Narrative:

It was a dark, rainy, low visibility night at ord. As we made the left turn at M5 onto M, ground switched us to tower frequency. Tower cleared us into position and hold. As we taxied for takeoff, I missed the last turn onto the runway and proceeded on the taxiway to runway 4/22. I then turned onto the concrete overrun area of runway 27L, which I thought was ok to taxi on. We were cleared to take off and only upon looking at the airport diagram, once we were airborne, did I realize that that area was not a taxiway.

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Original NASA ASRS Text

Title: MD80S ACFT TAXIING FOR TKOF, RPTR CAPT MISSED THE TXWY TO THE RWY, TURNED AROUND TO BACK TRACK AND ENCROACHED ON AN AREA NOT AUTH FOR TAXIING.

Narrative: IT WAS A DARK, RAINY, LOW VISIBILITY NIGHT AT ORD. AS WE MADE THE L TURN AT M5 ONTO M, GND SWITCHED US TO TWR FREQ. TWR CLRED US INTO POS AND HOLD. AS WE TAXIED FOR TKOF, I MISSED THE LAST TURN ONTO THE RWY AND PROCEEDED ON THE TXWY TO RWY 4/22. I THEN TURNED ONTO THE CONCRETE OVERRUN AREA OF RWY 27L, WHICH I THOUGHT WAS OK TO TAXI ON. WE WERE CLRED TO TAKE OFF AND ONLY UPON LOOKING AT THE ARPT DIAGRAM, ONCE WE WERE AIRBORNE, DID I REALIZE THAT THAT AREA WAS NOT A 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.