Good point. If all comms are out then get within range and make a telephone call. If there was gradual loss of cabin pressure resulting in a hypoxic event then they would be none the wiser and the aircraft would follow its assigned course. If it was a sudden event that damaged systems then how come altitude and heading changed in a seemingly controlled manner? Acars must have useful information that would answer many of these questions. I only suppose that there is something the Malaysians havent come to terms with yet.