TTN, I think that is not quite the same. What you possibly experienced was the onset of vertigo - and the need to pee?
I had that once in the Varisty. The hatch to the bomb aimer's compartment was open and I was sat on the floor with my legs dangling in the void. The ground was 4000 feet below. The brain ignored the hard shell of the aircraft and told me I was sitting on the edge of a 4000 feet precipice. I needed a pee then!
There was also the documented case of the Jaguar pilot on a high transit to Akrotiri. He was over Italy or the Med at 30k odd with that strange indefined horizon below and blue sky above. He felt he was sitting on a knife edge. Again it was vertigo and not a true phobia.