Three weeks after an Air India Boeing 787 crashed, investigators are still piecing together what went wrong. In the meantime, aviation safety experts have begun to narrow their thinking.

More than two weeks after the deadly crash of an Air India plane that killed all but one of the 242 people on board, investigators and the airline are studying possible dual engine failure as a scenario that prevented the Boeing Co.

Data recovery from the flight data recorders aboard Air India flight 171, which tragically crashed on June 12, began this past week.