I was directly involved in the immediate aftermath at Lockerbie and remember asking one of the pathologists about the likelihood of passengers being aware of their situation. She explained that there would be an initial loss of consciousness due to lack of oxygen then, after falling between 5,500 to 11,000 feet, some people would have regained conciousness for the remainder of their descent. The first body I came across was that of Suzanne Miazga, who had landed on her back on the narrow grass strip right at the door of the ambulance station.
The debris from Pan Am 103 was spread over an 80-odd mile corridor, with some being found over on the east coast of England, so I would expect that if a similar fate has befallen the Malaysia flight, such evidence will not take much longer to find - even at sea.
GC