Narrative:

RVR on runways 26 and 27 at iah was going up and down, 1600- 3000 ft. There was a NOTAM published for the ILS to runway 27 that raised the decision ht and visibility for the approach. We elected to use runway 26 because of this. All other traffic was using runway 27. Notamed minimal visibility was 4000 ft RVR. We were cleared for the ILS runway 26 at iah at 4000 ft MSL, and intercepted the localizer and GS at that altitude. At 3- 4 mi outside the FAF approach gave new visibility readings. Runway 26 was partially blocked and not understood. At 1 mi to the marker runway 26 visibility was called at 1600 ft RVR. We continued and landed without incident. In recent training, I understood that once you are established on the GS and localizer that you are on the final approach segment and can continue regardless of new visibility reports. The first officer and I discussed it during the approach and he did not object. Afterwards he did object and I discussed it further with the chief pilot. He agreed with the first officer. I would really like to discuss this with one of your investigators. Callback conversation with reporter revealed the following information: reporter was given the reference to the rule that applies to the required procedure to use when the reported WX indicates below landing WX minimums before the OM is reached inbound on the final approach segment. Only when the final approach fix is not indicated, but the aircraft is established on final inbound can the approach be continued if the WX is reported at that time below minimum. This was a commuter operations with an ATR42 type aircraft.

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Original NASA ASRS Text

Title: CAPT OF AN MDT CONTINUED AN ILS APCH AFTER HE WAS GIVEN A WX RPT OF BELOW LNDG MINIMUM PRIOR TO REACHING THE FINAL APCH FIX.

Narrative: RVR ON RWYS 26 AND 27 AT IAH WAS GOING UP AND DOWN, 1600- 3000 FT. THERE WAS A NOTAM PUBLISHED FOR THE ILS TO RWY 27 THAT RAISED THE DECISION HT AND VISIBILITY FOR THE APCH. WE ELECTED TO USE RWY 26 BECAUSE OF THIS. ALL OTHER TFC WAS USING RWY 27. NOTAMED MINIMAL VISIBILITY WAS 4000 FT RVR. WE WERE CLRED FOR THE ILS RWY 26 AT IAH AT 4000 FT MSL, AND INTERCEPTED THE LOC AND GS AT THAT ALT. AT 3- 4 MI OUTSIDE THE FAF APCH GAVE NEW VISIBILITY READINGS. RWY 26 WAS PARTIALLY BLOCKED AND NOT UNDERSTOOD. AT 1 MI TO THE MARKER RWY 26 VISIBILITY WAS CALLED AT 1600 FT RVR. WE CONTINUED AND LANDED WITHOUT INCIDENT. IN RECENT TRAINING, I UNDERSTOOD THAT ONCE YOU ARE ESTABLISHED ON THE GS AND LOC THAT YOU ARE ON THE FINAL APCH SEGMENT AND CAN CONTINUE REGARDLESS OF NEW VISIBILITY RPTS. THE FO AND I DISCUSSED IT DURING THE APCH AND HE DID NOT OBJECT. AFTERWARDS HE DID OBJECT AND I DISCUSSED IT FURTHER WITH THE CHIEF PLT. HE AGREED WITH THE FO. I WOULD REALLY LIKE TO DISCUSS THIS WITH ONE OF YOUR INVESTIGATORS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR WAS GIVEN THE REF TO THE RULE THAT APPLIES TO THE REQUIRED PROC TO USE WHEN THE RPTED WX INDICATES BELOW LNDG WX MINIMUMS BEFORE THE OM IS REACHED INBOUND ON THE FINAL APCH SEGMENT. ONLY WHEN THE FINAL APCH FIX IS NOT INDICATED, BUT THE ACFT IS ESTABLISHED ON FINAL INBOUND CAN THE APCH BE CONTINUED IF THE WX IS RPTED AT THAT TIME BELOW MINIMUM. THIS WAS A COMMUTER OPS WITH AN ATR42 TYPE ACFT.

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.