Well, we are a bit confused too, but we take the C/G from the weight and balance and input the data to the performance program, and a new number comes out. Why they are different sometimes is a mystery, but we are trying to get an answer from the computer geeks that sell this thing. Sometimes they are off by a tenth, sometimes they are off by 1.2 units.
One thing you have to remember is, our fleet standardization stopped after the 1st plane. We have four different thrust engines, 5 different gross weights, more other small differences that i can hardly remember. This is a performance program sold by Teledyne, it fairly widely used, (so i'm told).