Narrative:

Clt was VFR, a line of thunderstorms had just passed leaving scattered cloud formation in area. Temperature dew point was close, winds were light out of 200 degrees at 6 KTS approximately. We were originally cleared for 18R visual approach to follow dash 8 aircraft. He was slow so approach asked if we would accept a visual to runway 23, we accepted. Proceeded direct to lecar 5 mi fix, from runway 23 descended to cross at 2700 ft. Speed was kept up to comply with request from approach 210 to lecar. As we approached lecar, scattered layer started to form on east side of airport, field was in sight. During this change from 18R to 23, I (captain) changed all frequency to give first officer localizer frequency for runway 23 and first officer heading. I did not switch his VOR navigation switch to VOR, he remained in LNAV. We intercepted the FMC centerline, configured the aircraft and proceeded northbound at the same time a scattered layer of cloud obscured the runway from view. We continued since we could see other portions of the airport. We believed we would clear the layer and be able to land. The autoplt remained connected and we descended to MDA. We cleared the scattered layer and found we were not in a position to land, the runway was off too far to the left. We performed a go around and landed on 18R. Factors: WX, short approach, visual instead of full approach, change of runway assignments close in. Corrective: should have stayed with original runway and slowed to follow traffic, MVFR WX conditions are not conducive to runway changes, FMC can give you a false sense of security because it's always accurate. This time it was off 3 to 5 mi, always back up with raw data VFR or IFR.

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Original NASA ASRS Text

Title: MLG ACCEPTS RWY CHANGE AND VISUAL APCH BUT ENCOUNTERS SCATTERED CLOUDS. MAKES MAP TO LAND ON ORIGINAL RWY.

Narrative: CLT WAS VFR, A LINE OF TSTMS HAD JUST PASSED LEAVING SCATTERED CLOUD FORMATION IN AREA. TEMP DEW POINT WAS CLOSE, WINDS WERE LIGHT OUT OF 200 DEGS AT 6 KTS APPROX. WE WERE ORIGINALLY CLRED FOR 18R VISUAL APCH TO FOLLOW DASH 8 ACFT. HE WAS SLOW SO APCH ASKED IF WE WOULD ACCEPT A VISUAL TO RWY 23, WE ACCEPTED. PROCEEDED DIRECT TO LECAR 5 MI FIX, FROM RWY 23 DSNDED TO CROSS AT 2700 FT. SPD WAS KEPT UP TO COMPLY WITH REQUEST FROM APCH 210 TO LECAR. AS WE APCHED LECAR, SCATTERED LAYER STARTED TO FORM ON E SIDE OF ARPT, FIELD WAS IN SIGHT. DURING THIS CHANGE FROM 18R TO 23, I (CAPT) CHANGED ALL FREQ TO GIVE FO LOC FREQ FOR RWY 23 AND FO HDG. I DID NOT SWITCH HIS VOR NAV SWITCH TO VOR, HE REMAINED IN LNAV. WE INTERCEPTED THE FMC CTRLINE, CONFIGURED THE ACFT AND PROCEEDED NBOUND AT THE SAME TIME A SCATTERED LAYER OF CLOUD OBSCURED THE RWY FROM VIEW. WE CONTINUED SINCE WE COULD SEE OTHER PORTIONS OF THE ARPT. WE BELIEVED WE WOULD CLR THE LAYER AND BE ABLE TO LAND. THE AUTOPLT REMAINED CONNECTED AND WE DSNDED TO MDA. WE CLRED THE SCATTERED LAYER AND FOUND WE WERE NOT IN A POS TO LAND, THE RWY WAS OFF TOO FAR TO THE L. WE PERFORMED A GAR AND LANDED ON 18R. FACTORS: WX, SHORT APCH, VISUAL INSTEAD OF FULL APCH, CHANGE OF RWY ASSIGNMENTS CLOSE IN. CORRECTIVE: SHOULD HAVE STAYED WITH ORIGINAL RWY AND SLOWED TO FOLLOW TFC, MVFR WX CONDITIONS ARE NOT CONDUCIVE TO RWY CHANGES, FMC CAN GIVE YOU A FALSE SENSE OF SECURITY BECAUSE IT'S ALWAYS ACCURATE. THIS TIME IT WAS OFF 3 TO 5 MI, ALWAYS BACK UP WITH RAW DATA VFR OR IFR.

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.