Narrative:

As we were cleared for taxi; we received a runway change from 01L to 01R. We queried the controller over this change; as our previous departure from las involved the same change; but was followed by a late change back to runway 01L. The controller indicated that 01R was the correct runway. I changed the departure in the FMC; verified performance for the new runway; and entered new takeoff speeds. We taxied around some construction on the way to runway 01R. We were cleared for takeoff; and taxied onto the runway. We completed the 'below the line' portion of the checklist. Captain called for standard power; and we noticed that the auto throttles were not advancing the throttles. The throttles were manually advanced slightly more; and the takeoff warning horn sounded. We realized the aircraft had not been properly configured. Speed was approx. 15-20 knots when we realized the mistake. We cleared the runway; configured the aircraft; completed the before takeoff checklist. Subsequent takeoff was uneventful. This was the third leg of the night; and thirteenth night leg of the trip. We were tired. The runway change; and the discussion with controller and ourselves concerning the possibility of a late change back to original runway. Got out of normal flow pattern. Long; slow taxi around construction. Increased attention to detail. Double or triple checking items after changes. Making sure flow pattern disruptions are mitigated properly.

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Original NASA ASRS Text

Title: B757 flight crew reports forgetting to configure their aircraft prior to attempting takeoff; due to distractions and fatigue. The takeoff warning horn sounds and the takeoff is rejected.

Narrative: As we were cleared for taxi; we received a runway change from 01L to 01R. We queried the controller over this change; as our previous departure from LAS involved the same change; but was followed by a late change back to RWY 01L. The controller indicated that 01R was the correct runway. I changed the departure in the FMC; verified performance for the new runway; and entered new takeoff speeds. We taxied around some construction on the way to runway 01R. We were cleared for takeoff; and taxied onto the runway. We completed the 'below the line' portion of the checklist. Captain called for standard power; and we noticed that the auto throttles were not advancing the throttles. The throttles were manually advanced slightly more; and the takeoff warning horn sounded. We realized the aircraft had not been properly configured. Speed was approx. 15-20 knots when we realized the mistake. We cleared the runway; configured the aircraft; completed the before takeoff checklist. Subsequent takeoff was uneventful. This was the third leg of the night; and thirteenth night leg of the trip. We were tired. The runway change; and the discussion with controller and ourselves concerning the possibility of a late change back to original runway. Got out of normal flow pattern. Long; slow taxi around construction. Increased attention to detail. Double or triple checking items after changes. Making sure flow pattern disruptions are mitigated properly.

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.