Risk or Uncertainty
We are pretty good at things. So good in fact, that a single error rarely causes a failure. Looking backwards, it is easy to see the chain of events that led to a failure or an accident however looking forward all we can see are the endless strings of possible connections.
Society is proficient at assessing the chance of an error - this is the assessment of risk. For example there is a possibility of one engine failure in 100,000 flight hours*.
Determining the chances of an uncertain event is not possible as the interconnections that lead up to them are almost infinite or at least looking forward, unknowable.
The best defense against uncertainty is action protocols based on planning and experience. For example in finance - never put all your eggs in one basket. In communication the sender ensures the receiver understands the message, in helicopters - no one ever walks toward the tail rotor. These individual actions break the chain of events or connections that could lead to a failure.
Unless one uses reflection and debriefing, you will never know if these defenses have been used or how close the edge of catastrophe that you have stumbled.
Manage both risk and uncertainty with a debrief and crew communication.
In Search of the Perfect Crew