Narrative:

Catii hgs approach. While approaching hou, I got initial ATIS, which was recorded at XA36. It was calling calm winds, 5 mi visibility, 500 ft broken, patchy fog, temperature 4 degrees, dewpoint 4 degrees, and using runway 12R. The captain thought this would be a good opportunity to practice a catiii hgs for currency. We briefed the regular approach, and were set up for a simulated catiii. When we got a bit closer, they advised that new ATIS was now current. When I got new ATIS, the only thing that had changed was the runway now switched to runway 4. The ATIS still gave the time of XA36. While on downwind, we could see the ground in most places and the patchy ground fog in isolated areas. In fact, we could see part of the airport. While on base, the approach controller said the visibility was 1/4 mi. Nothing about RVR was said. We decided that we would continue using the special catii, which we needed 1600 RVR. We intercepted the localizer and GS and switched to tower. When at approximately 800 ft MSL (750 ft AGL) the controller said that the RVR was 800 ft for runway 4. At that point I looked at the captain and asked if we could do this on an hgs approach. He stated that he felt we could do a 'look see,' and we continued the approach. I called 'minimums' at 98 ft RA, and he said 'landing.' we landed without further incident and taxied to the gate. We both looked in the fom and couldn't find anywhere where it prohibited what we had just done. We both, for some reason, have in the back of our minds that we had read a memo with something to do with this, but were not sure. I feel what we did was legal, but I just have a nagging feeling that I read somewhere that we couldn't. An area of concern on this incident is who is responsible for giving/getting the RVR report? When you approach an airport and they are calling visibility of 5 mi and ceiling of 500 ft, you go into the mindset that this will be an 'easy' approach. I wonder in hindsight what the RVR was doing, while we were on the base leg of the approach. We kind of have an attitude of 'don't ask, don't tell.' if the visibility is so up and down, wouldn't you think the controller would initiate some kind of dialogue to indicate that? The frequency did not seem that busy at the time of our approach. I am in no way implicating the controller to be at fault, I am simply asking a question. We were the last crew to get in successfully, as word soon got out about the RVR. I would like to know if we did anything wrong (I'm sure you will tell us), and when the controllers are supposed to initiate telling us what the RVR was. I will also pay a little bit closer attention to the words 'patchy fog' in the ATIS. Even though you are in the sun, the WX can still be lousy.

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Original NASA ASRS Text

Title: B737-300 CREW QUESTIONED THE APCH LEGALITY AFTER PASSING THE FINAL APCH FIX, AND THE RVR WENT BELOW MINIMUMS.

Narrative: CATII HGS APCH. WHILE APCHING HOU, I GOT INITIAL ATIS, WHICH WAS RECORDED AT XA36. IT WAS CALLING CALM WINDS, 5 MI VISIBILITY, 500 FT BROKEN, PATCHY FOG, TEMP 4 DEGS, DEWPOINT 4 DEGS, AND USING RWY 12R. THE CAPT THOUGHT THIS WOULD BE A GOOD OPPORTUNITY TO PRACTICE A CATIII HGS FOR CURRENCY. WE BRIEFED THE REGULAR APCH, AND WERE SET UP FOR A SIMULATED CATIII. WHEN WE GOT A BIT CLOSER, THEY ADVISED THAT NEW ATIS WAS NOW CURRENT. WHEN I GOT NEW ATIS, THE ONLY THING THAT HAD CHANGED WAS THE RWY NOW SWITCHED TO RWY 4. THE ATIS STILL GAVE THE TIME OF XA36. WHILE ON DOWNWIND, WE COULD SEE THE GND IN MOST PLACES AND THE PATCHY GND FOG IN ISOLATED AREAS. IN FACT, WE COULD SEE PART OF THE ARPT. WHILE ON BASE, THE APCH CTLR SAID THE VISIBILITY WAS 1/4 MI. NOTHING ABOUT RVR WAS SAID. WE DECIDED THAT WE WOULD CONTINUE USING THE SPECIAL CATII, WHICH WE NEEDED 1600 RVR. WE INTERCEPTED THE LOC AND GS AND SWITCHED TO TWR. WHEN AT APPROX 800 FT MSL (750 FT AGL) THE CTLR SAID THAT THE RVR WAS 800 FT FOR RWY 4. AT THAT POINT I LOOKED AT THE CAPT AND ASKED IF WE COULD DO THIS ON AN HGS APCH. HE STATED THAT HE FELT WE COULD DO A 'LOOK SEE,' AND WE CONTINUED THE APCH. I CALLED 'MINIMUMS' AT 98 FT RA, AND HE SAID 'LNDG.' WE LANDED WITHOUT FURTHER INCIDENT AND TAXIED TO THE GATE. WE BOTH LOOKED IN THE FOM AND COULDN'T FIND ANYWHERE WHERE IT PROHIBITED WHAT WE HAD JUST DONE. WE BOTH, FOR SOME REASON, HAVE IN THE BACK OF OUR MINDS THAT WE HAD READ A MEMO WITH SOMETHING TO DO WITH THIS, BUT WERE NOT SURE. I FEEL WHAT WE DID WAS LEGAL, BUT I JUST HAVE A NAGGING FEELING THAT I READ SOMEWHERE THAT WE COULDN'T. AN AREA OF CONCERN ON THIS INCIDENT IS WHO IS RESPONSIBLE FOR GIVING/GETTING THE RVR RPT? WHEN YOU APCH AN ARPT AND THEY ARE CALLING VISIBILITY OF 5 MI AND CEILING OF 500 FT, YOU GO INTO THE MINDSET THAT THIS WILL BE AN 'EASY' APCH. I WONDER IN HINDSIGHT WHAT THE RVR WAS DOING, WHILE WE WERE ON THE BASE LEG OF THE APCH. WE KIND OF HAVE AN ATTITUDE OF 'DON'T ASK, DON'T TELL.' IF THE VISIBILITY IS SO UP AND DOWN, WOULDN'T YOU THINK THE CTLR WOULD INITIATE SOME KIND OF DIALOGUE TO INDICATE THAT? THE FREQ DID NOT SEEM THAT BUSY AT THE TIME OF OUR APCH. I AM IN NO WAY IMPLICATING THE CTLR TO BE AT FAULT, I AM SIMPLY ASKING A QUESTION. WE WERE THE LAST CREW TO GET IN SUCCESSFULLY, AS WORD SOON GOT OUT ABOUT THE RVR. I WOULD LIKE TO KNOW IF WE DID ANYTHING WRONG (I'M SURE YOU WILL TELL US), AND WHEN THE CTLRS ARE SUPPOSED TO INITIATE TELLING US WHAT THE RVR WAS. I WILL ALSO PAY A LITTLE BIT CLOSER ATTN TO THE WORDS 'PATCHY FOG' IN THE ATIS. EVEN THOUGH YOU ARE IN THE SUN, THE WX CAN STILL BE LOUSY.

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.