Narrative:

In order to make the taxi diagrams for iah more user-friendly, I took them to enlarge the portions we typically use, specifically the northeast corner from gates to runway 15L where numerous txwys intersect. The ramp area was also enlarged and graphically depicts both spots 1 and 2, but does not show a center taxi lane. The center lane is referenced only by a note on the bottom right of the page with an arrow extending to the south ramp area. I had highlighted this note, but it was hidden from view when I folded the enlarged diagram in half and placed it under my chart clip. In hindsight, I should have rewritten that note, as I did other pertinent notes, into the chart area that would be continuously visible. As it happened, we pushed nose west for runway 15L. Ramp cleared us to spot 1. I crossed the first taxi lane (that led to spot 2) then followed the next taxi lane to what I expected to be spot 1. But as I rolled up to the end, the lane terminated in a triangle labeled 'B747' etc. I looked at the tarmac to my left and there was spot 1. We had followed the center taxi lane. The first officer, unaware of the mistake, called ATC saying we were at spot 1. ATC issued taxi instructions to runway 15L. Since no other aircraft were observed anywhere near us on the ramp, we taxied with a slight left jog toward spot 1 and along the specified route to runway 15L. ATC made no complaints.

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Original NASA ASRS Text

Title: CL65 CAPT HAS DIFFICULTY DETERMINING THE CLRNC ROUTING DURING TAXI OUT DUE TO SPECIFIC HELPFUL NOTES HE HAD INADVERTENTLY HIDDEN FROM VIEW.

Narrative: IN ORDER TO MAKE THE TAXI DIAGRAMS FOR IAH MORE USER-FRIENDLY, I TOOK THEM TO ENLARGE THE PORTIONS WE TYPICALLY USE, SPECIFICALLY THE NE CORNER FROM GATES TO RWY 15L WHERE NUMEROUS TXWYS INTERSECT. THE RAMP AREA WAS ALSO ENLARGED AND GRAPHICALLY DEPICTS BOTH SPOTS 1 AND 2, BUT DOES NOT SHOW A CTR TAXI LANE. THE CTR LANE IS REFED ONLY BY A NOTE ON THE BOTTOM R OF THE PAGE WITH AN ARROW EXTENDING TO THE S RAMP AREA. I HAD HIGHLIGHTED THIS NOTE, BUT IT WAS HIDDEN FROM VIEW WHEN I FOLDED THE ENLARGED DIAGRAM IN HALF AND PLACED IT UNDER MY CHART CLIP. IN HINDSIGHT, I SHOULD HAVE REWRITTEN THAT NOTE, AS I DID OTHER PERTINENT NOTES, INTO THE CHART AREA THAT WOULD BE CONTINUOUSLY VISIBLE. AS IT HAPPENED, WE PUSHED NOSE W FOR RWY 15L. RAMP CLRED US TO SPOT 1. I CROSSED THE FIRST TAXI LANE (THAT LED TO SPOT 2) THEN FOLLOWED THE NEXT TAXI LANE TO WHAT I EXPECTED TO BE SPOT 1. BUT AS I ROLLED UP TO THE END, THE LANE TERMINATED IN A TRIANGLE LABELED 'B747' ETC. I LOOKED AT THE TARMAC TO MY L AND THERE WAS SPOT 1. WE HAD FOLLOWED THE CTR TAXI LANE. THE FO, UNAWARE OF THE MISTAKE, CALLED ATC SAYING WE WERE AT SPOT 1. ATC ISSUED TAXI INSTRUCTIONS TO RWY 15L. SINCE NO OTHER ACFT WERE OBSERVED ANYWHERE NEAR US ON THE RAMP, WE TAXIED WITH A SLIGHT L JOG TOWARD SPOT 1 AND ALONG THE SPECIFIED RTE TO RWY 15L. ATC MADE NO COMPLAINTS.

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.