In-flight upset - 154 km west of Learmonth, WA, 7 October 2008,

• The flight crew provided inputs to the EFCS, either indirectly using the autopilotor directly using the flight crew controls. The controls included the sidestickcontrollers (or sidesticks) to manoeuvre the aircraft in pitch and roll, and footoperatedrudder pedals to control yaw.• The air data and inertial reference system (ADIRS) provided information onimportant flight parameters such as airspeed, altitude, angle of attack (AOA),and attitude to the EFCS and autopilot, as well as to the flight displays used bythe crew.Figure 3: Simplified overview of the relationship between aircraft systems1.6.3 Electrical flight control system (EFCS)System overviewThe A330’s electrical flight control system (EFCS) was a ‘fly-by-wire’ system.That is, there was no direct mechanical linkage between most of the flight crew’scontrols and the flight control surfaces. 25 Flight control computers sent movementcommands via electrical signals to hydraulic actuators that were connected to thecontrol surfaces. 26 The computers sensed the response of the control surfaces tothese commands, and adjusted the commands as required.Figure 4 provides an overview of the Airbus fly-by-wire system, and Figure 5shows the flight control surfaces on the A330.25A330s are described as either ‘basic’ or ‘enhanced’ models (QPA was an enhanced model). Basicmodels have a mechanically-controlled rudder while the later enhanced models have fly-by-wirerudder control. For both models, elevator trim included a mechanical backup.26On a conventional airplane‚ inputs from the pilots or the autopilot were transmitted to thehydraulic actuators by an arrangement of mechanical components.- 10 -