Article 50 Montreal Convention
Article 50 of the Montreal Convention (Convention For the Unification of Certain Rules for International Carriage by Air) is titled Insurance. It is under Chapter VI (Other Provisions).
States Parties shall require their carriers to maintain adequate insurance covering their liability under this Convention. A carrier may be required by the State Party into which it operates to furnish evidence that it maintains adequate insurance covering its liability under this Convention.
See also: Article 49 Montreal Convention