Narrative:

Received exit from hold clearance. I read back routing and an altitude change to leave 12000 ft to descend to 10000 ft. Controller accepted entire readback. Prior to passing 11000 ft, he noticed our descent and questioned it. He had us level off at 11000 ft. He claimed not to have issued the descent. I don't know how we could have prevented this, as I heard a descent clearance, my first officer heard the descent clearance, and the controller accepted the readback. Supplemental information from acn 415791: crew coordination worked good. Physical and verbal checks and balances were used to confirm our descent action. Controller stated he had a high workload due to sudden, without warning, closing of the arrival corridor. He may have just forgotten his full clearance to our aircraft.

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Original NASA ASRS Text

Title: ZAU CTLR ISSUES DSCNT CLRNC TO EA32 THEN TELLS CREW THEY ARE DSNDING BELOW CLRED ALT.

Narrative: RECEIVED EXIT FROM HOLD CLRNC. I READ BACK ROUTING AND AN ALT CHANGE TO LEAVE 12000 FT TO DSND TO 10000 FT. CTLR ACCEPTED ENTIRE READBACK. PRIOR TO PASSING 11000 FT, HE NOTICED OUR DSCNT AND QUESTIONED IT. HE HAD US LEVEL OFF AT 11000 FT. HE CLAIMED NOT TO HAVE ISSUED THE DSCNT. I DON'T KNOW HOW WE COULD HAVE PREVENTED THIS, AS I HEARD A DSCNT CLRNC, MY FO HEARD THE DSCNT CLRNC, AND THE CTLR ACCEPTED THE READBACK. SUPPLEMENTAL INFO FROM ACN 415791: CREW COORD WORKED GOOD. PHYSICAL AND VERBAL CHKS AND BALS WERE USED TO CONFIRM OUR DSCNT ACTION. CTLR STATED HE HAD A HIGH WORKLOAD DUE TO SUDDEN, WITHOUT WARNING, CLOSING OF THE ARR CORRIDOR. HE MAY HAVE JUST FORGOTTEN HIS FULL CLRNC TO OUR ACFT.

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.