Flight game AI algorithm?

Question

Greetings all,

I am in the designing phase of one of my hobby projects.I am going to develop a 3D air-combat game. (inspired by HAWX). But I am wondering how the AI works for enemy crafts? I guess they do not move along a path (pathfinding on a graph)as in FPS games. What kind of algorithms can I use for enemy craft movement? Are there any AI libraries I can use for this?

Note: I use irrlicht engine, C++ as my development environment.