i would sit down and wait for the plane to crash...... maybe scream a bit... panick like hell for sure....and hope i fall into a cardiac arrest before i die so i don't feel it..
FACT: most people don"t die from the initial impact it's self... they die from the flames/fumes that the plane makes when it hits the ground... so i would also try to be near a door and hold on real tight... and try to lay real flat on the ground so i don't fly allover the place breaking my bones so i can't get to an exit.

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