Brace yourself for impact. If you know you’re going to crash, brace yourself. Return your seat back to its full upright position and assume one of two "brace positions."
If the seat or bulkhead in front of you is close enough to easily reach, place one hand palm-down on the back of that seat, cross the other hand palm-down over the first hand, and rest your forehead against your hands (don’t lace your fingers). It is also sometimes recommended to put your head directly against the seat in front of you and lace your fingers behind your head, tucking your upper arms against the sides of your head.