A focus on the fuel switches in a preliminary assessment raised questions about the pilots’ actions, but much is still unknown about Flight 171.

The Air India airliner carrying 230 passengers and 12 crew members was on its way to the United Kingdom when it crashed into a building shortly after takeoff on June 12, killing all aboard, except for one survivor, and several people on the ground, according to authorities.

Following is a timeline of key events in the investigation to date: An Air India Boeing 787 Dreamliner bound for London crashes shortly after takeoff from Ahmedabad city, killing all but one of the 242 people on board.