Why is it that we check CG without gas in the tank rather than with gas in the tank? There is always a logical explanation , but I usually am unable to see it. I suppose that the plane flies with various amounts of gas in the tank, so it would seem reasonable to check CG with either NO gas in the tank , or with the tank FULL. But that would mean that the plane would be unbalanced with any amount in between? Obviously this is not the case! Any explanation would be greatly appreciated.