A contract of carriage is a contract between a carrier of goods or passengers and the consignor, consignee or passenger. Contracts of carriage typically define the rights, duties and liabilities of parties to the contract, addressing topics such as acts of God and including clauses such as force majeure. Among common carriers, they are usually evidenced by standard terms and conditions printed on the reverse of a ticket or carriage document.
In July 2010, it became widely public that Southwest Airlines had classified mechanical difficulties as an act of God in their contract of carriage, expanding the definition formerly shared with Delta, American, Continental and United. This was later clarified by the airline as mechanical difficulties beyond the airline's control, as for instance the failure of the air traffic control system, or fuel delivery systems operated by airports.