In ORM, what does probability measure?

• A. The severity of the mission impact
• B. The likelihood that a hazard will occur
• C. The frequency of exposure
• D. The cost of controls

Answer: (B)

Probability in ORM is about how likely a hazard is to occur during an operation. It’s a measure of chance, not of how severe the outcome would be, nor how often you’re exposed to the hazard, nor the cost of addressing it. In ORM, risk is evaluated by combining probability with the severity of potential consequences to determine an overall risk level that guides how you apply controls. For example, a wet deck might have a higher probability of causing a slip under rainy conditions, while the severity would describe how bad a slip could be. If the deck is rarely wet, probability is low even if a slip could be serious. The other factors—severity of mission impact, frequency of exposure, and cost of controls—describe different aspects of risk or management decisions, but they’re not what probability itself measures.