Narrative:

I was working arrival/departure radar with a developmental. We had 8-10 aircraft on the frequency. The developmental issued traffic to both of the aircraft involved. Small aircraft X was circling over the city at various altitudes but was indicating a 2900' MSL when traffic was issued to him as an small aircraft Y sebnd from waterloo at 2500' MSL. Traffic was also issued to small aircraft Y as sebnd flying locally over the city at various altitudes and the pilot reported the other aircraft in sight. 3 or 4 mins later, small aircraft X said an aircraft came very close to him as he had apparently descended from 2900' MSL to about 2550' MSL. Recommendations: we, ATC, should have instructed small aircraft X to stay at 3000' MSL until he had small aircraft Y in sight. Also, small aircraft Y pilot should not have descended his aircraft into the altitude of small aircraft X especially after acknowledging ATC as to the small aircraft Y at 2500' MSL and heading for the area that he was flying in.

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Original NASA ASRS Text

Title: SMA CAME INTO CLOSE PROX TO ANOTHER SMA AFTER TRAFFIC WAS ISSUED.

Narrative: I WAS WORKING ARR/DEP RADAR WITH A DEVELOPMENTAL. WE HAD 8-10 ACFT ON THE FREQ. THE DEVELOPMENTAL ISSUED TFC TO BOTH OF THE ACFT INVOLVED. SMA X WAS CIRCLING OVER THE CITY AT VARIOUS ALTS BUT WAS INDICATING A 2900' MSL WHEN TFC WAS ISSUED TO HIM AS AN SMA Y SEBND FROM WATERLOO AT 2500' MSL. TFC WAS ALSO ISSUED TO SMA Y AS SEBND FLYING LOCALLY OVER THE CITY AT VARIOUS ALTS AND THE PLT RPTED THE OTHER ACFT IN SIGHT. 3 OR 4 MINS LATER, SMA X SAID AN ACFT CAME VERY CLOSE TO HIM AS HE HAD APPARENTLY DSNDED FROM 2900' MSL TO ABOUT 2550' MSL. RECOMMENDATIONS: WE, ATC, SHOULD HAVE INSTRUCTED SMA X TO STAY AT 3000' MSL UNTIL HE HAD SMA Y IN SIGHT. ALSO, SMA Y PLT SHOULD NOT HAVE DSNDED HIS ACFT INTO THE ALT OF SMA X ESPECIALLY AFTER ACKNOWLEDGING ATC AS TO THE SMA Y AT 2500' MSL AND HDG FOR THE AREA THAT HE WAS FLYING IN.

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.