Narrative:

IFR inbound to pdk, we were handed off to atl approach. Descended to 3000' assigned heading 320 degrees. We called out opp traffic to atl approach at co-altitude about 1 mi at 10 O'clock, 'but no near miss,' a few mins later. Small aircraft Y, white with blue trim, passed under our aircraft (about 35' below) heading approximately 090 degrees. I called out the near miss to atl approach and received the following reply: 'I'm sorry, but we have numerous VFR traffic in the area.' this response begs lots of questions: 1) our mode C was functioning properly. Are not all aircraft required to squawk a mode C? If so, why wouldn't the atl approach facility receive automatic warning about conflicting traffic? 2) from the vectors being given our aircraft it was obvious they were keeping us on the fringe of TCA. However, the aircraft that nearly struck us was certainly coming out of the geographic area of the TCA, even if 3000' might be below the floor at our position. 3) I'm concerned that the controller equipment was malfunctioning, not adequate to track all of the aircraft within the control zone, obsolete, that the controller was not adequately trained, there was not intra-controller coordination on passing traffic information, or all of the above. This report is submitted with the hope it will give FAA support for additional equipment/personnel funding if required, and assist flight safety enhancements in and near all TCA's.

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Original NASA ASRS Text

Title: NMAC BETWEEN GA-TWIN AND SMA. SEE AND AVOID SITUATION. PLT DEVIATION.

Narrative: IFR INBND TO PDK, WE WERE HANDED OFF TO ATL APCH. DSNDED TO 3000' ASSIGNED HDG 320 DEGS. WE CALLED OUT OPP TFC TO ATL APCH AT CO-ALT ABOUT 1 MI AT 10 O'CLOCK, 'BUT NO NEAR MISS,' A FEW MINS LATER. SMA Y, WHITE WITH BLUE TRIM, PASSED UNDER OUR ACFT (ABOUT 35' BELOW) HDG APPROX 090 DEGS. I CALLED OUT THE NEAR MISS TO ATL APCH AND RECEIVED THE FOLLOWING REPLY: 'I'M SORRY, BUT WE HAVE NUMEROUS VFR TFC IN THE AREA.' THIS RESPONSE BEGS LOTS OF QUESTIONS: 1) OUR MODE C WAS FUNCTIONING PROPERLY. ARE NOT ALL ACFT REQUIRED TO SQUAWK A MODE C? IF SO, WHY WOULDN'T THE ATL APCH FAC RECEIVE AUTOMATIC WARNING ABOUT CONFLICTING TFC? 2) FROM THE VECTORS BEING GIVEN OUR ACFT IT WAS OBVIOUS THEY WERE KEEPING US ON THE FRINGE OF TCA. HOWEVER, THE ACFT THAT NEARLY STRUCK US WAS CERTAINLY COMING OUT OF THE GEOGRAPHIC AREA OF THE TCA, EVEN IF 3000' MIGHT BE BELOW THE FLOOR AT OUR POS. 3) I'M CONCERNED THAT THE CTLR EQUIP WAS MALFUNCTIONING, NOT ADEQUATE TO TRACK ALL OF THE ACFT WITHIN THE CTL ZONE, OBSOLETE, THAT THE CTLR WAS NOT ADEQUATELY TRAINED, THERE WAS NOT INTRA-CTLR COORD ON PASSING TFC INFO, OR ALL OF THE ABOVE. THIS RPT IS SUBMITTED WITH THE HOPE IT WILL GIVE FAA SUPPORT FOR ADDITIONAL EQUIP/PERSONNEL FUNDING IF REQUIRED, AND ASSIST FLT SAFETY ENHANCEMENTS IN AND NEAR ALL TCA'S.

Data retrieved from NASA's ASRS site as of August 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.