Narrative:

The situation occurred on the second day of a 3-DAY trip involving 10 flight segments, 9 of which were in medium large transport type a. This particular flight was in an medium large transport type B. It occurred on the first flight of the day after a short overnight (8 hours, 41 mins off duty). On takeoff, the confign warning horn sounded as power was applied. A quick assessment showed no problem so I advised the first officer to reject the takeoff (speed less than 50 KTS). We advised tower and exited runway. On taxi-back to the runway we noted flaps in the 1 degree position, which we normally use on the type a. The type B requires flaps of either 5 degrees or 15 degrees for takeoff. We selected flaps 5 degrees and made a normal takeoff. V speeds were taken from the ACARS screen and were 5 degrees speeds, but we obviously overlooked the 5 dem message. Frankly, both of us forgot we were in a type B as most of our flying together this month has been in a type a. Cockpits are essentially identical. Should have detected the problem by comparing V speeds on ACARS with V speeds on FLIP chart. This probably would have alerted us to need for 5 degrees. Am considering using 5 degrees for takeoffs on both models now. Will also be more alert for this problem now.

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Original NASA ASRS Text

Title: ACR MLG REJECTED TKOF BECAUSE FLAPS WERE SET WRONG.

Narrative: THE SITUATION OCCURRED ON THE SECOND DAY OF A 3-DAY TRIP INVOLVING 10 FLT SEGMENTS, 9 OF WHICH WERE IN MLG TYPE A. THIS PARTICULAR FLT WAS IN AN MLG TYPE B. IT OCCURRED ON THE FIRST FLT OF THE DAY AFTER A SHORT OVERNIGHT (8 HRS, 41 MINS OFF DUTY). ON TKOF, THE CONFIGN WARNING HORN SOUNDED AS PWR WAS APPLIED. A QUICK ASSESSMENT SHOWED NO PROB SO I ADVISED THE F/O TO REJECT THE TKOF (SPD LESS THAN 50 KTS). WE ADVISED TWR AND EXITED RWY. ON TAXI-BACK TO THE RWY WE NOTED FLAPS IN THE 1 DEG POS, WHICH WE NORMALLY USE ON THE TYPE A. THE TYPE B REQUIRES FLAPS OF EITHER 5 DEGS OR 15 DEGS FOR TKOF. WE SELECTED FLAPS 5 DEGS AND MADE A NORMAL TKOF. V SPDS WERE TAKEN FROM THE ACARS SCREEN AND WERE 5 DEGS SPDS, BUT WE OBVIOUSLY OVERLOOKED THE 5 DEM MESSAGE. FRANKLY, BOTH OF US FORGOT WE WERE IN A TYPE B AS MOST OF OUR FLYING TOGETHER THIS MONTH HAS BEEN IN A TYPE A. COCKPITS ARE ESSENTIALLY IDENTICAL. SHOULD HAVE DETECTED THE PROB BY COMPARING V SPDS ON ACARS WITH V SPDS ON FLIP CHART. THIS PROBABLY WOULD HAVE ALERTED US TO NEED FOR 5 DEGS. AM CONSIDERING USING 5 DEGS FOR TKOFS ON BOTH MODELS NOW. WILL ALSO BE MORE ALERT FOR THIS PROB NOW.

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.