-Specify the flight dynamics model to use. Can be one of jsb, larcsim, yasim,
-magic, balloon, ada, external, or null.
+Specify the flight dynamics model to use. Name may be one of jsb, larcsim,
+yasim, magic, balloon, ada, external, or null.
+.TP
+.BI "--fg-aircraft=" "path"
+Specify an additional path to search for aircraft directories. (can be repeated)