Hi Dave, are these black lines about a few cm long and about one pixel width, appearing above the airplane? Do they appear in certain scenery backgrounds only, and do you observe them when the FPS become higher? What type of monitor are you using, and the refresh rate?

This problem could be caused by the relatively slower refresh rate of your monitor. Under "graphics" menu in AFPD, try enabling the vertical sync and see if this helps. This may bring your FPS down however.

Alternatively, see if you can increase the refresh rate of your monitor, and see what happens.