Narrative:

At our assigned altitude 6000', our electric altimeter displayed an off flag. We were advised by controller we should be at 6000'. Our barometric altimeters read 600' and my first officer responded, 'we are level at 6000'.' this intermittent flag could not be duplicated on the ground at acy. Upon termination of flight at msp the flag reappeared and maintenance observed flag and removed altimeter for repair.

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Original NASA ASRS Text

Title: ALTIMETER SYSTEM MALFUNCTION MAY HAVE LED TO ALT DEVIATION.

Narrative: AT OUR ASSIGNED ALT 6000', OUR ELECTRIC ALTIMETER DISPLAYED AN OFF FLAG. WE WERE ADVISED BY CTLR WE SHOULD BE AT 6000'. OUR BAROMETRIC ALTIMETERS READ 600' AND MY F/O RESPONDED, 'WE ARE LEVEL AT 6000'.' THIS INTERMITTENT FLAG COULD NOT BE DUPLICATED ON THE GND AT ACY. UPON TERMINATION OF FLT AT MSP THE FLAG REAPPEARED AND MAINT OBSERVED FLAG AND REMOVED ALTIMETER FOR REPAIR.

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.