Narrative:

Dtw was in north flow. After pushback; we contacted ramp control for further instructions. We were told to taxi to spot 5 and contact ground control. We taxied west to taxiway K; then south toward what we thought was spot 5. After receiving taxi instructions to runway 4R; ground control notified us that we had taxied onto an active taxiway (K) without a clearance. We thought that the north ramp consisted of the area leading up to the median separating taxiways K and Y.this event occurred due to lack of attention to detail. The chart for the north ramp (10-9D) clearly shows that spot 5 is located on 'taxilane' east rather than taxiway K. Furthermore; gate notes; as well as text on the company departure page indicate the necessity to contact ground control prior to push back from those gates; as their proximity leads directly onto an active taxiway. We also noticed airport markings on the ramp area between the north ramp and the movement area - these markings were difficult to notice from our starting location.I think that it would not be difficult for a crew that is unfamiliar with the dtw north ramp to make a similar error in the future. An illustration on the north ramp chart 10-9D of a line demarcating the north ramp from the movement area would have helped to prevent this occurrence. Likewise; a cautionary note in the company pages to supplement the current text would be helpful.

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Original NASA ASRS Text

Title: Air carrier flight crew reported misunderstanding Ramp Control's taxi instructions and taxied on an active taxiway without clearance from Ground Control.

Narrative: DTW was in north flow. After pushback; we contacted Ramp Control for further instructions. We were told to taxi to Spot 5 and contact Ground Control. We taxied west to taxiway K; then south toward what we thought was Spot 5. After receiving taxi instructions to runway 4R; Ground Control notified us that we had taxied onto an active taxiway (K) without a clearance. We thought that the North Ramp consisted of the area leading up to the median separating taxiways K and Y.This event occurred due to lack of attention to detail. The chart for the North Ramp (10-9D) clearly shows that Spot 5 is located on 'Taxilane' E rather than Taxiway K. Furthermore; Gate notes; as well as text on the Company Departure page indicate the necessity to contact Ground Control prior to push back from those gates; as their proximity leads directly onto an active taxiway. We also noticed airport markings on the ramp area between the North Ramp and the movement area - these markings were difficult to notice from our starting location.I think that it would not be difficult for a crew that is unfamiliar with the DTW North Ramp to make a similar error in the future. An illustration on the North Ramp chart 10-9D of a line demarcating the North Ramp from the movement area would have helped to prevent this occurrence. Likewise; a cautionary note in the Company pages to supplement the current text would be helpful.

Data retrieved from NASA's ASRS site 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.