Narrative:

Flight planned for good weather at arrival and arrival fuel of 11;200 pounds. Due to enroute turbulence we spent a good amount of time at lower than flight planned altitude; but had a better than planned ground speed which counterbalanced the extra fuel burn. However; within about 50 miles of destination; due to deteriorating weather we received extensive vectors during approach sequencing; mostly at 180 KTS and below 15;000 ft in icing conditions. Fuel burn rate throughout the traffic pattern was averaging 8;000 to 8;500 pounds per hour. Due to the vectoring and icing conditions we burned 4;000 pounds more than flight planned fuel and landed with about 7;000 pounds. Even though this is legal; it is not an acceptable margin for the 767.we need to recognize that the flight environment is unpredictable and we need to stop flight planning for fuel margins that are at the limits of legality because in many cases they are below the limits of prudence; and do not contain acceptable margins of safety. Weather and traffic can change drastically without notice. Pilots should not be placed in the position of having to ask for extra fuel on every flight in order to have an acceptable reserve because this creates an implicit pressure to lower the margins of safety in the interest of cost savings. In the long run this will not save any money because it will lead to more fuel stops; diversions; and ultimately may lead to an accident. Our flight planning system needs to be changed in order to reflect this.

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Original NASA ASRS Text

Title: B767-200 flight crew reports burning significantly more fuel than planned during arrival to SFO due to weather.

Narrative: Flight planned for good weather at arrival and arrival fuel of 11;200 pounds. Due to enroute turbulence we spent a good amount of time at lower than flight planned altitude; but had a better than planned ground speed which counterbalanced the extra fuel burn. However; within about 50 miles of destination; due to deteriorating weather we received extensive vectors during approach sequencing; mostly at 180 KTS and below 15;000 FT in icing conditions. Fuel burn rate throughout the traffic pattern was averaging 8;000 to 8;500 pounds per hour. Due to the vectoring and icing conditions we burned 4;000 pounds more than flight planned fuel and landed with about 7;000 pounds. Even though this is legal; it is not an acceptable margin for the 767.We need to recognize that the flight environment is unpredictable and we need to stop flight planning for fuel margins that are at the limits of legality because in many cases they are below the limits of prudence; and do not contain acceptable margins of safety. Weather and traffic can change drastically without notice. Pilots should not be placed in the position of having to ask for extra fuel on every flight in order to have an acceptable reserve because this creates an implicit pressure to lower the margins of safety in the interest of cost savings. In the long run this will not save any money because it will lead to more fuel stops; diversions; and ultimately may lead to an accident. Our flight planning system needs to be changed in order to reflect this.

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.