When fueling my 747-400, how much of the fuel goes in which of the tanks? 25% in the AUXs, 50% in the mains right and left, and 25% in the centre? What are the proportions? What does it look like for other planes?CheersCR

Fuel is not loaded by percentages but rather by the amount that is needed to get you from departure to destination plus any alternate and reserve amounts required by regulations, and any other fuel the pilot in command deems necessary.This is why it is important to flight plan so you'd have a pretty good idea of the fuel requirements for a flight. The rule is that the main wing tanks are filled first, then the remaining amount of trip fuel is loaded into the center tanks.The fuel in the center tanks is always burned first, then the wing tanks. This is to reduce wing flexing under load and the risk of them snapping.

:) you fill up the auxillary tanks first ... then the left and right tanks .. then the center main tank .... and so on.The center tanks shouldn't be filled unless the wing tanks (aux, left main and right main) are filled first ... the center tanks should ideally be empty on landing ... the weight of the fuel in the center tank would stress the airframe and wings (bending "moments") :)

Excellent! Thank you, this was just the answer I was looking for!