Narrative:

Routine flight from den to msp. I was off the ATC frequency to copy msp ATIS, and to give company our in-range call. When I returned to frequency, I asked my first officer if there were any changes to our last clearance. He told me that ATC had cleared us to cross 20 mi west of fcm VOR at FL200. I saw he had written the clearance down on his pad as such, and had properly programmed the FMC. We were on a non-standard routing with a clearance I had never received in msp before, but, I had flown with this particular first officer many times before. He is a very competent pilot and I had no reason to doubt the clearance. Shortly after passing the clearance fix, I was questioned by ATC as to what altitude we were at. I told him FL200. He next asked what our last clearance was, and I told 20 west of fcm at FL200. He immediately cleared us to 10000 ft. I asked why he questioned us and was told that our clearance was supposed to be 20 west of fcm at 10000 ft. I questioned my first officer, who swears to the original clearance. I told ATC and he said not to worry, there were no traffic conflicts and it may have just been a misunderstanding. In the future, when there is a clearance change that occurs when one of us is off frequency, I will have ATC repeat it for both to hear. Supplemental information from acn 245944: also gave us a restriction of cross 20 west of fcm at FL200. I programmed this into the FMC and advised captain of the clearance when he was done talking to company and getting the ATIS. After crossing 20 west of fcm at 200 and approaching fcm, ATC (different controller) asked us what was our assigned altitude. When we responded, we also asked why and he said we appeared high and that standard altitude there was 10000 ft. I looked at my written copy of the clearance and couldn't tell if the first number was a 1 or a 2 due to poor legibility. My recollection was FL200, but that may have been mixed up with '20 west' I had set 20000 in the autoplt mode control panel and programmed FL200 in the computer. ATC said 'don't worry,' and gave us further descent.

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Original NASA ASRS Text

Title: AN ACR MLG MISUNDERSTOOD FL200 FOR 10000 FT IN A DSCNT AND ENDED UP HIGH ON THE DSCNT PROFILE.

Narrative: ROUTINE FLT FROM DEN TO MSP. I WAS OFF THE ATC FREQ TO COPY MSP ATIS, AND TO GIVE COMPANY OUR IN-RANGE CALL. WHEN I RETURNED TO FREQ, I ASKED MY FO IF THERE WERE ANY CHANGES TO OUR LAST CLRNC. HE TOLD ME THAT ATC HAD CLRED US TO CROSS 20 MI W OF FCM VOR AT FL200. I SAW HE HAD WRITTEN THE CLRNC DOWN ON HIS PAD AS SUCH, AND HAD PROPERLY PROGRAMMED THE FMC. WE WERE ON A NON-STANDARD ROUTING WITH A CLRNC I HAD NEVER RECEIVED IN MSP BEFORE, BUT, I HAD FLOWN WITH THIS PARTICULAR FO MANY TIMES BEFORE. HE IS A VERY COMPETENT PLT AND I HAD NO REASON TO DOUBT THE CLRNC. SHORTLY AFTER PASSING THE CLRNC FIX, I WAS QUESTIONED BY ATC AS TO WHAT ALT WE WERE AT. I TOLD HIM FL200. HE NEXT ASKED WHAT OUR LAST CLRNC WAS, AND I TOLD 20 W OF FCM AT FL200. HE IMMEDIATELY CLRED US TO 10000 FT. I ASKED WHY HE QUESTIONED US AND WAS TOLD THAT OUR CLRNC WAS SUPPOSED TO BE 20 W OF FCM AT 10000 FT. I QUESTIONED MY FO, WHO SWEARS TO THE ORIGINAL CLRNC. I TOLD ATC AND HE SAID NOT TO WORRY, THERE WERE NO TFC CONFLICTS AND IT MAY HAVE JUST BEEN A MISUNDERSTANDING. IN THE FUTURE, WHEN THERE IS A CLRNC CHANGE THAT OCCURS WHEN ONE OF US IS OFF FREQ, I WILL HAVE ATC REPEAT IT FOR BOTH TO HEAR. SUPPLEMENTAL INFO FROM ACN 245944: ALSO GAVE US A RESTRICTION OF CROSS 20 W OF FCM AT FL200. I PROGRAMMED THIS INTO THE FMC AND ADVISED CAPT OF THE CLRNC WHEN HE WAS DONE TALKING TO COMPANY AND GETTING THE ATIS. AFTER XING 20 W OF FCM AT 200 AND APCHING FCM, ATC (DIFFERENT CTLR) ASKED US WHAT WAS OUR ASSIGNED ALT. WHEN WE RESPONDED, WE ALSO ASKED WHY AND HE SAID WE APPEARED HIGH AND THAT STANDARD ALT THERE WAS 10000 FT. I LOOKED AT MY WRITTEN COPY OF THE CLRNC AND COULDN'T TELL IF THE FIRST NUMBER WAS A 1 OR A 2 DUE TO POOR LEGIBILITY. MY RECOLLECTION WAS FL200, BUT THAT MAY HAVE BEEN MIXED UP WITH '20 W' I HAD SET 20000 IN THE AUTOPLT MODE CTL PANEL AND PROGRAMMED FL200 IN THE COMPUTER. ATC SAID 'DON'T WORRY,' AND GAVE US FURTHER DSCNT.

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.