Definition
In risk assessment, likelihood is an estimate of how probable it is that a given hazard will actually result in an unsafe event. It is one of the two factors used in a risk matrix, paired with severity, and is typically rated on a scale such as probable, occasional, remote, or improbable.
Plain English
Likelihood is how likely something is to happen. When assessing risk, you ask: how often, or how realistically, could this hazard actually cause a problem?
Context Anchor
Used when assessing risk before or during a flight, such as judging weather, aircraft condition, pilot readiness, or route choices.
Derivation
Likelihood comes from 'likely,' meaning probable or expected. Probability comes from the Latin probabilis, meaning 'provable' or 'credible.' Both words point to the same idea: how believable it is that something will occur.
Why Pilots Care
Accurate judgment of likelihood allows a pilot to rank hazards by real risk and choose appropriate mitigations instead of reacting to every possible threat.
Grounding Statement
If the chance of the event happening is high, the likelihood is high, even before you consider how serious the result would be.
Intuition Check
Likelihood does not mean “how bad would it be?” It means “how likely is it to happen?” The “how bad” part is judged separately.
Example Sentence 1
When assessing the risk of a night cross-country, the instructor rated the likelihood of encountering icing as remote based on the forecast.
Example Sentence 2
High likelihood of gusty crosswinds led the instructor to recommend a different runway for the student’s first solo.