A320 CREW QUESTIONS WHETHER THEY HAD LEGAL LNDG MINIMUMS AT ROC.

Narrative

WHILE BEING VECTORED FOR A NIGHT INST APCH AT ROC; THE APCH CTLR ADVISED US THAT A PIREP FROM A FLT THAT HAD JUST LANDED INDICATED THAT THE PREVAILING VISIBILITY WAS ACTUALLY GREATER THAN THAT BEING RPTED; SO MUCH SO THAT THE CREW QUESTIONED THE ACCURACY OF THE RVR EQUIP (MINIMUMS ILS RWY 22 ARE RVR 2400 FT OR 1/2 MI). AS WE CONTINUED ON VECTORS; THE CTLR UPDATED THE ATIS TO INCLUDE VISIBILITY OF 3/4 MI (NO RVR GIVEN AT THAT TIME). HE ALSO GAVE US A SECOND PIREP FROM ANOTHER ACR THAT CONCURRED WITH THE FIRST RPT. WE ACCEPTED THE APCH CLRNC WITH VISIBILITY GREATER THAN 1/2 MI AND (WHAT WE CONSIDERED UNRELIABLE) RVR OF LESS THAN 2400 FT. AFTER WE HAD PASSED THE FAF INBOUND; THE TWR UPDATED THE RVR TO 2000 FT AND THEN 2200 FT. APCHING 1000 FT MSL (DECISION ALT 760 FT); WE PICKED UP THE APCH LIGHTS AND RWY; AS EXPECTED; AND LANDED UNEVENTFULLY. DURING TAXI; WE RELAYED OUR OBSERVATION THAT AFFIRMED THE ESTIMATED VISIBILITY OF 3/4 - 1 MI. THE ISSUE HERE IS ONE OF LEGALITY MORE THAN ANYTHING. OUR OPERATING SPECS ALLOW US TO CONTINUE AN APCH INSIDE THE FAF WITH LESS THAN REQUIRED RVR; AS LONG AS WE GET THE RVR AND THE VISUAL CUES NECESSARY TO COMPLETE A STABILIZED APCH TO LNDG BY THE TIME WE REACH THE CATI DECISION ALT. IN THIS CASE; WE HAD MORE THAN THE REQUIRED PREVAILING VISIBILITY; BUT NOT THE RVR. THE CONTRIBUTING FACTORS HERE WERE THE 2 PIREPS AND UNCERTAINTY WHETHER RVR WAS STILL CTLING IN THIS SIT. (ALTHOUGH IT WAS CERTAINLY SUSPECT; THE RVR SYS WAS STILL CONSIDERED OPERATIONAL BY ATC.) A SECONDARY FACTOR FOR ME PERSONALLY COULD HAVE BEEN FATIGUE IN THAT I HAD AWOKEN THAT MORNING AT XA00. COMBINED; THESE FACTORS AFFECTED THE DECISION-MAKING PROCESS.