The Hazard Risk Assessment Matrix is derived from MIL-STD-882B. The matrix provides a systematic method for assigning a hazard level to a failure event based on the severity and frequency of the event.
The hazard level consists of one number and one letter. The number represents the severity of the event. The numbers represent: (1) Death, system loss, or irreversible environmental damage; (2) Severe injury, occupational illness, major system damage, or reversible severe environmental damage; (3) Injury requiring medical attention, illness, system damage, or mitigatible environmental damage; (4) Possible minor injury, minor system damage, or minimal environmental damage.
The letter of the hazard level represents the Frequency of Occurence. The letters represent: (A) Expected to occur frequently; (B) Will occur several times in the life of an item; (C) Likely to occur sometime in the life of an item; (D) Unlikely, but possible to occur in the life of an item; (E) So unlikely, it can be assumed occurrence may not be experienced.
As can be seen from the table, each hazard level is associated with a risk category. Risk categories assist risk-management team members in differentiating credible high-hazard threats that may result in loss of life and property from less probable risks, therefore aiding management in risk vs. cost decisions.