With what appears to be a tank gauging error, it looks as if the a/c quite possibly has been flying with 1100kg'ish 'missing' for a while in the left tank. I would have expected some reports of trim abnormality.
Does Air France do a fuel check before departure (remaining fuel plus amount added vs. FOB indicated)?
- this will not necessarliy pick up such an error, especially if the error came about gradually. A sudden jump of 1100kg should have shown if this process is done regularly.
It looks as if they were 'lucky' the 'engine failure' has not happened before on this ship.