The passengers and crew of missing Malaysia Airlines Flight MH370 most likely died from suffocation and coasted lifelessly into the ocean on autopilot, Australian officials said Thursday.

In a 55-page report, the Australian Transport Safety Board outlined how investigators had arrived at this conclusion after comparing the conditions on the flight with previous disasters, although it contained no new evidence from within the jetliner.

The report narrowed down the possible final resting place from thousands of possible routes, while noting the absence of communications and the steady flight path and a number of other key abnormalities in the course of the ill-fated flight.