Editing Aircraft flight control system (section)

===Secondary controls===
{{Main|Trim tab|Flap (aircraft)|Air brake (aircraft)|Spoiler (aeronautics)|Leading edge slats|Variable-sweep wing}}
In addition to the primary flight controls for roll, pitch, and yaw, there are often secondary controls available to give the pilot finer control over flight or to ease the workload.  The most commonly available control is a wheel or other device to control [[Flight control surfaces#Elevator trim|elevator trim]], so that the pilot does not have to maintain constant backward or forward pressure to hold a specific pitch [[Aircraft attitude|attitude]]<ref>Thom,1988. p. 87.</ref> (other types of trim, for [[rudder]] and [[ailerons]], are common on larger aircraft but may also appear on smaller ones).  Many aircraft have [[flap (aircraft)|wing flaps]], controlled by a switch or a mechanical lever or in some cases are fully automatic by computer control, which alter the shape of the wing for improved control at the slower speeds used for take-off and landing.   Other secondary flight control systems may include [[Leading edge slats|slats]], [[Spoiler (aeronautics)|spoilers]], [[Air brake (aircraft)|air brakes]] and [[variable-sweep wing]]s.