Air India's deadly plane crash that killed at least 270 people has triggered a wave of speculation about what led to the world's worst aviation disaster in a decade, but authorities are slowly narrowing down areas of investigation.

The deadly crash of Air India Flight 171 last week has centered renewed scrutiny on the airplane's manufacturer, Boeing. This time it's the 787 Dreamliner in investigators' sights. The accident, which killed over 270 people, was the first fatal crash for the Dreamliner since the model began flying in 2011.