9gmax
While 9g is much too much for me your comments on the somatogravic illusion are interesting. As you probably know the illusion is caused by a long sustained longitudinal acceleration that causes someone sitting down to think the force on their back means they are laying on their back and so very nose up.
To suffer from it (as well as needing the sustained accel) one needs to reject all other cues to one's attitude to say nothing of not look at or believe the (probably) three attitude indicators.
Many problems with ones pink body, which are of little consequence when sitting watching the TV, can be quite off-putting - even serious - when flying especially if they are asymmetric. Blocked or sticky sinuses and Eustachian tubes, hard wax scraping at an ear drum and of course any infection of the inner ear balance organs, can lead to a remarkable level of confusion if at the same time you can't see out. Normally the messages from one's eyes are so powerful that they kill stone dead confusion (manifesting perhaps as a touch of dizziness) from these other sources.
But when you can't see..............