did everyone already know this?
The passengers were never informed of the impending crash. (Not a surprise, as a Captain and First Officer with the wherewithal to inform the crew and passengers wouldn't have stopped flying the plane.) Similarly, the flight attendants did not give brace instructions.
The blackbox shows a very poor approach followed by at least 19 seconds of failure to fly the aircraft. The surviving passengers say they knew the aircraft was in trouble a good bit before the impact. (Given the swings of the aircraft, it seems unlikely to all be 20/20 hindsight.) We are told there were a number of deaths due to head injury (flying seats etc).
If the flight attendants had given the "heads down" instructions, perhaps we'd have a few more survivors.
Should the attendants have recognized the need to take matters into their own hands?