This site is being deprecated.
Please see the official X‑Plane Support page for help.
X-Plane 9 is no longer being updated, so if it doesn't work on the latest Mac OS, there will not be a patch from Laminar Research for it.
Sierra is fairly new, so X-Plane 10 has not been tested on it yet. You could try the free demo and see how it goes. The full sim is basically the same, aside from having no time limit and all scenery.
Note that X-Plane does not support Force touch trackpads.
This site is no longer being actively maintained.