Narrative:

The problem was the pilot read back the wrong altitude and due to traffic or some other coordination task that I was performing, I missed the incorrect read back. No conflict occurred with any other aircraft.

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Original NASA ASRS Text

Title: ACR X ENTERED ARTCC AIRSPACE AT WRONG ALT. OP DEV.

Narrative: THE PROB WAS THE PLT READ BACK THE WRONG ALT AND DUE TO TFC OR SOME OTHER COORD TASK THAT I WAS PERFORMING, I MISSED THE INCORRECT READ BACK. NO CONFLICT OCCURRED WITH ANY OTHER 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.