I would accomplish turning by animation only, the ai would not think about turning but rather just simple vector and point math.
Easing to a heading and then rotating the sprite to face its heading would give the effect your after.
You would only rotate the sprite towards a heading if it is a defined amount close to other planes,
otherwise it rotates towards whatever direction it is already going.
You've given me a great idea for a simple example, I'll try to have it done by Christmas, I'm also working on releasing my whole library that I use for making games, and then also releasing an editor I made that turns art into code.