Any explanations? (Black object following plane)

I live in Santa Cruz. As i was waiting for a bus there was a beautiful sunset over the ocean so i gazed out for a while. I noticed a plane come into view and once it came into frontal view i noticed a small black object.

At first i thought it was a bird, but after a minute i realized this small object was following or was next to the plane on the opposing side. Whatever it was, it was pacing the plane, would drop back, and then come forward again. For a few seconds it seemed as if it disappeared then it came back into view.

Anyway, the plane was commercial definitely, and the object was roughly the between the size of a large SUV - monster truck if i had to guess.

[edit on 10-3-2009 by Ex Plures-Unus]

I think you forgot to include the pics or video.

Did it look anything like this?



Sorry, didn't know the embed was off.
Link

[edit on 11-3-2009 by becomingaware]