Article 40 Montreal Convention

Article 40 of the Montreal Convention (Convention For the Unification of Certain Rules for International Carriage by Air) is titled Respective Liability of Contracting and Actual Carriers. It is under Chapter V (Carriage by Air Performed by a Person other than the Contracting Carrier).

If an actual carrier performs the whole or part of carriage which, according to the contract referred to in Article 39, is governed by this Convention, both the contracting carrier and the actual carrier shall, except as otherwise provided in this Chapter, be subject to the rules of this Convention, the
former for the whole of the carriage contemplated in the contract, the latter solely for the carriage which it performs.

See also: Article 39 Montreal Convention