60 years ago: The famous Boeing 707 prototype barrel roll over Lake Washington
Interestingly enough, if the occupants weren't looking outside, a "1G roll" would feel almost the same as level flight; here's a video showing how "gravity" seems to invert along with the plane:https://www.youtube.com/watch?v=pMWxuKcD6vEThis is also why pilots can become spatially disoriented:https://en.wikipedia.org/wiki/Spatial_disorientation