Why do accidents and mishaps happen?
Can accidents and mishaps be prevented?
How are accidents and mishaps prevented?

System Safety Paradigms:
· Mishaps can be eliminated or prevented by controlling the risk factors involved
· Mishaps result from the occurrence of hazards existing within a product, process or system
· Hazards are typically man-made; they result from the combination of system laws and standard hazard sources existing within a product, process or system
· Risk is the likelihood a hazard will become a mishap combined with the expected damage consequences from the mishap
· Through the system safety process hazards are identified, risk is determined and safety methods are applied to eliminate or reduce the risk
· The cost of performing system safety is generally less than the costs of not performing it (i.e., mishap costs)

System Laws (that spawn hazards):
· All things mechanical will eventually fail
· Humans will eventually error; human error is a consequence of natural human fallibility (not necessarily negligence)
· Poor product designs and procedures can lead humans to commit errors
· All functions and processes have the capability for unintended consequences
· Humans will always eventually error, but mishaps can be prevented.


· Safety
· Hazard
· Mishap

The basic interrelated goals of system safety are to:
· Proactively prevent product/system accidents and mishaps
· Protect the system and its users, the public and the environment from mishaps
· Identify and eliminate/control hazards
· Design and develop a system presenting minimal mishap risk
· Create a safe system by intentionally designing safety into the overall system fabric

There are several “system laws” that essentially state that systems have a natural proclivity to fail.  These laws create hazard existence factors which explain the various reasons why hazards exist within systems.  The system laws illuminating why hazards exist include:
· Systems must include and utilize components that are naturally hazardous
· Physical items will always eventually fail
· Humans do commit performance errors and always will
· System components are often combined together with sneak paths and integration flaws
· Systems are often designed with unintended functions that are not recognized
· Environmental factors can influence safe functioning of components
· Software is typically too complex to completely test for safety validation