The operator shall be considered to be making use of a civil aircraft when his servants or agents are using the civil aircraft in the course of their employment, whether or not within the scope of their authority.
The registered owner of the civil aircraft shall be presumed to be the operator and shall be liable as such unless, in the proceedings for the determination of his liability, he proves that some other person was the operator and, in so far as legal procedures permit, takes appropriate measures to make that other person a party in the proceedings.
Article 159 If a person makes use of a civil aircraft without the consent of the person entitled to its navigational control and caused a damage to third parties on the surface, the person entitled to the navigation control, unless he proves that he has exercised due care to prevent such use, shall be jointly and severally liable with the unlawful user.
Article 160 Any person who would otherwise be liable under the provisions of this Chapter shall not be liable if the damage is the direct consequence of armed conflict or civil disturbance.
Any person who would otherwise be liable under the provision of this Chapter shall not be liable if such person has been deprived of the right to use the civil aircraft by the public authority according to law.