Narrative:

While taxiing from the ramp to runway 34L; I accidentally passed taxiway A13; the turn off to the runway. Taxiway a turns into taxiway G1; but it's still a straight taxiway. We'd already switched and talked to tower at that time. We realized what had happened about the same time tower called us. He said we were on G1; that it may not be strong enough for our weight and that we would need to do a 180. The first officer asked if that could be accomplished on the general aviation ramp; which he said we could. During the turn toward the general aviation ramp; our left main gear departed the taxiway briefly; but at the time; we didn't know. After turning around on that ramp; we continued up taxiway G2 to the regular taxiway; and followed instructions to taxiway A13. We were cleared for takeoff; but due to a fuel system alert; and probably better decision making; by then; we taxied back to the gate; where maintenance personnel inspected the gear; and worked through the alert. Unfortunately; this was human error. I was looking straight down the taxiway; which continues past the turnoff to the runway. It's pretty dark on that taxiway; and the only sign for taxiway A13 is on the left; which is opposite the turn direction; and is one of 3 small signs all together; and I accidentally missed it. My first thought; once we realized where we were was to stop and get towed; but it was about then that the controller spoke to us and said we needed to do the 180. To prevent another event like this; I would suggest a couple things. First; for me personally; is to obviously pay even closer attention; both to the chart and taxiways. That sign for the A13 turnoff is there; although it's not very prominent. Like the first officer and I discussed; we have to be 100% on; 100% of the time. I know we're all human and that's not realistic; but that's the aviation industry. I have to absolutely be certain at all times where I am. Having said that; I would also suggest some improvement to that area in the way of better signs. I feel there should be something pretty distinct at that intersection indicating 'you're at the end of the runway.' hindsight being 20/20; I would have told the controller that we were going to stop; even though we were told otherwise.

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Original NASA ASRS Text

Title: Air Carrier Captain reported experiencing a taxiway incursion at SMF airport. Then while turning the aircraft around; the left main gear went off the taxiway.

Narrative: While taxiing from the ramp to Runway 34L; I accidentally passed Taxiway A13; the turn off to the runway. Taxiway A turns into Taxiway G1; but it's still a straight taxiway. We'd already switched and talked to Tower at that time. We realized what had happened about the same time Tower called us. He said we were on G1; that it may not be strong enough for our weight and that we would need to do a 180. The First Officer asked if that could be accomplished on the General Aviation ramp; which he said we could. During the turn toward the General Aviation ramp; our left main gear departed the taxiway briefly; but at the time; we didn't know. After turning around on that ramp; we continued up Taxiway G2 to the regular taxiway; and followed instructions to Taxiway A13. We were cleared for takeoff; but due to a fuel system alert; and probably better decision making; by then; we taxied back to the gate; where maintenance personnel inspected the gear; and worked through the alert. Unfortunately; this was human error. I was looking straight down the taxiway; which continues past the turnoff to the runway. It's pretty dark on that taxiway; and the only sign for Taxiway A13 is on the left; which is opposite the turn direction; and is one of 3 small signs all together; and I accidentally missed it. My first thought; once we realized where we were was to stop and get towed; but it was about then that the controller spoke to us and said we needed to do the 180. To prevent another event like this; I would suggest a couple things. First; for me personally; is to obviously pay even closer attention; both to the chart and taxiways. That sign for the A13 turnoff is there; although it's not very prominent. Like the First Officer and I discussed; we have to be 100% on; 100% of the time. I know we're all human and that's not realistic; but that's the aviation industry. I have to absolutely be certain at all times where I am. Having said that; I would also suggest some improvement to that area in the way of better signs. I feel there should be something pretty distinct at that intersection indicating 'You're at the end of the runway.' Hindsight being 20/20; I would have told the controller that we were going to stop; even though we were told otherwise.

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.