Narrative:

ZAU cleared us to cross SW40 ord at 10000' altitude setting 30.43. At approximately 10500' I glanced at our company altitude setting and read 29.43. I asked the control to reconfirm altitude setting, and now he says sorry about that it's 29.43. By this time we went below LOM down to about 9300. Now the control said 'ok to maintain 9000 and turned us over to approach control. Nothing else said.

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Original NASA ASRS Text

Title: ARTCC RADAR CTLR GAVE THE WRONG ALTIMETER SETTING AND LATER CORRECTED AFTER THE ACFT HAD OVERSHOT ALT.

Narrative: ZAU CLRED US TO CROSS SW40 ORD AT 10000' ALT SETTING 30.43. AT APPROX 10500' I GLANCED AT OUR COMPANY ALT SETTING AND READ 29.43. I ASKED THE CTL TO RECONFIRM ALT SETTING, AND NOW HE SAYS SORRY ABOUT THAT IT'S 29.43. BY THIS TIME WE WENT BELOW LOM DOWN TO ABOUT 9300. NOW THE CTL SAID 'OK TO MAINTAIN 9000 AND TURNED US OVER TO APCH CTL. NOTHING ELSE SAID.

Data retrieved from NASA's ASRS site as of August 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.