slats11
It is only for claims in excess of this cap (USD $170000 approx) that negligence has to be established [under the Montreal Convention].
Not sure about the details of the earlier Warsaw convention.
Not an aviation lawyer, but years ago I indirectly encountered some issues regarding an Indonesian airline crash and liability under the Warsaw Convention.
My recollection is the liability caps under the Warsaw Convention apply notwithstanding any claim of negligence by the airline or its employees. (One reason why lawyers sometimes tried to sue a third party not subject to those limits, such as an aircraft or component manufacturer.)