B737 CAPT DID NOT ABORT THE TKOF WHEN HE RECEIVED A TKOF WARNING HORN.

Narrative

FLT FROM SFO TO RNO. THIS WAS OUR FOURTH FLT THIS DAY; ALL IN THE SAME ACFT. WE'D HAD NO MECHANICAL IRREGULARITIES PRIOR TO THIS FLT. ALL THROUGH-FLT AND PREDEP CHKS WERE NORMAL. PUSHBACK WAS ON TIME. THIS WAS THE CAPT'S LEG. CLRED INTO POS AND HOLD RWY 1R. CLRED FOR TKOF; BRAKES RELEASED. THROTTLES ADVANCED SLIGHTLY AND NORMAL; EVEN SPOOLING OF ENGS CONFIRMED AT 40% N1. CAPT THEN BEGAN TO FURTHER ADVANCE THROTTLES UNTIL THE TKOF WARNING HORN WAS HEARD. THE CAPT RETARDED THE THROTTLES PARTIALLY UNTIL THE WARNING HORN SILENCED (HORN IS TRIGGERED BY THROTTLE'S POS BEING BEYOND VERT POS AND ACFT NOT BEING PROPERLY CONFIGURED FOR TKOF). WE WERE JUST BEGINNING TO ROLL AT APPROX 15-25 KTS. THE CAPT AND I BOTH QUICKLY SCANNED THE STABILIZER TRIM AND FOUND IT IN THE GREEN (NORMAL) BAND. THE CAPT THEN QUICKLY PUSHED ON TOP OF THE SPD BRAKE/SPOILER LEVER AND SEATED IT IN THE 'DOWN DETENT' (PROPER POS). HE THEN ADVANCED THE THROTTLES TOWARD TKOF THRUST. ESTIMATED AIRSPD NOW APPROX 40 KTS AND DISTANCE TRAVELED 100-200 FT MAX. THE TKOF HORN DID NOT RESOUND. CAPT MADE THE NORMAL CALL 'SET TKOF THRUST.' I HAD PLENTY OF TIME TO FINE TUNE THE THRUST BEFORE MAKING THE '80 KTS; THRUST SET' CALL AT 80 KTS. REMAINDER OF TKOF AND FLT NORMAL AND WITHOUT EVENT. AT CRUISE THE CAPT AND I REVIEWED OUR ACTIONS AND AGREED THAT; WITH RETROSPECT; A BETTER COURSE OF ACTION WOULD HAVE BEEN TO ABORT THE TKOF; CLR THE RWY AND EVALUATE THE WARNING HORN ONCE STOPPED AND CLR; AS CALLED FOR BY OUR COMPANY'S SOP'S. THE CAPT'S ACTIONS INDICATED TO ME HIS DESIRE TO CONTINUE THE TKOF. FEELING AS HE DID THAT OUR SIT WAS SAFE; I DID NOT INSIST ON AN ABORT. NONETHELESS; WE BOTH FEEL THAT THE SOP'S ARE INTENDED TO PROTECT CREWS; THE PAX; AND THE ACFT FROM POTENTIAL MISHAPS THAT HAVE OCCURRED BEFORE; AND THAT TO DISREGARD THEM EVEN IN A RELATIVELY BENIGN SIT SUCH AS OURS; IS TO DEVELOP A BAD HABIT AND PERHAPS INVITE LATER DISASTER. WE'RE STILL UNSURE AS TO HOW THE SPD BRAKE LEVER BECAME UNSEATED. WE HAD NO PROBS IN THE PREVIOUS 3 FLTS OR THE FOLLOWING DAY'S 4 FLTS. FINALLY; OUR RESPONSE TO THE SIT (TO CONTINUE THE TKOF) WAS BASED ON OUR PERCEPTIONS OF THE SIT; AMPLE RWY; LOW AIRSPD; AND LIGHT TKOF WT. NONETHELESS; BEING AN AIRLINE PLT REQUIRES; AT TIMES; TO SHOW DISCIPLINE AND REACT TO A SIT AS TRAINED; AND NOT EVALUATE AND MAKE A DECISION AS THE SIT UNFOLDS. SUPPLEMENTAL INFO FROM ACN 405236: A BETTER COURSE OF ACTION MIGHT HAVE BEEN TO DISCONTINUE THE TKOF COMPLETELY AND CLR THE RWY TO DETERMINE THE CAUSE OF THE WARNING IN A LOWER PRESSURE SIT.