Narrative:

It was my second time in stl and the first time to taxi to runway 12L. The early morning was still dark with an indefinite ceiling and visibility at 7/8 of a mi with light rain. There was no landing traffic at the early hour and one other departing turbojet, who was directed to follow me. We were cleared to taxi from the ramp to runway 12L via taxiway east. Immediately after crossing runway 12R at taxiway east, tower cleared us for takeoff on runway 12L. The copilot was accomplishing the before takeoff checklist as we approached the intersection of txwys east, C, and P. I could see runway 12L, but in the dark, rain, and low visibility, it appeared to extend past the intersection. In order to get the full length for takeoff, I could turn slightly left and take the next right. That course of action put us on runway 6/24, which was an active runway with no traffic. Tower was notified and they directed us to taxi down runway 6 to runway 12R for takeoff, which we did. Reviewing what happened, the visual cue of the short overrun, or taxiway, connecting runway 12L to runway 6/24 and my unfamiliarity with the airport contributed to the confusion. One possible recommendation is that in low visibility, aircraft use taxiway C from the ramp area instead of taxiway east when runway 12L is in use. As a side note: this departure represented a radical change in body clock, with the previous departures at the first flight of the work day coming at XA00 eastern and XA39 eastern.

Related reports:

Google
 

Original NASA ASRS Text

Title: RWY INCURSION, UNAUTH RWY ENTRY OP XING.

Narrative: IT WAS MY SECOND TIME IN STL AND THE FIRST TIME TO TAXI TO RWY 12L. THE EARLY MORNING WAS STILL DARK WITH AN INDEFINITE CEILING AND VISIBILITY AT 7/8 OF A MI WITH LIGHT RAIN. THERE WAS NO LNDG TFC AT THE EARLY HR AND ONE OTHER DEPARTING TURBOJET, WHO WAS DIRECTED TO FOLLOW ME. WE WERE CLRED TO TAXI FROM THE RAMP TO RWY 12L VIA TXWY E. IMMEDIATELY AFTER XING RWY 12R AT TXWY E, TWR CLRED US FOR TKOF ON RWY 12L. THE COPLT WAS ACCOMPLISHING THE BEFORE TKOF CHKLIST AS WE APCHED THE INTXN OF TXWYS E, C, AND P. I COULD SEE RWY 12L, BUT IN THE DARK, RAIN, AND LOW VISIBILITY, IT APPEARED TO EXTEND PAST THE INTXN. IN ORDER TO GET THE FULL LENGTH FOR TKOF, I COULD TURN SLIGHTLY L AND TAKE THE NEXT R. THAT COURSE OF ACTION PUT US ON RWY 6/24, WHICH WAS AN ACTIVE RWY WITH NO TFC. TWR WAS NOTIFIED AND THEY DIRECTED US TO TAXI DOWN RWY 6 TO RWY 12R FOR TKOF, WHICH WE DID. REVIEWING WHAT HAPPENED, THE VISUAL CUE OF THE SHORT OVERRUN, OR TXWY, CONNECTING RWY 12L TO RWY 6/24 AND MY UNFAMILIARITY WITH THE ARPT CONTRIBUTED TO THE CONFUSION. ONE POSSIBLE RECOMMENDATION IS THAT IN LOW VISIBILITY, ACFT USE TXWY C FROM THE RAMP AREA INSTEAD OF TXWY E WHEN RWY 12L IS IN USE. AS A SIDE NOTE: THIS DEP REPRESENTED A RADICAL CHANGE IN BODY CLOCK, WITH THE PREVIOUS DEPS AT THE FIRST FLT OF THE WORK DAY COMING AT XA00 EASTERN AND XA39 EASTERN.

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.