Dodging a Caitlyn's Ace in the Hole
Has anyone ever tried to flash behind the incoming projectile to dodge it? I haven't found anything related to this, maybe someone here knows if this is possible.
You won't be able to dodge the projectile by flashing over it. Once the shot is fired there is no way of dodging it by movement alone.
The only ways of dodging a Cait Ult are: Spellshields, stasis or someone standing between the initial target and the projectile.
Flashing behind the ult will merely cause it to change directions. The same happens if you are being teleported somewhere else.
Considering that the game puts aside reality's physics, and since Caitlyn's Ace in the Hole isn't a skillshot ability, then it isn't dodgeable: it goes straight to the position you are (works as a homing shot).
You can only deny that damage by positioning right behind other friendly champions or Banshee's Veil spellshield.