Narrative:

Deviation from clearance taxi/ramp. Taxiing from gate to runway 9L. Instructions: right on txwys B, A7, T, H and runway 9L. Turned onto taxiway a instead of taxiway B. Realized my mistake shortly thereafter and attempted to turn out to taxiway B at next intersection as first officer attempted to notify ground of our/my error. Radio frequency very busy (go figure). Initial turn missing taxiway B was after looking at sign identing taxiway B, which seemed to have been physically close enough to taxiway a to be misleading. At some airports, such as ord, the inner is taxiway a and the outer taxiway B. At some airports, such as stl, taxiway B is the inner and taxiway a is the outer. I may sometimes find confusion between what is taxiway a and what is taxiway B, but I always know the inner from the outer. It would be good if this were standardized, so that taxiway a is always the inner and taxiway B is always the outer. Also after going the wrong way the best course of action would be to stop until it is worked out with the ground controller. The first officer had the commercial chart out, but looked down (to attend to another duty) just as I made the wrong turn. Callback conversation with reporter revealed the following information: the captain reported he was momentarily confused approaching the taxiway. The first officer had the airport plate page out, and was following along. The captain considers the first officer a superior pilot. After the captain had the taxiway incursion the ATCT ground controller told them there was no problem.

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Original NASA ASRS Text

Title: MD82 CREW HAD A TXWY INCURSION AFTER THE CAPT MISSED THE TURN ONTO TXWY B AT ORD.

Narrative: DEV FROM CLRNC TAXI/RAMP. TAXIING FROM GATE TO RWY 9L. INSTRUCTIONS: R ON TXWYS B, A7, T, H AND RWY 9L. TURNED ONTO TXWY A INSTEAD OF TXWY B. REALIZED MY MISTAKE SHORTLY THEREAFTER AND ATTEMPTED TO TURN OUT TO TXWY B AT NEXT INTXN AS FO ATTEMPTED TO NOTIFY GND OF OUR/MY ERROR. RADIO FREQ VERY BUSY (GO FIGURE). INITIAL TURN MISSING TXWY B WAS AFTER LOOKING AT SIGN IDENTING TXWY B, WHICH SEEMED TO HAVE BEEN PHYSICALLY CLOSE ENOUGH TO TXWY A TO BE MISLEADING. AT SOME ARPTS, SUCH AS ORD, THE INNER IS TXWY A AND THE OUTER TXWY B. AT SOME ARPTS, SUCH AS STL, TXWY B IS THE INNER AND TXWY A IS THE OUTER. I MAY SOMETIMES FIND CONFUSION BTWN WHAT IS TXWY A AND WHAT IS TXWY B, BUT I ALWAYS KNOW THE INNER FROM THE OUTER. IT WOULD BE GOOD IF THIS WERE STANDARDIZED, SO THAT TXWY A IS ALWAYS THE INNER AND TXWY B IS ALWAYS THE OUTER. ALSO AFTER GOING THE WRONG WAY THE BEST COURSE OF ACTION WOULD BE TO STOP UNTIL IT IS WORKED OUT WITH THE GND CTLR. THE FO HAD THE COMMERCIAL CHART OUT, BUT LOOKED DOWN (TO ATTEND TO ANOTHER DUTY) JUST AS I MADE THE WRONG TURN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CAPT RPTED HE WAS MOMENTARILY CONFUSED APCHING THE TXWY. THE FO HAD THE ARPT PLATE PAGE OUT, AND WAS FOLLOWING ALONG. THE CAPT CONSIDERS THE FO A SUPERIOR PLT. AFTER THE CAPT HAD THE TXWY INCURSION THE ATCT GND CTLR TOLD THEM THERE WAS NO PROB.

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.