Narrative:

This event occurred while taxiing out for takeoff. It was near midnight and near the end of our duty day. When running the final items on the before takeoff checklist; the captain stated he could not find the take-off warn test switch. We held the taxi; increased the cockpit illumination and we still couldn't find the switch. At that point; I searched the flight manual (FM) for the switch and the configuration check procedure. I was taken aback when I didn't see any language that would say something along the lines of; '...for tail #(s); the take-off warn test switch is located...' I was in a bit of disbelieve that the aircraft may not actually have the switch. I couldn't recollect any operations notes that may have addressed the issue of aircraft not equipped with the switch. That said; I pulled out my flashlight and carefully scanned the entire control panel for the switch. Once we concluded that indeed there was no switch; I looked in the FM for the configuration settings covered in the take-off warn system. I found the list on FM 3.90.9 which we used to manually check that the speed brake; trim; flaps/leading edge devices were in the takeoff positions along with ensuring the parking brake was off. After this manual check; both the captain and I felt we had complied with the intent/function of the switch and felt that we were completely safe for takeoff. Now; at least speaking for myself; in the back of my mind I was thinking that this had to be a known issue that was being addressed in the background or that somehow; the switch was there somewhere and we were missing it. I'm sure that some fatigue contributed to that thought and to the lack of follow up other than this [report].

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Original NASA ASRS Text

Title: Boeing 737 flight crew reported being unable to locate the takeoff warning test switch.

Narrative: This event occurred while taxiing out for takeoff. It was near midnight and near the end of our duty day. When running the Final Items on the Before Takeoff checklist; the Captain stated he could not find the Take-off Warn Test Switch. We held the taxi; increased the cockpit illumination and we still couldn't find the switch. At that point; I searched the Flight Manual (FM) for the switch and the configuration check procedure. I was taken aback when I didn't see any language that would say something along the lines of; '...for tail #(s); the Take-Off Warn Test Switch is located...' I was in a bit of disbelieve that the aircraft may not actually have the switch. I couldn't recollect any operations notes that may have addressed the issue of aircraft not equipped with the switch. That said; I pulled out my flashlight and carefully scanned the entire control panel for the switch. Once we concluded that indeed there was no switch; I looked in the FM for the configuration settings covered in the Take-Off Warn system. I found the list on FM 3.90.9 which we used to manually check that the Speed Brake; Trim; Flaps/Leading Edge devices were in the takeoff positions along with ensuring the parking brake was off. After this manual check; both the captain and I felt we had complied with the intent/function of the switch and felt that we were completely safe for takeoff. Now; at least speaking for myself; in the back of my mind I was thinking that this had to be a known issue that was being addressed in the background or that somehow; the switch was there somewhere and we were missing it. I'm sure that some fatigue contributed to that thought and to the lack of follow up other than this [Report].

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.