Fuel Density and Metering
So on a recent long haul trip from a cold climate to a warm climate I noticed a big difference in the specific gravity of the fuel uplifted to the aircraft in the cold country vs the hot country. This is of course expected but got me thinking.
When we are flying out of a hot country, with temperatures in the high 30s/low 40s (Celsius) and with hot fuel being pumped into the tanks what is the effect on the aircraft once we are airborne and the fuel cools to near or below freezing? As we climb the fuel Density will increase and hence the volume will decrease. Question, is this accounted for during fuel planning? And is fuel metered to the engines by weight or volume?
This then brings me to the next question. Why do we do fuel planning by weight? Sure we need to know the weight of the fuel in the tanks. But when deciding burn should we not be more concerned with litres and then work out the weight afterward? Thanks.