System Safety Concepts
Dave Balderston
Office of System Safety
March 26, 2003
Outline
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Introduction
References
System Concepts
Safety Risk Management Concepts
Implementation Issues
2
References
• FAA Order 8040.4, “Safety Risk
Management”
• Draft System Safety Handbook especially
Chapter 15, Operational Risk
Management
located at www.asy.faa.gov (Safety Risk
Management)
3
Introduction
• System safety approach provides a
comprehensive and disciplined, but flexible
methodology for identifying and addressing
safety concerns
• Use system perspective to understand complete
situation
• Address safety concerns using system concepts
• Simple, common sense approach—do it all the
time; a formalized approach can help do it
better.
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Basic Questions
• What is going on?
– Design analysis or system monitoring
• What should we worry about?
– Hazard identification
• How much should we worry?
– Risk assessment
• What should we do?
– Risk management
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Definition of System
• Composite of people, procedures, materials,
tools, equipment, facilities, and software
• Operating in a specific environment
• To perform a specific task or achieve a specific
purpose, support or mission requirement
– Such as the provision of crash/fire rescue
services
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Major Components of System
for Landing Aircraft
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Airport Infrastructure
Air Traffic Control Functions
Aircraft and Crew
Environmental Factors
How do these system components need to
interact to assure that aircraft land
safely?
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Safety Management Concepts
• Safety Goal: Avoid safety losses (death or
injury)
• Strategy: Manage safety risk (likelihood
and severity of potential losses)
• Implementation: Identify and control
hazards (conditions that lead to increased
safety risk)
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Safety Risk Management
Strategy
• Design Analysis/System Monitoring
– What is going on?
• Hazard Identification
– What should we worry about?
• Risk Assessment
– How much should we worry?
• Risk Management
– What should we do about it?
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Safety Assurance Steps
• Designing in safety assurance
(must be done in system development)
• Maintaining and strengthening safety
assurance
(Infrastructure support—procedures, training,
maintenance, etc.)
• “Real Time” safety assurance
(Operations)
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Safety Order of Precedence
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Reduce risk through design (strongest)
Incorporate safety devices
Provide warning devices
Develop procedures and training
(weakest—the “human factors” issue)
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Implementation Issues
• Understand the problem in system terms
– Appropriate definition of system
– Effective system monitoring (inadequate system
monitoring can be a hazard)
– Involvement of all key stakeholders
• Disciplined risk management process, even if
expert judgment is the best available evidence
– Hazard identification and prioritization
– Risk assessment
– Risk management
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Example: Land and Hold
Short Operations Risk
Assessment
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Joint FAA/Industry Team
Identified hazards, assessed risks
Used expert judgment
Report located at www.asy.faa.gov under
Safety Risk Management heading
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Conclusion
• System Perspective
• Safety Risk Management Process
• Implementation Issues
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