What is the test for determining whether a passenger was injured on board a passenger's flight, or during embarking or disembarking?

The three-part test outlined in the American jurisprudence, beginning with Acevedo v. Iberia, considers the passenger's activity at the time of the injury, the whereabouts of the passenger when injured and, finally, the extent to which the carrier was exercising control over the passenger when determining the question of whether the injury occurred on board, or during embarking or disembarking.