Narrative:

Landed on runway 19L, exited taxiway west. Ground told us to taxi to gate via a left turn onto txwys D to G to the ramp and to contact ramp control. As we progressed northbound on taxiway D, we made a right turn onto a taxiway (we thought it was taxiway G) but it turned out to be taxiway Z. We told ground that we had missed the turn onto taxiway G and if we should make a 180 degrees and back track? The controller replied 'no problem, taxi via txwys Z to west, contact ramp control upon joining taxiway west.' I called ramp and said that we were inbound. Ramp told us to stop where we were and that we had cut off an aircraft northbound on taxiway G. We had stopped the aircraft in the intersection of txwys west and G. The ramp controller asked us for 'our numbers,' which both of us really did not understand what he wanted. After 10 seconds or so, he clarified that he wanted to know what our gate was, and told us to taxi to the gate. There had been a DC9 taxiing north on taxiway G between txwys B and west and was not a factor, at least 1000 ft away (as we came to a stop he had dimmed his taxi light). Also, there was another carrier hooked up to a tug near taxi spot X which did not seem to be moving. Factors: 1) ground-ramp coordination. Based on a different taxi route than was originally issued, we should have been issued alternate instructions to either hold short of taxiway west on taxiway Z and call the ramp or, to make the turn at taxiway west and to hold short of taxiway D on taxiway west and call ramp. 2) familiarity. The usual taxi flow from runway 19L is via taxiway west, although the issued route was not that difficult to follow, the taxiway we turned onto (taxiway Z) is not depicted on the dec/xa/03, 10-9 for las (it parallels taxiway G just to the west and has taxiway lighting and taxi marks, but did not have a sign or paint near where we made the turn). At the end of 5 long legs and facing an aircraft swap we did not catch the error until we had already made the turn. 3) if taxiway Z was not 'officially' open yet, it should have had some sort of lighting, barricades or other markings that would have cued us into seeing that it was not our taxiway.

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Original NASA ASRS Text

Title: B737 FLT CREW INADVERTENTLY TURN ONTO NEW, NOT YET OFFICIAL TXWY Z, INSTEAD OF CLRED TXWY G.

Narrative: LANDED ON RWY 19L, EXITED TXWY W. GND TOLD US TO TAXI TO GATE VIA A L TURN ONTO TXWYS D TO G TO THE RAMP AND TO CONTACT RAMP CTL. AS WE PROGRESSED NBOUND ON TXWY D, WE MADE A R TURN ONTO A TXWY (WE THOUGHT IT WAS TXWY G) BUT IT TURNED OUT TO BE TXWY Z. WE TOLD GND THAT WE HAD MISSED THE TURN ONTO TXWY G AND IF WE SHOULD MAKE A 180 DEGS AND BACK TRACK? THE CTLR REPLIED 'NO PROB, TAXI VIA TXWYS Z TO W, CONTACT RAMP CTL UPON JOINING TXWY W.' I CALLED RAMP AND SAID THAT WE WERE INBOUND. RAMP TOLD US TO STOP WHERE WE WERE AND THAT WE HAD CUT OFF AN ACFT NBOUND ON TXWY G. WE HAD STOPPED THE ACFT IN THE INTXN OF TXWYS W AND G. THE RAMP CTLR ASKED US FOR 'OUR NUMBERS,' WHICH BOTH OF US REALLY DID NOT UNDERSTAND WHAT HE WANTED. AFTER 10 SECONDS OR SO, HE CLARIFIED THAT HE WANTED TO KNOW WHAT OUR GATE WAS, AND TOLD US TO TAXI TO THE GATE. THERE HAD BEEN A DC9 TAXIING N ON TXWY G BTWN TXWYS B AND W AND WAS NOT A FACTOR, AT LEAST 1000 FT AWAY (AS WE CAME TO A STOP HE HAD DIMMED HIS TAXI LIGHT). ALSO, THERE WAS ANOTHER CARRIER HOOKED UP TO A TUG NEAR TAXI SPOT X WHICH DID NOT SEEM TO BE MOVING. FACTORS: 1) GND-RAMP COORD. BASED ON A DIFFERENT TAXI RTE THAN WAS ORIGINALLY ISSUED, WE SHOULD HAVE BEEN ISSUED ALTERNATE INSTRUCTIONS TO EITHER HOLD SHORT OF TXWY W ON TXWY Z AND CALL THE RAMP OR, TO MAKE THE TURN AT TXWY W AND TO HOLD SHORT OF TXWY D ON TXWY W AND CALL RAMP. 2) FAMILIARITY. THE USUAL TAXI FLOW FROM RWY 19L IS VIA TXWY W, ALTHOUGH THE ISSUED RTE WAS NOT THAT DIFFICULT TO FOLLOW, THE TXWY WE TURNED ONTO (TXWY Z) IS NOT DEPICTED ON THE DEC/XA/03, 10-9 FOR LAS (IT PARALLELS TXWY G JUST TO THE W AND HAS TXWY LIGHTING AND TAXI MARKS, BUT DID NOT HAVE A SIGN OR PAINT NEAR WHERE WE MADE THE TURN). AT THE END OF 5 LONG LEGS AND FACING AN ACFT SWAP WE DID NOT CATCH THE ERROR UNTIL WE HAD ALREADY MADE THE TURN. 3) IF TXWY Z WAS NOT 'OFFICIALLY' OPEN YET, IT SHOULD HAVE HAD SOME SORT OF LIGHTING, BARRICADES OR OTHER MARKINGS THAT WOULD HAVE CUED US INTO SEEING THAT IT WAS NOT OUR TXWY.

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.