Narrative:

Flight plan calculated fuel burn incorrectly. Flight plan time and distance did not match filed routing. Flight plan fuel calculations understated flying distance by 51 mi (of low altitude flying) which understated fuel burn by about 1000 pounds. Discussed fuel shortfall and en route WX with dispatcher before departure. Jointly decided to top off fuel adding 1300 pounds. Actual fuel burn exceeded planned burn by 1700 pounds. Planned burn 33600 pounds. Actual burn takeoff to touchdown 35300 pounds. 5-7 mins extra flying time due to thunderstorm deviations. Analysis indicates planned burn on flight plan was inaccurate for 2 reasons: 1) routing to first fix problem -- flight plan calculated the distance for the first segment as a straight line from ZZZ to xxxxx intersection (13 flying mi; magnetic course 112). The filed routing however was the SID which rtes us for a total flying distance of 26 mi. 2) routing from last fix problem -- last segment of the flight plan showed a flying distance of 14 mi direct from yyyyy to ZZZ1 on a 157 magnetic course. The filed routing was the STAR arrival for approximately flying distance of 52 mi. Flight plan time and fuel calculations must correspond to filed route.

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Original NASA ASRS Text

Title: AIRBUS DETAILS THE INACCURACIES IN HIS ACR'S FUEL PLANNING COMPUTER PROGRAM.

Narrative: FLT PLAN CALCULATED FUEL BURN INCORRECTLY. FLT PLAN TIME AND DISTANCE DID NOT MATCH FILED ROUTING. FLT PLAN FUEL CALCULATIONS UNDERSTATED FLYING DISTANCE BY 51 MI (OF LOW ALT FLYING) WHICH UNDERSTATED FUEL BURN BY ABOUT 1000 LBS. DISCUSSED FUEL SHORTFALL AND ENRTE WX WITH DISPATCHER BEFORE DEP. JOINTLY DECIDED TO TOP OFF FUEL ADDING 1300 LBS. ACTUAL FUEL BURN EXCEEDED PLANNED BURN BY 1700 LBS. PLANNED BURN 33600 LBS. ACTUAL BURN TKOF TO TOUCHDOWN 35300 LBS. 5-7 MINS EXTRA FLYING TIME DUE TO TSTM DEVS. ANALYSIS INDICATES PLANNED BURN ON FLT PLAN WAS INACCURATE FOR 2 REASONS: 1) ROUTING TO FIRST FIX PROB -- FLT PLAN CALCULATED THE DISTANCE FOR THE FIRST SEGMENT AS A STRAIGHT LINE FROM ZZZ TO XXXXX INTXN (13 FLYING MI; MAGNETIC COURSE 112). THE FILED ROUTING HOWEVER WAS THE SID WHICH RTES US FOR A TOTAL FLYING DISTANCE OF 26 MI. 2) ROUTING FROM LAST FIX PROB -- LAST SEGMENT OF THE FLT PLAN SHOWED A FLYING DISTANCE OF 14 MI DIRECT FROM YYYYY TO ZZZ1 ON A 157 MAGNETIC COURSE. THE FILED ROUTING WAS THE STAR ARR FOR APPROX FLYING DISTANCE OF 52 MI. FLT PLAN TIME AND FUEL CALCULATIONS MUST CORRESPOND TO FILED RTE.

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.