LNDG MINIMUMS -- ACR CONTINUES APCH EVEN THOUGH THE FLC WAS ADVISED; PRIOR TO THE FAF; THAT THE VISIBILITY WAS BELOW MINIMUMS.

Narrative

I WAS FLYING AS FO (PNF) ON A FLT FROM LCH TO IAH AFTER A REDUCED REST OVERNIGHT IN LCH. WX WAS IFR FOR THE FLT AND A NORMAL TKOF AND DEP WAS MADE. ENRTE CONDITIONS WERE VMC; HOWEVER; HOUSTON; IAH WAS IMC. I OBTAINED THE CURRENT ATIS AT THE TIME WHICH WAS CALLING FOR INDEFINITE CEILINGS 1/4 MI IN FOG AND RELAYED TO THE CAPT THE WX INFO. INCLUDED IN OUR WX PACKAGE WAS A NOTAM FOR IAH RWY 27 WHICH STATED THAT RVR 4000 FT IS THE MINIMUMS FOR THE ILS DUE TO A CRANE LOCATED IN THE VICINITY OF THE NEW ATC TWR. WE DECIDED THAT THE ILS TO RWY 26 WOULD BE THE BEST APCH BECAUSE RVR WAS RPTED TO BE GREATER THAN MINIMUMS. (I BELIEVE THAT THEY WERE CALLING FOR 1800 FT BUT IT WAS UP AND DOWN ALL MORNING). WE WERE TOLD TO JOIN THE LOC FOR RWY 26 AND THE CAPT ESTABLISHED THE ACFT ON THE LOC AND GS AT WHICH POINT HE ASKED IF WE WERE CLRED FOR THE APCH. APCH CTL THEN CLRED US FOR THE ILS RWY 26 APCH; RWY 26 RVR 1300 FT. WE WERE STILL OUTSIDE THE MARKER AND I WAS ABOUT TO ASK IF THIS WAS OK. HE THEN STATED 'IF YOU ARE WONDERING ABOUT THIS WE ARE STILL GOOD TO GO BECAUSE WE WERE ESTABLISHED ON THE APCH AND THE GS IS THE FINAL APCH FIX AND THE RVR WENT BELOW MINIMUMS AFTER WE WERE ESTABLISHED ON THE GS.' WITHIN A FEW SECONDS LATER; THE CAPT CALLED FOR GEAR DOWN; LNDG CHK. THE LNDG CHKLIST WAS ACCOMPLISHED AND A NORMAL LNDG WAS MADE. AFTER LNDG; TAXI; PARKING; AND SHUTDOWN WERE ALL MADE WITHOUT INCIDENT. AFTER DEPARTING THE ACFT; I QUERIED THE CAPT ABOUT THE DECISION TO CONTINUE THE APCH. HE REPLIED THAT IN HIS LAST PROFICIENCY CHK THAT THE SAME SIT WAS SIMULATED; AND HE WAS INSTRUCTED THAT BECAUSE HE WAS ESTABLISHED ON THE APCH (REGARDLESS OF DISTANCE IMPLIED) AND HAD INTERCEPTED THE GS THAT HE WAS ALREADY BEYOND THE FINAL APCH FIX AND COULD CONTINUE THE APCH. I DO NOT BELIEVE THAT THIS IS THE CASE. THE FINAL APCH FIX ON AN ILS IS THE PUBLISHED GS INTERCEPT ALT ON THE APCH PLATE. THIS IS WHERE THE FINAL APCH SEGMENT IS FLOWN; YOU CANNOT BEGIN TO FLY THE FINAL APCH SEGMENT OF AN ILS UNLESS THE RWY VISIBILITY ARE AT OR GREATER THAN PUBLISHED MINIMUMS. I THINK WE GOT CAUGHT WHEN WE INTERCEPTED THE GS ABOVE THE PUBLISHED INTERCEPT ALT; AND WE WERE NOTIFIED THAT THE RVR WAS LESS THAN PUBLISHED MINIMUMS. A MISSED APCH SHOULD HAVE BEEN EXECUTED AT THAT POINT. SEVERAL FACTORS CONTRIBUTED TO THE OCCURRENCE. FIRST WAS A CONFUSION ON THE REGS AND PROCS FOR AN ILS APCH. SECOND WAS MY ACCEPTANCE OF THE CAPT'S EXPLANATION DUE IN PART TO HIS STATUS AS A CHK AIRMAN; WHOM I THOUGHT KNOWS EVERYTHING. THIRD WAS THE FATIGUE AND STRESS CAUSED BY THE REDUCED REST THE NIGHT BEFORE; AND CONCERN FOR THE AIRLINE COMPANY ITSELF. I KNOW THAT I SHOULD HAVE PERSISTED WITH MY QUESTIONING OF THE APCH; CAPTS AND CHK AIRMAN DON'T KNOW IT ALL. LASTLY THIS WHOLE MESS COULD HAVE BEEN AVOIDED IF WE HAD CHOSEN THE ILS TO RWY 27; BECAUSE THE NOTAM WAS NOT IN EFFECT!