Narrative:

I reported to pit operations for what was to be an FAA certification flight to bermuda. After reading the flight plan, I told the captain that the fuel load didn't look right. It was more like an medium large transport burn than an large transport. We were filed at FL410 and attributed the light fuel load to the much higher than normal cruise altitude, and the fact that we were flying a virtually empty aircraft (20 passenger). The captain called the dispatcher and requested a new release/flight plan for FL370. The captain further discussed the light fuel load with the dispatcher and added extra fuel for the trip. After taking off, the F/east immediately began to track our fuel burn and noticed that we were, for no obvious reason, falling farther and farther behind on our fuel burn. (At har, we were down 2000+#, and at top of climb we were down over 3000#.) the captain requested a clearance to hold and instructed me to request clearance to bwi to obtain a new release and more fuel. It was then noticed that there was a problem with our computerized flight plan. The fuel burn was based on an aircraft gross weight of 48000# (almost 100000# less than our actual weight). We, as pilots, become accustomed to the daily use of computer flight plans. We become overly trusting in their accuracy.

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Original NASA ASRS Text

Title: ACR LGT MADE TKOF WITH LESS THAN REQUIRED FUEL LOAD. FLT WAS A PROVING FLT FOR FAA ROUTE CERTIFICATION.

Narrative: I RPTED TO PIT OPS FOR WHAT WAS TO BE AN FAA CERTIFICATION FLT TO BERMUDA. AFTER READING THE FLT PLAN, I TOLD THE CAPT THAT THE FUEL LOAD DIDN'T LOOK RIGHT. IT WAS MORE LIKE AN MLG BURN THAN AN LGT. WE WERE FILED AT FL410 AND ATTRIBUTED THE LIGHT FUEL LOAD TO THE MUCH HIGHER THAN NORMAL CRUISE ALT, AND THE FACT THAT WE WERE FLYING A VIRTUALLY EMPTY ACFT (20 PAX). THE CAPT CALLED THE DISPATCHER AND REQUESTED A NEW RELEASE/FLT PLAN FOR FL370. THE CAPT FURTHER DISCUSSED THE LIGHT FUEL LOAD WITH THE DISPATCHER AND ADDED EXTRA FUEL FOR THE TRIP. AFTER TAKING OFF, THE F/E IMMEDIATELY BEGAN TO TRACK OUR FUEL BURN AND NOTICED THAT WE WERE, FOR NO OBVIOUS REASON, FALLING FARTHER AND FARTHER BEHIND ON OUR FUEL BURN. (AT HAR, WE WERE DOWN 2000+#, AND AT TOP OF CLB WE WERE DOWN OVER 3000#.) THE CAPT REQUESTED A CLRNC TO HOLD AND INSTRUCTED ME TO REQUEST CLRNC TO BWI TO OBTAIN A NEW RELEASE AND MORE FUEL. IT WAS THEN NOTICED THAT THERE WAS A PROB WITH OUR COMPUTERIZED FLT PLAN. THE FUEL BURN WAS BASED ON AN ACFT GROSS WT OF 48000# (ALMOST 100000# LESS THAN OUR ACTUAL WT). WE, AS PLTS, BECOME ACCUSTOMED TO THE DAILY USE OF COMPUTER FLT PLANS. WE BECOME OVERLY TRUSTING IN THEIR ACCURACY.

Data retrieved from NASA's ASRS site as of August 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.