FLC OF A WDB CARGO FLT DIVERTED TO LAND BASED ON INSUFFICIENT FUEL FOR DEST CAUSED BY A HIGHER FUEL BURN DUE TO 90000 LBS MORE CARGO THAN PLANNED.

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THE ACFT B747 FREIGHTER SCHEDULED FOR A FLT FROM JFK TO ANC. ACFT WAS FUELED AS PER DATA ON THE COMPUTER FLT PLAN. TKOF DATA WAS COMPUTED BY THE FLC FOR THE ACTUAL TKOF GROSS WT. TKOF AND CLB TO CRUISE ALT WAS NORMAL. APPROX 1 HR AFTER DEP THE CAPT (ME) NOTED WE WERE OVERBURNING 4500 LBS PER HR. WE BEGAN TO INVESTIGATE THE REASON FOR THIS. BY TAKING A CLOSER LOOK AT THE COMPUTER FLT PLAN WE FOUND THAT THE COMPUTER FLT PLAN WAS BASED ON A CARGO WT OF 11400 LBS. ACTUAL CARGO WAS 100800 LBS. THE REASON FOR THE OVERBURNING WAS BECAUSE WE WERE ALMOST 90000 LBS HEAVIER THAN WHAT THE COMPUTER FLT PLAN WAS BASED ON. I DETERMINED THAT OUR FUEL AT LNDG ANC WOULD BE 6000 LBS WHICH WAS UNACCEPTABLE. AFTER CHKING THE WX AT EDMONTON; ALBERTA; WE DIVERTED THERE FOR FUEL. THE REST OF THE FLT TO ANC WAS UNEVENTFUL. COMPUTER GENERATED FLT PLANS ARE ONLY AS GOOD AS THE DATA INPUTTED INTO IT. MAKE YOUR OWN PERSONAL CHKLIST AND CHK; CHK; AND RECHK. INSIST YOUR CREW BACK YOU UP INDEPENDENTLY SO ERRORS OF THIS SORT MAY NOT HAPPEN AGAIN.