An official report on the world’s deadliest aviation accident in a decade, seen by CNN, has answered one key question – but raised others.

Authorities in India have released the preliminary results of their investigation into the the Boeing 787-8 Dreamliner crash in June that killed 229 of the 230 passengers aboard and all 12 crew members.

Investigators are probing the wreckage and cockpit recorders to understand what went wrong just after take-off. The Air India flight climbed to 625 feet in clear weather before losing location data 50 seconds in, per Flightradar24. Saturday's 15-page report offers early insights.