So around 400kgs to be considered unusable and 2000Kg total in the wing tanks equals a QRH Low fuel state drill activation.....and your computer flight plan shows divert. fuel less than 2400 kgs.
Is it wise in view of the QRH warnings to load computer flight plan fuel pluss 2400kgs?
Has the computer missed the implications of 400kgs of unusable fuel?
Has the computer disregarded the operational implications of low fuel state flight?