An example of usability testing is the development of fly-by-wire flight controls. Fly-by-wire flight controls eliminate the mechanical linkages between the flight controls and the aircraft control surfaces. Sensors communicate the demanded flight response and then apply realistic force feedback to the fly-by-wire controls using motors. The behavior of fly-by-wire flight controls is defined by control algorithms. Changes in algorithm parameters can translate into more or less flight response from a given flight control input. Likewise, changes in the algorithm parameters can also translate into more or less force feedback for a given flight control input. The “correct” parameter values are a subjective measure. Therefore, it is important to get input from numerous man-in-the-loop tests to obtain optimal parameter values.