Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Loss Of Aircraft Control
Air Traffic Control Provided Assistance; Flight Crew Rejected Takeoff
Procedure
The Captain was pilot flying. Once cleared onto runway for takeoff; we were taxiing into position; and while making the turn to centerline; the engines were spooled up to about 40% N1. The Captain then adjusted his body position in his seat; inadvertently pushing the thrust levers past the position where the auto-throttles engaged; powering the engines up to full takeoff power; before we were completely lined up on centerline. This forced us through centerline and aimed towards the grass between taxiways 'X' and 'X1'. Immediately pulling the power back to idle; the Captain regained control and steered back to centerline. We then exited the runway at 'X1' which was about 1;000 feet from where we entered onto the runway; taxied back to runway; ran the before takeoff checklist and departed.Waiting until completely lined up on runway centerline before spooling the engines up past idle thrust. An additional measure that would have prevented this from happening is waiting until lined up on runway before arming the auto-throttle.
The First Officer of an Embraer EMB175 reported that they aborted takeoff because the throttles were inadvertently pushed past auto-throttle position for takeoff.