Narrative:

While descending into birmingham, ZME gave us a clearance to descend to flight level 210 by 80 mi southwest of vulcan VOR, and then, 'pilot's discretion' to what I believed was 11000 ft. I read back clearance, and set 21000 ft in altitude preselect. Upon reaching FL210, I reset altitude preselect to 11000 ft. Mem inquired about our altitude while we descended through FL220. We reported our altitude, and were handed off to atlanta. I checked in with atlanta and advised I was descending to 11000 ft. While descending through approximately 12000 ft, I observed traffic north of our position, and commented to the first officer that ATC did not call out that traffic. Just about then, atlanta asked us to say our altitude. I advised 11500 ft descending to 11000 ft. ATC advised our clearance was supposed to be 13000 ft. I said negative, I had read back 11000 ft. Center said they would check their tapes, and I said I would file a report. Supplemental information from acn 298506: we were en route IFR, from houston (iah) to birmingham (bhm). Memphis gave us clearance to cross 80 NM out of vulcan VOR (vuz), at or below FL210, then descend and maintain 11000 ft (from what we heard and understood). I was the PF, so the captain read back the clearance, as stated above. We were out of 11500 ft for 11000 ft, when the controller asked us, 'wasn't your assigned altitude 13000 ft?' they had thought we were descending to 13000 ft, and if that was so, we must have misunderstood the final clearance, and the controllers had not corrected the captain's readback to clear up the misunderstanding.

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Original NASA ASRS Text

Title: A CORPORATE JET FLC THOUGHT THAT THEY WERE CLRED TO DSND TO 11000 FT, AND READBACK SAME, TWICE. ARTCC CTLR'S TWICE, FAILED TO HEAR READBACK ERROR, AND ACFT DSNDED BELOW THE ALT THAT CTR HAD ASSIGNED -- CONFLICTING WITH TFC.

Narrative: WHILE DSNDING INTO BIRMINGHAM, ZME GAVE US A CLRNC TO DSND TO FLT LEVEL 210 BY 80 MI SW OF VULCAN VOR, AND THEN, 'PLT'S DISCRETION' TO WHAT I BELIEVED WAS 11000 FT. I READ BACK CLRNC, AND SET 21000 FT IN ALT PRESELECT. UPON REACHING FL210, I RESET ALT PRESELECT TO 11000 FT. MEM INQUIRED ABOUT OUR ALT WHILE WE DSNDED THROUGH FL220. WE RPTED OUR ALT, AND WERE HANDED OFF TO ATLANTA. I CHKED IN WITH ATLANTA AND ADVISED I WAS DSNDING TO 11000 FT. WHILE DSNDING THROUGH APPROX 12000 FT, I OBSERVED TFC N OF OUR POS, AND COMMENTED TO THE FO THAT ATC DID NOT CALL OUT THAT TFC. JUST ABOUT THEN, ATLANTA ASKED US TO SAY OUR ALT. I ADVISED 11500 FT DSNDING TO 11000 FT. ATC ADVISED OUR CLRNC WAS SUPPOSED TO BE 13000 FT. I SAID NEGATIVE, I HAD READ BACK 11000 FT. CTR SAID THEY WOULD CHK THEIR TAPES, AND I SAID I WOULD FILE A RPT. SUPPLEMENTAL INFO FROM ACN 298506: WE WERE ENRTE IFR, FROM HOUSTON (IAH) TO BIRMINGHAM (BHM). MEMPHIS GAVE US CLRNC TO CROSS 80 NM OUT OF VULCAN VOR (VUZ), AT OR BELOW FL210, THEN DSND AND MAINTAIN 11000 FT (FROM WHAT WE HEARD AND UNDERSTOOD). I WAS THE PF, SO THE CAPT READ BACK THE CLRNC, AS STATED ABOVE. WE WERE OUT OF 11500 FT FOR 11000 FT, WHEN THE CTLR ASKED US, 'WASN'T YOUR ASSIGNED ALT 13000 FT?' THEY HAD THOUGHT WE WERE DSNDING TO 13000 FT, AND IF THAT WAS SO, WE MUST HAVE MISUNDERSTOOD THE FINAL CLRNC, AND THE CTLRS HAD NOT CORRECTED THE CAPT'S READBACK TO CLR UP THE MISUNDERSTANDING.

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.