Narrative:

On a dual x-country from stone mountain, GA to macon at 3000', student contacted mcn approach to advise of our altitude, location, and intentions of landing at mcn. We were approximately 23 mi northwest of mcn when we were told to stand by. After a few minutes we called again and were given a squawk code, and a heading of 190 degree. Approximately 5 mi from the airport we were given an altitude which she and I understood as 2000', and a heading of 140 degree. She acknowledged the transmission. Approximately 3 mi from the field, on an extended left base for runway 5, we both spotted traffic at our 10 O'clock position. It was another high wing small aircraft at what appeared to be approximately 300' crossing us from left to right. In the next few seconds the controller called us to verify our altitude. When I reported 2000' he then called our traffic and advised us that we had been assigned 2500'. I then acknowledged we had understood 2000'. Once on the ground I called approach control by telephone to verify that we had been given 2000'. The man I spoke with said he had already listened to the tape and we had been given 2500'. I asked him to tell me what my student acknowledged to this clearance and he said 'roger'. I must add that I teach my students to read back clrncs, mainly to verify that they have heard correctly. I must also bring to light that both my student and I were wearing headsets and our plane is equipped with mode C which was on at the time of the occurrence. After discussing the matter with the gentleman on the phone he advised me that he was the controller at the time of the discrepancy. My main concern, as a flight instructor who practices 'safety first', is that even though we had spotted our traffic and if in fact I did get a clearance to only 2500', why was I not asked to verify my altitude before our altitudes and our flight paths were so critical?

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Original NASA ASRS Text

Title: NMAC. ALT DEVIATION OVERSHOOT IN DESCENT.

Narrative: ON A DUAL X-COUNTRY FROM STONE MOUNTAIN, GA TO MACON AT 3000', STUDENT CONTACTED MCN APCH TO ADVISE OF OUR ALT, LOCATION, AND INTENTIONS OF LNDG AT MCN. WE WERE APPROX 23 MI NW OF MCN WHEN WE WERE TOLD TO STAND BY. AFTER A FEW MINUTES WE CALLED AGAIN AND WERE GIVEN A SQUAWK CODE, AND A HDG OF 190 DEG. APPROX 5 MI FROM THE ARPT WE WERE GIVEN AN ALT WHICH SHE AND I UNDERSTOOD AS 2000', AND A HDG OF 140 DEG. SHE ACKNOWLEDGED THE XMISSION. APPROX 3 MI FROM THE FIELD, ON AN EXTENDED LEFT BASE FOR RWY 5, WE BOTH SPOTTED TFC AT OUR 10 O'CLOCK POSITION. IT WAS ANOTHER HIGH WING SMA AT WHAT APPEARED TO BE APPROX 300' XING US FROM LEFT TO RIGHT. IN THE NEXT FEW SECONDS THE CTLR CALLED US TO VERIFY OUR ALT. WHEN I REPORTED 2000' HE THEN CALLED OUR TFC AND ADVISED US THAT WE HAD BEEN ASSIGNED 2500'. I THEN ACKNOWLEDGED WE HAD UNDERSTOOD 2000'. ONCE ON THE GND I CALLED APCH CTL BY TELEPHONE TO VERIFY THAT WE HAD BEEN GIVEN 2000'. THE MAN I SPOKE WITH SAID HE HAD ALREADY LISTENED TO THE TAPE AND WE HAD BEEN GIVEN 2500'. I ASKED HIM TO TELL ME WHAT MY STUDENT ACKNOWLEDGED TO THIS CLRNC AND HE SAID 'ROGER'. I MUST ADD THAT I TEACH MY STUDENTS TO READ BACK CLRNCS, MAINLY TO VERIFY THAT THEY HAVE HEARD CORRECTLY. I MUST ALSO BRING TO LIGHT THAT BOTH MY STUDENT AND I WERE WEARING HEADSETS AND OUR PLANE IS EQUIPPED WITH MODE C WHICH WAS ON AT THE TIME OF THE OCCURRENCE. AFTER DISCUSSING THE MATTER WITH THE GENTLEMAN ON THE PHONE HE ADVISED ME THAT HE WAS THE CTLR AT THE TIME OF THE DISCREPANCY. MY MAIN CONCERN, AS A FLT INSTRUCTOR WHO PRACTICES 'SAFETY FIRST', IS THAT EVEN THOUGH WE HAD SPOTTED OUR TFC AND IF IN FACT I DID GET A CLRNC TO ONLY 2500', WHY WAS I NOT ASKED TO VERIFY MY ALT BEFORE OUR ALTS AND OUR FLT PATHS WERE SO CRITICAL?

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.