Narrative:

While being vectored on to ILS 19R at mke, a new altitude indicator installed that morning started to give me conflicting information with my other instruments just outside the OM in IMC conditions. While trying to determine which of the instruments was failing I lost 200 ft of altitude and started off course, this was soon corrected and milwaukee approach never said anything, which the deviation was not very great. As I broke out of the clouds at 1200 ft AGL, the aircraft was back on course and altitude with the ILS approach. Once in VFR conditions I then requested to remain VFR and return back to a local airport where the aircraft is based, and it was easily determined upon entering VFR conditions that the altitude indicator had failed.

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Original NASA ASRS Text

Title: PLT OF SMA ON APCH TO MKE HAD ALTIMETER PROBLEM, EXCURSIONED FROM ALT.

Narrative: WHILE BEING VECTORED ON TO ILS 19R AT MKE, A NEW ALT INDICATOR INSTALLED THAT MORNING STARTED TO GIVE ME CONFLICTING INFO WITH MY OTHER INSTS JUST OUTSIDE THE OM IN IMC CONDITIONS. WHILE TRYING TO DETERMINE WHICH OF THE INSTS WAS FAILING I LOST 200 FT OF ALT AND STARTED OFF COURSE, THIS WAS SOON CORRECTED AND MILWAUKEE APCH NEVER SAID ANYTHING, WHICH THE DEV WAS NOT VERY GREAT. AS I BROKE OUT OF THE CLOUDS AT 1200 FT AGL, THE ACFT WAS BACK ON COURSE AND ALT WITH THE ILS APCH. ONCE IN VFR CONDITIONS I THEN REQUESTED TO REMAIN VFR AND RETURN BACK TO A LCL ARPT WHERE THE ACFT IS BASED, AND IT WAS EASILY DETERMINED UPON ENTERING VFR CONDITIONS THAT THE ALT INDICATOR HAD FAILED.

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.