B737-500 HAD COMPUTED TKOF NUMBERS USING 1 DEG FLAPS. NOT AUTH ON THIS ACFT. AS THE FO; PF; ADVANCED THE THRUST LEVERS GOT A TKOF WARNING HORN AND ABORTED THE TKOF. SET FLAPS PROPERLY AT 5 DEGS AND WAS CLRED FOR ANOTHER TKOF.

Narrative

WE WERE CLRED TO TKOF ON RWY 20L. UPON ALIGNING WITH THE RWY; I GAVE THE ACFT TO MY FO; WHO RAN UP THE ENGS TOWARD TKOF THRUST. AS HE ADVANCED THE PWR LEVERS; THE TKOF WARNING HORN SOUNDED; SIGNALING SOMETHING WAS NOT PROPERLY SET FOR TKOF. BEFORE REACHING 20 KTS I ASSUMED CTL OF THE ACFT; WE TAXIED OFF THE RWY AFTER TELLING THE TWR WE WOULD NEED A FEW MINS TO SORT THINGS OUT. I CALLED FOR FLAPS 5 DEGS; AS WE WERE AT FLAPS 1 DEG; I RAN THE PWR LEVERS UP; AND THE HORN REMAINED SILENT. IT THEN OCCURRED TO BOTH OF US THAT WE WERE IN A 500 SERIES ACFT WHERE ONLY FLAPS 5 DEGS IS AN ACCEPTABLE TKOF SETTING. OUCH! ORIGINALLY WE WERE TO GET A 200 SERIES ACFT; AND I HAD PREPARED A BRIEF TO BE DONE WITH WHOEVER MY FO MIGHT BE. IT INCLUDED A DISCUSSION OF WHEN TO USE FLAPS 1 DEG. THAT SET THE STAGE FOR FO TO ERRANTLY COMPUTE PERFORMANCE FIGURES FOR THAT SETTING. THE ONLY PROB IS THAT THERE ARE NO FIGURES IN THE PERFORMANCE MANUAL FOR FLAPS 1 DEG FOR A 500 SERIES ACFT. NONETHELESS; IN FO MIND'S EYE; HE SAW FLAPS 1 DEG NUMBERS (WHICH ACTUALLY WERE CORRECT FLAPS 5 DEG NUMBERS) AND SET UP THE FLAPS 5 DEGS TKOF V SPD NUMBERS. WHEN I CALLED FOR FLAPS AFTER THE AFTER START CHKLIST WAS COMPLETED; HE SET FLAPS 1 DEG AS PER MY BRIEF. (APPARENTLY; WE WERE STILL BOTH STUCK IN THE FLAPS 1 DEG MODE AS PER MY PREFLT BRIEF.) WE RECONFIRMED 'FLAPS 1 DEG; GREEN LIGHT; DETENT' DURING THE PRETKOF CHKLIST AS WE PROCEEDED TOWARD THE RWY. AFTER EXITING THE RWY; I STOPPED THE ACFT; AND MADE AN ANNOUNCEMENT THAT WE HAD A READING THAT WE FOUND UNACCEPTABLE; THAT WE HAD CORRECTED THE PROB; THAT THERE WAS NO NEED FOR ALARM; AND THAT WE WERE GOING TO CONTINUE THE FLT. AFTER LEAVING 10000 FT; I CALLED THE 'A' FLT ATTENDANT FORWARD TO ASK ABOUT THE ATMOSPHERE AMONG THE PAX WHEN WE PULLED PWR; LEFT THE RWY; MADE THE ANNOUNCEMENT; AND PROCEEDED ON OUR FLT. HE SAID THAT THERE WAS NO APPREHENSION THAT HE COULD DETECT; AND THAT SOMEONE ACTUALLY MADE A SMALL JOKE ABOUT THE INCIDENT AFTER THE ANNOUNCEMENT; THAT THERE WERE A FEW LAUGHS; AND THINGS WERE NOMINAL. THE REST OF THE FLT PROCEEDED NORMALLY. FO AND I REVIEWED THE INCIDENT AND CAME UP WITH THESE CONCLUSIONS: 1) I HAD PREDISPOSED US TO THE INCIDENT WITH MY PREFLT BRIEFING; 2) FO HAD SOMEHOW; IN HIS MIND'S EYE; READ ALL THE PERFORMANCE FIGURES AS BEING FOR FLAPS 1 DEG; AND SO SET THAT SETTING FOR TKOF DESPITE THERE BEING NO FLAPS 1 DEG PERFORMANCE DATA IN THE PERFORMANCE MANUAL; 3) THE ABSENCE OF THE OLD STICKERS IN THE 500 SERIES ACFT SIGNIFYING THAT FLAPS 1 DEG WAS NOT AN ACCEPTABLE SETTING WAS UNWISE; AND 4) THAT IT WOULD BE PRUDENT FOR THE CAPT TO RUN THE PWR RAPIDLY LEVERS FORWARD; AND THEN BACK TO THE IDLE SOMETIME PRIOR TO TAKING THE RWY TO ENSURE THAT ALL SETTINGS WERE ACCEPTABLE FOR TKOF AS FAR AS THE TKOF WARNING HORN WAS CONCERNED.