So it crashed in the ocean. Didnt see that one coming.
I imagine the black box may be difficult or even impossible to find. The ocean in that area is several miles deep and they still dont know exactly where it went down.
Hypoxia might just be a good answer. My guess is that at least half, probably most passengers, would have a cell phone. Unconsciousness, is the only thing that would keep those people from phoning anyone they could. If they find bodies, they could tell if they died from oxygen starvation. What is the range of a cell phone?
NOAA Ocean Explorer: Technology: Submersibles
Malaysia PM: Missing jet crashed into Indian Ocean | The Times of Israel
Satellite images and data released by Australia, China and France in recent days have identified possible debris in the area that may be linked to the disappearance of the plane on March 8 with 239 people on board — two-thirds of them Chinese.
The ocean depth in the search area ranges between 1,150 meters (3,770 feet) and 7,000 meters (23,000 feet), and the US Pacific Command said it was sending a black box locator in case a debris field is located.