Usually a set of two horizontal fins, or small wings, that protrude from the tail of an aircraft. These usually contain control surfaces known as elevators or elevons, which serve to change the airflow past the aircraft in such a way as to raise or lower the pitch of the vehicle. They are typically controlled by pulling back or pushing forward on the controls (yoke, stick, etc.) and usually in smaller aircraft have small tabs, controlled from the cockpit or cabin, which allow the pilot to trim the airplane to maintain the proper pitch during normal flight.