Although an aircraft can be operated throughout a wide range of attitudes, airspeeds, and power settings, it can be designed to fly hands-off within only a very limited combination of these variables. Trim systems are used to relieve the pilot of the need to maintain constant pressure on the flight controls, and usually consist of flight deck controls and small hinged devices attached to the trailing edge of one or more of the primary flight control surfaces.

Designed to help minimise a pilot’s workload, trim systems aerodynamically assist movement and position of the flight control surface to which they are attached. Common types of trim systems include trim tabs, balance tabs, antiservo tabs, ground adjustable tabs, and an adjustable stabiliser.

Ground adjustable trim tabs: Some trimming tabs are not adjustable in flight, but can be adjusted on the ground, to correct a permanent out of trim condition. They are usually found on ailerons. They operate in the same manner as the adjustable tabs.

The ground adjustable trim tab is a non-movable metal tab on a flight control which is adjusted on the ground to optimise the inflight characteristics of an aircraft.