Date: 201811
Local time of day: 1801-2400
Location: SMF.Airport, CA
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Taxi
ATC / advisory: Ground SMF
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Situational Awareness
Second reporter function: Captain; Pilot Flying
Anomaly: Deviation / Discrepancy - Procedural Clearance; Ground Event / Encounter Object; Ground Incursion Taxiway
Detector: Automation Air Traffic Control; Person Flight Crew
When detected: Taxi
Result: Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew Returned To Gate; General Maintenance Action
Contributing factors: Airport; Human Factors
Primary problem: Human Factors

Narrative: We were taxiing on the parallel for takeoff on 34L at SMF. We were cleared for takeoff prior to reaching the turnoff for the runway. As a result; we began running the before takeoff check below the line. My head was down reading the checklist. I called for [engine checklist] and the Captain looked down at the engine instruments to see if they were normal. This occurred right as we were reaching the turnoff to the runway. When we both picked up our heads; we realized that we had missed the turn. We began to coordinate to have a tug tow us back. We also asked whether the taxiway was stressed for our airplane. In the confusion; while we were working ATC and ramp frequencies; ATC told us another company aircraft made the same mistake earlier and they cleared us to continue straight ahead and onto the apron for a 180 and then taxi back onto G1 or G2; our discretion. When we made the turn onto G1; we were notified by ATC that we ran over a taxi light on our right side. We went back to the ramp to have it inspected and to report it to the duty officer. After the airplane was inspected and cleared and the company authorized our departure; we had an uneventful flight to ZZZ1. We were both heads down while taxiing with visual illusion as well. Clearance should be B2; A; A13 to 34L. Put in the notes of the company pages that there is a risk of overshooting the runway entrance to 34L so it will be briefed.


Second narrative: We were cleared to taxi. My mental picture of the taxi was to the end of Taxiway A and right turn on the runway. I called for below the line after being cleared to takeoff. When we should have turned onto the runway; the checklist item required me to check the engine instruments. When I looked back up we noticed we should have turned. We informed Ground and they said continue on G1 and turn around on the ramp and taxi back. We asked if the taxi was stressed for our aircraft. While standing by we contacted our Ramp Maintenance to tow us. Ground Control came back and gave us taxi instructions to continue on G1 that our company aircraft just did the same thing. We proceeded as instructed. After turning around and back on to Taxiway A; we were told that we took out a taxi light. We then taxi back to gate to have gear inspected. No damage was found. Then continued flight. Both heads down in cockpit while aircraft was taxing.


Synopsis: Air carrier flight crew reported experiencing a taxiway incursion during taxi at SMF airport. Flight crew stated they hit a taxiway light while turning the aircraft around.