Page 101 - Serious Incident Prevention How to Achieve and Sustain Accident-Free Operations in Your Plant or Company

CH07pp068-82 4/10/02 12:50 PM Page 79

Understanding the Risks 79

TABLE 7-1
Suggested Mishap Severity Categories Based on MIL-STD-882D 5
Description
Criteria Category Environmental, Safety, and Health Result

Catastrophic 1 Could result in death, permanent total disability, loss
exceeding $1M, or irreversible severe environmental
damage that violates law or regulation.

Critical II Could result in permanent partial disability, injuries or
occupational illness that may result in hospitalization of
at least three personnel, loss exceeding $200K but less
than $1M, or reversible environmental damage causing
a violation of law or regulation.
Marginal III Could result in injury or occupational illness resulting
in one or more lost work day(s), loss exceeding $10K
but less than $200K, or mitigatible environmental dam-
age without violation of law or regulation where
restoration activities can be accomplished.
Negligible IV Could result in injury or illness not resulting in a lost
work day, loss exceeding $2K but less than $10K, or
minimal environmental damage not violating law or
regulation.

Assigning a quantitative mishap probability to a potential design or proce-
dural hazard is generally not possible early in the design process. At that
stage, a qualitative mishap probability may be derived from research, analy-
sis, and evaluation of historical safety data from similar systems.
Supporting rationale for assigning a mishap probability is documented in
hazard analysis reports. Suggested qualitative mishap probability levels are
shown in Table 7-2.

TABLE 7-2
Suggested Mishap Probability Levels (Based on MIL-STD-882D) 7
Description* Level Specific Individual Item Fleet or Inventory**
Frequent A Likely to occur often in the life Continuously experienced
of an item, with a probability of
-1
occurrence greater than 10 in
that life
Probable B Will occur several times in the Will occur frequently
life of an item, with a probability
-1
of occurrence less than 10 in
that life