Narrative:

Approaching slc from sna the ATIS said runway 34L with visibility of 7/8 mi and variable. Closer in, they changed to runway 16R. I do not know why the wind was only 250/07. Runway 34L is a CAT III runway and runway 16R is only a CAT I runway. The visibility for 16R ILS was above the 1800 RVR and the first officer was flying and to make a CAT I approach with an autoland. On base leg we were at 7000 ft. We were given an intercept heading of 130 degrees and 'cleared for the ILS 16R approach to maintain 7000 ft until established on the localizer.' after established on the localizer, we were authorized to descend to 6100 ft. The autoplt established on the localizer and we chose to stay at 7000 ft as we were under the GS at 7000 ft and let the autoplt intercept the GS at 7000 ft. At about 6700 ft going down the GS, approach advised that the 16R visibility at touchdown RVR was 1600 and rollout was 800 ft. That was below the 1800 touchdown RVR for 16R and runway was only a CAT I runway. The copilot and I talked briefly about whether we were legal to continue the approach as we had GS intercept and that we believed we were inside the final approach fix and therefore legal to continue the approach to mins of 200 ft AGL. The aircraft behind us broke off his approach as he was not legal for the approach. We were both (first officer and I) convinced we had passed the final approach fix as we had GS intercept. We continued the automatic approach to mins. At about 300 AGL we could see about 3/4 of the approach lights clearly, but could not see the runway end. We descended 100 below mins and at that time we could see the runway end lights. We continued and automatic landed. The visibility past the end of the runway was very good (more than 1/2 mi). The approach was safe and we were able to land from mins, but were we legal. That was the question. We had to wait 15 mins on the ground for our gate to open up. We used that time to look at our operations specifications to determine if we were legal or not. We determined that technically we were not legal to shoot the approach. We, at first, believed we were by the FAF at GS intercept altitude of 7000 ft, reading we learned the FAF was the OM or GS intercept at the GS intercept altitude of 6100 ft on the approach plate. This is a fact I will not easily forget, but at the time you have very little time to make a decision about am I legal or not. You could go into a holding pattern for 15 mins. I do wish we had a third crew member to help us who is a lawyer. If I have enough time, I can find the answer to almost anything, but sometimes I cannot always give you a correct answer off the top of my head.

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Original NASA ASRS Text

Title: ACR CONTINUES ON CAT I APCH AT GS INTERCEPT WHEN RVR DECREASES BELOW MINS.

Narrative: APCHING SLC FROM SNA THE ATIS SAID RWY 34L WITH VISIBILITY OF 7/8 MI AND VARIABLE. CLOSER IN, THEY CHANGED TO RWY 16R. I DO NOT KNOW WHY THE WIND WAS ONLY 250/07. RWY 34L IS A CAT III RWY AND RWY 16R IS ONLY A CAT I RWY. THE VISIBILITY FOR 16R ILS WAS ABOVE THE 1800 RVR AND THE FO WAS FLYING AND TO MAKE A CAT I APCH WITH AN AUTOLAND. ON BASE LEG WE WERE AT 7000 FT. WE WERE GIVEN AN INTERCEPT HDG OF 130 DEGS AND 'CLRED FOR THE ILS 16R APCH TO MAINTAIN 7000 FT UNTIL ESTABLISHED ON THE LOC.' AFTER ESTABLISHED ON THE LOC, WE WERE AUTHORIZED TO DSND TO 6100 FT. THE AUTOPLT ESTABLISHED ON THE LOC AND WE CHOSE TO STAY AT 7000 FT AS WE WERE UNDER THE GS AT 7000 FT AND LET THE AUTOPLT INTERCEPT THE GS AT 7000 FT. AT ABOUT 6700 FT GOING DOWN THE GS, APCH ADVISED THAT THE 16R VISIBILITY AT TOUCHDOWN RVR WAS 1600 AND ROLLOUT WAS 800 FT. THAT WAS BELOW THE 1800 TOUCHDOWN RVR FOR 16R AND RWY WAS ONLY A CAT I RWY. THE COPLT AND I TALKED BRIEFLY ABOUT WHETHER WE WERE LEGAL TO CONTINUE THE APCH AS WE HAD GS INTERCEPT AND THAT WE BELIEVED WE WERE INSIDE THE FINAL APCH FIX AND THEREFORE LEGAL TO CONTINUE THE APCH TO MINS OF 200 FT AGL. THE ACFT BEHIND US BROKE OFF HIS APCH AS HE WAS NOT LEGAL FOR THE APCH. WE WERE BOTH (FO AND I) CONVINCED WE HAD PASSED THE FINAL APCH FIX AS WE HAD GS INTERCEPT. WE CONTINUED THE AUTO APCH TO MINS. AT ABOUT 300 AGL WE COULD SEE ABOUT 3/4 OF THE APCH LIGHTS CLRLY, BUT COULD NOT SEE THE RWY END. WE DSNDED 100 BELOW MINS AND AT THAT TIME WE COULD SEE THE RWY END LIGHTS. WE CONTINUED AND AUTO LANDED. THE VISIBILITY PAST THE END OF THE RWY WAS VERY GOOD (MORE THAN 1/2 MI). THE APCH WAS SAFE AND WE WERE ABLE TO LAND FROM MINS, BUT WERE WE LEGAL. THAT WAS THE QUESTION. WE HAD TO WAIT 15 MINS ON THE GND FOR OUR GATE TO OPEN UP. WE USED THAT TIME TO LOOK AT OUR OPS SPECS TO DETERMINE IF WE WERE LEGAL OR NOT. WE DETERMINED THAT TECHNICALLY WE WERE NOT LEGAL TO SHOOT THE APCH. WE, AT FIRST, BELIEVED WE WERE BY THE FAF AT GS INTERCEPT ALT OF 7000 FT, READING WE LEARNED THE FAF WAS THE OM OR GS INTERCEPT AT THE GS INTERCEPT ALT OF 6100 FT ON THE APCH PLATE. THIS IS A FACT I WILL NOT EASILY FORGET, BUT AT THE TIME YOU HAVE VERY LITTLE TIME TO MAKE A DECISION ABOUT AM I LEGAL OR NOT. YOU COULD GO INTO A HOLDING PATTERN FOR 15 MINS. I DO WISH WE HAD A THIRD CREW MEMBER TO HELP US WHO IS A LAWYER. IF I HAVE ENOUGH TIME, I CAN FIND THE ANSWER TO ALMOST ANYTHING, BUT SOMETIMES I CANNOT ALWAYS GIVE YOU A CORRECT ANSWER OFF THE TOP OF MY HEAD.

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.