Narrative:

I departed with an IFR clearance through a thin overcast. My altitude limit was 4500 ft. When my altimeter read 4500 ft, I was on top in VFR conditions. I cancelled IFR, and proceeded VFR with flight following with local approach controller. After about 5 mins, approach called. The controller indicated that I had climbed through 4500 ft to 5500 ft, but no traffic conflict had occurred. I had not remembered climbing past 4500 ft while on an IFR clearance. I acknowledged the transmission and continued the flight. Before the VFR flight terminated, I discovered my error. I am quite embarrassed to admit that I misset my altimeter by 1000 ft prior to takeoff. I received the local AWOS altimeter setting of 30.66, but mistakenly set 29.66 on the altimeter. There had been a 7:8 pressure change since my last flight. Without thinking, I just used the last 2 digits, ignoring the first two. From the 'old' setting, it took just a small correction to set to the 'nearest' .66 ie, 29.66. This was my error. Subsequently, when I 'leveled off' at 4500 ft, my real altitude was 5500 ft (as indicated by ATC). I picked up AWOS and set the altimeter while taxiing. That was a factor in my error. If I would have done this parked in the run-up area, I would have been more focused on detail. Also, when I first contacted approach, I dutifully indicated my present altitude. The error should have been idented at that time. However, ATC acknowledged my report and the error was not discovered. My error, but in this case, ATC should have idented the error at initial contact.

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Original NASA ASRS Text

Title: C185 PLT OVERSHOOTS CRUISE ALT BY 1000 FT DUE TO MISSET ALTIMETER.

Narrative: I DEPARTED WITH AN IFR CLRNC THROUGH A THIN OVCST. MY ALT LIMIT WAS 4500 FT. WHEN MY ALTIMETER READ 4500 FT, I WAS ON TOP IN VFR CONDITIONS. I CANCELLED IFR, AND PROCEEDED VFR WITH FLT FOLLOWING WITH LCL APCH CTLR. AFTER ABOUT 5 MINS, APCH CALLED. THE CTLR INDICATED THAT I HAD CLBED THROUGH 4500 FT TO 5500 FT, BUT NO TFC CONFLICT HAD OCCURRED. I HAD NOT REMEMBERED CLBING PAST 4500 FT WHILE ON AN IFR CLRNC. I ACKNOWLEDGED THE XMISSION AND CONTINUED THE FLT. BEFORE THE VFR FLT TERMINATED, I DISCOVERED MY ERROR. I AM QUITE EMBARRASSED TO ADMIT THAT I MISSET MY ALTIMETER BY 1000 FT PRIOR TO TKOF. I RECEIVED THE LCL AWOS ALTIMETER SETTING OF 30.66, BUT MISTAKENLY SET 29.66 ON THE ALTIMETER. THERE HAD BEEN A 7:8 PRESSURE CHANGE SINCE MY LAST FLT. WITHOUT THINKING, I JUST USED THE LAST 2 DIGITS, IGNORING THE FIRST TWO. FROM THE 'OLD' SETTING, IT TOOK JUST A SMALL CORRECTION TO SET TO THE 'NEAREST' .66 IE, 29.66. THIS WAS MY ERROR. SUBSEQUENTLY, WHEN I 'LEVELED OFF' AT 4500 FT, MY REAL ALT WAS 5500 FT (AS INDICATED BY ATC). I PICKED UP AWOS AND SET THE ALTIMETER WHILE TAXIING. THAT WAS A FACTOR IN MY ERROR. IF I WOULD HAVE DONE THIS PARKED IN THE RUN-UP AREA, I WOULD HAVE BEEN MORE FOCUSED ON DETAIL. ALSO, WHEN I FIRST CONTACTED APCH, I DUTIFULLY INDICATED MY PRESENT ALT. THE ERROR SHOULD HAVE BEEN IDENTED AT THAT TIME. HOWEVER, ATC ACKNOWLEDGED MY RPT AND THE ERROR WAS NOT DISCOVERED. MY ERROR, BUT IN THIS CASE, ATC SHOULD HAVE IDENTED THE ERROR AT INITIAL CONTACT.

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.