No, of course not. Go back to Sid's post 1671 for context. A lot depends on the a/c and instrumentation and the accuracy of it. Fuel uplifted is just one factor and is absurdly confused by kg vs l.
I believe that mass (kg) should be the only measure in use by people. In the old days, before modern electronics, gauges almost invariably read volumetrically, and the kg computed from that. Given that there is a 20% difference between vol/mass this is an accident waiting to happen when some poor sod has his mind on other things....it happens. It'll be safer when all imperial measurements go for good, as well.
We are talking about an accident that happened when seemingly it shouldn't have. These are reliable a/c in service round the world and generally well-liked by pilots (usually the best endorsement).
Coming back to the actual question - do we know for certain that there was 400kg fuel on board? No. On the contrary we can be sure that there was not exactly 400kg (other than by sheer chance with long odds). How much more or less than 400?
