UNAUTHORIZED RWY OP ENTRY.

Narrative

COPLT CALLED PHL GND CTL FOR TAXI INSTRUCTIONS; WHICH WERE TO TAXI TO RWY 9L. I TAXIED OUT OF OUR PARKING AREA STRAIGHT AHEAD AND CROSSED 9L; PROCEEDING TO 27L. TWR ADVISED US OF OUR MISTAKE AND GAVE US ROUTING BACK TO RWY 9L. NO OTHER ACFT WERE MOVING ON THE GND AT THIS TIME; NOR WERE ANY TAKING OFF OR LNDG (UNUSUAL FOR PHL). NO CONFLICTS EXISTED (I DID CLR 9L BEFORE XING IT). COMMENTS: THIS IS A CLASSIC HEARBACK ERROR ON MY PART. THE SAME AS THE ONES I HAVE BEEN READING ABOUT IN 'CALLBACK' FOR THE LAST MANY MONTHS. I HAD BEEN FLYING THIS SAME TRIP FOR THE LAST SEVERAL WKS; ALWAYS USING RWY 27L FOR DEP. I WAS PREPARED TO TAXI TO 27L; I STARTED BOTH ENGS FOR THE SHORT TAXI; I HEARD (WANTED TO HEAR) 27L IN THE TAXI INSTRUCTIONS; AND I PRESSED ON AS NORMAL (?) TO 27L! THIS WAS MY FIFTH STRAIGHT DAY OF FLYING AND I FEEL THAT MY ATTN AND CONCENTRATION WERE FADING DUE TO MANY EARLY WAKE-UPS AND FEW LONG BREAKS. I WAS LOOKING FORWARDED TO GETTING HOME THIS SAME EVENING. (REASONS FOR INCREASED VIGILANCE!) COMMENTS: I DON'T KNOW WHERE MY COPLT'S ATTN WAS DIRECTED AT THE TIME WE CROSSED THE 9L RWY. HE WAS OBVIOUSLY DOING SOMETHING OTHER THAN PAYING ATTN OUTSIDE THE ACFT (AS WT AND BAL; TKOF SPDS; ETC) OR WAS TOTALLY UNFAMILIAR WITH THE TAXI RTE. EVEN THOUGH HE READ BACK THE TAXI CLRNC; HE WAS UNAWARE OF OUR ERROR UNTIL GND CTLR CONTACTED US. HE HAD MADE SURE THAT I KNEW THAT HE WAS A 'VERY EXPERIENCED' PLT; HAVING FLOWN CAPT FOR OTHER AIRLINES. I WOULD BE INTERESTED IN READING HIS NASA RPT ON THIS INCIDENT! HE FELT THE INCIDENT WAS NO BIG DEAL. I FELT TOTALLY EMBARRASSED AND BELIEVED IT TO BE A MAJOR ERROR; ESPECIALLY IN A 2 MAN COCKPIT ACR!