Narrative:

We opened our flight plan with FSS and then called for and received fly following from atl departure. We were advised that our mode C was indicating 500' higher than our altimeter showed. I advised ATC of the error and promised that I would have it attended to upon returning to mccollum. We climbed between clouds to 5500' only to find higher tops at our altitude. We called ATC and advised we needed higher whereupon we initiated a climb. At 6500' we found ourselves still dodging cloud tops and the 'scattered' clouds were significantly restricting our ability to see the surface. We decided to descend, advised ATC of our intentions and recieved an acknowledgement. We descended to 3500' feeling that this altitude provided sufficient cloud clearance and surface visibility. We advised ATC of our new altitude, and resumed the x-c lesson. 32 NM from mccollum, 1 NM north of gwinnett co airport, my student and I were engaged in spotting ground references when suddenly a cabin class twin passed about 500' in front of us and about 100' below our altitude, headed southwest and descending. Both my student and I shouted expletives and then fell silent for about 10-15 seconds. I then called ATC and asked if the twin was in radar contact. ATC responded 'affirmative, he's approximately 2 mi southwest of your position at 2600'.' when I advised of the proximity of the pass ATC responded 'roger'. In general, I have had no problems with ATC. I understand that atlanta is a very busy area and that controllers get busy. I understand that conditions were VFR and legally speaking I was responsible for collision avoidance. But this controller was not that busy, I was in radar contact and using flight following because atlanta is a busy area and because of poor visibility. And when I called ATC he acknowledged that both myself and the twin were in radar contact. I was shaken but will continue to use flight following because I have found it a very useful tool. But I am worried about my student. No matter what I do from now on, one of his most vivid memories will be of a near miss while supposedly under the watchful eye of ATC.

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Original NASA ASRS Text

Title: CLOSE PROX GA-SMA GA-SMT NW OF ATL.

Narrative: WE OPENED OUR FLT PLAN WITH FSS AND THEN CALLED FOR AND RECEIVED FLY FOLLOWING FROM ATL DEP. WE WERE ADVISED THAT OUR MODE C WAS INDICATING 500' HIGHER THAN OUR ALTIMETER SHOWED. I ADVISED ATC OF THE ERROR AND PROMISED THAT I WOULD HAVE IT ATTENDED TO UPON RETURNING TO MCCOLLUM. WE CLBED BTWN CLOUDS TO 5500' ONLY TO FIND HIGHER TOPS AT OUR ALT. WE CALLED ATC AND ADVISED WE NEEDED HIGHER WHEREUPON WE INITIATED A CLB. AT 6500' WE FOUND OURSELVES STILL DODGING CLOUD TOPS AND THE 'SCATTERED' CLOUDS WERE SIGNIFICANTLY RESTRICTING OUR ABILITY TO SEE THE SURFACE. WE DECIDED TO DSND, ADVISED ATC OF OUR INTENTIONS AND RECIEVED AN ACKNOWLEDGEMENT. WE DSNDED TO 3500' FEELING THAT THIS ALT PROVIDED SUFFICIENT CLOUD CLRNC AND SURFACE VISIBILITY. WE ADVISED ATC OF OUR NEW ALT, AND RESUMED THE X-C LESSON. 32 NM FROM MCCOLLUM, 1 NM N OF GWINNETT CO ARPT, MY STUDENT AND I WERE ENGAGED IN SPOTTING GND REFERENCES WHEN SUDDENLY A CABIN CLASS TWIN PASSED ABOUT 500' IN FRONT OF US AND ABOUT 100' BELOW OUR ALT, HEADED SW AND DSNDING. BOTH MY STUDENT AND I SHOUTED EXPLETIVES AND THEN FELL SILENT FOR ABOUT 10-15 SECS. I THEN CALLED ATC AND ASKED IF THE TWIN WAS IN RADAR CONTACT. ATC RESPONDED 'AFFIRMATIVE, HE'S APPROX 2 MI SW OF YOUR POS AT 2600'.' WHEN I ADVISED OF THE PROX OF THE PASS ATC RESPONDED 'ROGER'. IN GENERAL, I HAVE HAD NO PROBS WITH ATC. I UNDERSTAND THAT ATLANTA IS A VERY BUSY AREA AND THAT CTLRS GET BUSY. I UNDERSTAND THAT CONDITIONS WERE VFR AND LEGALLY SPEAKING I WAS RESPONSIBLE FOR COLLISION AVOIDANCE. BUT THIS CTLR WAS NOT THAT BUSY, I WAS IN RADAR CONTACT AND USING FLT FOLLOWING BECAUSE ATLANTA IS A BUSY AREA AND BECAUSE OF POOR VISIBILITY. AND WHEN I CALLED ATC HE ACKNOWLEDGED THAT BOTH MYSELF AND THE TWIN WERE IN RADAR CONTACT. I WAS SHAKEN BUT WILL CONTINUE TO USE FLT FOLLOWING BECAUSE I HAVE FOUND IT A VERY USEFUL TOOL. BUT I AM WORRIED ABOUT MY STUDENT. NO MATTER WHAT I DO FROM NOW ON, ONE OF HIS MOST VIVID MEMORIES WILL BE OF A NEAR MISS WHILE SUPPOSEDLY UNDER THE WATCHFUL EYE OF ATC.

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.