Untamo!
I have TrackIR5 and can confirm this from day one of the game. I made a post but no one else was having the problem as far as I was aware. Mostly the problem comes when you push the side of your head towards your shoulder then climb or dive and and move your head up or down... A quick shake of the head and it frees off. What is this called, yaw? I could net tell at first if it was a feature of High G and hanging in the belt or being squashed but im convinced its a bug now.
My solution was to be less animated when flying
