Are the Chaos Fleet's carrier-based aviation units more like insane mechanical-biological hybrids like the Helbrute, or are they trained pilots? (Or maybe a bit of both)

I remember hearing about Chaos Space Marines mounting their servants in their craft, and over time they became one with their craft, going crazy, except that it wasn't like on the ground, where flying required precise takeoffs and landings and the ability to control the three dimensions. A person who is completely out of control cannot fly a plane out to fight and then fly back smoothly.

Or are they trained-rebels from the IoM . to not succumb to Chaos' influence and retain their own judgment?

Or could they be anything, and the Chaos Warband just said "let's push all the planes out there and see what we can do?"