Narrative:

I was working as the radar controller at csg TRACON. I had all 3 sectors combined and was not overly busy. Aircraft X was northbound indicating 3500' on his mode C. Aircraft Y was also northbound and had reported level at 3000' (VFR), but was non-mode C. When the aircraft were about 6 mi apart, I noticed that they would probably be close and decided to call traffic in a minute when they were more likely to be able to see each other. A few mins later, I received a call from aircraft X reporting another aircraft had crossed his nose at his altitude. I advised him that the other aircraft was reported 500' lower. He insisted that the aircraft was at his altitude. I called the second aircraft, advised him of the traffic and of the altitude report. I reissued the altimeter and asked him to verify altitude. He again reported level at 3000'. Obviously, the first pilot may have misjudged the altitude, but there were certainly several things that could have been done differently. 1) I should have called traffic as soon as I saw the possible conflict so that both pilots would have been alert. 2) had the second aircraft been mode C equipped, it would have provided a double-check for his altimeter. 3) the controller's handbook 7110.65 should give more clear requirements for issuing traffic advisories between 2 VFR aircraft since there is no sep requirement for them in an arsa.

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Original NASA ASRS Text

Title: ACFT X HAD AIRBORNE CONFLICT WITH ACFT Y IN ARSA.

Narrative: I WAS WORKING AS THE RADAR CTLR AT CSG TRACON. I HAD ALL 3 SECTORS COMBINED AND WAS NOT OVERLY BUSY. ACFT X WAS NBOUND INDICATING 3500' ON HIS MODE C. ACFT Y WAS ALSO NBOUND AND HAD RPTED LEVEL AT 3000' (VFR), BUT WAS NON-MODE C. WHEN THE ACFT WERE ABOUT 6 MI APART, I NOTICED THAT THEY WOULD PROBABLY BE CLOSE AND DECIDED TO CALL TFC IN A MINUTE WHEN THEY WERE MORE LIKELY TO BE ABLE TO SEE EACH OTHER. A FEW MINS LATER, I RECEIVED A CALL FROM ACFT X RPTING ANOTHER ACFT HAD CROSSED HIS NOSE AT HIS ALT. I ADVISED HIM THAT THE OTHER ACFT WAS RPTED 500' LOWER. HE INSISTED THAT THE ACFT WAS AT HIS ALT. I CALLED THE SECOND ACFT, ADVISED HIM OF THE TFC AND OF THE ALT RPT. I REISSUED THE ALTIMETER AND ASKED HIM TO VERIFY ALT. HE AGAIN RPTED LEVEL AT 3000'. OBVIOUSLY, THE FIRST PLT MAY HAVE MISJUDGED THE ALT, BUT THERE WERE CERTAINLY SEVERAL THINGS THAT COULD HAVE BEEN DONE DIFFERENTLY. 1) I SHOULD HAVE CALLED TFC AS SOON AS I SAW THE POSSIBLE CONFLICT SO THAT BOTH PLTS WOULD HAVE BEEN ALERT. 2) HAD THE SECOND ACFT BEEN MODE C EQUIPPED, IT WOULD HAVE PROVIDED A DOUBLE-CHK FOR HIS ALTIMETER. 3) THE CTLR'S HANDBOOK 7110.65 SHOULD GIVE MORE CLEAR REQUIREMENTS FOR ISSUING TFC ADVISORIES BTWN 2 VFR ACFT SINCE THERE IS NO SEP REQUIREMENT FOR THEM IN AN ARSA.

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.