG HDG (FROM 120 DEGS) TO FOLLOW THE ARR RTE. AT THE SAME TIME, WE WERE CLRED FROM 11000 FT TO 6000 FT (NOT SURE) REF THE TFC. MY LAST SIGHTING OF THE TFC WAS AT ABOUT THE 8 O'CLOCK POS AND STILL WBOUND. APCH ALSO ADVISED THE MLG CREW OF OUR POS AND WAS ADVISED THAT THEY HAD US IN SIGHT. WE SLOWED TO 210 KTS AND BEGAN OUR DSCNT. EARLY INTO OUR DSCNT, AN MLG PASSED UNDER US. THAT TFC APCHED FROM THE 5:30 POS, AT ABOUT 10000 FT. OUR ALT WAS ABOUT 10500 FT. I HAD EITHER INITIALLY IDENTED THE WRONG TFC OR, THE TFC I SAW TURNED SBOUND AFTER IT PASSED BEHIND ME -- EITHER WAY I SHOULD NOT HAVE BEGUN MY DSCNT. I AM SURPRISED THAT APCH CTL AND THE MLG DID NOT CATCH MY MISTAKE, IT'S HARD TO KEEP TRACK OF AN ACFT AT THE 6 O'CLOCK POS! I BELIEVE THAT COCKPIT WORKLOAD CONTRIBUTED TO MY ERROR. BUSY PHASE OF FLT, WITH CHKLISTS AND PROGRAMMING FOR THE APCH.

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.