UFO spotted at airplane height over Tempe, AZ.

It seems to be some sort of aircraft/drone that is able to hover and move very precisely when it does shift. I watched the object track planes taking off from the sky harbor for about 10 minutes before it took off. The object was way above usual drone height as well. As it tracked the planes it would shift in quick 90 or 180 degree rotations. I have videos of it rotating but the best and most interesting is when it flys off. Has anyone seen this kind of thing? FYI: The object flys away in the last 18 seconds of the video.