My F-4 buddy told me of a night AR where they were flying through a slanted layer of clouds. Dave said his back seater asked if he "was okay" and Dave realized he had the jet flying sideways as he fought the vertigo induced by the odd visual cues.
My first assignment out of UPT was the venerable Lockheed Racer, more commonly known as the T-33 Shooting Star. Crews referred to it as the stretch F-80.
The T-33s were used by ADCOM as interceptor target support, proficiency flying for headquarters peuks, and various mission support activities (some really interesting stories here).
One crisp, clear Southern California winter night we were flying a target mission out of Pt Magu. Pretty simple. Fly west over the Pacific for about 350 miles, turn around, fly east to land, and harass the interceptors along the way with our under wing chaff and ecm pods. We were on the east bound leg on this moonless, pitch dark night when I noticed my partner in the front seat was slowly banking to the right. I asked what he was doing and he replied “nothing” and snapped back on the proper heading. After a few minutes it started happening again. I took a closer look out front to see a series of boat and drill rig lights that formed an artificial horizon line. My front seater was subconsciously lining up with this fake horizon. He eventually went to pure instrument flying until the coastline came into view.
Another time on a similar mission out of Elgin AFB, Fl, we were to fly due south checking frequency reception over the Gulf for ATC. On departure out of Elgin we encountered scattered towering cumulus clouds. As we climbed, the cloud layers thickened along with intermittent lightening. Did I mention that it was monsoon season? I was again in the rear cockpit this leg, enjoying the light show. The lucky dude up front was having a tough time even flying on instruments due to the lightening and turbulence. He admitted to being extremely spatially disoriented. So, I pulled the much hated instrument flying hood from its storage behind my seat, over my head, and attached it to the top of my instrument panel, completely blocking the light show from view. I flew the rest of the sortie under the beloved instrument hood. My bud enjoyed about three hours of disorienting, psychedelic light show. On our last frequency with ATC on the southbound leg started to get scratchy and broken. The controller told us that when he quit answering us to fly south another ten minutes, then turn around and head back. Sure was a dark, nasty night.