Narrative:

Cleared to taxi south, cross runway 26 threshold, takeoff runway 26L. As I reached the south edge of runway 26 and looked ahead to runway 26L, I mistook it for the parallel taxiway. I turned sharply to line up on what I now thought was runway 26L. The first officer immediately stated we were on runway 26R. I directed the first officer to inform tower we were exiting runway 26R to the north side. Controller stated no harm, no foul. Darkness was a factor in identing runways/txwys. Also, some airports I transit have the 'new' in-taxiway amber lights across the taxiway to further identify/locate a runway hold short line runway 26L does not. The absence of those lights was not so much the factor as the fact that it looked 'different.' ie, if no airport had those lights, then I may have been more inclined to look out ahead and look for a runway (runway 26L). But since at some airports when you don't see the amber lights, it means there is no runway threshold there, I suddenly thought I had passed all runways. Supplemental information from acn #566436: cleared to taxi across runway 26R to runway 26L while crossing runway 26R, some confusion ensued as to what runway we were cleared onto. I asked the tower if we were cleared for takeoff on runway 26R, and he stated 'you better hurry.' we did not feel this clarified our instructions so we exited the runway immediately and got back in line for takeoff. The controller said, 'no harm, no foul.

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Original NASA ASRS Text

Title: B737 CREW CONFUSED RWY 26R FOR RWY 26L AND LINED UP ON RWY 26R FOR TKOF.

Narrative: CLRED TO TAXI S, CROSS RWY 26 THRESHOLD, TKOF RWY 26L. AS I REACHED THE S EDGE OF RWY 26 AND LOOKED AHEAD TO RWY 26L, I MISTOOK IT FOR THE PARALLEL TXWY. I TURNED SHARPLY TO LINE UP ON WHAT I NOW THOUGHT WAS RWY 26L. THE FO IMMEDIATELY STATED WE WERE ON RWY 26R. I DIRECTED THE FO TO INFORM TWR WE WERE EXITING RWY 26R TO THE N SIDE. CTLR STATED NO HARM, NO FOUL. DARKNESS WAS A FACTOR IN IDENTING RWYS/TXWYS. ALSO, SOME ARPTS I TRANSIT HAVE THE 'NEW' IN-TXWY AMBER LIGHTS ACROSS THE TXWY TO FURTHER IDENT/LOCATE A RWY HOLD SHORT LINE RWY 26L DOES NOT. THE ABSENCE OF THOSE LIGHTS WAS NOT SO MUCH THE FACTOR AS THE FACT THAT IT LOOKED 'DIFFERENT.' IE, IF NO ARPT HAD THOSE LIGHTS, THEN I MAY HAVE BEEN MORE INCLINED TO LOOK OUT AHEAD AND LOOK FOR A RWY (RWY 26L). BUT SINCE AT SOME ARPTS WHEN YOU DON'T SEE THE AMBER LIGHTS, IT MEANS THERE IS NO RWY THRESHOLD THERE, I SUDDENLY THOUGHT I HAD PASSED ALL RWYS. SUPPLEMENTAL INFO FROM ACN #566436: CLRED TO TAXI ACROSS RWY 26R TO RWY 26L WHILE XING RWY 26R, SOME CONFUSION ENSUED AS TO WHAT RWY WE WERE CLRED ONTO. I ASKED THE TWR IF WE WERE CLRED FOR TKOF ON RWY 26R, AND HE STATED 'YOU BETTER HURRY.' WE DID NOT FEEL THIS CLARIFIED OUR INSTRUCTIONS SO WE EXITED THE RWY IMMEDIATELY AND GOT BACK IN LINE FOR TKOF. THE CTLR SAID, 'NO HARM, NO FOUL.

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.