Definition
The risk that remains after controls or mitigations have been applied to a hazard. It is the level of risk a pilot or instructor knowingly accepts because it cannot be eliminated entirely.
Plain English
The risk left over after you've done what you can to reduce it. You've taken sensible steps, and what remains is what you're choosing to live with.
Context Anchor
Seen in risk management discussions when comparing the original risk of a flight or training activity with the risk left after safety actions are taken.
Derivation
Residual comes from the Latin residuum, meaning 'that which is left behind.' In risk management, it points to the portion of risk that remains after action has been taken.
Why Pilots Care
Pilots must decide whether the remaining risk is acceptable before flight; accepting excessive residual risk can lead to incidents or accidents.
Analogy
If you drive more slowly on a wet road, you reduce the chance of losing control, but you do not make the road completely risk-free. The remaining chance of a problem is like residual risk.
Grounding Statement
A flight may become safer after changes are made, but there is usually still some remaining risk to recognize and accept deliberately.
Intuition Check
Residual risk does not mean a tiny risk or a risk you can ignore. It means the risk still left after safety steps have been taken.
Example Sentence 1
After delaying departure to let the thunderstorms pass, the instructor briefed the student on the residual risk of lingering gusty winds at the destination.
Example Sentence 2
The safety report noted that the residual risk of fuel exhaustion remained low because of the added fuel stop.