Here is an interesting blog that you can refer to for the AI algorithm for Flight game.
Path Following is not Pathfinding
How your AI determines to follow this path is something completely different and is referred to as Path Following. The typical strategy for Path Following is to allow your AI to look ahead of where it's traveling to see if it can short cut the path to making more natural curved movements.
Havok AI Demo at GDC 2011
The scene with numerous flying AI's
An inverted view of the navigation volume