Narrative:

We had taxi instruction to taxi to 22R intersection west. Shortly thereafter they amended instruction for takeoff 22 right full length. That became confusing with crossing a runway; going through hotspot; etc. We lost situational awareness in the process. We were cleared for takeoff quite some time prior to getting to the runway. The captain lined up on taxiway papa. Having already been cleared for takeoff the captain had already advanced the thrust levers up a bit and I took aircraft control. I slowly advanced the thrust levers and before pressing toga (take-off / go-around) I realized we were not on a runway but a taxiway. I stopped the aircraft immediately. ATC came on as I was stopping telling us to stop. They then told us to taxi on to 22R back taxi and we were cleared for takeoff.

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Original NASA ASRS Text

Title: B737 First Officer reported the Captain lined up for take off on a taxiway and started departure roll.

Narrative: We had taxi instruction to taxi to 22R intersection W. Shortly thereafter they amended instruction for takeoff 22 R full length. That became confusing with crossing a runway; going through hotspot; etc. We lost situational awareness in the process. We were cleared for takeoff quite some time prior to getting to the runway. The Captain lined up on taxiway papa. Having already been cleared for takeoff the Captain had already advanced the thrust levers up a bit and I took aircraft control. I slowly advanced the thrust levers and before pressing TOGA (Take-Off / Go-Around) I realized we were not on a runway but a taxiway. I stopped the aircraft immediately. ATC came on as I was stopping telling us to stop. They then told us to taxi on to 22R back taxi and we were cleared for takeoff.

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.