SA227 FO QUESTIONS THE LEGALITY OF A LOW RVR TKOF AT BIL.

Narrative

AFTER PREFLT WAS COMPLETE; I LISTENED TO ATIS WHICH RPTED THE ARPT VISIBILITY AT 1/4 SM WITH FREEZING FOG. I KNEW THE VISIBILITY WAS OK FOR DEP ON THIS PART 121 FLT. AFTER THE PAX WERE BOARDED; WE COMMENCED DEICING; STARTED ENGS AND BEGAN TAXIING FOR DEP. WE COMPLETED THE TAXI CHKS AND WERE DISCUSSING OUR HOLDOVER TIME (WE HAD ABOUT 4 MINS REMAINING). AS WE NEARED THE DEP END OF THE RWY; GND CTL CALLED US AND TOLD US THE RVR WAS 1000 FT. I ASKED THE CAPT IF THAT WAS ACCEPTABLE BECAUSE I COULD NOT SPECIFICALLY REMEMBER THE REQUIREMENTS FOR DEP BELOW 1/4 SM VISIBILITY. HE SAID HE DIDN'T KNOW BUT DIDN'T SEEM WORRIED. WE GOT TO THE END AND CALLED TWR FOR DEP. TWR SAID WE WERE CLR FOR TKOF AND THE RVR WAS NOW 1200 FT. WE DEPARTED WITHOUT INCIDENT. AFTER WE WERE AIRBORNE (ABOVE 10000 FT); I GOT OUT OUR COMPANY OPS MANUAL AND TURNED TO THE SECTION FOR DEP MINIMUMS. I READ THAT FOR DEP WITH RVR AT 1200 FT WE MUST HAVE CTRLINE LIGHTING; CTRLINE MARKINGS; AND 2 RVR RPTING SYS. THIS ARPT DID NOT HAVE CTRLINE LIGHTING; THUS THE LOWEST VISIBILITY WE COULD TAKE OFF WAS 1600 RVR. SEVERAL FACTORS CONTRIBUTED TO THIS SIT. FIRST; IT HAD BEEN MORE THAN 8 MONTHS SINCE WE HAD NEEDED TO WORRY ABOUT A DEP WITH SUCH LOW VISIBILITY. THIS WAS THE FIRST LOW VISIBILITY DAY OF THE WINTER SEASON AND SINCE ATIS WAS RPTING 1/4 SM VISIBILITY; WE HAD NOT REVIEWED THE PROCS FOR DEP BELOW 1600 FT RVR. SECONDLY; THE RPT OF 1000 FT RVR BY GND CTL CAUGHT US OFF GUARD. IT WAS RPTED AS WE NEARED THE DEP END OF THE RWY (LESS THAN 1 MIN FROM DEP). THIRDLY; SINCE WE HAD ONLY A FEW MINS REMAINING ON OUR HOLDOVER TIME; I FELT A LITTLE RUSHED AND DIDN'T FEEL I HAD TIME TO SEARCH THE OPS MANUAL TO DETERMINE IF IT WAS LEGAL. FOURTHLY; I DIDN'T FEEL WE WERE DOING ANYTHING WRONG; AS NEITHER THE CAPT NOR THE TWR INDICATED ANY APPREHENSION TO DEPARTING OR ANY OBJECTION TO THE RVR RPTS. SEVERAL THINGS CAN BE DONE TO PREVENT A SIT LIKE THIS FROM RECURRING. FIRST; I MUST KNOW THE FARS; REGS; COMPANY OPS SPECS; AND APPROPRIATE PROCS AT ALL TIMES; AND MEMORIZE APPLICABLE ONES WHICH I MAY NOT HAVE TIME TO LOOK UP. SECONDLY; I MUST PERIODICALLY REVIEW THESE PROCS AND KNOW THEM BEFORE I NEED THEM (NOT WAIT UNTIL WINTER HITS). AND THIRDLY; I MUST NOT DEPEND ON THE CAPT KNOWING EVERYTHING NOR EXPECT THE TWR TO STOP US FROM DOING SOMETHING THAT IS AGAINST OUR PROCS.