B737-300 captain elects to divert to las when his fuel calculations indicate less than satisfactory ...

Attributes
ACN	379540
Time
Date	199709
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : mkc
State Reference	MO
Altitude	msl bound lower : 31000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zkc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	cruise other other
Route In Use	enroute other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 15000 flight time type : 5000
ASRS Report	379540
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	non adherence : far other anomaly other
Independent Detector	other flight crewa other other : unspecified
Resolutory Action	other
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

En route from cmh to lax. Preflight, the FMC was loaded with all the appropriate data from the flight release, including route, winds aloft for each NAVAID, and arrival information for lax. The fuel load was 28700 pounds with a burn of 21900 pounds. I mentally estimated 20000 pounds to xchk the release fuel. I had 4000 pounds reserve and 2500 pounds extra fuel. En route abeam mkc, after checking time/fuel and entering downline waypoints, a message on the FMC said we would land in lax with less than our reserve of 4000 pounds. I verified all flight and route data. Went to long range cruise and lowered our flight index. The fuel still showed an arrival fuel of 3000 pounds in lax. I contacted dispatcher and informed him of our arrival fuel in lax. We agreed to take another fix abeam cos. The FMC still indicated 3000 pounds arrival fuel in lax. I told the dispatcher I was uncomfortable with this arrival fuel and would divert to las for fuel. He agreed. We refueled in las and continued to lax without any further delay. Supplemental information from 380273: crew called 10 mins prior to departure and asked for clarification of flight release showing a tailwind component of 59 KTS. I went through the release with the captain and since I planned extra fuel of 3900 pounds we both felt comfortable to initiate the flight. After conversing with a fellow dispatcher, the same scenario occurred with a cmh-lax flight that landed short in las. After re-executing the flight plan 2 and 3 times in the system, I used the backup, cadis flight planning system, which showed a dramatic change in burn. I sent the flight crew a new cadis release so that the flight would be operating with accurate winds and burn. The company continues to operate this system knowing this information is incorrect and still operates the long haul portion of the system with the risk of stopping short for fuel. Due to the fact that the flight planning system is calculating inaccurate burns the dispatcher is at risk of violation and risking the safety of flight.

Original NASA ASRS Text

Title: B737-300 CAPT ELECTS TO DIVERT TO LAS WHEN HIS FUEL CALCULATIONS INDICATE LESS THAN SATISFACTORY RESERVE FUEL AT LAX. THE COMPUTER FLT PLAN IN CMH INDICATED A TOTAL RESERVE OF 6500 LBS LNDG LAX. AN UNEXPLAINED ERROR OR LOSS OF 3500 LBS OF FUEL.

Narrative: ENRTE FROM CMH TO LAX. PREFLT, THE FMC WAS LOADED WITH ALL THE APPROPRIATE DATA FROM THE FLT RELEASE, INCLUDING RTE, WINDS ALOFT FOR EACH NAVAID, AND ARR INFO FOR LAX. THE FUEL LOAD WAS 28700 LBS WITH A BURN OF 21900 LBS. I MENTALLY ESTIMATED 20000 LBS TO XCHK THE RELEASE FUEL. I HAD 4000 LBS RESERVE AND 2500 LBS EXTRA FUEL. ENRTE ABEAM MKC, AFTER CHKING TIME/FUEL AND ENTERING DOWNLINE WAYPOINTS, A MESSAGE ON THE FMC SAID WE WOULD LAND IN LAX WITH LESS THAN OUR RESERVE OF 4000 LBS. I VERIFIED ALL FLT AND RTE DATA. WENT TO LONG RANGE CRUISE AND LOWERED OUR FLT INDEX. THE FUEL STILL SHOWED AN ARR FUEL OF 3000 LBS IN LAX. I CONTACTED DISPATCHER AND INFORMED HIM OF OUR ARR FUEL IN LAX. WE AGREED TO TAKE ANOTHER FIX ABEAM COS. THE FMC STILL INDICATED 3000 LBS ARR FUEL IN LAX. I TOLD THE DISPATCHER I WAS UNCOMFORTABLE WITH THIS ARR FUEL AND WOULD DIVERT TO LAS FOR FUEL. HE AGREED. WE REFUELED IN LAS AND CONTINUED TO LAX WITHOUT ANY FURTHER DELAY. SUPPLEMENTAL INFO FROM 380273: CREW CALLED 10 MINS PRIOR TO DEP AND ASKED FOR CLARIFICATION OF FLT RELEASE SHOWING A TAILWIND COMPONENT OF 59 KTS. I WENT THROUGH THE RELEASE WITH THE CAPT AND SINCE I PLANNED EXTRA FUEL OF 3900 LBS WE BOTH FELT COMFORTABLE TO INITIATE THE FLT. AFTER CONVERSING WITH A FELLOW DISPATCHER, THE SAME SCENARIO OCCURRED WITH A CMH-LAX FLT THAT LANDED SHORT IN LAS. AFTER RE-EXECUTING THE FLT PLAN 2 AND 3 TIMES IN THE SYS, I USED THE BACKUP, CADIS FLT PLANNING SYS, WHICH SHOWED A DRAMATIC CHANGE IN BURN. I SENT THE FLC A NEW CADIS RELEASE SO THAT THE FLT WOULD BE OPERATING WITH ACCURATE WINDS AND BURN. THE COMPANY CONTINUES TO OPERATE THIS SYS KNOWING THIS INFO IS INCORRECT AND STILL OPERATES THE LONG HAUL PORTION OF THE SYS WITH THE RISK OF STOPPING SHORT FOR FUEL. DUE TO THE FACT THAT THE FLT PLANNING SYS IS CALCULATING INACCURATE BURNS THE DISPATCHER IS AT RISK OF VIOLATION AND RISKING THE SAFETY OF FLT.

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

B737-300 captain elects to divert to las when his fuel calculations indicate less than satisfactory reserve fuel at lax. The computer flight plan in cmh indicated a total reserve of 6500 pounds landing lax. An unexplained error or loss of 3500 pounds of fuel.