Narrative:

While on final to san 27 localizer RVR was called at 5500-4500 ft. Our charts show only visibility requirements of 1 3/4, not RVR. Tower called visibility at 2 mi. We have no reference to guide us on whether we could use mi or RVR on approach. We did not have time or fuel to go missed approach while we looked up appropriate conversion and could not find any guidance after we landed. We were given WX of 800 ft broken 2 rain showers. Before we were on the final approach segment, the aircraft ahead of us was given RVR of 5500 ft. Our plates show required visibility of 1 3/4 mi, with no RVR value given. The approach, in hard rain, is bad enough, requiring 2 pilots' full attention to fly the profile for a safe approach and landing. We had no time to look up legalities when a conflicting visibility value is given. Looking back, we should have missed and diverted for several reasons. By its definition, RVR top value is 6000 ft, which is less than 1 3/4 mi. So, if any RVR is given, and if it is indeed controling, visibility is less than the CAT C approach minimums. I recommend that an F-4 be added to san flight plans clarifying that if the tower gives an RVR value for the localizer 27 approach, it is below our minimums automatically. I further recommend that part 1 have some firm guidance to cover out situation.

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Original NASA ASRS Text

Title: VISIBILITY RPT FIRST IN MI, THEN RVR CONFUSED FLC AND ACFT LANDED BELOW VISIBILITY MINIMUMS.

Narrative: WHILE ON FINAL TO SAN 27 LOC RVR WAS CALLED AT 5500-4500 FT. OUR CHARTS SHOW ONLY VISIBILITY REQUIREMENTS OF 1 3/4, NOT RVR. TWR CALLED VISIBILITY AT 2 MI. WE HAVE NO REF TO GUIDE US ON WHETHER WE COULD USE MI OR RVR ON APCH. WE DID NOT HAVE TIME OR FUEL TO GO MISSED APCH WHILE WE LOOKED UP APPROPRIATE CONVERSION AND COULD NOT FIND ANY GUIDANCE AFTER WE LANDED. WE WERE GIVEN WX OF 800 FT BROKEN 2 RAIN SHOWERS. BEFORE WE WERE ON THE FINAL APCH SEGMENT, THE ACFT AHEAD OF US WAS GIVEN RVR OF 5500 FT. OUR PLATES SHOW REQUIRED VISIBILITY OF 1 3/4 MI, WITH NO RVR VALUE GIVEN. THE APCH, IN HARD RAIN, IS BAD ENOUGH, REQUIRING 2 PLTS' FULL ATTN TO FLY THE PROFILE FOR A SAFE APCH AND LNDG. WE HAD NO TIME TO LOOK UP LEGALITIES WHEN A CONFLICTING VISIBILITY VALUE IS GIVEN. LOOKING BACK, WE SHOULD HAVE MISSED AND DIVERTED FOR SEVERAL REASONS. BY ITS DEFINITION, RVR TOP VALUE IS 6000 FT, WHICH IS LESS THAN 1 3/4 MI. SO, IF ANY RVR IS GIVEN, AND IF IT IS INDEED CTLING, VISIBILITY IS LESS THAN THE CAT C APCH MINIMUMS. I RECOMMEND THAT AN F-4 BE ADDED TO SAN FLT PLANS CLARIFYING THAT IF THE TWR GIVES AN RVR VALUE FOR THE LOC 27 APCH, IT IS BELOW OUR MINIMUMS AUTOMATICALLY. I FURTHER RECOMMEND THAT PART 1 HAVE SOME FIRM GUIDANCE TO COVER OUT SIT.

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.