Why is measuring fuel quantity in pounds more accurate than in gallons?

Measuring fuel quantity in pounds provides a more accurate representation of the fuel’s actual weight, which is less affected by environmental factors compared to measuring in gallons.

When specifying fuel volume in gallons, the amount of fuel can vary significantly with changes in temperature. As temperature increases, fuel expands and occupies a larger volume, while it contracts when temperature decreases. This thermal expansion meaningfully affects the volume reading, leading to potential inaccuracies in the estimated fuel quantity if it’s only expressed in gallons. Since the weight of the fuel remains constant regardless of temperature changes, measuring in pounds provides a dependable indicator of the actual fuel available for use, ensuring that pilots and maintenance personnel know the precise amount of fuel regardless of temperature variations.

This focus on weight rather than volume allows for more accurate calculations related to fuel management and performance during flight operations.