Why AI rebase air units all turns?

Why AI rebase air units all turns?

It's freak boring! Every turn two AI send all planes to another city and next turn returns to original city. I selected No figth and moviment animation but doesn't work for air units. Now i have to waiting a lot every turn!

I think the AI just moves all units around all the time to prevent them from blocking your path too much. The aircraft are included in this system as well, despite the fact that they can't get in the way.