Narrative:

The aircraft, B747-100, was scheduled for a flight from jfk to anchorage. Aircraft was fueled as per data on the computer flight plan (cfp). Takeoff data was figured by the flight crew for the actual takeoff gross weight. Takeoff and climb to cruise altitude was normal. Fuel checks were done at approximately 30 min intervals. We began to notice that we were overburning approximately 4500 pounds per hour. After 2 hours we had overburned 10000 pounds. We then began to investigate the reason for this by taking a closer look at the computer flight plan. We found that the computer flight plan was based on a cargo weight of 11400 pounds, actual cargo weight 100800 pounds -- a difference of 89400 pounds. The reason we were overburning was because we were almost 90000 pounds heavier than what the computer flight plan was based on. We determined our fuel at landing anchorage would be approximately 6000 pounds, which was unacceptable. After checking at edmonton, alberta we diverted there for fuel. The rest of the flight to anchorage was uneventful. Computer generated flight plans are only as good as the data inputted into it. The old saying, 'garbage in, garbage out.' many times the estimated cargo weight is given in the computer flight plan which is usually within 2000 pounds of actual cargo weight. The number 11400 is missing a '0' between the two 1's, i.e., 101400 would have been within 1000 pounds of the actual weight. Unfortunately this error was not found until after takeoff. I now look at computer flight plans much more carefully, comparing actual aircraft data to that on the computer flight plan. Because humans are inputting the data to computer flight plans there may be an error on your next computer flight plan so check, check, and rechk -- find mistakes, errors on the ground, not after takeoff.

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Original NASA ASRS Text

Title: WRONG WT AND BAL INFO INPUT INTO CFP. HAD TO MAKE FUEL STOP.

Narrative: THE ACFT, B747-100, WAS SCHEDULED FOR A FLT FROM JFK TO ANCHORAGE. ACFT WAS FUELED AS PER DATA ON THE COMPUTER FLT PLAN (CFP). TKOF DATA WAS FIGURED BY THE FLC FOR THE ACTUAL TKOF GROSS WT. TKOF AND CLB TO CRUISE ALT WAS NORMAL. FUEL CHKS WERE DONE AT APPROX 30 MIN INTERVALS. WE BEGAN TO NOTICE THAT WE WERE OVERBURNING APPROX 4500 LBS PER HR. AFTER 2 HRS WE HAD OVERBURNED 10000 LBS. WE THEN 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 WT 100800 LBS -- A DIFFERENCE OF 89400 LBS. THE REASON WE WERE OVERBURNING WAS BECAUSE WE WERE ALMOST 90000 LBS HEAVIER THAN WHAT THE COMPUTER FLT PLAN WAS BASED ON. WE DETERMINED OUR FUEL AT LNDG ANCHORAGE WOULD BE APPROX 6000 LBS, WHICH WAS UNACCEPTABLE. AFTER CHKING AT EDMONTON, ALBERTA WE DIVERTED THERE FOR FUEL. THE REST OF THE FLT TO ANCHORAGE WAS UNEVENTFUL. COMPUTER GENERATED FLT PLANS ARE ONLY AS GOOD AS THE DATA INPUTTED INTO IT. THE OLD SAYING, 'GARBAGE IN, GARBAGE OUT.' MANY TIMES THE ESTIMATED CARGO WT IS GIVEN IN THE COMPUTER FLT PLAN WHICH IS USUALLY WITHIN 2000 LBS OF ACTUAL CARGO WT. THE NUMBER 11400 IS MISSING A '0' BTWN THE TWO 1'S, I.E., 101400 WOULD HAVE BEEN WITHIN 1000 LBS OF THE ACTUAL WT. UNFORTUNATELY THIS ERROR WAS NOT FOUND UNTIL AFTER TKOF. I NOW LOOK AT COMPUTER FLT PLANS MUCH MORE CAREFULLY, COMPARING ACTUAL ACFT DATA TO THAT ON THE COMPUTER FLT PLAN. BECAUSE HUMANS ARE INPUTTING THE DATA TO COMPUTER FLT PLANS THERE MAY BE AN ERROR ON YOUR NEXT COMPUTER FLT PLAN SO CHK, CHK, AND RECHK -- FIND MISTAKES, ERRORS ON THE GND, NOT AFTER TKOF.

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.