This site is being deprecated.
Please see the official X‑Plane Support page for help.
Make sure you're logged into the Apple ID you used to purchase the aircraft with in the device Settings. Make sure it's using the correct ID under the iTunes & App store section. Then close the app entirely (by double pressing in the home button then swiping up on the app) and restart. You may need to restore purchases in the app's settings as well.
This site is no longer being actively maintained.