FLC BECAME DISORIENTED IN LOW VISIBILITY CONDITIONS AND FAILED TO FOLLOW TAXI INSTRUCTIONS. DURING THE TAXI THE ACFT NEARLY BLOCKED THE TAXI RTE OF ANOTHER ACFT.

Narrative

WE PUSHED A FEW MINS EARLY FOR AN XF30 DEP FROM IND ARPT. THE WX WAS UNEXPECTEDLY FOGGY AND THE RVR WAS RPTED VARYING FROM 500 FT TO 1400 FT DEPENDING ON THE RWY. AFTER AN UNEVENTFUL PUSHBACK AND ENGS START; WE WERE ISSUED THE FOLLOWING TAXI INSTRUCTIONS: TAXI TO RWY 5R; TAXI ON TXWY J; CROSS RWY 14/32; L ON TXWY P; R ON TXWY C.' PRIOR TO TAXI; WITH THE PARKING BRAKE STILL SET; THE FO AND I CONCURRED ON OUR TAXI INSTRUCTIONS REFING AN ARPT DIAGRAM (10-9). WITH VISIBILITY MINIMAL AND NO TXWY MARKERS VISIBLE; WE AGREED WE WERE AT THE END OF CONCOURSE C; FACING SE. WE WOULD NEED TO TAXI FORWARD THEN R ON TXWY J. THAT WAS OUR FIRST MISTAKE. UNLIKE THE PREVIOUS EXPERIENCES WE BOTH HAD IN INDIANAPOLIS OF ARRIVING AND DEPARTING FROM TXWY C1 OR TXWY C3; THIS MORNING WE DEPARTED FROM TXWY C2. UNBEKNOWNST TO US; TAXIING FORWARD THEN TURNING PUT US ON TXWY M. AS WE TAXIED NW ON TXWY M; THE FIRST TXWY MARKER WE CAME UPON INDICATED WE WERE APCHING TXWY G. I IMMEDIATELY STOPPED THE ACFT; SET THE PARKING BRAKE AND NOTIFIED GND CTL WE HAD MADE AN ERROR. AGAIN INCORRECTLY IDENTING OUR ORIGINAL START POINT; I TOLD GND I THOUGHT WE WERE ON TXWY H2; HOLDING SHORT OF TXWY G. AS I NOTICED A LIGHT MOVING FROM 2 O'CLOCK TO 1 O'CLOCK; I HEARD GND CLR ANOTHER ACFT TO TURN OFF TXWY G ONTO TXWY M. AS I WATCHED THIS LIGHT APPEAR TO TURN TOWARDS US; I BROADCAST ON GND CTL FREQ FOR 'THE ACFT ON TXWY G STOP.' HE COMPLIED IMMEDIATELY. I THEN NOTIFIED GND WE WERE IN FACT ON TXWY M FACING NW; HOLDING SHORT OF TXWY G. GND CTL THEN RERTED THE OTHER ACFT THEN CLRED US WITH FURTHER INSTRUCTIONS TO CONTINUE TAXIING TO RWY 5R. THE REMAINDER OF TAXI AND TKOF WAS UNEVENTFUL. THE RVR ON TKOF WAS 600/600/800. OUR MISTAKES ARE BLATANTLY OBVIOUS. WE INCORRECTLY IDENTED OUR POS TWICE WHILE TAXIING IN MINIMUM VISIBILITY CONDITIONS. I BELIEVE A MAJOR CONTRIBUTING FACTOR TO THOSE MISTAKES WAS THE EXTREMELY EARLY DEP TIME FOR A WEST COAST CREW. OUR WAKE-UP TIME WAS XD30 LCL OR XA30 HOME DOMICILE TIME. THE PREVIOUS DAY WE HAD A WAKEUP TIME OF XB15 HOME DOMICILE TIME. THE INTERRUPTION TO OUR NORMAL SLEEP PATTERNS IN COMBINATION WITH EXTREMELY LOW VISIBILITY AND THE SCARCITY OF TXWY MARKERS IN THE NEAR VICINITY CONTRIBUTED TO THIS SIT; A POSSIBLE INCIDENT AND POTENTIALLY CATASTROPHIC ACCIDENT.