Automating routine work leaves operators only the rare emergencies, for which they are now out of practice.
Bainbridge's 1983 paper. Air France 447 in 2009 is the case: autopilot disengaged in conditions the crew had rarely hand-flown, and the recovery required a skill automation had made rare.
In practice
- A pilot who has hand-flown four approaches in two years is asked to hand-fly one in weather that defeated the automation.
- A controller whose alerts are handled automatically for eleven months must handle the twelfth manually, having lost the practice.