Risk
Section 06: System Safety & Functional Safety
Definition
The combination of the probability (or frequency) of occurrence of a harmful event and the severity of that event. In system safety analysis, risk is assessed by evaluating how likely a failure condition is to occur and how severe its effects would be on the aircraft, its occupants, and people on the ground. Risk assessment is the basis for determining whether a design meets safety objectives: each failure condition must have a probability of occurrence commensurate with its severity classification.
Where This Shows Up
Risk is the central concept linking failure probability to failure severity. The safety objectives in regulations like 14 CFR 25.1309 and CS 25.1309 establish an inverse relationship: more severe failure conditions must be shown to be less probable. This risk-based framework underlies all system safety analysis in aviation.
Primary Sources
Defines risk in the context of system safety assessment and provides methods for risk evaluation.
FAA Advisory Circular defining the relationship between failure condition severity and probability objectives.
Related Terms
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