Narrative:

On descent into dtw on the polar one arrival we were cleared to cross polar x-n at 12000 ft. It was the first officer's leg using the B autoplt. As we descended through 14000 ft the altitude alerter went off. I noticed it was too high. As I began to see what was wrong, the aircraft leveled off at 13000 ft. I couldn't figure out what was going on. Was there a problem with the altitude alerter? What was happening? I told the first officer we were too high, that we were at 13000 ft not 12000 ft. He said we are at 12000 ft. It was at that time that I realized that his altimeter was set at 29.42 hg instead of 30.42 hg, putting us 1000 ft high. I pointed it out to him. He reset to 30.42 hg, and began a quick descent to 12000 ft. In the confusion, I am not sure if we were above 12000 ft at polar, as we had gotten down early, but figure we may have been 300-500 ft high. There were no comments from ATC. I believe that when we did the descent checklist, I did not catch the missed set altimeter either visually or hearing it read. It seems I have noticed quite a few first officer's only say FL180 descending through FL180 and do not repeat the altimeter setting as our procedures call for. Thus, when the descent checklist is read, the only response you hear is 'set and crosschecked.' I think it would be a good procedure to add this to the altimeter's and bug's checklist inquiry to back up the FL180 callout.

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Original NASA ASRS Text

Title: A B737 LEVELS OFF AT 13000 FT INSTEAD OF 12000 FT AS SET INTO THE ALT SELECT WINDOW DUE TO THE FO HAVING THE WRONG ALTIMETER SETTING.

Narrative: ON DSCNT INTO DTW ON THE POLAR ONE ARR WE WERE CLRED TO CROSS POLAR X-N AT 12000 FT. IT WAS THE FO'S LEG USING THE B AUTOPLT. AS WE DSNDED THROUGH 14000 FT THE ALT ALERTER WENT OFF. I NOTICED IT WAS TOO HIGH. AS I BEGAN TO SEE WHAT WAS WRONG, THE ACFT LEVELED OFF AT 13000 FT. I COULDN'T FIGURE OUT WHAT WAS GOING ON. WAS THERE A PROB WITH THE ALT ALERTER? WHAT WAS HAPPENING? I TOLD THE FO WE WERE TOO HIGH, THAT WE WERE AT 13000 FT NOT 12000 FT. HE SAID WE ARE AT 12000 FT. IT WAS AT THAT TIME THAT I REALIZED THAT HIS ALTIMETER WAS SET AT 29.42 HG INSTEAD OF 30.42 HG, PUTTING US 1000 FT HIGH. I POINTED IT OUT TO HIM. HE RESET TO 30.42 HG, AND BEGAN A QUICK DSCNT TO 12000 FT. IN THE CONFUSION, I AM NOT SURE IF WE WERE ABOVE 12000 FT AT POLAR, AS WE HAD GOTTEN DOWN EARLY, BUT FIGURE WE MAY HAVE BEEN 300-500 FT HIGH. THERE WERE NO COMMENTS FROM ATC. I BELIEVE THAT WHEN WE DID THE DSCNT CHKLIST, I DID NOT CATCH THE MISSED SET ALTIMETER EITHER VISUALLY OR HEARING IT READ. IT SEEMS I HAVE NOTICED QUITE A FEW FO'S ONLY SAY FL180 DSNDING THROUGH FL180 AND DO NOT REPEAT THE ALTIMETER SETTING AS OUR PROCS CALL FOR. THUS, WHEN THE DSCNT CHKLIST IS READ, THE ONLY RESPONSE YOU HEAR IS 'SET AND XCHKED.' I THINK IT WOULD BE A GOOD PROC TO ADD THIS TO THE ALTIMETER'S AND BUG'S CHKLIST INQUIRY TO BACK UP THE FL180 CALLOUT.

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.