Narrative:

We were initially cleared for an ILS approach to runway 25L. Just before vector to base leg, this was changed to a VOR approach to runway 25L. I found my approach plate and briefed for the approach. We configured the approach per company policy with my side in map mode and the first officer in VOR mode. As we turned final approach, I noticed a difference in alignment between our 2 instruments, so I began to xref the first officer's instruments which were in raw VOR mode. While I was doing this, approach control confirmed I was 1/2 mi north of course, but we corrected quickly to the course. The international relief officer was also monitoring the approach. At the 9 mi fix we were required to leave 4000 ft and descend to 3000 ft. Because of the high workload, I saw my mileage indicator read 9 mi (it was reading distance to the OM, not the VOR) and I began a descent. I had descended 400 ft when I realized I was not reading the correct mileage (the first officer's VOR raw data) and began correcting back to 4000 ft. We were then given descent to 3000 ft by approach control. The rest of the approach was normal. In the future, I believe that it would be wiser to have both captain and first officer set to raw data in this case, it is just too confusing to have both sides using different data if for some reason they don't agree.

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Original NASA ASRS Text

Title: AN ACR FLC FLYING B767 ACFT TO EDFF DSNDED PRIOR TO THE LEGAL STEPDOWN FIX FOR THE VOR APCH.

Narrative: WE WERE INITIALLY CLRED FOR AN ILS APCH TO RWY 25L. JUST BEFORE VECTOR TO BASE LEG, THIS WAS CHANGED TO A VOR APCH TO RWY 25L. I FOUND MY APCH PLATE AND BRIEFED FOR THE APCH. WE CONFIGURED THE APCH PER COMPANY POLICY WITH MY SIDE IN MAP MODE AND THE FO IN VOR MODE. AS WE TURNED FINAL APCH, I NOTICED A DIFFERENCE IN ALIGNMENT BTWN OUR 2 INSTS, SO I BEGAN TO XREF THE FO'S INSTS WHICH WERE IN RAW VOR MODE. WHILE I WAS DOING THIS, APCH CTL CONFIRMED I WAS 1/2 MI N OF COURSE, BUT WE CORRECTED QUICKLY TO THE COURSE. THE INTL RELIEF OFFICER WAS ALSO MONITORING THE APCH. AT THE 9 MI FIX WE WERE REQUIRED TO LEAVE 4000 FT AND DSND TO 3000 FT. BECAUSE OF THE HIGH WORKLOAD, I SAW MY MILEAGE INDICATOR READ 9 MI (IT WAS READING DISTANCE TO THE OM, NOT THE VOR) AND I BEGAN A DSCNT. I HAD DSNDED 400 FT WHEN I REALIZED I WAS NOT READING THE CORRECT MILEAGE (THE FO'S VOR RAW DATA) AND BEGAN CORRECTING BACK TO 4000 FT. WE WERE THEN GIVEN DSCNT TO 3000 FT BY APCH CTL. THE REST OF THE APCH WAS NORMAL. IN THE FUTURE, I BELIEVE THAT IT WOULD BE WISER TO HAVE BOTH CAPT AND FO SET TO RAW DATA IN THIS CASE, IT IS JUST TOO CONFUSING TO HAVE BOTH SIDES USING DIFFERENT DATA IF FOR SOME REASON THEY DON'T AGREE.

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.