I have flights for both sides flying around in there right now. It was a quick mission build so they may do some strange things, but they are in there and they want to kill you.
You can just up in free flight and try to find them. They should run for several hours until either, they all get shot down, they run out of gas, or the arena crashes. For the next couple of days I'm going to try to keep AI in the arena at most times, if anyone wants to try them out.
At 8pm est today we are going to stop that and test a different mission. Warning: We may have some arena crashes, but that helps us try to pinpoint issues.