Narrative:

During taxi for takeoff we were informed to be ready for either runway 25 for takeoff and to hold short of 25L. We recomputed the numbers for 25L put the new runway in the flight plan and waited short of the runway for assignment. We were then told to cross 25L and 25R and turn right for full length on 25R and line up and wait. The first officer recomputed the numbers for 25R and put the new runway in the FMS. As I pushed the power up to turn onto the runway we got the takeoff warning horn and realized that we had not configured for takeoff. We probably could have asked to hold on the runway but we did not want to rush to configure so we told ATC that we needed to taxi clear of the runway to finish our checklist. They had us turn right on the first taxi way and to let them know when we were ready. We were never moving over 10 or 15 knots and did not use the brakes. We ran the rejected takeoff checklist to make sure we did not miss anything; then the after landing checklist; configured for runway 25R and completed the before takeoff checklist for an uneventful takeoff.the basic cause of this event was not knowing the departure runway and having to put new runways in the FMS three times. No excuse; but we just missed completing the checklist before taking the runway for takeoff.I usually wait until a runway assignment to configure. In this case lax has 25G available for both runways so we could have configured and then only had to enter the new runway into the FMS for the SID for each of the runway changes.

Related reports:

Google
 

Original NASA ASRS Text

Title: MD11 flight crew has their departure runway changed twice during taxi to the runway and forgets to accomplish the before takeoff checklist above the line. The takeoff warning sounds when thrust is pushed up due to flaps not being set and the takeoff is rejected at 10 knots.

Narrative: During taxi for takeoff we were informed to be ready for either Runway 25 for takeoff and to hold short of 25L. We recomputed the numbers for 25L put the new runway in the flight plan and waited short of the runway for assignment. We were then told to cross 25L and 25R and turn right for full length on 25R and line up and wait. The first officer recomputed the numbers for 25R and put the new runway in the FMS. As I pushed the power up to turn onto the runway we got the takeoff warning horn and realized that we had not configured for takeoff. We probably could have asked to hold on the runway but we did not want to rush to configure so we told ATC that we needed to taxi clear of the runway to finish our checklist. They had us turn right on the first taxi way and to let them know when we were ready. We were never moving over 10 or 15 knots and did not use the brakes. We ran the rejected takeoff checklist to make sure we did not miss anything; then the after landing checklist; configured for Runway 25R and completed the before takeoff checklist for an uneventful takeoff.The basic cause of this event was not knowing the departure runway and having to put new runways in the FMS three times. No excuse; but we just missed completing the checklist before taking the runway for takeoff.I usually wait until a runway assignment to configure. In this case LAX has 25G available for both runways so we could have configured and then only had to enter the new runway into the FMS for the SID for each of the runway changes.

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.