And we are back to cold water shock.
Immersion suits and air bottles (STASS or equivalent) would at least have given them a fighting chance.
Even being shown a video of how to escape underwater would have better than nothing.
Planned flight over water out of auto range of land with water temp less than 5 degrees.........
I keep coming back to the water temps too, especially since it looks like the doors were off, hence the harnesses.
The video shows the fuselage partially submerging on first contact with the water (floats underwater), then a fairly quick roll-over. With the doors off, that cabin would have filled with frigid water very quickly. I wonder if a doors-closed flight might have given them a little more time.
I've done photo shoots (real ones) in a harness with doors off, but never over water at those temps.