AN A319 FLT CREW TOOK OFF WITH AIRSPD BUGS SET TO A WT 10000 LBS BELOW ACTUAL WT; WHEN WTS CAME IN VERY LATE IN TAXI.

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ON TAXI OUT WE HAD DELAYED LOAD PLANNING FINAL WTS. WE GOT THE WTS APCHING THE HOLD SHORT LINE AND UNDER TWR'S REQUEST TO TAKE POS AND HOLD; WE RUSHED THE FINAL PREPARATION. IN THE AIRBUS REQUIRED MATH OF ADDING THE LOAD PLANNING'S ZFW (117.2) TO THE ACFT FUEL (15.5) THE FO MIS-ADDED AND GOT 122.7 (VICE 132.7). THE ACFT SEEMED TO HANDLE FINE; DESPITE HAVING SPDS BASED ON 10000 LBS TOO LIGHT. AFTER ABOUT AN HR IN FLT THE FMGC HAD A NOTE TO 'CHK GW' WHICH RESULTED IN US FINDING AND CORRECTING THE ERROR. QUESTION/SUGGESTION: WHY DO WE HAVE THE PROC TO ADD ACTUAL FUEL TO LOAD PLANNING COMPUTED ZFW? THEY SHOULD KNOW OUR FUEL AS CLOSE AS THE ZFW; AND THUS BE ABLE TO COMPUTE A SUFFICIENTLY CLOSE TOGW. THIS WOULD ELIMINATE THE ERRORS THAT OCCUR DURING RUSHED MATH AT THE HOLD SHORT LINE (COMMON WITH LATE LOAD PLANNING WTS). SUPPLEMENTAL INFO FROM ACN 703117: ENTERED WRONG GROSS WT INTO MCDU AT TKOF. WE DID NOT GET FINAL WTS UNTIL WE WERE AT THE END OF RWY. WE RECEIVED TKOF CLRNC AT THE SAME TIME WE GOT THE FINAL WTS. I RUSHED TO DO THE MATH TO CALCULATE THE GROSS WT AND COMPLETE THE TKOF CHKLIST AND MADE A MISTAKE ON THE MATH (FORGOT TO CARRY THE 1...PUBLIC SCHOOL). I ENTERED A WT THAT WAS 10000 LBS LIGHTER THAN THE ACTUAL WT. WE DISCOVERED THE MISTAKE INFLT WHEN MESSAGE CAME UP ON MCDU -- CHK GW. I ALLOWED MYSELF TO GET RUSHED TRYING TO FINALIZE THE WTS; FINISH THE CHKLIST AND RESPOND TO TWR WHILE CAPT WAS TAXIING ONTO RWY FOR TKOF. (MY MISTAKE NOT THE CAPT'S.)