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What is Hazard Analysis?
Introduction
Definition
Hazard analysis is a
process used to determine how a system can cause hazards to occur and then
reducing the risks to an acceptable level. The process consists of: (1) the
developer of the system determining what could go wrong with the system, (2)
determining how the effects of the failure can be mitigated, and (3)
implementing and testing mitigations. System Level
The analysis must start
with the system level and include the component, the user (if any), operator
(if any), and environment hazards. Once the hazards are determined and the
risk assessment (with predefined quantitative definitions) is assigned, the
hazards can be assigned to hardware and/or software as appropriate. Software Level
The software hazards are
then further broken down into a Fault Tree, which is a top-down approach to
determine the functions that cause and the ones that mitigate the associated
hazards. At the end of the fault tree analysis, the safety engineer needs to
show the risk is lower due to the mitigations in place. The mitigations must
be testable in order for the developer to demonstrate to the FDA that they
have installed the mitigation and it is effective. Performing Hazard Analysis
There are several methods
available for performing the hazard analysis. The most common types are
Failure Modes and Effects Analysis (FMEA) and Fault Tree Analysis (FTA).
Since the software does not have a meantime between failures (MTBF), Ascent
has found the FTA method to be superior in the software safety analysis. Levels of Risk
Ascent uses a three-range
process for determining acceptable levels of risk. The three ranges are
acceptable, ALARP, and unacceptable, which are defined below:
The determination of how
faults can occur requires an individual or team of people with extensive
experience in the development of similar types of systems such as real-time
embedded systems, PC systems, workstations, or other like processes. Ascent
Technologies uses a structured process for the development of software, which
greatly enhances the ability of the safety engineers in the performance of
hazard analysis. |
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