Narrative:

Many thanks to socal approach for their assistance in providing vectors and 'time' so the first officer and I could identify and solve a nuisance stick shaker warning problem before commencing an instrument approach into lax. When we told approach that we needed time, they gave us good headings and altitudes. When we said we needed to go to ontario airport they handed us off. When we asked for more time to troubleshoot they let us hold near pdz VOR, and when we asked to return to lax for an approach they did their best to get us back into the arrival flow. The problem: the B737-400 has 2 stall warning system. On takeoff at sea on the flight described here, a momentary stall warning was detected during gear retraction. It was dark and we were heavy and we both agreed that our airspeed and confign were correct and that the warning (which occurred on the first officer's stick shaker only) was from system #2. The safest thing to do was to continue to lax. But lax WX was not coming up to VFR as forecast so our plan was to not conduct an instrument approach until we had confirmed the warning was erroneous and not real. We covered everything over the 2 hour flight, (ie, circuit breakers, weight, instruments, confign, power) talked to the company, and arranged ontario as our alternate (in the clear, calm winds). We accepted clearance for vectors to the approach at lax in order to start slowing and configuring to assess our airplane and stall warning system and right away we saw that we had a nuisance stall warning at normal speeds with flaps extended. We could not positively identify the correct circuit breakers to pull to deactivate system #2 so it took us some time to discover that we could fly an approach normally by just adding the maximum wind and gust correction of 20 KIAS to not activate the malfunctioning stall warning. Approach and landing normal. The reason we couldn't find the stall warning circuit breakers is that they are labeled 'smc.' (stall management computer.) since our company does not provide us with a circuit breaker panel chart and index (or key), I am requesting that they do so. I'm glad we landed without pulling circuit breakers because on this airplane we would have received at least 1 additional failure of an associated system caused by the pulled circuit breakers. Throughout this ordeal ATC was good to us. Our extra hour of holding fuel gave us the time we needed -- without it we would have landed at ontario with a nuisance warning. There is not an abnormal checklist to go to in order to deactivate a nuisance warning.

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Original NASA ASRS Text

Title: A B737-400 ACR FLC HAS AN INTERMITTENT, NUISANCE STALL WARNING ON THE #2 SYS WHEN THE FLAPS ARE EXTENDED. AFTER TROUBLESHOOTING IN THE LAX AREA, THE FLC MAKES A SAFE LNDG AT VREF +20 KIAS.

Narrative: MANY THANKS TO SOCAL APCH FOR THEIR ASSISTANCE IN PROVIDING VECTORS AND 'TIME' SO THE FO AND I COULD IDENT AND SOLVE A NUISANCE STICK SHAKER WARNING PROB BEFORE COMMENCING AN INST APCH INTO LAX. WHEN WE TOLD APCH THAT WE NEEDED TIME, THEY GAVE US GOOD HEADINGS AND ALTS. WHEN WE SAID WE NEEDED TO GO TO ONTARIO ARPT THEY HANDED US OFF. WHEN WE ASKED FOR MORE TIME TO TROUBLESHOOT THEY LET US HOLD NEAR PDZ VOR, AND WHEN WE ASKED TO RETURN TO LAX FOR AN APCH THEY DID THEIR BEST TO GET US BACK INTO THE ARR FLOW. THE PROB: THE B737-400 HAS 2 STALL WARNING SYS. ON TKOF AT SEA ON THE FLT DESCRIBED HERE, A MOMENTARY STALL WARNING WAS DETECTED DURING GEAR RETRACTION. IT WAS DARK AND WE WERE HVY AND WE BOTH AGREED THAT OUR AIRSPD AND CONFIGN WERE CORRECT AND THAT THE WARNING (WHICH OCCURRED ON THE FO'S STICK SHAKER ONLY) WAS FROM SYS #2. THE SAFEST THING TO DO WAS TO CONTINUE TO LAX. BUT LAX WX WAS NOT COMING UP TO VFR AS FORECAST SO OUR PLAN WAS TO NOT CONDUCT AN INST APCH UNTIL WE HAD CONFIRMED THE WARNING WAS ERRONEOUS AND NOT REAL. WE COVERED EVERYTHING OVER THE 2 HR FLT, (IE, CIRCUIT BREAKERS, WT, INSTS, CONFIGN, PWR) TALKED TO THE COMPANY, AND ARRANGED ONTARIO AS OUR ALTERNATE (IN THE CLR, CALM WINDS). WE ACCEPTED CLRNC FOR VECTORS TO THE APCH AT LAX IN ORDER TO START SLOWING AND CONFIGURING TO ASSESS OUR AIRPLANE AND STALL WARNING SYS AND RIGHT AWAY WE SAW THAT WE HAD A NUISANCE STALL WARNING AT NORMAL SPDS WITH FLAPS EXTENDED. WE COULD NOT POSITIVELY IDENT THE CORRECT CIRCUIT BREAKERS TO PULL TO DEACTIVATE SYS #2 SO IT TOOK US SOME TIME TO DISCOVER THAT WE COULD FLY AN APCH NORMALLY BY JUST ADDING THE MAX WIND AND GUST CORRECTION OF 20 KIAS TO NOT ACTIVATE THE MALFUNCTIONING STALL WARNING. APCH AND LNDG NORMAL. THE REASON WE COULDN'T FIND THE STALL WARNING CIRCUIT BREAKERS IS THAT THEY ARE LABELED 'SMC.' (STALL MGMNT COMPUTER.) SINCE OUR COMPANY DOES NOT PROVIDE US WITH A CIRCUIT BREAKER PANEL CHART AND INDEX (OR KEY), I AM REQUESTING THAT THEY DO SO. I'M GLAD WE LANDED WITHOUT PULLING CIRCUIT BREAKERS BECAUSE ON THIS AIRPLANE WE WOULD HAVE RECEIVED AT LEAST 1 ADDITIONAL FAILURE OF AN ASSOCIATED SYS CAUSED BY THE PULLED CIRCUIT BREAKERS. THROUGHOUT THIS ORDEAL ATC WAS GOOD TO US. OUR EXTRA HR OF HOLDING FUEL GAVE US THE TIME WE NEEDED -- WITHOUT IT WE WOULD HAVE LANDED AT ONTARIO WITH A NUISANCE WARNING. THERE IS NOT AN ABNORMAL CHKLIST TO GO TO IN ORDER TO DEACTIVATE A NUISANCE WARNING.

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.