Functional Complexity Failures and Automation Surprises: the Mysterious Case of Controlled Flight into Stall (CFIS)
Nineteen modern airliner Loss of Control (LOC) accidents resulting in aerodynamic stalls were analyzed. These accidents involved structurally and mechanically sound aircraft decelerating through the 1.3VStall buffer to the stall airspeed - i.e. a Controlled Flight into Stall (CFIS). The analysis produced three main observations: First, the accidents were “functional complexity” failures -- the result of a complex sequence of behaviors of the automation functions. There were no consistent: failures that triggered the events (e.g. sensor failures), effects of triggering events on the automation (e.g. mode change), or commands issued by the automation (e.g. thrust setting). Second, the pilots were unable to intervene effectively due to the absence on the flight deck of relevant information and salient cues to monitor these rare events or their effects. Third, there was no single intervention that could mitigate all of these accidents. Implications for flight deck procedures, training and automation design are discussed.
& Mauro, R.
(2015). Functional Complexity Failures and Automation Surprises: the Mysterious Case of Controlled Flight into Stall (CFIS). 18th International Symposium on Aviation Psychology, 488-493.