The craft is incontrollable using the keyboard. The PIDs for the controllers are published as pitch PID respectively roll PID.
Those PID should be in the responsevity of the ship reaction to the user input, not in the resposevity of the controller. The keyboard has only 0 or 100 :).
Check a tutorial in Unity how to make this more resposive and have a better user experience.
You better connect the key input (or give the posibility to chose) to the actual heading and pitch axis in the nav. There is a comment in steams.