Flying through the clouds on an IFR flight can be one of the most exhilarating things you can do. There’s nothing quite like busting in and out of ‘the soup’. Even better, there’s no feeling quite like seeing the runway appear at the end of an instrument approach. But flying through the clouds is not without risk: between 5-10% of all general aviation accidents result from spatial disorientation, and of those accidents, 90% of them are fatal.

Why Disorientation Happens In The Clouds?
Your eyes are your primary sensory input when you’re flying. You look outside, you see which way the sky is pointing, and you adjust your airplane. But all of that falls apart when you’re in the clouds…

Source: Avoiding Spatial Disorientation On Your Next Instrument Flight | Boldmethod