2. SYSTEM SAFETY
Definitions:
System Safety: The application of engineering and
management principles, criteria, and techniques to optimize all
aspects of safety within the constraints or operational
effectiveness, time, and cost throughout all phases of the
system life cycle.
Fail Safe: A design feature that ensures that the system
remains safe or in the event of a failure will cause the system
to revert to a state which will not cause a mishap.
Hazard Probability: The aggregate probability of occurrence
of the individual events that create a specific hazard.
Hazard Severity: An assessment of the consequences of the
worst credible mishap that could be caused by a specific
hazard.
3. Management: the act, manner, or practice of managing,
supervising, or controlling.
Hazard: existing or potential condition that can result in or
contribute to a mishap.
Fault: a weakness or defect; mistake or error
Failure: inability of a system, subsystem, component, or part to
perform its required function within specified limits.
Emergency: unintended circumstance bearing clear and present
danger to personnel or property which required immediate
response.
System: a group of interrelated, interacting, or interdependent
constituents forming a complex whole; a functionally related group
of elements.
Risk: as applies to safety is the exposure to the chance of injury or
loss.
SYSTEM SAFETY
4. SYSTEM SAFETY
System Safety made a significant contribution to the improvement
of all types of aviation safety through engineering design processes
and operational safety processes.
Differences between basic system safety steps (methodology) and
that of Operational Risk Management steps are only in the degree of
generality. See below:
System Safety Process:
Define Objectives
System Description
Hazard Identification
Hazard Analysis
Risk Evaluation
Hazard Controls
5. LIFE CYCLE SAFETY
The portions of the life cycle of an air transport
category aircraft that we will be concerned with
are:
Concept and Definition phases
Detailed design, fabrication and development
Deployment and Operations
Modifications
6. Failure Modes and Effects Analyses:
FMEA/FMECA is performed on system components.
There are several things that such analyses provide:
Failure modes for the part / component.
History of those failure modes expressed in failure rates λ,
usually a function of time, failure mode frequencies, and
severity of the failure or what impact does it have on the
functioning of the item.
Cause of the failure
Affect upon the next higher level of the system or
subsystem.
Criticality which is simply the product of the failure rate,
failure mode frequency, and the severity expressed as a
fraction.
7. THE SYSTEM SAFETY HIERARCHY
System Safety Program:
•System Safety Program Plan
•System Safety Tasks
•System Safety Engineering
•Hazard Analyses
•Design Requirements
•Hazard Risk Assessments
•Probability (Reliability Analyses)
•Severity (Quantitative Analyses)
•Risk indices
•Safety Reporting
•Contract Documents
•Safety Recommendations
(continued)
8. THE SYSTEM SAFETY HIERARCHY
•System Safety Applications
•Preliminary Analyses
•Design Changes
•Operational Analyses
•Life Cycle Support
•Verification of Controls
•Risk Acceptance
•Documentation
•Reviews
9. OVERVIEW OF ORM
Operational Risk Management Processes
•Identify potential hazards
•Access the risks
•Analyze risk control measures
•Make control decisions
•Implement risk controls
•Supervise and review
OPERATIONAL RISK
MANAGEMENT
10. OPERATIONAL RISK
MANAGEMENT
Rules for making risk decisions:
Accept no unnecessary risk
Make risk decisions at the appropriate level
Benefits of taking risk must outweigh the costs
Integrate ORM into task planning and execution
11. OPERATIONAL RISK
MANAGEMENTMore Risk Definitions:
Identified Risk: Risk that has been determined through
various tools.
Acceptable Risk: Identified risk that is allowed to persist
without further controls.
Unacceptable Risk: The risk than cannot be tolerated.
Unidentified Risk: Risk that has not been determined.
Residual Risk: Sum of acceptable and unidentified risk.
18. FUTURE TRENDS OF AVIATION
SAFETY
1.Swing more towards automation in operations,
maintenance, etc.
• How do you determine the risk of upgrades to
computers and the communication systems?
• Where doe the pilot fit into the loop?
• Where does the safety manager fit into the loop?
19.
20. 2. ORM begins to spend more time on reducing
pilot error which drives more simulation and
automation.
3.System Safety has become passé’ and is being
superseded by Software Safety Analyses.
4. Human Factors have reached the point where
only major design changes in aircraft will
accommodate the safest man-machine interface
and that leads back to automation changes.
FUTURE TRENDS OF AVIATION
SAFETY
21. 5.Life Cycle of the aircraft get extended; esp. in
times of tight economics.
6. Systems approaches to all safety are the
trend.
FUTURE TRENDS OF AVIATION
SAFETY
NASA Dryden Research Aircraft Photo Collection
NASA Dryden X-43A Photo Collection
NASA Dryden X-43A Photo Collection
22. 5.Life Cycle of the aircraft get extended; esp.
in times of tight economics.
6. Systems approaches to all safety are the
trend.
FUTURE TRENDS OF AVIATION
SAFETY
NASA Dryden Research Aircraft Photo Collection
NASA Dryden X-43A Photo Collection
Eclipse EM-0008-04: Eclipse QF-106 tethered flight
#4
23. Eclipse EC97-44357-13: Eclipse project QF-106
and C-141A climbs out under tow on first tethered
flight December 20, 1997
NASA Dryden Research Aircraft Photo Collection
