Depressingly, over the years I found that there were lies,damned lies and weight and balance sheets. In the process of working from the as weighed figure to the notional basic weight, and then the aircrew working forwards to the role equipped weight, the opportunities for error were huge because the numbers were so large. Instances like fixed ballast added when role mods were incorporated, but not removed when when the mod was removed, role equipment weights incorrect (invariably heavier). In one case the manufacturer’s figures for an aircraft submitted for test were in error, resulting in a hasty correction when challenged. And so on!