Narrative:

While in cruise, altitude was questioned by ATC. It was discovered that my encoding altimeter was indicating me off by 100-200 ft. ATC may have had erroneous readings. They suggested that that could be the case.

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Original NASA ASRS Text

Title: A BE55 PLT IS QUESTIONED BY ZDV CTLR AS TO HIS READING ON HIS ALTIMETER. CTR'S READING SHOWED ACFT MODE C TO BE 100-200 FT TOO HIGH.

Narrative: WHILE IN CRUISE, ALT WAS QUESTIONED BY ATC. IT WAS DISCOVERED THAT MY ENCODING ALTIMETER WAS INDICATING ME OFF BY 100-200 FT. ATC MAY HAVE HAD ERRONEOUS READINGS. THEY SUGGESTED THAT THAT COULD BE THE CASE.

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.