Narrative:

The problem arose when I set 186 degrees in the obs when 196 degrees should have been set. I was on the VOR 21 approach to ZZZ. ATC gave me a heading to establish myself on the radial. I had 186 degrees set on the obs when 196 degrees should have been set. ATC issued the approach clearance and to maintain 2500 ft until established on the radial. The obs centered, so I descended to 1900 ft per IAP. After 12.4 DME, I descended to 1120 ft (the MDA). ATC informed me that I was 1.5 mi east of the approach course. I initiated a missed approach. By this time I had realized my mistake and successfully completed a second approach. I attributed most of the incident to fatigue. (I was toward the end of my duty period.)

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Original NASA ASRS Text

Title: A PA60 ATX PLT SETS THE WRONG INBOUND RADIAL FOR AN IAP VOR DME APCH AND IS RPTED TO BE 1 PT 5 NM E OF THE DESIRED APCH COURSE BY APCH CTLR.

Narrative: THE PROB AROSE WHEN I SET 186 DEGS IN THE OBS WHEN 196 DEGS SHOULD HAVE BEEN SET. I WAS ON THE VOR 21 APCH TO ZZZ. ATC GAVE ME A HDG TO ESTABLISH MYSELF ON THE RADIAL. I HAD 186 DEGS SET ON THE OBS WHEN 196 DEGS SHOULD HAVE BEEN SET. ATC ISSUED THE APCH CLRNC AND TO MAINTAIN 2500 FT UNTIL ESTABLISHED ON THE RADIAL. THE OBS CTRED, SO I DSNDED TO 1900 FT PER IAP. AFTER 12.4 DME, I DSNDED TO 1120 FT (THE MDA). ATC INFORMED ME THAT I WAS 1.5 MI E OF THE APCH COURSE. I INITIATED A MISSED APCH. BY THIS TIME I HAD REALIZED MY MISTAKE AND SUCCESSFULLY COMPLETED A SECOND APCH. I ATTRIBUTED MOST OF THE INCIDENT TO FATIGUE. (I WAS TOWARD THE END OF MY DUTY PERIOD.)

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.