A B757-200 FLT CREW LEARNED 1 HR AFTER TKOF THAT THE ACFT WAS 4400 LBS HEAVIER THAN THE WT MANIFEST SHOWED.

Narrative

FLT WAS DELAYED TWICE TO ADD MORE PAX. WE WERE ON RLS 3 WHEN WE FINALLY WERE RELEASED BY OPS; OUR ZERO FUEL WT HAD GONE UP WITH EACH NEW RELEASE DUE TO ADDING OF PAX. WE BLOCKED OUT 18 MINS LATE (XA13); HOWEVER; WE HAD TO WAIT 16 MINS TO RECEIVE OUR FINAL WTS. WE HAD SENT MESSAGES TO LOAD PLANNING ABOUT NEEDING OUR WTS. FINALLY WE RECEIVED OUR WTS WITH A LOAD OF 10/146 LAP 2. ZERO FUEL WT WAS 170329 LBS. THIS WAS BELOW OUR ZERO FUEL WT FORECAST; SO WE INPUT THE INFO AND LAUNCHED AT XA29Z. AT XB42 ENRTE AT CRUISE; WE RECEIVED A MESSAGE SAYING THAT OUR PAX COUNT WAS 21/158 LAP 2; NOT 10/146 AND I WOULD CONFIRM. I HAD THE FLT ATTENDANTS DO A MANUAL COUNT (WHICH IS NOT REQUIRED BEFORE PUSHBACK ANYMORE) AND THEY CONFIRMED THAT THE PAX COUNT WAS 21/158 LAP 2. I FORWARDED THE INFO TO LOAD PLANNING AND THEY SENT ME A REVISED FINAL WT MANIFEST WITH A ZERO FUEL WT NOW OF 174727 LBS! WE WERE 4400 LBS HEAVIER AT TKOF THAN WHAT WE ORIGINALLY BEEN TOLD. WE HAD DONE A REDUCED THRUST TKOF BASED ON THE LIGHTER NUMBERS. THIS IS UNSETTLING TO SAY THE LEAST. WE ARE NOT TO HAVE THE FLT ATTENDANTS DO A MANUAL COUNT DUE TO THEIR ERRORS; HOWEVER; THIS IS THE SECOND TIME I HAVE RECEIVED REVISED WTS AFTER DEP DUE TO ERRORS ON LOAD PLANNING'S PART. WHERE IS THE CHK AND BAL IN THE NEW SYS? HOW AM I TO TRUST LOAD PLANNING? ON A HOT SUMMER'S DAY IN DEN; AN ERROR OF THIS TYPE COULD BE CATASTROPHIC. THIS MAKES ME WANT TO DO A MAX THRUST TKOF SINCE I CANNOT TRUST LOAD PLANNING TO GET ME THE RIGHT INFO.