Narrative:

I flight planned flight ZZZ-ZZZ2-ZZZ3-ZZZ with our flight planning system which is what we use for all flight plans. I requested a flight plan for the final leg ZZZ3 to ZZZ with a 25000 pound payload and alternate. The ZZZ3-ZZZ flight came back with a fuel burn of 2757 pounds; flight time of 49 mins and distance of 305 mi. The actual distance for this flight is 481 mi and takes about 1 hour 17 mins and will burn about 7600 pounds of fuel. With the alternate and 45 min reserve fuel on this flight and 300 pounds of taxi fuel; the required fuel came up to 10335 pounds. Neither the flight crew nor myself noticed that this was a light fuel load for this flight thus operated with 10400 pounds of fuel and landed in ZZZ with 4200 pounds of fuel; far short of what he would have needed to divert to an alternate. This seemed to be a single anomaly in the flight planning system that could not be explained by our flight planning vector. During my shift on aug/xa/06; I requested at least 54 flight plans with this computer system. I am responsible for the WX; regulatory compliance and safety of all these flts. I do not have time in an 8 hour shift to check that the computer generated flight plans are using the correct distances on our stored rtes. Supplemental information from acn 706148: first officer called me after landing in ZZZ; saying flight plan had an unusually short flight time. I compared the total distance between this flight plan and a flight plan on another aircraft flying ZZZ3-ZZZ -- the distance on the bad flight plan was short by 176 mi. Neither the dispatchers nor the flight crew caught this error. As a result; the flight landed ZZZ with only 4200 pounds of fuel.

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Original NASA ASRS Text

Title: A COMPUTER FLT PLAN ANOMALY ALLOWED A B737-400 TO OPERATE WITH LESS FUEL THAN REQUIRED AND SO HAD INSUFFICIENT ALTERNATE FUEL.

Narrative: I FLT PLANNED FLT ZZZ-ZZZ2-ZZZ3-ZZZ WITH OUR FLT PLANNING SYS WHICH IS WHAT WE USE FOR ALL FLT PLANS. I REQUESTED A FLT PLAN FOR THE FINAL LEG ZZZ3 TO ZZZ WITH A 25000 LB PAYLOAD AND ALTERNATE. THE ZZZ3-ZZZ FLT CAME BACK WITH A FUEL BURN OF 2757 LBS; FLT TIME OF 49 MINS AND DISTANCE OF 305 MI. THE ACTUAL DISTANCE FOR THIS FLT IS 481 MI AND TAKES ABOUT 1 HR 17 MINS AND WILL BURN ABOUT 7600 LBS OF FUEL. WITH THE ALTERNATE AND 45 MIN RESERVE FUEL ON THIS FLT AND 300 LBS OF TAXI FUEL; THE REQUIRED FUEL CAME UP TO 10335 LBS. NEITHER THE FLT CREW NOR MYSELF NOTICED THAT THIS WAS A LIGHT FUEL LOAD FOR THIS FLT THUS OPERATED WITH 10400 LBS OF FUEL AND LANDED IN ZZZ WITH 4200 LBS OF FUEL; FAR SHORT OF WHAT HE WOULD HAVE NEEDED TO DIVERT TO AN ALTERNATE. THIS SEEMED TO BE A SINGLE ANOMALY IN THE FLT PLANNING SYS THAT COULD NOT BE EXPLAINED BY OUR FLT PLANNING VECTOR. DURING MY SHIFT ON AUG/XA/06; I REQUESTED AT LEAST 54 FLT PLANS WITH THIS COMPUTER SYS. I AM RESPONSIBLE FOR THE WX; REGULATORY COMPLIANCE AND SAFETY OF ALL THESE FLTS. I DO NOT HAVE TIME IN AN 8 HR SHIFT TO CHK THAT THE COMPUTER GENERATED FLT PLANS ARE USING THE CORRECT DISTANCES ON OUR STORED RTES. SUPPLEMENTAL INFO FROM ACN 706148: FO CALLED ME AFTER LNDG IN ZZZ; SAYING FLT PLAN HAD AN UNUSUALLY SHORT FLT TIME. I COMPARED THE TOTAL DISTANCE BTWN THIS FLT PLAN AND A FLT PLAN ON ANOTHER ACFT FLYING ZZZ3-ZZZ -- THE DISTANCE ON THE BAD FLT PLAN WAS SHORT BY 176 MI. NEITHER THE DISPATCHERS NOR THE FLT CREW CAUGHT THIS ERROR. AS A RESULT; THE FLT LANDED ZZZ WITH ONLY 4200 LBS OF FUEL.

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