Narrative:

I was captain on a B747-100 for a flight. While waiting #1 for takeoff, the amber leading edge flap warning light began to intermittently illuminate (blink) on the pilot's front panel. The warning indication was confirmed by the intermittent illumination of the corresponding amber leading edge flap warning light on the flight engineer's panel. With these 2 indications, a return to ramp was a required action. But, at the time this was not fully realized. Takeoff was performed with intermittent leading edge flap warning lights illuminating and an intermittent takeoff warning horn sounding (chirping). This continued for approximately the first 40% of the takeoff roll and then all warning indications cleared themselves up. I decided to continue the takeoff roll since the indications cleared. At the time, I did not fully realize the potential danger of the situation. At that time, our slot time for destination was about to expire and this could have potentially cost us a delay for an unknown time period. Also, on the previous flight before ours, a similar maintenance write-up had occurred and been cleared as an indication problem. So, taking these 2 circumstances into account, we did not fully look into the requirement for a return to ramp as specified in our MEL as we should have. The first 1/2 of the takeoff roll was an uncomfortable situation with the takeoff warning horn chirping and I prefer never to do that again. Also, after landing at our destination, I fully realized the incorrectness of my actions for having taken off as spelled out in the MEL. I believe I made this lapse in judgement by pressuring myself to go and not be delayed, and by relying too much on the sign-off for a previous write-up. Although the problem did end up being an indication problem, it could have potentially been the real thing. I believe that I have realized to not just thrust something that happened before, and that every flight is a new situation. I was lucky this time.

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Original NASA ASRS Text

Title: CARGO B747-100 FLC CAPT CONTINUED TKOF WITH AN INTERMITTENT LEADING EDGE FLAP BLINKING WARNING LIGHT AND TKOF HORN SOUNDING.

Narrative: I WAS CAPT ON A B747-100 FOR A FLT. WHILE WAITING #1 FOR TKOF, THE AMBER LEADING EDGE FLAP WARNING LIGHT BEGAN TO INTERMITTENTLY ILLUMINATE (BLINK) ON THE PLT'S FRONT PANEL. THE WARNING INDICATION WAS CONFIRMED BY THE INTERMITTENT ILLUMINATION OF THE CORRESPONDING AMBER LEADING EDGE FLAP WARNING LIGHT ON THE FE'S PANEL. WITH THESE 2 INDICATIONS, A RETURN TO RAMP WAS A REQUIRED ACTION. BUT, AT THE TIME THIS WAS NOT FULLY REALIZED. TKOF WAS PERFORMED WITH INTERMITTENT LEADING EDGE FLAP WARNING LIGHTS ILLUMINATING AND AN INTERMITTENT TKOF WARNING HORN SOUNDING (CHIRPING). THIS CONTINUED FOR APPROX THE FIRST 40% OF THE TKOF ROLL AND THEN ALL WARNING INDICATIONS CLRED THEMSELVES UP. I DECIDED TO CONTINUE THE TKOF ROLL SINCE THE INDICATIONS CLRED. AT THE TIME, I DID NOT FULLY REALIZE THE POTENTIAL DANGER OF THE SIT. AT THAT TIME, OUR SLOT TIME FOR DEST WAS ABOUT TO EXPIRE AND THIS COULD HAVE POTENTIALLY COST US A DELAY FOR AN UNKNOWN TIME PERIOD. ALSO, ON THE PREVIOUS FLT BEFORE OURS, A SIMILAR MAINT WRITE-UP HAD OCCURRED AND BEEN CLRED AS AN INDICATION PROB. SO, TAKING THESE 2 CIRCUMSTANCES INTO ACCOUNT, WE DID NOT FULLY LOOK INTO THE REQUIREMENT FOR A RETURN TO RAMP AS SPECIFIED IN OUR MEL AS WE SHOULD HAVE. THE FIRST 1/2 OF THE TKOF ROLL WAS AN UNCOMFORTABLE SIT WITH THE TKOF WARNING HORN CHIRPING AND I PREFER NEVER TO DO THAT AGAIN. ALSO, AFTER LNDG AT OUR DEST, I FULLY REALIZED THE INCORRECTNESS OF MY ACTIONS FOR HAVING TAKEN OFF AS SPELLED OUT IN THE MEL. I BELIEVE I MADE THIS LAPSE IN JUDGEMENT BY PRESSURING MYSELF TO GO AND NOT BE DELAYED, AND BY RELYING TOO MUCH ON THE SIGN-OFF FOR A PREVIOUS WRITE-UP. ALTHOUGH THE PROB DID END UP BEING AN INDICATION PROB, IT COULD HAVE POTENTIALLY BEEN THE REAL THING. I BELIEVE THAT I HAVE REALIZED TO NOT JUST THRUST SOMETHING THAT HAPPENED BEFORE, AND THAT EVERY FLT IS A NEW SIT. I WAS LUCKY THIS TIME.

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.