Mishap risk index

See Mishap Risk Index (MRI) and Safety Order of Precedence (SOOP) for additional related information. 

The HRI is an index number indicating qualitatively the relative risk of a hazard. It is derived from the HRI matrix by identifying the matrix cell resulting from the intersection of the hazard likelihood and hazard severity values. In a typical HRI matrix, such as the matrix in MIL-STD-882, there are 20 cells created by a 4 x 5 matrix. The matrix cells are labeled with an index number of 1 through 20, where 1 represents the highest risk and 20 the lowest risk. The smaller the HRI number, the higher the safety risk presented by the hazard. The HRI number establishes the safety significance of a hazard and who can accept the risk for the hazard. It should be noted that the HRI is also often referred to as the mishap risk index (MRI). However, since hazard risk and mishap risk are really the same entity, then the HRI and the MRI are really the same entity, just viewed from two different perspectives. 

The Hazard Risk Index (HRI) matrix is a risk management tool used by system safety for hazard/mishap risk assessment. The HRI matrix establishes the relative level of potential mishap risk presented by an individual hazard. By comparing the calculated qualitative severity and likelihood values for a hazard against the predefined criteria in the HRI matrix, a level of risk is... 

The HRI matrix also goes by other names however, regardless of the name used, the matrices are essentially the same entity because hazard risk is the same entity as mishap risk. Some of the alternate names include Risk Hazard Index (RHI) matrix, MRI matrix, and Mishap Risk Assessment Matrix (MRAM). 

It should be noted that hazard risk and mishap risk are the same entity, just viewed from two different perspectives. Therefore, the MRI matrix and the Hazard Risk Index (HRI) matrix are essentially identical tools thus, a more detailed definition is provided under the Hazard Risk Index (HRI) matrix definition. 

See Hazard Risk Index (HRI) Matrix for additional related information. MISHAP RISK ANALYSIS... 

Arbitrary categories have been established in MIL-STD-882 that provides qualitative measures for the most reasonable likelihood of occurrence of a mishap and for the outcome severity of a mishap. For example, if the safety analyst assesses that an event will occur frequently, it is assigned an index level A, or if it occurs occasionally, it is given an index level C. This qualitative index value is then used in qualitative risk calculations and assessments. 

---