According to Article 17, paragraph 1 of the Convention for the Unification of Certain Rules for International Carriage by Air in 1999, the carriers take the responsibility to pay compensation to passengers for their death or personal injury in the event of an accident occurring on or off the aircraft. However, the definition of “accident”in the convention is implicit, when“accident”occurs, and the judgement of it depends on the court of justice in different countries, which leads to the uncertainty in the judicial practice in various countries. However, the determination of this term is essential, because it determines whether passengers can be compensated according to the Convention. At present, in judicial practice, the methods to judge whether an event is an accident or not include:“tripartite tests”and“double tests”. Compared to the“tripartite tests”,“double tests”are more likely to judge an incident as an“accident”so that passengers can get compensation. However, at this stage, the judgment of“accident”should adopt the theory of“tripartite tests”, which focus more on the inherent risk of air transportation.