Air Force System Safety Handbook - System Safety Society

1.1 Definitions: System Safety and
Safety System.
To employ the concepts of system safety, it is necessary to
understand what system safety is and what system safety
strives to do.
The ultimate objective of any organization within the Air Force
is maximizing combat capability. One element in this
maximizing process is protecting and conserving combat
weapon systems and their support equipment. Preventing
mishaps and reducing system losses is one important aspect
of conserving these resources. System safety contributes to
mishap prevention by minimizing system risks due to hazards
consistent with other cost, schedule, and design requirements.
The fundamental objective of system safety is to identify,
eliminate or control, and document system hazards. This
hierarchy of goals, illustrated in Figure 1-1, is the crucial
framework for defining system safety. (41:15)
Figure 1-1
MAX
COMBAT
CAPABILITY
CONSERVE COMBAT
RESOURCES
PREVENT/MITIGATE MISHAP LOSSES
EVALUATE AND MINIMIZE SYSTEM RISKS
IDENTIFY, CONTROL, AND DOCUMENT SYSTEM HAZARDS
System Safety Goals
System Safety. The application of engineering and management
principles, criteria, and techniques to optimize all aspects
of safety within the constraints of operational effectiveness,
time, and cost throughout all phases of the system life cycle.
System. A composite, at any level of complexity, of personnel,
procedures, materials, tools, equipment, facilities, and
software. The elements of this composite entity are used
together in the intended operational or support environment to
perform a given task or achieve a specific production, support,
or mission requirement.
Safety. Freedom from those conditions that can cause death,
injury, occupational illness, or damage to or loss of equipment
or property, or damage to the environment. (30:3)
CHAPTER 1
INTRODUCTION TO SYSTEM SAFETY
1
Some clarifications are needed with these definitions. Absolute
safety is not possible because complete freedom from all
hazardous conditions is not possible. Therefore, safety is a
relative term that implies a level of risk that is both perceived
and accepted. You will also note that “system” is also a relative
term. A subsystem is a system itself with predetermined
boundaries. System safety is not an absolute quantity either.
System safety is an optimized level of risk that is constrained
by cost, time, and operational effectiveness (performance).
System safety requires that risk be evaluated and the level of
risk accepted or rejected by an authority. This is the basic
origin of system safety’s requirement for both engineering and
management functions. Finally, system safety is a discipline
employed from the initial design steps through system
demilitarization or disposal (a.k.a. “cradle to grave or “womb to
tomb”).
1.2 System Safety Objectives.
A safe system is achieved through the implementation and
careful execution of a system safety program. As stated previously,
the ultimate objective of system safety is MAXIMIZED
COMBAT CAPABILITY. The objectives of a system safety
program are to ensure: (30:2)
a. Safety, consistent with mission requirements is
designed into the system in a timely, cost-effective
manner.
b. Hazards are identified, evaluated, and eliminated, or
the associated risk reduced to a level acceptable to
the managing activity (MA) throughout the entire life
cycle of a system.
c. Historical safety data, including lessons learned
from other systems, are considered and used.
d. Minimum risk is sought in accepting and using new
designs, materials, and production and test
techniques.
e. Actions taken to eliminate hazards or reduce risk to
a level acceptable to the MA are documented.
f. Retrofit actions are minimized.
g. Changes in design, configuration, or mission
requirements are accomplished in a manner that
maintains a risk level acceptable to the MA.
h. Consideration is given to safety, ease of disposal,
and demilitarization of any hazardous materials
associated with the system.
i. Significant safety data are documented as “lessons
learned” and are submitted to data banks, design
handbooks, or specifications.
j. Hazards identified after production are minimized
consistent with program restraints.