We need to think about when the first bit of this matrix is completed - normally well before any actual load figures arrive with you. Often it is on the outbound leg where a decision has been made about return fuel load and RTOW calculated. Should you then decide on turn-round that you don't like the weather at base and wish to add another 3T to the fuel, you have effectively raised Col C by 3T. The matter of whether ZFW exceeds MZFW is normally determined without reference to this part of the loadsheet. When you look at a DCS generated loadsheet (the ones I have used, anyway), this 'Col C' figure does not appear at all.In addition, none of the 'manual' loadsheets I have ever used show TOW in the matrix so, as we have said, the primary purpose of it is for looking at 'underload' (and, effectively, planned underload). I admit, however, if I had a negative underload I would certainly have a good look at it!!
I apologise to Capt Claret for the 'castigation' I rendered - he was actually quite right in reality. It is just that it is an unusual way to determine MZFW exceedence and since the Col C figure goes up 1T for every extra tonne of fuel up to max tanks a little impractical and confusing as Haroon has found.
In practice having established our limiting TOW via Cols A and B we work from the left column where actual weights are totted up and check a/c indices, limitations, load, weight and fuel figures are correct with no exceedences.