BAE4100 ACFT CROSSES RWY 21C AT DTW WITHOUT CLRNC.

Narrative

ACFT WAS ON THE 4TH LEG OF A 5 LEG DAY. CREW WAS WELL RESTED AND THE FIRST 3 LEGS WERE ALL UNEVENTFUL; CONDUCTED IN VMC CONDITIONS AND 'ON-TIME.' THE 4TH LEG WAS FLT AB FROM IAD TO DTW. TAXI; TKOF; CLBOUT; AND ENRTE PHASES WERE UNEVENTFUL. FO WAS FLYING THIS SEGMENT. THE LAST 30 MINS OF THE FLT WERE CONDUCTED IN IMC CONDITIONS. WX AT DTW WAS 2000 FT BROKEN AND 1 1/2 MI VISIBILITY IN LIGHT SNOW. A COUPLED ILS APCH WAS FLOWN TO RWY 21L AT DTW. ACFT LANDED NORMALLY AND WAS INSTRUCTED BY TWR TO TAXI ON TXWY F AND HOLD SHORT OF RWY 21C. FO READ BACK THE INSTRUCTIONS TO TWR AND THEN THE CAPT READ BACK THE INSTRUCTIONS TO THE FO. BOTH PLTS UNDERSTOOD. FO TOOK EYES OFF TAXI EVOLUTION FOR APPROX 15 SECONDS TO PERFORM POSTLNDG DUTIES. UPON COMPLETION OF POSTLNDG DUTIES; FO LOOKED UP AND BOTH PLTS REALIZED THE ACFT WAS ENCROACHING UPON RWY 21C. CAPT RAPIDLY ADVANCED THE PWR LEVERS TO CLR THE RWY ASAP VICE STOP ON THE RWY. AN ACFT HAD JUST TAKEN OFF OF RWY 21C AND WAS AT APPROX 600 FT AND TURNING OVERHEAD. BLOWING SNOW OBSCURED THE HOLD SHORT MARKINGS AND WE SUSPECT SNOW COVERED THE RWY SIGN FOR RWY 21C. VISIBILITY WAS POOR AND DETERIORATING RAPIDLY. THE FO WAS UNFAMILIAR WITH DTW; HAVING BEEN THERE ONLY ONCE PREVIOUSLY. THE CAPT HAD FLOWN TO DTW ON NUMEROUS OCCASIONS AND WAS FAMILIAR. THE EXPECTED TAXI TO THE GATE WAS BRIEFED PRIOR TO THE APCH; AND THIS WAS RECEIVED BY THE CREW. SNOW OBSCURING THE HOLD SHORT MARKS IS THE BEST EXPLANATION FOR THIS RWY XING. TXWYS WERE COVERED WITH PACKED SNOW; AND NEW SNOW WAS FALLING/BLOWING. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT EACH PLT KNEW THE INSTRUCTIONS REGARDING WHERE TO TURN OFF THE RWY AND TO HOLD SHORT OF THE NEXT RWY. THEIR PROB WAS THEY COULD NOT FIND ANYTHING TO HELP THEM LOCATE WHERE THE RWY WAS LOCATED. THERE WAS ENOUGH SNOW COVERAGE THAT TAXI LINES WERE NOT VISIBLE; NOR WERE ANY HOLD SHORT LINES VISIBLE. NO SIGNS ALERTING THEM TO RWY WERE VISIBLE. PLT REALLY WOULD LIKE TO SEE AN ILLUMINATED TFC LIGHT INSTALLED TO GIVE THEM A RED OR GREEN LIGHT TO HELP CTL ACFT MOVEMENT ACROSS THE RWY. THEY FELT THAT EVEN IF IT WERE SNOW COVERED THE SNOW WOULD PROBABLY GLOW THE COLOR THAT WAS ILLUMINATED. THEY HAVE MET 7 TIMES WITH THE FSDO TO ANSWER THEIR QUESTIONS. THERE WILL BE NO VIOLATION; BUT THE FSDO WILL BE RECOMMENDING A CHANGE IN SIGNAGE AT THAT INTXN. FSDO WAS NOT BOTHERED AS MUCH BY THE RWY INCURSION; BUT WHEN THE FLT CROSSED THE ACTIVE RWY WITHOUT CLRNC; THAT DREW THE IRE OF FSDO. SUPPLEMENTAL INFO FROM ACN 358075: AS WE CAUTIOUSLY TAXIED BECAUSE OF THE CONDITIONS WE OBSERVED AN ACFT ABOUT 500 FT HIGH AND IN A L TURN AND REALIZED WE HAD ENCROACHED ON THE RWY WE WERE TO HOLD SHORT OF. DUE TO NOT KNOWING WHETHER OR NOT ANOTHER ACFT WAS TO BE USING THE RWY. I ELECTED TO CONTINUE XING WITHOUT AUTHORIZATION TO AVOID ANY SEPARATION INFRINGEMENT. HAD I STOPPED I WOULD HAVE HAD PART OF MY ACFT ON AN ACTIVE RWY. CRM WAS EXCELLENT BTWN CREW MEMBERS AND WE WERE PROCEEDING WITH CAUTION. SOLUTION: THE YELLOW FLASHING LIGHTS WORK WELL IN BOTH GETTING YOUR ATTN AS WELL AS IDENTING THE RWY. NOTE: OUR COMPANY HAS HAD 5 SUCH OCCURRENCES AND WE ARE REALLY CONCERNED OF THE POSSIBLE CONSEQUENCES AND ARE LOOKING FOR SOLUTIONS FOR OUR TRAINING TO IMPLEMENT AND WOULD WELCOME ANY SUGGESTIONS.