Narrative:

Taxiing out using variable flap position for takeoff. Runway change due to MEL item requiring no tailwind. First officer (I) repositioned flap for 17L and checklist was definitely accomplished and crew verified flap and slat position on panel and gauges. Throttle check for takeoff warning accomplished and no warning. As power was advanced for takeoff, warning horn immediately sounded. Captain aborted takeoff (speed approximately 10 KTS). Flaps were at 0 degrees with slate extended. Crew repositioned flaps. Again verified on gauges and panel light for slats. Checked takeoff warning (no warning) and made an uneventful takeoff. I am positive that the flap handle was knocked out by me when I was reaching to adjust radar. With variable flap settings on this aircraft the detent on some aircraft get worn out and this allows the handle to move back to the forward position. Since our flap setting was very low, the handle did not have to move very far. I have heard this situation happening to other crews and I have experienced partial flap retraction on takeoff roll with flaps moving on their own. After the tragedy in detroit I am very careful about the confign of the aircraft. This incident has not made me double-check again even after the checklist has been accomplished. Pilots (myself included) can easily be lulled into complacency, especially after the checks are done. I am very grateful the warning system broke the chain of events of a potentially serious situation.

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Original NASA ASRS Text

Title: TKOF ABORTED ACCOUNT FLAP WARNING.

Narrative: TAXIING OUT USING VARIABLE FLAP POS FOR TKOF. RWY CHANGE DUE TO MEL ITEM REQUIRING NO TAILWIND. F/O (I) REPOSITIONED FLAP FOR 17L AND CHKLIST WAS DEFINITELY ACCOMPLISHED AND CREW VERIFIED FLAP AND SLAT POS ON PANEL AND GAUGES. THROTTLE CHK FOR TKOF WARNING ACCOMPLISHED AND NO WARNING. AS PWR WAS ADVANCED FOR TKOF, WARNING HORN IMMEDIATELY SOUNDED. CAPT ABORTED TKOF (SPD APPROX 10 KTS). FLAPS WERE AT 0 DEGS WITH SLATE EXTENDED. CREW REPOSITIONED FLAPS. AGAIN VERIFIED ON GAUGES AND PANEL LIGHT FOR SLATS. CHKED TKOF WARNING (NO WARNING) AND MADE AN UNEVENTFUL TKOF. I AM POSITIVE THAT THE FLAP HANDLE WAS KNOCKED OUT BY ME WHEN I WAS REACHING TO ADJUST RADAR. WITH VARIABLE FLAP SETTINGS ON THIS ACFT THE DETENT ON SOME ACFT GET WORN OUT AND THIS ALLOWS THE HANDLE TO MOVE BACK TO THE FORWARD POS. SINCE OUR FLAP SETTING WAS VERY LOW, THE HANDLE DID NOT HAVE TO MOVE VERY FAR. I HAVE HEARD THIS SITUATION HAPPENING TO OTHER CREWS AND I HAVE EXPERIENCED PARTIAL FLAP RETRACTION ON TKOF ROLL WITH FLAPS MOVING ON THEIR OWN. AFTER THE TRAGEDY IN DETROIT I AM VERY CAREFUL ABOUT THE CONFIGN OF THE ACFT. THIS INCIDENT HAS NOT MADE ME DOUBLE-CHK AGAIN EVEN AFTER THE CHKLIST HAS BEEN ACCOMPLISHED. PLTS (MYSELF INCLUDED) CAN EASILY BE LULLED INTO COMPLACENCY, ESPECIALLY AFTER THE CHKS ARE DONE. I AM VERY GRATEFUL THE WARNING SYS BROKE THE CHAIN OF EVENTS OF A POTENTIALLY SERIOUS SITUATION.

Data retrieved from NASA's ASRS site as of July 2007 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.