Dragon NPC perching issue

[Akabeth]

In the interest of keeping my post brief, one of my CK NPCs somehow manages to break free from his routine at random -- sometimes via loading save files, other times when I modify my .esp.

 

http://i1183.photobucket.com/albums/x464/lonetac287/ScreenShot214.jpg

 

But the core issue is illustrated above -- he often prefers to perch midair. I'm hoping someone can point out what I may be doing wrong since none of my solutions short of complete replacement of all entries (body data, ai packages, etc.) seem to be working properly.

 

Thanks. :)