A side-stick or sidestick controller is an aircraft control column that is located on the side console of the pilot, usually on the righthand side, or outboard on a two-seat flightdeck. Typically this is found in aircraft that are equipped with fly-by-wire control systems. The throttle controls are typically located to the left of a single pilot or centrally on a two-seat flightdeck. Only one hand is required to operate it; two hand operation is neither possible nor necessary. The side-stick is used in many modern military fighter aircraft, such as the F-16 Fighting Falcon, Mitsubishi F-2, Dassault Rafale, and F-22 Raptor, and also on civil aircraft, such as the Sukhoi Superjet 100, Airbus A320 and all subsequent Airbus aircraft, including the largest passenger jetin service, the Airbus A380. It is also used in very new helicopter models like the 525 by Bell. This arrangement contrasts with the more conventional design where the stick is located in the centre of the cockpit between the pilot's legs, called a "centre stick". In the centre stick design, like traditional airplane yokes, both the pilot's and co-pilot's controls are mechanically connected together so each pilot has a sense of the control inputs of the other. In typical Airbus side-stick implementations, the sticks are independent, the so-called ‘passive’ side-stick. The plane's computer either aggregates multiple inputs or a pilot can press a "priority button" to lock out inputs from the other side-stick. However, if both side-sticks are moved in different directions, then both inputs are cancelled out and an aural "dual input" warning sounds. Examples of this occurrence include the 2009 crash of Air France Flight 447, and the 2015 crash of Indonesia AirAsia Flight 8501. However a later, significant, development is the 'active' side-stick, which is in the new Gulfstream G500/G600 series business jet aircraft. In this system, movements in one side-stick produce the same actions in the other side-stick and therefore provides valuable feedback to the other pilot. This addresses the earlier criticisms of the 'passive' side-stick. The 'active' side-stick also provides tactile feedback to the pilot during manual flight and many believe it will become the standard for all new ‘FBW’ aircraft. Such an 'active' side-stick can also be used to increase pilots’ adherence to a safe flight envelope by applying a force feedback when the pilot makes a control input that would bring the aircraft closer to the borders of the safe flight envelope. This reduces the risk of pilots entering dangerous states of flights outside the operational borders while maintaining the pilots' final authority and increasing their situation awareness.
