AN LJ55 CREW; TAXIING FOR TKOF AT PHL; TAXIED ACROSS AN ACTIVE RWY WITHOUT A CLRNC.

Narrative

WHILE TAXIING OUT FROM FBO AT PHL FOR DEP ON RWY 27L; WE WERE CLRED VIA TXWYS A AND D TO HOLD SHORT OF RWY 26. I WAS READING THE TAXI CHKLIST TO THE PF; AND PERFORMING VARIOUS TAXI ITEMS. WE STOPPED AND HELD SHORT OF RWY 26 ON TXWY D. WE WERE THEN CLRED TO CROSS RWY 26 AND TOLD TO HOLD SHORT OF RWY 35 ON TXWY K. I READ BACK THE CLRNC; AND THE PF PROCEEDED TO TAXI. I WENT BACK TO PERFORMING CHKLIST ITEMS; WHILE READING FROM THE CHKLIST. I WAS NOT AT THE MOMENT LOOKING OUTSIDE. WE WERE MOVING S ON TXWY D; WHICH PARALLELS RWY 35; AND INTERSECTS WITH RWY 27R. INSTEAD OF TURNING R (W) ON TXWY K TO HOLD SHORT OF RWY 35; THE PF CONTINUED S ON TXWY D AND CROSSED RWY 27R WITHOUT CLRNC; EXPECTING TO HOLD SHORT OF RWY 35 AT THE APCH END ON TXWY S. THIS ERROR WAS BROUGHT TO OUR ATTN BY GND. AT NO TIME WAS THERE A CONFLICT WITH ANOTHER ACFT. WE ACKNOWLEDGED THE ERROR; AND WERE CLRED TO TAXI TO RWY 27L; AND DEP. WE ARE BASED AT PHL; AND ARE VERY FAMILIAR WITH THE ENVIRONMENT. THE USUAL RTE OUT TO RWY 27L IS TXWY A; TXWY D XING BOTH RWY 26 AND RWY 27R; WHEN CLRED; THEN CROSS RWY 35 AT TXWY S TO RWY 27L. WE BOTH HEARD THE CLRNC; AND I NOTED A NOD FROM THE PF; BUT THE CHANGE TO THE 'USUAL' RTE APPARENTLY DIDN'T REGISTER. I SHOULD NOT HAVE HAD MY HEAD DOWN PERFORMING COCKPIT DUTIES WHILE MOVING; THUS REMOVING A CHK ON THE PF. IF I HAD BEEN LOOKING; I WOULD HAVE BROUGHT THE ERROR TO HIS ATTN BEFORE HE ENTERED AN ACTIVE RWY. SUPPLEMENTAL INFO FROM ACN 537283: CLRED TO TAXI ACROSS RWY 26 ON TXWY D HOLD SHORT OF RWY 35 AT TXWY K. NORMAL RTE TO RWY 27L IS TXWY D ACROSS RWY 26; RWY 27R; HOLD SHORT OF RWY 35 AT TXWY S. I'VE DONE THIS RTE SO MANY TIMES THAT I MUST HAVE BEEN ON AUTO OR SOMETHING AS I DID CROSS RWY 27R WITHOUT A CLRNC TO DO SO. COPLT WAS HEAD DOWN RUNNING THE CHKLIST AND DID NOT CATCH MY ERROR.