Narrative:

Phl was down to single runway (9L) due to snow removed on 9R and runway lighting problems on 35. The single runway operation, poor WX and peak travel time all combined to produce a very congested traffic situation. The ATIS was reporting the visibility at 1 1/2 in light ice pellets and fog. While on the vectored base leg for the ILS to 9R, sidestep to 9L, tower visibility was reported as 1 1/4. Upon hearing a change in visibility, the captain and I both checked our individual approach charts. While rechking the minimums, phl asked if we still had adequate visibility to shoot the approach. The captain said aloud that we did indicate that he expected me to relay that message to phl. As a category C aircraft, we required 1 1/2 while categories a & B require only 1 mi. Our approach speed was within the category B range however, so I told phl we did have minimums. We intercepted the final approach course, and while descending to minimums, gained visibility contact outside of 3 mi out. We sidestepped to 9L and landed west/O difficulty or incident. Upon shutdown we both retrieved our manuals and discussed the visibility question. The captain had merely misread the approach plate, feeling 1 mi was all that was required for the approach. I questioned his decision, but rationalized that our speed was within the category B minimums. Answer: when in doubt, talk it out. Further study indicated that, while when using speeds in the CAT D range you must adhere to CAT D minimums, but while using speeds in the CAT B range you must still adhere to the CAT C minimums, if your aircraft is certified as CAT C. A more broad preventative action would be to include those things we take for granted (charts, etc) in you personal study for proficiency. If you don't know exactly what each and every #/symbol means, look it up while you're on the ground--it's much easier and safer. Take nothing for granted.

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Original NASA ASRS Text

Title: MLG SHOT APCH WITH WX BELOW LEGAL MINIMUMS.

Narrative: PHL WAS DOWN TO SINGLE RWY (9L) DUE TO SNOW REMOVED ON 9R AND RWY LIGHTING PROBS ON 35. THE SINGLE RWY OPERATION, POOR WX AND PEAK TRAVEL TIME ALL COMBINED TO PRODUCE A VERY CONGESTED TFC SITUATION. THE ATIS WAS RPTING THE VISIBILITY AT 1 1/2 IN LIGHT ICE PELLETS AND FOG. WHILE ON THE VECTORED BASE LEG FOR THE ILS TO 9R, SIDESTEP TO 9L, TWR VISIBILITY WAS RPTED AS 1 1/4. UPON HEARING A CHANGE IN VISIBILITY, THE CAPT AND I BOTH CHKED OUR INDIVIDUAL APCH CHARTS. WHILE RECHKING THE MINIMUMS, PHL ASKED IF WE STILL HAD ADEQUATE VISIBILITY TO SHOOT THE APCH. THE CAPT SAID ALOUD THAT WE DID INDICATE THAT HE EXPECTED ME TO RELAY THAT MESSAGE TO PHL. AS A CATEGORY C ACFT, WE REQUIRED 1 1/2 WHILE CATEGORIES A & B REQUIRE ONLY 1 MI. OUR APCH SPD WAS WITHIN THE CATEGORY B RANGE HOWEVER, SO I TOLD PHL WE DID HAVE MINIMUMS. WE INTERCEPTED THE FINAL APCH COURSE, AND WHILE DSNDING TO MINIMUMS, GAINED VIS CONTACT OUTSIDE OF 3 MI OUT. WE SIDESTEPPED TO 9L AND LANDED W/O DIFFICULTY OR INCIDENT. UPON SHUTDOWN WE BOTH RETRIEVED OUR MANUALS AND DISCUSSED THE VISIBILITY QUESTION. THE CAPT HAD MERELY MISREAD THE APCH PLATE, FEELING 1 MI WAS ALL THAT WAS REQUIRED FOR THE APCH. I QUESTIONED HIS DECISION, BUT RATIONALIZED THAT OUR SPD WAS WITHIN THE CATEGORY B MINIMUMS. ANSWER: WHEN IN DOUBT, TALK IT OUT. FURTHER STUDY INDICATED THAT, WHILE WHEN USING SPDS IN THE CAT D RANGE YOU MUST ADHERE TO CAT D MINIMUMS, BUT WHILE USING SPDS IN THE CAT B RANGE YOU MUST STILL ADHERE TO THE CAT C MINIMUMS, IF YOUR ACFT IS CERTIFIED AS CAT C. A MORE BROAD PREVENTATIVE ACTION WOULD BE TO INCLUDE THOSE THINGS WE TAKE FOR GRANTED (CHARTS, ETC) IN YOU PERSONAL STUDY FOR PROFICIENCY. IF YOU DON'T KNOW EXACTLY WHAT EACH AND EVERY #/SYMBOL MEANS, LOOK IT UP WHILE YOU'RE ON THE GND--IT'S MUCH EASIER AND SAFER. TAKE NOTHING FOR GRANTED.

Data retrieved from NASA's ASRS site as of August 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.