Narrative:

We had been holding briefly at msn VOR on our flight inbound to ord. We were pulled out of the hold and given a series of radar vectors toward ord. I had been off the ATC frequency communicating with dispatch about the hold and about information relative to our next flight. Then approximately simultaneously the following things occurred, I switched back to ATC. The captain became agitated about something dispatch had said and switched off ATC to talk to them. A F/a came to the cockpit and began asking questions about gates and connections. ATC cleared us to descend to 8000'. I read back the clearance to 8000' and set 8000' in the altitude alerter. We had been descending when the clearance was received and so we continued to descend to 8000' where the autoplt leveled us off. Moments later the controller said 'verify you are at 9000''. I said 'negative. We are at 8000''. He said 'climb immediately to 9000''. He then asked 'did you readback 8000' or 9000'?' I said '8000'' and that was the end of it. The problem now is that with the confusion in the cockpit, I can't swear whether the controller really did initially say 8000' or 9000'. I am certain that I did readback 8000' and that due to the high workload, the controller didn't 'hearback' my readback of 8000'.

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Original NASA ASRS Text

Title: ACR MLG ALT DEVIATION OVERSHOT DURING DESCENT.

Narrative: WE HAD BEEN HOLDING BRIEFLY AT MSN VOR ON OUR FLT INBND TO ORD. WE WERE PULLED OUT OF THE HOLD AND GIVEN A SERIES OF RADAR VECTORS TOWARD ORD. I HAD BEEN OFF THE ATC FREQ COMMUNICATING WITH DISPATCH ABOUT THE HOLD AND ABOUT INFO RELATIVE TO OUR NEXT FLT. THEN APPROX SIMULTANEOUSLY THE FOLLOWING THINGS OCCURRED, I SWITCHED BACK TO ATC. THE CAPT BECAME AGITATED ABOUT SOMETHING DISPATCH HAD SAID AND SWITCHED OFF ATC TO TALK TO THEM. A F/A CAME TO THE COCKPIT AND BEGAN ASKING QUESTIONS ABOUT GATES AND CONNECTIONS. ATC CLRED US TO DSND TO 8000'. I READ BACK THE CLRNC TO 8000' AND SET 8000' IN THE ALT ALERTER. WE HAD BEEN DSNDING WHEN THE CLRNC WAS RECEIVED AND SO WE CONTINUED TO DSND TO 8000' WHERE THE AUTOPLT LEVELED US OFF. MOMENTS LATER THE CTLR SAID 'VERIFY YOU ARE AT 9000''. I SAID 'NEGATIVE. WE ARE AT 8000''. HE SAID 'CLB IMMEDIATELY TO 9000''. HE THEN ASKED 'DID YOU READBACK 8000' OR 9000'?' I SAID '8000'' AND THAT WAS THE END OF IT. THE PROB NOW IS THAT WITH THE CONFUSION IN THE COCKPIT, I CAN'T SWEAR WHETHER THE CTLR REALLY DID INITIALLY SAY 8000' OR 9000'. I AM CERTAIN THAT I DID READBACK 8000' AND THAT DUE TO THE HIGH WORKLOAD, THE CTLR DIDN'T 'HEARBACK' MY READBACK OF 8000'.

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.