Saw this on youtube earlier:
https://www.youtube.com/watch?v=Zkybrp6cgO4
Made me think about how common an experience it is to have the back of someones seat in my face when im on a plane, it happens probably 80% of the time when i travel nowadays.
one time a fella turned around and gave me a heads up, which was nice. most of the time it happens the moment the plane takes off and occasionally causes disruption, like getting water spliied all over me as im mid-gulp or getting smacked in the face as im getting something out of the compartment on the back of the seat.
In my view it's pretty rude to do it without at least turning around and giving a nod, and especially if it's a tall person behind you who's got feck all leg room in the first place.