Narrative:

Upon arriving at the aircraft, an EICAS message concerning antiskid was noticed and maintenance was called to address the problem. At pushback time, maintenance notified us that the problem was a bad transducer on 1 wheel and the antiskid would have to be deferred. The captain and I looked at the MEL concerning antiskid and quickly figured the takeoff data from this document and we initially felt that the airplane at its present weight would not be allowed to take off. About that time, dispatch ACARS'ed us to call them, which the captain left to do. When he returned, he said dispatch gave us numbers using pack off data and we were ok to depart. After takeoff, we looked at the numbers again to see just how dispatch came up with their numbers and found that we should have refused takeoff based on the actual gross weight. In fact, dispatch had mistakenly used the numbers for flaps 5 degrees rather than 15 degrees. Flaps 15 degrees is the only authority/authorized confign based on the MEL. Rushing to push as close to schedule as possible was the main culprit in this discrepancy. Pilots must always ensure all takeoff criteria is met without relying on others to do the number crunching. Had we taken 10 more mins we would have realized something was wrong and called dispatch again to correct it.

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Original NASA ASRS Text

Title: A B767 WAS DISPATCHED IN NON COMPLIANCE WITH THE ANTISKID DEFERRED PER THE MEL, BUT DID NOT MEET FLAP SETTING AND WT TKOF REQUIREMENTS.

Narrative: UPON ARRIVING AT THE ACFT, AN EICAS MESSAGE CONCERNING ANTISKID WAS NOTICED AND MAINT WAS CALLED TO ADDRESS THE PROB. AT PUSHBACK TIME, MAINT NOTIFIED US THAT THE PROB WAS A BAD TRANSDUCER ON 1 WHEEL AND THE ANTISKID WOULD HAVE TO BE DEFERRED. THE CAPT AND I LOOKED AT THE MEL CONCERNING ANTISKID AND QUICKLY FIGURED THE TKOF DATA FROM THIS DOCUMENT AND WE INITIALLY FELT THAT THE AIRPLANE AT ITS PRESENT WT WOULD NOT BE ALLOWED TO TAKE OFF. ABOUT THAT TIME, DISPATCH ACARS'ED US TO CALL THEM, WHICH THE CAPT LEFT TO DO. WHEN HE RETURNED, HE SAID DISPATCH GAVE US NUMBERS USING PACK OFF DATA AND WE WERE OK TO DEPART. AFTER TKOF, WE LOOKED AT THE NUMBERS AGAIN TO SEE JUST HOW DISPATCH CAME UP WITH THEIR NUMBERS AND FOUND THAT WE SHOULD HAVE REFUSED TKOF BASED ON THE ACTUAL GROSS WT. IN FACT, DISPATCH HAD MISTAKENLY USED THE NUMBERS FOR FLAPS 5 DEGS RATHER THAN 15 DEGS. FLAPS 15 DEGS IS THE ONLY AUTH CONFIGN BASED ON THE MEL. RUSHING TO PUSH AS CLOSE TO SCHEDULE AS POSSIBLE WAS THE MAIN CULPRIT IN THIS DISCREPANCY. PLTS MUST ALWAYS ENSURE ALL TKOF CRITERIA IS MET WITHOUT RELYING ON OTHERS TO DO THE NUMBER CRUNCHING. HAD WE TAKEN 10 MORE MINS WE WOULD HAVE REALIZED SOMETHING WAS WRONG AND CALLED DISPATCH AGAIN TO CORRECT IT.

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.