Narrative:

During my preflight analysis of the dispatch release I found an error in the calculation of our total fuel burn to iad. After discovery of this error; dispatch was contacted. Our total planned fuel burn to iad was 3828. By examining the detailed flight plan; I determined that the computer inaccurately had us burning 28 pounds of fuel from passing over the elsin intersection on the shannon 2 arrival into iad and landing at iad. 28 pounds of fuel represents about 2 mins of fuel burn at idle thrust. Elsin is not the last point on this arrival. There is a point to the north or south that you would continue to fly to on the arrival depending on runway confign. None of this burn was accounted for; nor the fuel required to fly an instrument approach. Dispatch stated that they were unable to add points to this arrival into iad to account for this additional burn. Because of this apparent computer limitation we came to an agreement that we would add 400 pounds to our burn to account for an approach into iad. This 400 pounds is the standard number we are trained to add when doing a long hand fuel problem for the emb -- both dispatchers and capts are trained to account for this during their training. This increased our fuel burn to 4228 and a new minimum of 6534; not 6128. A consistent inaccurately calculated burn to iad that is apparently the result of a software limitation did not account for real life fuel burn scenarios on the arrival and approach phases into iad. Actual burn on this flight to iad was 4160 pounds. A comprehensive fix needs to resolve this software limitation to give our crews accurate fuel burn information into iad from all arrs. Without this fix; crews will consistently overburn right through their usual 500 pounds of contingency fuel and land at reserve fuel levels. Any operational abnormality such as holding or diversion due to WX will only amplify this inaccuracy and result in possible diversions; minimum fuel and fuel emergency declarations.

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Original NASA ASRS Text

Title: FLT CREW DISCOVERED THAT FLT PLANNED FUEL WAS INSUFFICIENT TO COMPLETE A NORMAL APCH INTO IAD.

Narrative: DURING MY PREFLT ANALYSIS OF THE DISPATCH RELEASE I FOUND AN ERROR IN THE CALCULATION OF OUR TOTAL FUEL BURN TO IAD. AFTER DISCOVERY OF THIS ERROR; DISPATCH WAS CONTACTED. OUR TOTAL PLANNED FUEL BURN TO IAD WAS 3828. BY EXAMINING THE DETAILED FLT PLAN; I DETERMINED THAT THE COMPUTER INACCURATELY HAD US BURNING 28 LBS OF FUEL FROM PASSING OVER THE ELSIN INTXN ON THE SHANNON 2 ARR INTO IAD AND LNDG AT IAD. 28 LBS OF FUEL REPRESENTS ABOUT 2 MINS OF FUEL BURN AT IDLE THRUST. ELSIN IS NOT THE LAST POINT ON THIS ARR. THERE IS A POINT TO THE N OR S THAT YOU WOULD CONTINUE TO FLY TO ON THE ARR DEPENDING ON RWY CONFIGN. NONE OF THIS BURN WAS ACCOUNTED FOR; NOR THE FUEL REQUIRED TO FLY AN INST APCH. DISPATCH STATED THAT THEY WERE UNABLE TO ADD POINTS TO THIS ARR INTO IAD TO ACCOUNT FOR THIS ADDITIONAL BURN. BECAUSE OF THIS APPARENT COMPUTER LIMITATION WE CAME TO AN AGREEMENT THAT WE WOULD ADD 400 LBS TO OUR BURN TO ACCOUNT FOR AN APCH INTO IAD. THIS 400 LBS IS THE STANDARD NUMBER WE ARE TRAINED TO ADD WHEN DOING A LONG HAND FUEL PROB FOR THE EMB -- BOTH DISPATCHERS AND CAPTS ARE TRAINED TO ACCOUNT FOR THIS DURING THEIR TRAINING. THIS INCREASED OUR FUEL BURN TO 4228 AND A NEW MINIMUM OF 6534; NOT 6128. A CONSISTENT INACCURATELY CALCULATED BURN TO IAD THAT IS APPARENTLY THE RESULT OF A SOFTWARE LIMITATION DID NOT ACCOUNT FOR REAL LIFE FUEL BURN SCENARIOS ON THE ARR AND APCH PHASES INTO IAD. ACTUAL BURN ON THIS FLT TO IAD WAS 4160 LBS. A COMPREHENSIVE FIX NEEDS TO RESOLVE THIS SOFTWARE LIMITATION TO GIVE OUR CREWS ACCURATE FUEL BURN INFO INTO IAD FROM ALL ARRS. WITHOUT THIS FIX; CREWS WILL CONSISTENTLY OVERBURN RIGHT THROUGH THEIR USUAL 500 LBS OF CONTINGENCY FUEL AND LAND AT RESERVE FUEL LEVELS. ANY OPERATIONAL ABNORMALITY SUCH AS HOLDING OR DIVERSION DUE TO WX WILL ONLY AMPLIFY THIS INACCURACY AND RESULT IN POSSIBLE DIVERSIONS; MINIMUM FUEL AND FUEL EMER DECLARATIONS.

Data retrieved from NASA's ASRS site as of May 2009 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.