Unsafe Control Actions

From Leveson, STAMP handbook, an unsafe control action is a control action that, in a particular context and worst-case environment, will lead to a hazard. It can be one of four types:
  1. Not providing the control action leads to a hazard.
  2. Providing the control action leads to a hazard.
  3. Providing a potentially safe control action but too early, too late, or in the wrong order.
  4. The control action lasts too long or is stopped too soon (for continuous control actions, not discrete ones).