Please please please don't believe everything that you read about this Qantas incident.
If you are strapped in, no harm will come to you during turbulence. It does not mean that you have to like the feelings of descending quickly.
Qantas flight QF32 from Singapore
We are not evolved to be that familiar with 3D movement like birds are. We cannot see an external reference point except sky so we have no idea how much we have moved during the turbulence. We feel it and we believe our senses. Our senses are not accurate but that does not matter to the brain - it will still produce fear chemicals if you do not know what is going on....