COMMUTER ACFT CROSSES RWY WITHOUT CLRNC.

Narrative

WE TAXIED INTO SFO ABOUT 17 MINS LATE. OUR NEXT DEP WAS FLT TO SJC SCHEDULED QUICK DEP TIME OF XA40. AS WE SHUT DOWN FO LEFT THE COCKPIT TO DO HIS DUTIES; I STAYED INSIDE AND PICKED UP THE DEP ATIS (WHICH HAD BEEN CALLING FOR RWY 28 DEPS FOR THAT DAY) AND THEN CALLED FOR CLRNC TO SJC. WE WERE GIVEN THE (SFO GAP #2) DEP WHICH CALLS FOR TRACKING THE 281 DEG RADIAL OFF OF SFO WHEN DEPARTING THE RWYS 28. I LOOK UP THE DEP PROC ON MY APCH PLATE AND SET THE #1 NAV TO THAT DEP. ON TAXI OUT; THE FO CALLED FOR TAXI. INSTRUCTION FROM GND CTL WAS TO TAXI TO RWY 1 L VIA INNER FOXTROT OUTER; WHICH THE FO READ BACK CORRECTLY. HOWEVER I MYSELF MISUNDERSTOOD THE CLRNC AND ONLY REMEMBER HEARING (INNER FOXTROT OUTER) WHICH IS ALSO A NORMAL RTE WHEN TAXING TO THE RWYS 28. AT THIS POINT WE BEGAN TO TAXI AND I DID NOT CONFIRM WITH THE FO WHAT RWY WE WERE TAXING TO. I JUST ASSUMED I WAS HEADED FOR RWYS 28 (THIS HAS NOW SET A TRAP FOR THE EVENTS TO COME). AS WE BEGAN TO TAXI I LOOKED OFF TO MY R. IN THE DISTANCE I REMEMBER SEEING A CARGO 727 TAXIING OUT FOR TKOF. AS WE ARE PERFORMING THE TAXI CHKLIST; WE COME TO THE PAX BRIEFING PORTION AT WHICH THE FO BRIEFS THE PEOPLE AND I MONITOR THE RADIOS. WE ARE NOW ON THE INNER TXWY AND APCHING INTXN FOXTROT. I STILL ASSUME TO BE TAXIING FOR THE RWYS 28. AS I APCH AND TRANSITION TO THE OUTER TXWY AT FOXTROT; I LOOK S TO THE DEP END OF RWYS 1 TO SEE IF THE RWYS ARE CLR AS I PREPARE TO CROSS THEM AT FOXTROT. AT THIS POINT; I NOTICE THAT RWY 1L CLR AND THAT THERE ARE NO ACFT ON THAT RWY. I AM NOW ALSO AWARE THAT THE 727 THAT I HAD SEEN EARLIER IS ON A TXWY; HDG OVER TO RWY 1R AND ALSO THAT THERE IS A 737 IN POS ON RWY 1R. AT THIS POINT I BEGIN TO QUESTION IF WE ARE CLRED TO CROSS THE RWYS 1. AS THE FO FINISHES THE PAX BRIEF AND COMES BACK ON; I ASK HIM TO CONFIRM WITH GND CTL IF WE ARE CLRED TO CROSS THE RWYS 1. LOOKING PUZZLED HE ASKS IF WE ARE CLRED TO CROSS THE RWYS 1; HE MAY HAVE BELIEVED THAT WE WERE GIVEN A RWY CHANGE TO RWY 28 WHILE HE WAS BRIEFING. THERE WAS A LITTLE RADIO CONGESTION AND WE GOT NO RESPONSE FROM GND CTL ON OUR REQUEST. BECAUSE RWY 1L WAS CLR OF ACFT; I DECIDED TO CROSS IT AND NOT DISRUPT ANY FLOW OF TFC THAT MIGHT BE COMING UP BEHIND US. AFTER PASSING OVER RWY 1L; I CAME TO A COMPLETE STOP BECAUSE OF THE 737 THAT WAS SITTING ON RWY 1R AND WE HAD NOT YET HEARD BACK FROM GND CTL. AT THIS POINT WE ARE SITTING BTWN RWYS 1L AND 1R ON INTXN FOXTROT. THE GND CTLR NOW CALLS US AND ASKS US WHERE WE ARE GOING; I RESPOND; TO THE RWYS 28. HER RESPONSE IS WE ARE USING THE RWYS 1. SHE THEN CLRS US TO CROSS RWY 1R TO TXWY LIMA AND DOWN TO THE DEP END OF THE RWYS 1 FOR TKOF. I FEEL THAT THERE ARE A FEW FACTORS THAT MAY HAVE PREVENTED THIS SIT. FIRST OF ALL ON THE BEGINNING OF TAXI; IF THERE IS ANY DOUBT OR MISUNDERSTANDING; RECONFIRM WITH EACH OTHER OR ASK GND CTL AGAIN. IF WE HAD BEEN FURTHER ALONG IN OUR CHKLIST; TO THE (CREW BRIEF) PHASE -- THIS ERROR PROBABLY WOULD HAVE BEEN DISCOVERED; BECAUSE WE DISCUSS DEP PROCS HDGS AND ALT. RADIO CONGESTION; IF WE HAD GOTTEN A RESPONSE BACK FROM GND CTL ON OUR INITIAL REQUEST WE MAY HAVE BEEN CORRECTED PRIOR TO XING. ONE LAST THING IS NEVER ASSUME TO BE HELPING OUT BY NOT DISRUPTING THE FLOW ON WORKLOAD OF OTHERS; FOR IF CONFLICT ARISES YOU WILL BE RESPONSIBLE. SUPPLEMENTAL INFO FROM ACN 307088: BECAUSE OF PRIOR LEG CAPT THOUGHT SFO WAS STILL USING THE RWYS 28. I TRY TO MAKE A HABIT OF READING BACK THE TAXI CLRNC TO BOTH THE GND CTLR AND AGAIN TO THE CAPT. THIS IS NOT YET REFLEXIVE AND I MAY NOT HAVE REPEATED IT A SECOND TIME TO THE CAPT.