B737-800 CREW HAD A RWY INCURSION AT ATL.

Narrative

FO'S LEG; WE HAD LANDED RWY 9R IN ATL. DAY VMC; VISUAL APCH; NORMAL LNDG AND ROLLOUT. FO TURNED OVER CTL OF AIRPLANE AT 60 KIAS. I ACKNOWLEDGED; ASSUMED CTL; AND EXITED RWY AT TXWY K. WHILE WE WERE EXITING RWY; TWR ISSUED INSTRUCTIONS TO HOLD SHORT OF RWY 9L. FO ACKNOWLEDGED HOLD SHORT INSTRUCTIONS. I WAS CLR ON THE NEED TO HOLD SHORT; NO CONFUSION. THIS WAS A RARE EVENT FOR ME TO HOLD SHORT OF RWY 9L ON TXWY K. I HAD DONE SO ON ADJACENT TXWY D HUNDREDS OF TIMES. FOR SOME REASON I LOST TRACK OF MY POS RELATIVE TO THE HOLD SHORT LINE. MY ATTN WAS FURTHER OUT; LOOKING AT THE RWY. I WAS TAXIING VERY SLOWLY; ABOUT A WALKING PACE. SUDDENLY I WAS AWARE THAT THE NOSE OF THE ACFT WAS BEYOND THE HOLD SHORT LINE. THIS WAS SIMULTANEOUS WITH THE TWR CTLR QUERYING US; 'YOU ARE HOLDING SHORT AREN'T YOU?' AND THE FO REPEATED TO ME 'HOLD SHORT.' HE THEN RESPONDED TO TWR: 'HOLDING SHORT.' I STOPPED IMMEDIATELY WITH THE NOSE OF THE ACFT ABOUT HALFWAY BTWN HOLD SHORT LINE AND RWY EDGE. AN INTL BOUND AIRBUS 340 ROTATED AND LIFTED OFF RIGHT IN FRONT OF OUR NOSE. VISIBILITY WAS EXCELLENT; MARKINGS WERE CLR. FOR SOME REASON; APCHING THIS RWY FROM THIS INTXN WAS DIFFERENT. IN THIS CASE AN INTXN AND RWY AREA I WAS VERY FAMILIAR WITH; BECAME UNFAMILIAR AND I LOST EXACT POSITIONAL AWARENESS. I HAVE BEEN AWARE OF RWY INCURSION ISSUES IN THE INDUSTRY. I GO TO MANY ARPTS WHERE THIS IS AN ISSUE. I PUT THIS AT THE TOP OF MY PRIORITY LIST; YET SOMEHOW ENDED UP PAST THE HOLD SHORT LINE. I HAVE NO EXCUSE; BUT I DON'T THINK I WOULD HAVE PASSED THE LINE IF THERE HAD BEEN FLASHING LIGHTS.