The way I understand it, the map resets and the base ownership is set to the next in rotation for that map. In other words, it's setting which bases are owned by which countries the next time that map is used.
Yes, it's a bummer that it has to reset that way...since many people are trying to land and all of a sudden they're 50+ miles from the nearest friendly base. But, as was said before, I too believe the sortie is thrown out if you can't land when the arena kicks you out.
Just another thing we all have to live with...I have more important things in the real world to worry about, so I don't get all worked up over it.