Schematic representation of the ATTAS test bed. The graphic shows the test equipment and fly-by-wire control surfaces. Electrohydraulic, digital fly-by-wire flight control system. This intervenes in the standard mechanical-hydraulic controls via electrohydraulically-operated clutches, which are connected to the control devices of the safety pilot sitting on the right. The safety pilot can disconnect the fly-by-wire linkages at any time and take over control with the mechanical system.