For 3D pathfinding I would recomend using A* pathfinding algorithm or even Near Optimal Hierarchical Patfinding (HPA*) http://aigamedev.com/open/review/nea...l-pathfinding/

If you decide to use A* pathfinding there was news post from Will regarding example for using A* pathfinding algorithm http://www.pascalgamedevelopment.com...How-A*-Is-Done
While the example shows A* pathfinding algorithm on 2D surface it can be easily converted to be used in 3D world becouse it bases on node system.

As for HPA* I haven't found any examples writen in pascal jet and that is a shame becouse HPA* is much more optimized and uses lots less memory than plain A*.