Narrative:

Departing from gate we were given the taxi clearance west bound on taxiway H; then B; J hold short runway 9R. We reviewed the airport diagram chart; and started the taxi out west bound on taxiway H. The chart appears to indicate that taxiway H turns into taxiway B just past the intersection of taxiway H and C; and it appears that taxiway B proceeds across runway 22R/4L. We followed what we thought from the chart was taxiway B across runway 22R/4L; as no hold short instruction was given for that runway; and prior to crossing verified landing traffic was exiting the runway. After crossing ATC instructed to hold short of taxiway J and contact them on a separate frequency. This is when we learned of our mistake and what the actual taxi route was supposed to be. They advised at that time that no traffic separation was compromised; no gars issued; and no immediate safety threat. Upon further review of the airport diagram the taxiway B curves to the left but the location of the taxiway designation for taxiway B on the diagram is misleading and is why we felt we were correctly following our taxi clearance. This event occurred because of a confusing airport diagram chart that inadequately shows the proper taxiway designation for the clearance we were issued. We were also severely delayed due to weather and the fact that our only FMS was deferred. We didn't know we had deviated from the clearance until we had crossed the runway. Better designation and clarification of the txwys in that area of the H intersection at B and of runway 22R/4L of the chicago ord airport diagram.

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Original NASA ASRS Text

Title: EMB 145 FLT CREW INADVERTENTLY CROSSED A RWY WHILE TAXIING FOR TKOF; CITING CONFUSION WITH CHART DEPICTION.

Narrative: DEPARTING FROM GATE WE WERE GIVEN THE TAXI CLRNC W BOUND ON TXWY H; THEN B; J HOLD SHORT RWY 9R. WE REVIEWED THE ARPT DIAGRAM CHART; AND STARTED THE TAXI OUT W BOUND ON TXWY H. THE CHART APPEARS TO INDICATE THAT TXWY H TURNS INTO TXWY B JUST PAST THE INTXN OF TXWY H AND C; AND IT APPEARS THAT TXWY B PROCEEDS ACROSS RWY 22R/4L. WE FOLLOWED WHAT WE THOUGHT FROM THE CHART WAS TXWY B ACROSS RWY 22R/4L; AS NO HOLD SHORT INSTRUCTION WAS GIVEN FOR THAT RWY; AND PRIOR TO CROSSING VERIFIED LNDG TFC WAS EXITING THE RWY. AFTER CROSSING ATC INSTRUCTED TO HOLD SHORT OF TXWY J AND CONTACT THEM ON A SEPARATE FREQUENCY. THIS IS WHEN WE LEARNED OF OUR MISTAKE AND WHAT THE ACTUAL TAXI ROUTE WAS SUPPOSED TO BE. THEY ADVISED AT THAT TIME THAT NO TFC SEPARATION WAS COMPROMISED; NO GARS ISSUED; AND NO IMMEDIATE SAFETY THREAT. UPON FURTHER REVIEW OF THE ARPT DIAGRAM THE TXWY B CURVES TO THE L BUT THE LOCATION OF THE TXWY DESIGNATION FOR TXWY B ON THE DIAGRAM IS MISLEADING AND IS WHY WE FELT WE WERE CORRECTLY FOLLOWING OUR TAXI CLRNC. THIS EVENT OCCURRED BECAUSE OF A CONFUSING ARPT DIAGRAM CHART THAT INADEQUATELY SHOWS THE PROPER TXWY DESIGNATION FOR THE CLRNC WE WERE ISSUED. WE WERE ALSO SEVERELY DELAYED DUE TO WEATHER AND THE FACT THAT OUR ONLY FMS WAS DEFERRED. WE DIDN'T KNOW WE HAD DEVIATED FROM THE CLRNC UNTIL WE HAD CROSSED THE RWY. BETTER DESIGNATION AND CLARIFICATION OF THE TXWYS IN THAT AREA OF THE H INTXN AT B AND OF RWY 22R/4L OF THE CHICAGO ORD ARPT DIAGRAM.

Data retrieved from NASA's ASRS site as of January 2009 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.