A stick shaker is a mechanical device that produces a pronounced vibration on the control yoke/stick of an aircraft to warn the pilot of an imminent stall.
Most modern transport aeroplanes are equipped with an angle of attack sensor. As an aeroplane will always stall at a given angle of attack (not airspeed) for a given configuration (flap and slat position). As the aeroplane’s angle of attack increases the sensor detects this change.
At the pre-set angle of attack, the sensor sent the information to a computer which sends the command to an electric motor. This motor vibrates the control column, imitating the effect of the aerodynamic buffet which you would feel in a small light aircraft, this system must not be confused with a stick pusher which automatically pushes the control column forward to correct the stall
The stick shaker is a warning device, and the stick pusher is a stall avoidance device.
Author – Antonio Moran