Narrative:

On an IFR flight from corpus christi international airport to mathis field, san angelo, tx, I continued to be told by center that I was 7 or 8 mi to the left of the arwy despite a centered needle on my #1 VOR. Approximately 100 mi from destination I discovered that the #1 VOR was not set in VOR mode, but in RNAV mode. I had set it in RNAV on an earlier flight into corpus christi to aid in locating the corpus christi airport. The airport waypoint is 7.6 mi south of the corpus christi VOR. On the return trip back to san angelo 2 days later, I did not change the RNAV function back to VOR function which moved the arwy 7.6 mi left or south of the actual location. This explained my centered needle on the #1 VOR needle and my actual 7.6 mi left of arwy location. Factors affecting performance: I was actually referring to the LORAN heading direct to san angelo and not closely monitoring my #1 VOR and #2 VOR. Had I been, I could have easily tuned both VOR's to the same station, centered both needles. The different headings indicated would have led to the discovery of the RNAV button being engaged instead of the RNAV on VOR #1. VFR flight conditions. The WX was cavu which led to complacency and sloppiness with regard to headings and tracking arwys accurately. Too much redundancy in cockpit can lead to complacency, also, in this case, I flew the LORAN even though my clearance was arwy.

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Original NASA ASRS Text

Title: PLT LEAVES RNAV ENGAGED WHEN BELIEVING HE IS FLYING A VOR AIRWAY. HEADING DEVIATION.

Narrative: ON AN IFR FLT FROM CORPUS CHRISTI INTL ARPT TO MATHIS FIELD, SAN ANGELO, TX, I CONTINUED TO BE TOLD BY CENTER THAT I WAS 7 OR 8 MI TO THE LEFT OF THE ARWY DESPITE A CENTERED NEEDLE ON MY #1 VOR. APPROX 100 MI FROM DEST I DISCOVERED THAT THE #1 VOR WAS NOT SET IN VOR MODE, BUT IN RNAV MODE. I HAD SET IT IN RNAV ON AN EARLIER FLT INTO CORPUS CHRISTI TO AID IN LOCATING THE CORPUS CHRISTI ARPT. THE ARPT WAYPOINT IS 7.6 MI S OF THE CORPUS CHRISTI VOR. ON THE RETURN TRIP BACK TO SAN ANGELO 2 DAYS LATER, I DID NOT CHANGE THE RNAV FUNCTION BACK TO VOR FUNCTION WHICH MOVED THE ARWY 7.6 MI LEFT OR S OF THE ACTUAL LOCATION. THIS EXPLAINED MY CENTERED NEEDLE ON THE #1 VOR NEEDLE AND MY ACTUAL 7.6 MI LEFT OF ARWY LOCATION. FACTORS AFFECTING PERFORMANCE: I WAS ACTUALLY REFERRING TO THE LORAN HDG DIRECT TO SAN ANGELO AND NOT CLOSELY MONITORING MY #1 VOR AND #2 VOR. HAD I BEEN, I COULD HAVE EASILY TUNED BOTH VOR'S TO THE SAME STATION, CENTERED BOTH NEEDLES. THE DIFFERENT HDGS INDICATED WOULD HAVE LED TO THE DISCOVERY OF THE RNAV BUTTON BEING ENGAGED INSTEAD OF THE RNAV ON VOR #1. VFR FLT CONDITIONS. THE WX WAS CAVU WHICH LED TO COMPLACENCY AND SLOPPINESS WITH REGARD TO HDGS AND TRACKING ARWYS ACCURATELY. TOO MUCH REDUNDANCY IN COCKPIT CAN LEAD TO COMPLACENCY, ALSO, IN THIS CASE, I FLEW THE LORAN EVEN THOUGH MY CLRNC WAS ARWY.

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.