Narrative:

A training flight was being conducted for a first officer. Numerous and multiple approachs were executed to mfd. The WX was up and down throughout the afternoon due to precipitation and fog. An ILS runway 32 approach was conducted to runway 32 at mfd airport. The WX was rain/fog (RVR 2400 ft) when the approach was initiated. Inside the final approach fix (OM, GS intercept) approach control told us to contact the mfd tower. On approximately a 2-3 mi final the tower was contacted and a clearance for the option to runway 32 was received. The tower also stated the RVR was at 2000 ft. When 100 ft above decision altitude was reached the approach lighting system was in full view. We continued the approach to the decision altitude, at which time the runway environment (threshold markings, touchdown zone, and centerline markings) came into full view. The aircraft was in a normal position to land and the runway environment was in sight. The first officer (PNF) called visual and we proceeded below decision altitude visually for a full stop landing on runway 32. In evaluating the situation, we could have abandoned the approach once the 2000 ft RVR report was received and we had reached the missed approach point. But as we approached 100 ft above decision altitude, we saw the appropriate environment (runway, lighting system) and continued. We had the required flight visibility (from cockpit) although the reported RVR was 2000 ft and 2400 ft RVR is published on plate. This has always seemed to be a gray area (part 91) and I, unfortunately, do not have the age old answer.

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Original NASA ASRS Text

Title: MDT ON TRAINING FLT QUESTIONS APCH AND LNDG WITH MINIMUMS LOW.

Narrative: A TRAINING FLT WAS BEING CONDUCTED FOR A FO. NUMEROUS AND MULTIPLE APCHS WERE EXECUTED TO MFD. THE WX WAS UP AND DOWN THROUGHOUT THE AFTERNOON DUE TO PRECIPITATION AND FOG. AN ILS RWY 32 APCH WAS CONDUCTED TO RWY 32 AT MFD ARPT. THE WX WAS RAIN/FOG (RVR 2400 FT) WHEN THE APCH WAS INITIATED. INSIDE THE FINAL APCH FIX (OM, GS INTERCEPT) APCH CTL TOLD US TO CONTACT THE MFD TWR. ON APPROX A 2-3 MI FINAL THE TWR WAS CONTACTED AND A CLRNC FOR THE OPTION TO RWY 32 WAS RECEIVED. THE TWR ALSO STATED THE RVR WAS AT 2000 FT. WHEN 100 FT ABOVE DECISION ALT WAS REACHED THE APCH LIGHTING SYS WAS IN FULL VIEW. WE CONTINUED THE APCH TO THE DECISION ALT, AT WHICH TIME THE RWY ENVIRONMENT (THRESHOLD MARKINGS, TOUCHDOWN ZONE, AND CTRLINE MARKINGS) CAME INTO FULL VIEW. THE ACFT WAS IN A NORMAL POS TO LAND AND THE RWY ENVIRONMENT WAS IN SIGHT. THE FO (PNF) CALLED VISUAL AND WE PROCEEDED BELOW DECISION ALT VISUALLY FOR A FULL STOP LNDG ON RWY 32. IN EVALUATING THE SIT, WE COULD HAVE ABANDONED THE APCH ONCE THE 2000 FT RVR RPT WAS RECEIVED AND WE HAD REACHED THE MISSED APCH POINT. BUT AS WE APCHED 100 FT ABOVE DECISION ALT, WE SAW THE APPROPRIATE ENVIRONMENT (RWY, LIGHTING SYS) AND CONTINUED. WE HAD THE REQUIRED FLT VISIBILITY (FROM COCKPIT) ALTHOUGH THE RPTED RVR WAS 2000 FT AND 2400 FT RVR IS PUBLISHED ON PLATE. THIS HAS ALWAYS SEEMED TO BE A GRAY AREA (PART 91) AND I, UNFORTUNATELY, DO NOT HAVE THE AGE OLD ANSWER.

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.