Narrative:

Upon descent into gck I was give a pilot discretion descent from 8000 to 5000'. After descending through 6500' and approximately 15 mi from gck, I started to cancel IFR. Just prior to cancelling IFR with center an small aircraft called ZKC stating he just departed gck and wanted to pick up IFR. Center's reply was to standby for clearance until he was clear of me. Small aircraft was advised of me as traffic and of my clearance. At this point I decided to stay with center for traffic advisory on the small aircraft, which I promptly received--small aircraft 12 O'clock, 12 mi. Center then asked small aircraft for his altitude. Reply was 5000', which sounded like lever at 5000'. At this point I stopped my descent at 5500' and was looking for the traffic in hopes of passing over him. Center then advised me again of traffic 12 O'clock, 5 mi. My reply was, 'not in sight.' center then asked the small aircraft for his altitude. Reply was, 'climbing toward 6000'.' this surprised me greatly for I had assumed the small aircraft was going to stay at 5000' according to his first altitude report. This put me head-to-head at close range and crossing altitudes with the traffic I did not see. I started down promptly from 5500' to get blow an altitude I felt the small aircraft was above. As I descended my eyes were looking for the small aircraft and not on my altitude. Shortly after descent and within 3 mi of gck airport center advised me clear of traffic and asked for my altitude. Reply was given--4500'. I then cancelled IFR with center. In reflection, I feel I should have cancelled IFR when first stated and stayed with center for VFR traffic advisories. This would have allowed me to descend to traffic pattern altitude, the proper altitude, and assured altitude sep with the small aircraft.

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Original NASA ASRS Text

Title: AIR TAXI PLT DISTRACTED BY WATCH FOR CLIMBING TRAFFIC DESCENDS BELOW ASSIGNED ALT.

Narrative: UPON DSNT INTO GCK I WAS GIVE A PLT DISCRETION DSNT FROM 8000 TO 5000'. AFTER DSNDING THROUGH 6500' AND APPROX 15 MI FROM GCK, I STARTED TO CANCEL IFR. JUST PRIOR TO CANCELLING IFR WITH CENTER AN SMA CALLED ZKC STATING HE JUST DEPARTED GCK AND WANTED TO PICK UP IFR. CENTER'S REPLY WAS TO STANDBY FOR CLRNC UNTIL HE WAS CLR OF ME. SMA WAS ADVISED OF ME AS TFC AND OF MY CLRNC. AT THIS POINT I DECIDED TO STAY WITH CENTER FOR TFC ADVISORY ON THE SMA, WHICH I PROMPTLY RECEIVED--SMA 12 O'CLOCK, 12 MI. CENTER THEN ASKED SMA FOR HIS ALT. REPLY WAS 5000', WHICH SOUNDED LIKE LEVER AT 5000'. AT THIS POINT I STOPPED MY DSNT AT 5500' AND WAS LOOKING FOR THE TFC IN HOPES OF PASSING OVER HIM. CENTER THEN ADVISED ME AGAIN OF TFC 12 O'CLOCK, 5 MI. MY REPLY WAS, 'NOT IN SIGHT.' CENTER THEN ASKED THE SMA FOR HIS ALT. REPLY WAS, 'CLBING TOWARD 6000'.' THIS SURPRISED ME GREATLY FOR I HAD ASSUMED THE SMA WAS GOING TO STAY AT 5000' ACCORDING TO HIS FIRST ALT RPT. THIS PUT ME HEAD-TO-HEAD AT CLOSE RANGE AND XING ALTS WITH THE TFC I DID NOT SEE. I STARTED DOWN PROMPTLY FROM 5500' TO GET BLOW AN ALT I FELT THE SMA WAS ABOVE. AS I DSNDED MY EYES WERE LOOKING FOR THE SMA AND NOT ON MY ALT. SHORTLY AFTER DSNT AND WITHIN 3 MI OF GCK ARPT CENTER ADVISED ME CLR OF TFC AND ASKED FOR MY ALT. REPLY WAS GIVEN--4500'. I THEN CANCELLED IFR WITH CENTER. IN REFLECTION, I FEEL I SHOULD HAVE CANCELLED IFR WHEN FIRST STATED AND STAYED WITH CENTER FOR VFR TFC ADVISORIES. THIS WOULD HAVE ALLOWED ME TO DSND TO TFC PATTERN ALT, THE PROPER ALT, AND ASSURED ALT SEP WITH THE SMA.

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.