B757-200
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Workload
Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented; Flight Crew Rejected Takeoff
Human Factors; Procedure
Pushed back onto ramp. Planned to depart runway XY with an RNAV departure as cleared. Expecting long taxi from ramp to [RWY] XY; but when we called for taxi; ATC issued departure/runway change to runway XX. As Captain; I was still in the long taxi mindset; so we started the (now very short) taxi to runway XX as the first officer worked on the runway and departure change. We arrived quickly at the hold short and simply forgot to configure. We went 'below the line' on taking the runway; thinking that the first part of the takeoff checklist was complete. On takeoff roll; as throttles were advanced; we received a takeoff configuration warning and immediately discontinued the takeoff. We communicated the situation with tower as we exited the runway. We then taxied back to the hold short; completed the required checklists; and completed an uneventful takeoff.Trying to do too much in too little time. When dealing with multiple changes; such as runway/SID changes; the urge to try and fit it all in the original timeline in the pilot's mind is very strong. Inevitably; this is when something slips through the cracks; in this case; an entire checklist. When something new or different occurs; that's the time to consciously slow down and double check everything. I learned a valuable lesson and am thankful for the protections afforded by the takeoff configuration warning system; although they are only a last line of defense. The first line is always the crew. When in doubt; slow down! If we had stopped the taxi still on the ramp and done the runway change there; things would have flowed much more normally through the 'cleared to configure' call. We would have given ourselves time instead of trying to do more with less time.
B757 Captain reports being issued a runway and SID change when calling for taxi. This results in the aircraft not being configured and the first part of the Before Takeoff Checklist not being accomplished. A takeoff warning sounds and the takeoff is rejected.