Narrative:

After commencing the takeoff roll; at approximately 120 knots; the takeoff configuration warning horn sounded. My initial reaction was to question what was wrong; not whether we should continue the takeoff or reject. I would estimate that there was a second or two before the sound of the warning horn even registered that something may be wrong. Unlike a warning light that illuminates; giving some indication of where a problem may lie; the aural warning is more shocking: since we employ the 'silent cockpit' method in the high-speed regime; the aural warning seems that much more alarming; almost as if someone is shouting out; 'there's a problem here.' I looked down to see if I could identify any immediate problem; but was overcome by the thought that we were quickly accelerating and that there was no time to evaluate whether we had an actual configuration problem or whether the warning horn was malfunctioning; so I brought the thrust levers to idle. Of course; with the thrust levers closed the rejected takeoff was initiated and the commitment to reject the takeoff was no longer in question. I performed the rest of the rejected takeoff procedure and cleared the runway.as soon as the aircraft was clear of the runway I took a look around the flight deck and concluded that the warning horn had likely malfunctioned and that the decision to reject the takeoff had not been the best course of action. In fact; I commented to the first officer that the reject was a 'mistake' and that I should have continued the takeoff.in addition to the pressure of the rapidity of the takeoff when making the 'go/no-go' decision; is the lingering thought that perhaps we; as a crew; had made an error during the pre-takeoff procedures. The new before takeoff checklist is a rather lengthy and unwieldy checklist that completely occupies the first officer (not just the first officer on this flight; but all first officers) despite the flight manual insistence that he maintain 'situational awareness.' the suggestion to maintain situational awareness ignores the fact that the first officer can only do one thing at a time; either devote his attention to what he is doing with the FMC/paperwork or look out the window at what is going on outside. This new checklist also requires the captain to taxi the aircraft while monitoring the inputs of the first officer; as evidenced by the required responses the captain must make to checklist challenges. This new checklist allows for configuration changes depending on whether the 'final' takeoff data reflects the preliminary data and allows the first officer to make such changes as indicated on the final performance information. With the huge workload and potential for error by limiting the verbalize; verify and monitor capacity of both pilots during a critical time the potential for error is greatly increased. Certainly; the before takeoff checklist includes a takeoff configuration check; which should warn of any incorrect configuration settings; but the potential for error is inherent in the design of this checklist.

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Original NASA ASRS Text

Title: B737 Flight Crew experiences a takeoff warning horn above 100 knots and rejects the takeoff; but believes that he made a mistake in doing so.

Narrative: After commencing the takeoff roll; at approximately 120 knots; the takeoff configuration warning horn sounded. My initial reaction was to question what was wrong; not whether we should continue the takeoff or reject. I would estimate that there was a second or two before the sound of the warning horn even registered that something may be wrong. Unlike a warning light that illuminates; giving some indication of where a problem may lie; the aural warning is more shocking: since we employ the 'silent cockpit' method in the high-speed regime; the aural warning seems that much more alarming; almost as if someone is shouting out; 'there's a problem here.' I looked down to see if I could identify any immediate problem; but was overcome by the thought that we were quickly accelerating and that there was no time to evaluate whether we had an actual configuration problem or whether the warning horn was malfunctioning; so I brought the thrust levers to idle. Of course; with the thrust levers closed the RTO was initiated and the commitment to reject the takeoff was no longer in question. I performed the rest of the rejected takeoff procedure and cleared the runway.As soon as the aircraft was clear of the runway I took a look around the flight deck and concluded that the warning horn had likely malfunctioned and that the decision to reject the takeoff had not been the best course of action. In fact; I commented to the first officer that the reject was a 'mistake' and that I should have continued the takeoff.In addition to the pressure of the rapidity of the takeoff when making the 'go/no-go' decision; is the lingering thought that perhaps we; as a crew; had made an error during the pre-takeoff procedures. The new Before Takeoff Checklist is a rather lengthy and unwieldy checklist that completely occupies the first officer (not just the first officer on this flight; but all first officers) despite the Flight Manual insistence that he maintain 'situational awareness.' The suggestion to maintain situational awareness ignores the fact that the first officer can only do one thing at a time; either devote his attention to what he is doing with the FMC/paperwork or look out the window at what is going on outside. This new checklist also requires the captain to taxi the aircraft while monitoring the inputs of the first officer; as evidenced by the required responses the captain must make to checklist challenges. This new checklist allows for configuration changes depending on whether the 'final' takeoff data reflects the preliminary data and allows the first officer to make such changes as indicated on the final performance information. With the huge workload and potential for error by limiting the verbalize; verify and monitor capacity of both pilots during a critical time the potential for error is greatly increased. Certainly; the Before Takeoff Checklist includes a takeoff configuration check; which should warn of any incorrect configuration settings; but the potential for error is inherent in the design of this checklist.

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.