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

exceeding a predefined safe flight envelope). Automatic flight-envelopeprotections included high AOA protection, load factor limitation, pitch attitudeprotection, roll attitude protection, and high speed protection.• Alternate law. The EFCS switched to alternate law if there were certain types orcombinations of failures within the flight control system or related systems.Some types of protection, such as high AOA protection, were not provided, andothers were provided using alternate logic.• Direct law. The EFCS switched to direct law in situations where there weremore failures of relevant, redundant systems in addition to those that led to thereversion to alternate law. No flight-envelope protections were provided, andcontrol surface deflection was proportional to sidestick and rudder pedalmovement by the flight crew.Pitch controlThe EFCS achieved control of the aircraft’s pitch by using two elevators and thetrimmable horizontal stabiliser (THS). The elevators provided short-term changes inpitch, and the THS provided longer-term changes where needed so that continuouselevator deflections were not required.Maximum elevator deflection was 30° nose-up and 15° nose-down. FCPC 1normally controlled the elevators (see section 2.1.1 for further details).Maximum THS deflection was 14° nose-up and 2° nose-down. In normal law and inmost cases in alternate law, the EFCS automatically controlled THS movement(known as ‘autotrim’). Autotrim was not available in direct law and with sometypes of failures in alternate law. However, the flight crew were always able tomanually control the trim by using the pitch trim wheels on the flight deck’s centrepedestal.Figure 6: Trimmable horizontal stabiliser and elevators on QPA- 12 -