Narrative:

In the descent to 8;000 ft; around FL180 I inadvertently set 29.20 instead of 30.20 on both my altimeter and the standby altimeter. I think we spoke the correct altimeter when discussing the ATIS; I don't know why I made this dumb mistake. I think I knew the correct altimeter in my mind and dialed up 29.20 and then subsequently thought I'd dialed up 30.20. I do not know if the first officer set 29.20 or 30.20; unfortunately; it is now clear that I only crosschecked and saw the last two numbers of his altimeter. We were vectored west of the final approach intersection; planning a visual approach; and although one of us called out of 9 for 8; I did not effectively crosscheck his or my altimeter again at this point as is my habit after reading past reports. We checked in with a new approach frequency and were immediately cleared for 4;000 ft; however she asked 'what altitude did you say you were leaving?' in a tone of voice that got our attention. At this point both the first officer and I realized that my altimeters were mis-set and I immediately corrected my settings. ATC did not indicate that there was a problem and we were not aware of any traffic conflicts. I find a mistake of this magnitude totally unacceptable. My personal corrective action includes being very careful to set the correct altimeters on my side; not rushing this step or performing it mindlessly and also looking at the entire altimeter setting; not just the last two numbers.

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Original NASA ASRS Text

Title: A B757 crew reported mis-set Captain and standby altimeters that were not noticed until after ATC questioned the aircraft's cleared altitude.

Narrative: In the descent to 8;000 FT; around FL180 I inadvertently set 29.20 instead of 30.20 on both my altimeter and the standby altimeter. I think we spoke the correct altimeter when discussing the ATIS; I don't know why I made this dumb mistake. I think I knew the correct altimeter in my mind and dialed up 29.20 and then subsequently thought I'd dialed up 30.20. I do not know if the First Officer set 29.20 or 30.20; unfortunately; it is now clear that I only crosschecked and saw the last two numbers of his altimeter. We were vectored west of the final approach intersection; planning a visual approach; and although one of us called out of 9 for 8; I did not effectively crosscheck his or my altimeter again at this point as is my habit after reading past reports. We checked in with a new approach frequency and were immediately cleared for 4;000 FT; however she asked 'What altitude did you say you were leaving?' in a tone of voice that got our attention. At this point both the First Officer and I realized that my altimeters were mis-set and I immediately corrected my settings. ATC did not indicate that there was a problem and we were not aware of any traffic conflicts. I find a mistake of this magnitude totally unacceptable. My personal corrective action includes being very careful to set the correct altimeters on my side; not rushing this step or performing it mindlessly and also looking at the entire altimeter setting; not just the last two numbers.

Data retrieved from NASA's ASRS site as of April 2012 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.