Again, the debate has become fixated on weight. With a computer performance programme, typically fifteen or so items of data have to be entered, of which weight is just one. A single mistaken or transposed digit will make nonsense of the end result. The only fatal instance that I'm aware of was the Halifax 747 where their mistake was to make the calculation based on the previous departure airfield to which the laptop had defaulted. As with the Emirates tailscrape, fatigue played a major part; the fatal flight was the return sector for a second Atlantic crossing in the same duty period.