Narrative:

Air carrier X reported just passing a blue and white small aircraft. I advised him I did not see any traffic in his vicinity. I asked him if the traffic appeared to be climbing on level at 4000'. Air carrier X advised traffic appeared to be level. Approximately 5 mi west of wal after the incident occurred, I observed a target on the radar scope heading westbound. When I checked my scope for its primary display it appeared to be acceptable. However, checking other scopes, the primary seemed to be lacking. We occasionally have problems to the west of aml with aircraft tangential to the radar antenna. The only solution I can see is to make mandatory all aircraft have operating xponders regardless of their position from major airports.

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Original NASA ASRS Text

Title: ACR CAME IN CLOSE PROX TO AN UNIDENTIFIED SMA AND REPORTED AN NMAC.

Narrative: ACR X RPTED JUST PASSING A BLUE AND WHITE SMA. I ADVISED HIM I DID NOT SEE ANY TFC IN HIS VICINITY. I ASKED HIM IF THE TFC APPEARED TO BE CLBING ON LEVEL AT 4000'. ACR X ADVISED TFC APPEARED TO BE LEVEL. APPROX 5 MI W OF WAL AFTER THE INCIDENT OCCURRED, I OBSERVED A TARGET ON THE RADAR SCOPE HDG WBND. WHEN I CHKED MY SCOPE FOR ITS PRIMARY DISPLAY IT APPEARED TO BE ACCEPTABLE. HOWEVER, CHKING OTHER SCOPES, THE PRIMARY SEEMED TO BE LACKING. WE OCCASIONALLY HAVE PROBS TO THE W OF AML WITH ACFT TANGENTIAL TO THE RADAR ANTENNA. THE ONLY SOLUTION I CAN SEE IS TO MAKE MANDATORY ALL ACFT HAVE OPERATING XPONDERS REGARDLESS OF THEIR POS FROM MAJOR ARPTS.

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.