Narrative:

Ground instructions were to taxi to runway 23R. When we approached runway 23R the runway was marked as runway 23D. I was looking for the third runway on my chart or the reason for the discrepancy. When I looked up the captain had taxied onto runway 23 right/D. He thought he was cleared to runway 23L with no instructions to hold short of runway 23R. Supplemental information from acn 466436: in mexico city, taxiing to runway 23R did not notice that I was approaching the active runway. The hold sign said runway 23D and there was a long back taxi to get to takeoff portion of runway. Previous aircraft appeared to be taxiing, when in actuality he was back taxiing into position and hold.

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Original NASA ASRS Text

Title: EA-32 CREW HAD A RWY INCURSION ON RWY 23R AT MMMX.

Narrative: GROUND INSTRUCTIONS WERE TO TAXI TO RWY 23R. WHEN WE APPROACHED RWY 23R THE RWY WAS MARKED AS RWY 23D. I WAS LOOKING FOR THE THIRD RWY ON MY CHART OR THE REASON FOR THE DISCREPANCY. WHEN I LOOKED UP THE CAPT HAD TAXIED ONTO RWY 23 R/D. HE THOUGHT HE WAS CLEARED TO RWY 23L WITH NO INSTRUCTIONS TO HOLD SHORT OF RWY 23R. SUPPLEMENTAL INFO FROM ACN 466436: IN MEXICO CITY, TAXIING TO RWY 23R DID NOT NOTICE THAT I WAS APPROACHING THE ACTIVE RWY. THE HOLD SIGN SAID RWY 23D AND THERE WAS A LONG BACK TAXI TO GET TO TAKEOFF PORTION OF RWY. PREVIOUS ACFT APPEARED TO BE TAXIING, WHEN IN ACTUALITY HE WAS BACK TAXIING INTO POSITION AND HOLD.

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.