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A B757-200 captain expressed his concern that the programing by which fmcs determine etas and arrival fuels is inordinately affected by the manner in which the selected STAR is constructed; some prescribing a direct route from the last fix direct to the airport and others ending at downwind legs from which the FMC assigns a conservative longer enroute time and applies the commensurate additional fuel burn to the predicted arrival fuel.
| Attributes | |
| ACN | 1032447 |
| Time | |
| Date | 201208 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ORD.Airport |
| State Reference | IL |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Route In Use | STAR BULLZ 3 |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 180 Flight Crew Total 27000 Flight Crew Type 4500 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural Other / Unknown Inflight Event / Encounter Fuel Issue |
Narrative:
As I've previously reported on many occasions; the FAA insists upon creating and utilizing charted arrival procedures which have no 'end point.' our FMC interprets this lack of an end point to add approximately 90 miles; 1;000 pounds of fuel burn and as much as a 30 minute longer ETA into the FMC arrival calculations. Once again; on my arrival at ord this afternoon; the FMC displayed a 50 mile error; 1;000 pounds landing fuel discrepancy; and 20 minute arrival time error. Upon discovering and verifying this error in flight; I requested and received a clearance change eliminating the bullz 3 arrival and adding the janesville 5 arrival; thus eliminating the multiple errors.
Original NASA ASRS Text
Title: A B757-200 Captain expressed his concern that the programing by which FMCs determine ETAs and arrival fuels is inordinately affected by the manner in which the selected STAR is constructed; some prescribing a direct route from the last fix direct to the airport and others ending at downwind legs from which the FMC assigns a conservative longer enroute time and applies the commensurate additional fuel burn to the predicted arrival fuel.
Narrative: As I've previously reported on many occasions; the FAA insists upon creating and utilizing charted arrival procedures which have no 'end point.' Our FMC interprets this lack of an end point to add approximately 90 miles; 1;000 LBS of fuel burn and as much as a 30 minute longer ETA into the FMC arrival calculations. Once again; on my arrival at ORD this afternoon; the FMC displayed a 50 mile error; 1;000 LBS landing fuel discrepancy; and 20 minute arrival time error. Upon discovering and verifying this error in flight; I requested and received a clearance change eliminating the BULLZ 3 arrival and adding the Janesville 5 arrival; thus eliminating the multiple errors.
Data retrieved from NASA's ASRS site as of July 2013 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.