Narrative:

Prior to takeoff, the first officer and I were tyring to determine whether we would be able to take off when we reached the departure runway, as we were over gross and needed to burn down the planned 900 pounds on taxi out. The ground traffic was light. The first officer had pulled up takeoff data for runway 22L using flaps 5 degrees. When we were cleared to taxi, it was for departure from runway 32L at T10, there were about 3 aircraft in front of us. He got data for the new runway and called load planning with a kid count and received a new lower zero fuel weight that brought us under maximum takeoff gross weight. Just as we were cleared for takeoff, the before takeoff checklist was completed. As we started the takeoff roll, the first officer noticed that he had flaps 5 degree data in front of him (for runway 22L) and the flaps were set to 1 degree. Out of concern that we would not meet takeoff performance criteria, he moved the flaps to 5 degrees and told me so. I had assumed the flaps were already at 5 degrees (we must have incorrectly done the before takeoff check) and elected to continue the takeoff. I looked down and saw that we were in, or rapidly approaching, the high speed regime. I noticed the flaps moving past 2 degrees and I was sure they would reach 5 degrees before V1. V speeds were called by the first officer for flaps 5 degrees and a normal takeoff profile was accomplished from that point on. I feel the high workload and time compression (as we had a short taxi) experienced by the first officer were the contributing factors that had the first officer heads down during the takeoff roll and unaware of how fast or far we had traveled down the runway at the time he moved the flap handle. We had a thorough debriefing after the incident and both agree that he should have called for an abort when the confusion arose rather than change the reconfign of the aircraft.

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Original NASA ASRS Text

Title: B737-500 CREW PLANNED A FLAPS 5 DEGS TKOF BECAUSE OF PERFORMANCE LIMITATIONS. BECAUSE OF A SHORT TAXI, RWY CHANGE, AND A MISSED BEFORE TKOF CHKLIST ITEM, THE CREW BEGAN TKOF WITH FLAPS 1 DEG. THE CREW DID NOT ABORT THE TKOF, BUT INSTEAD SELECTED FLAPS 5 DEGS DURING TKOF ROLL.

Narrative: PRIOR TO TKOF, THE FO AND I WERE TYRING TO DETERMINE WHETHER WE WOULD BE ABLE TO TAKE OFF WHEN WE REACHED THE DEP RWY, AS WE WERE OVER GROSS AND NEEDED TO BURN DOWN THE PLANNED 900 LBS ON TAXI OUT. THE GND TFC WAS LIGHT. THE FO HAD PULLED UP TKOF DATA FOR RWY 22L USING FLAPS 5 DEGS. WHEN WE WERE CLRED TO TAXI, IT WAS FOR DEP FROM RWY 32L AT T10, THERE WERE ABOUT 3 ACFT IN FRONT OF US. HE GOT DATA FOR THE NEW RWY AND CALLED LOAD PLANNING WITH A KID COUNT AND RECEIVED A NEW LOWER ZERO FUEL WT THAT BROUGHT US UNDER MAX TKOF GROSS WT. JUST AS WE WERE CLRED FOR TKOF, THE BEFORE TKOF CHKLIST WAS COMPLETED. AS WE STARTED THE TKOF ROLL, THE FO NOTICED THAT HE HAD FLAPS 5 DEG DATA IN FRONT OF HIM (FOR RWY 22L) AND THE FLAPS WERE SET TO 1 DEG. OUT OF CONCERN THAT WE WOULD NOT MEET TKOF PERFORMANCE CRITERIA, HE MOVED THE FLAPS TO 5 DEGS AND TOLD ME SO. I HAD ASSUMED THE FLAPS WERE ALREADY AT 5 DEGS (WE MUST HAVE INCORRECTLY DONE THE BEFORE TKOF CHK) AND ELECTED TO CONTINUE THE TKOF. I LOOKED DOWN AND SAW THAT WE WERE IN, OR RAPIDLY APCHING, THE HIGH SPD REGIME. I NOTICED THE FLAPS MOVING PAST 2 DEGS AND I WAS SURE THEY WOULD REACH 5 DEGS BEFORE V1. V SPDS WERE CALLED BY THE FO FOR FLAPS 5 DEGS AND A NORMAL TKOF PROFILE WAS ACCOMPLISHED FROM THAT POINT ON. I FEEL THE HIGH WORKLOAD AND TIME COMPRESSION (AS WE HAD A SHORT TAXI) EXPERIENCED BY THE FO WERE THE CONTRIBUTING FACTORS THAT HAD THE FO HEADS DOWN DURING THE TKOF ROLL AND UNAWARE OF HOW FAST OR FAR WE HAD TRAVELED DOWN THE RWY AT THE TIME HE MOVED THE FLAP HANDLE. WE HAD A THOROUGH DEBRIEFING AFTER THE INCIDENT AND BOTH AGREE THAT HE SHOULD HAVE CALLED FOR AN ABORT WHEN THE CONFUSION AROSE RATHER THAN CHANGE THE RECONFIGN OF THE ACFT.

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.