The London-bound flight crashed shortly after takeoff, descending rapidly from 650 feet and killing 241 of the 242 people on board, along with casualties on the ground.

The investigation into the Air India flight 171 crash is focusing on the movement of the engine fuel control switches, following an analysis of the Boeing 787's flight and voice data recorders

Investigators are still piecing together what went wrong. In the meantime, aviation safety experts have begun to narrow their thinking.