Narrative:

I was dispatched and departed on a validation flight (for a scheduled carrier to operative large transport to bda) with less fuel than required by far 121.645(B). Due to what appears to be a software problem with a new commercial computer flight plan service, a flight plan with a different format than our domestic flight plan was computed with the wrong gross weight resulting in a fuel load less than required. (The previous day the same validation flight with the same crew had to return west/O completing the flight due to an HF radio failure. The computed flight plan was computed correctly.) during preflight, I discussed with the dispatcher adding 4700# of fuel and lowering the cruise altitude from FL410 to no higher than FL370. I believed the lower fuel burn on the flight plan to be because of the light payload; 19 passenger (6 FAA and 13 company management personnel); no cargo and the higher cruising altitude. During preflight, a lower aft body overheat detector would not test. This, along with an MEL item, had several company management personnel, mechanics and FAA personnel interrupting our pre-departure and normal cockpit duties. All these factors helped me overlook my previous error. At the top of climb, the F/east informed me we were 1000 pounds over burn. This seemed excessive, even though we were kept at a lower altitude, then asked to climb to FL390 by ATC. 150 NM further we were 2000# over flight plan burn. Although we had WX and enough fuel to make bda with VFR fuel reserves, far 121645(C), by time we could have been redispatched, we would have used some of that fuel. Therefore, we diverted to departure airport.

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Original NASA ASRS Text

Title: ON VALIDATION FLT WITH FAA, PLUS OBSERVERS, FLT CREW OF LGT MISCALCULATED THEIR FUEL BURN BEYOND PLAN ENROUTE CAUSED CAPT TO DECIDE TO RETURN TO POINT OF ORIGIN.

Narrative: I WAS DISPATCHED AND DEPARTED ON A VALIDATION FLT (FOR A SCHEDULED CARRIER TO OPERATIVE LGT TO BDA) WITH LESS FUEL THAN REQUIRED BY FAR 121.645(B). DUE TO WHAT APPEARS TO BE A SOFTWARE PROB WITH A NEW COMMERCIAL COMPUTER FLT PLAN SVC, A FLT PLAN WITH A DIFFERENT FORMAT THAN OUR DOMESTIC FLT PLAN WAS COMPUTED WITH THE WRONG GROSS WT RESULTING IN A FUEL LOAD LESS THAN REQUIRED. (THE PREVIOUS DAY THE SAME VALIDATION FLT WITH THE SAME CREW HAD TO RETURN W/O COMPLETING THE FLT DUE TO AN HF RADIO FAILURE. THE COMPUTED FLT PLAN WAS COMPUTED CORRECTLY.) DURING PREFLT, I DISCUSSED WITH THE DISPATCHER ADDING 4700# OF FUEL AND LOWERING THE CRUISE ALT FROM FL410 TO NO HIGHER THAN FL370. I BELIEVED THE LOWER FUEL BURN ON THE FLT PLAN TO BE BECAUSE OF THE LIGHT PAYLOAD; 19 PAX (6 FAA AND 13 COMPANY MGMNT PERSONNEL); NO CARGO AND THE HIGHER CRUISING ALT. DURING PREFLT, A LOWER AFT BODY OVERHEAT DETECTOR WOULD NOT TEST. THIS, ALONG WITH AN MEL ITEM, HAD SEVERAL COMPANY MGMNT PERSONNEL, MECHS AND FAA PERSONNEL INTERRUPTING OUR PRE-DEP AND NORMAL COCKPIT DUTIES. ALL THESE FACTORS HELPED ME OVERLOOK MY PREVIOUS ERROR. AT THE TOP OF CLB, THE F/E INFORMED ME WE WERE 1000 LBS OVER BURN. THIS SEEMED EXCESSIVE, EVEN THOUGH WE WERE KEPT AT A LOWER ALT, THEN ASKED TO CLB TO FL390 BY ATC. 150 NM FURTHER WE WERE 2000# OVER FLT PLAN BURN. ALTHOUGH WE HAD WX AND ENOUGH FUEL TO MAKE BDA WITH VFR FUEL RESERVES, FAR 121645(C), BY TIME WE COULD HAVE BEEN REDISPATCHED, WE WOULD HAVE USED SOME OF THAT FUEL. THEREFORE, WE DIVERTED TO DEP ARPT.

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.