India, June 12 -- A year has passed since Air India flight AI-171 plunged from the skies above Ahmedabad and exploded into the BJ Medical College campus, killing 260 people and leaving behind one of the most baffling mysteries in Indian aviation history.

The Boeing 787 Dreamliner was meant to be a routine flight from Ahmedabad to London Gatwick. Instead, it became a disaster that unfolded in just 32 seconds - a chain of events so brief that investigators are still struggling to explain exactly why it happened.

On Friday, the Aircraft Accident Investigation Bureau (AAIB) is expected to release a status update on its probe. Officials familiar with the matter have cautioned that the document will not answer the question everyone has been a...