Narrative:

Location: dfw. We were taxiing for takeoff on runway 18L. Contacted west ground on the bridge and were given straight ahead for runway 18L, which would be intersection Z takeoff. Asked the first officer to request a new tps since we didn't have data for intersection Z takeoff. Continued taxi, noting that there was only one other aircraft ahead of us. That aircraft had been holding short of runway 18L for awhile, so I thought it was probably going to the hangar, and expected that we would be cleared for takeoff as soon as we got to the runway. That assumption for whatever reason became a belief that we had been cleared into position on the runway. As we approached the runway, I asked the first officer, still busy with her takeoff data, if she was ready. She said, that we were not cleared into position and that we were still on ground control. I immediately stopped the aircraft, but we still crossed the hold short line by several feet. We were not obstructing the runway, and I had checked the final approach for traffic, so there was no conflict with landing traffic. We contacted the tower controller who did not express concern. Event was like ground school where you pretty much go when you're ready, possibly a little fatigue, and hoping for an expeditious departure since we were 2 hours late, are possible reasons.

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Original NASA ASRS Text

Title: AN S80 PIC CROSSES THE HOLD SHORT LINE FOR RWY 18L, BELIEVING HE HAD BEEN CLRED INTO POS AT DFW, TX.

Narrative: LOCATION: DFW. WE WERE TAXIING FOR TKOF ON RWY 18L. CONTACTED W GND ON THE BRIDGE AND WERE GIVEN STRAIGHT AHEAD FOR RWY 18L, WHICH WOULD BE INTXN Z TKOF. ASKED THE FO TO REQUEST A NEW TPS SINCE WE DIDN'T HAVE DATA FOR INTXN Z TKOF. CONTINUED TAXI, NOTING THAT THERE WAS ONLY ONE OTHER ACFT AHEAD OF US. THAT ACFT HAD BEEN HOLDING SHORT OF RWY 18L FOR AWHILE, SO I THOUGHT IT WAS PROBABLY GOING TO THE HANGAR, AND EXPECTED THAT WE WOULD BE CLRED FOR TKOF AS SOON AS WE GOT TO THE RWY. THAT ASSUMPTION FOR WHATEVER REASON BECAME A BELIEF THAT WE HAD BEEN CLRED INTO POS ON THE RWY. AS WE APCHED THE RWY, I ASKED THE FO, STILL BUSY WITH HER TKOF DATA, IF SHE WAS READY. SHE SAID, THAT WE WERE NOT CLRED INTO POS AND THAT WE WERE STILL ON GND CTL. I IMMEDIATELY STOPPED THE ACFT, BUT WE STILL CROSSED THE HOLD SHORT LINE BY SEVERAL FEET. WE WERE NOT OBSTRUCTING THE RWY, AND I HAD CHKED THE FINAL APCH FOR TFC, SO THERE WAS NO CONFLICT WITH LNDG TFC. WE CONTACTED THE TWR CTLR WHO DID NOT EXPRESS CONCERN. EVENT WAS LIKE GND SCHOOL WHERE YOU PRETTY MUCH GO WHEN YOU'RE READY, POSSIBLY A LITTLE FATIGUE, AND HOPING FOR AN EXPEDITIOUS DEP SINCE WE WERE 2 HRS LATE, ARE POSSIBLE REASONS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.