yeah, it's a bit controversial, basically to fly a helicopter you need to use peripheral vision a lot, and the main reason you have motion sickness it’s the movement on your peripherals. Ideally it should be a dynamic vignette based on helicopter movement and rotation. I’ve done this optional, so it’s up to you to select what works better for you

Hasn't it been proven that adding a virtual nose (in this case the oxygen mask) lowers motions sickness for most people? Why is this removing the helmet then? lol