There are widespread differences in interpretation of“accident”in Article 17, paragraph 1, of the Montreal Convention of 1999. It leads to the inability of judicial practice to make a unanimous judgment in the application of“accident”, which is contrary to the original intention of unity and certainty. The interpretation of “accident”with private law should not completely apply the interpretation method of the Vienna Convention on the Law of Treaties of 1969. The general legal interpretation method in jurisprudence can be used to finally deter? mine the elements of“accident”. Firstly,“accident”has a unique meaning of air transportation, including inde? pendent value and instrumental value; secondly,“accident”must be an unusual and unexpected event; thirdly, “accident”must be an event caused by other elements except the passengers themselves; fourthly, passengers must prove the existence of“accident”and that“accident”is the proximate cause of loss; and finally, whether the“accident”needs to be related to the inherent risks of air transport or the operation of the aircraft is flexible.